aboutsummaryrefslogblamecommitdiffstats
path: root/erts/emulator/beam/dist.c
blob: 5566055de029fc8664df7fdf0893bcc4739c5efd (plain) (tree)
1
2
3
4
5
6
7
8
9
3380
3381
3382
3383
3384
3385
3386
3387
3388
3389
3390
3391
3392
3393
3394
3395
3396
3397
3398
3399
3400
3401
3402
3403
3404
3405
3406
3407
3408
3409
3410
3411
3412
3413
3414
3415
3416
3417
3418
3419
3420
3421
3422
3423
3424
3425
3426
3427
3428
3429
3430
3431
3432
3433
3434
3435
3436
3437
3438
3439
3440
3441
3442
3443
3444
3445
3446
3447
3448
3449
3450
3451
3452
3453
3454
3455
3456
3457
3458
3459
3460
3461
3462
3463
3464
3465
3466
3467
3468
3469
3470
3471
3472
3473
3474
3475
3476
3477
3478
3479
3480
3481
3482
3483
3484
3485
3486
3487
3488
3489
3490
3491
3492
3493
3494
3495
3496
3497
3498
3499
3500
3501
3502
3503
3504
3505
3506
3507
3508
3509
3510
3511
3512
3513
3514
3515
3516
3517
3518
3519
3520
3521
3522
3523
3524
3525
3526
3527
3528
3529
3530
3531
3532
3533
3534
3535
3536
3537
3538
3539
3540
3541
3542
3543
3544
3545
3546
3547
3548
3549
3550
3551
3552
3553
3554
3555
3556
3557
3558
3559
3560
3561
3562
3563
3564
3565
3566
3567
3568
3569
3570
3571
3572
3573
3574
3575
3576
3577
3578
3579
3580
3581
3582
3583
3584
3585
3586
3587
3588
3589
3590
3591
3592
3593
3594
3595
3596
3597
3598
3599
3600
3601
3602
3603
3604
3605
3606
3607
3608
3609
3610
3611
3612
3613
3614
3615
3616
3617
3618
3619
3620
3621
3622
3623
3624
3625
3626
3627
3628
3629
3630
3631
3632
3633
3634
3635
3636
3637
3638
3639
3640
3641
3642
3643
3644
3645
3646
3647
3648
3649
3650
3651
3652
3653
3654
3655
3656
3657
3658
3659
3660
3661
3662
3663
3664
3665
3666
3667
3668
3669
3670
3671
3672
3673
3674
3675
3676
3677
3678
3679
3680
3681
3682
3683
3684
3685
3686
3687

                   
  
                                                        
  


                                                                   
  






                                                                           
  


























                                                  
                             
                           
 

                                










                                                                
                                         
 
                                                






                                                                   


                                                            

                            

                                                          






                                                                               
                                                         

                                                                          



















                                                                              

                             

















                                         
                                                                        



                                                                       






                                  





                                                     

                                                         











                                  
                                                                   



                                                                         
                                        







                                                                    
                                                                            




                                                       
                                                               





                                                    



                                                 























































                                                                         
               


















                                                                 
                                                                   




                                                                        
                                    
                      
                            
                                        
                                                                   













                                                                            
                              
































                                                                               
                                                                












                                                                 
                                                                          




















                                                                      
                                  














                                                                                    
                                   

                                                     


                                        
                      
                                         

















                                                                        





                                           








































                                                                                  








                                                                              

                             


                                                       
                                                     
 




                                                                       
                                       
                              
                                                           



                               
 

                                                                   
                








                                                                             
             
                                                           
 




                                                                             
                                                          
                                                      
 

                                                                   
             
 

                                                     
         
 
















                                                                  
     
                                            





                                    
                                                            


                                                     
                                                                                      

                                                        
                                                 


                                                 
                                           
                                                   
                                             



                                                
                                           

                                                      
                                             






























                                                                                 


                   












                                                   



                                           
                                            





















                                                                       
                                  










































                                                                  
                                   














                                                                   
                                     
                                                         















                                      
                                       

                                       
                                         


     




                                                        
                                                    





















                                                                           
                                         


                                                        
                                                     







                                                                       
















                                                                           
                                     
                                                                          

                        
 
                                      

                          




                                                                    
                                     
                                                                            
            
 
                        
                                      

                          










                                                                          



                                     









                                                              
                                      

                          









                                                                               

                                     
 
                        



                                           
                                      

                          










                                                                             

                                     
 
                        



                                             
                                          

                          


   
                                                                     

              
                      
                                    
            




                         


                                      
      
 
                                                 



                                                                         
                    

                                                                              
                                                                        
                                                   



                                                                                
                                     
                                   




                                                                 
      

                     
                                       
                                                                       
        
                                                                                



                                                                       



                                               
               


   

                                                        

              
                      
                                    
            




                         


                                       
      
 
                                                 



                                                                              
                    

                                                                              
                                                                        
                                                   


                                                                                

                                                         
                                   




                                                                 
      

                     
                                                                    
                                                                      
        
                                                                 
                                                               



                                                                       



                                               
               







                                                                      

                                     
                    
                                 


                         



                                     
      
 
                        
                               






                                                                                
                    

                                                     




                                                                            
                                                    

                                                                          
                                   




                                                                 
      

                                                                         
                                 
                                      

                          




                                                                                






                                                              
                                 
                                       

                          




                                                                                 


                                     
 


                                                               
 
                                      

                          





                                                                           


                                     
 


                                                               
 
                                      

                          








                                                             



                                           









                                                                              













                                                
 


                                    
                                      
                               
                                     



                         






                           
                                                            
                             
                            





                     
                     

                        
                               

      
                                            




                                                    

                                                  
                 
     
                  
                        

                                                  
                 
     





















                                                               
                                                        















                                                                                         

                                          



                                                                        
                                                                        
                                               

                            
                                                                                    


                                 
                          







                                                                             
                                                                         
                                 
                             





                                            


                                 



                                                     
                                 

















                                                                           
                                                               






                                                             
                                                                               



                                                              
                                                             





                                                      


                                 

                        


                                                 






                                                           
                                                        

                                                             
                                                               














                                                                 



                                 




                                                        



                                 
























                                                                           
                                        

                                                                               
                                                                                   











                                                                           


                                 



                                                                        



                                 














                                                                            
                                                             







                                                      
                         



                                 









                                                                            



                                                          





                                                 


                                                 
                                                     














                                                             
                                                                       





                                                                 
                                                                      

                                                



                     



                                 









                                                                            


                                                      
                      


                                 
                                  












                                                                                
                                                                       





                                                                 
                                                                          

                                                







                                                                              
                                    


                                                                              



                                 




                                                               



                                 













                                                               

                                  



                         
                                                             




                                               
                            








                                                                     
                              








                                                                               







                                     
                






                                     
         

                                                          





                                                  
                                                            






















                                                                              




                                                                            














                                                           






                                     
                









                                                          
         
                                                  









                                                   



                          


                                 

                                              


                                                 







                                                             

                             

     
                                 


                                                      
                                              

                               





                                                                           
             
                             
                                 


                                                      
           
                                              
                                                           



                               
                                                                       
 


















                                                                             
              
 




                                          
 

                                              
 


                                                                             
 

                                         
 







                                                              
 

                                                                                                 

                                                            






                                                                                        
                                               






                                                           
 




                                                                                
 




















                                                                                                    
             





                                                                                                                      
             
 











                                                                                    
              

                                                                           
               























                                                                                 
 






























                                                                                              
 








































                                                                                              
                                                                                          
         

     


                                                                                     
     
                  

 









                                                     
                                 
                                                                  
                                          

                       
                    



                                       


                                                                          



                                                              
      





















                                                       
                                 
                                                                  
                                          
















                                                                
                    



                                       


                                                                          



                                                               
      








                                                                
                    
                                                 
                      

















                                                              

                  



                                                     
                              
                                                        


                                                    
                                                                      

                                                                     
                                                        







                                        
                                                                     













                                                     
                                   



                                    
                                     





                                               
                                                                
 


                          
                                                               





                                           
                                          








                                                       

                                                                             
                                                     
                      






                                        
                                               








                                                                         

                                                                           










































                                                                            

                                                                  






                                                                             
                                          








                                                       

                                                                             
                                                                               
                                   






















                                                                     
                                       


                                       
                                                   

                                                       


                                                                     
                                             


                                                            

            
                                             







                                  
                                       

                                       
                                         




















                                                   



                                              



                                 
                                          






















                                                           
                                       
                                       
                                         







                                                         
                                           





                                                 
                                             









                                              
                    



                                             


                                                                          



                                                           
      












                                                               
                                       

                                                  
                                         






                                              
               




                                                                  
                                                      


                                                      
                                    
                                                                                     
















                                                                          
                                                                       


















                                                                       
                                                                  




                                                                               
                                                                 














                                                                    
                                                                



                                                                              
                                                                                    






                                                                  
                                                                                  


























                                                                              
                                                                       



















                                                                        
                                                                             























                                                                       


                                                



























































                                                                               

                                           
                                                          





                                                  







                                                                             

                                                                      





                                                              
                                                 
                                                                    
                                                   


                                                     
                                  
                   


                                                                     
                                    































































                                                                           
                                                      

                                                                            


















                                                                           



                                                            

                            
                                                  
                                          












                                                                  
                                       
                                                       
                                         







                                                  
                                                                        
 





                                                                             
                                                                           
     

















                                                        
                                   
                            
                                     









                                                                        

                   












                                                                         
                              










































                                                                        
                                        





                                                                 

                                                          

















                                               
                          
                                                                             


                                                                              






                                                                         




















































                                                                        
                                                        




                               


                        









                                                                            
                                                                            



                                         


                               


               
                                                 
 
                                                      


                                                 
                                                            









                                                
                                                       
                  








                                                                        



                                                    















                                                                  
                                                   


                          
                    



                            













                                                                        

                                                               




                   
                                                                     


                                                                       
                                 


                   
                             

     

                                                    
                                               

                                                 
     
                                                     

               
                                                              



                                    
                                               

                                        
                                                     





                                 
                          

                                                                     
                                                    
                              
                                                                         


                              
                                                              


                                                                       
                                                                  

             
                                                      

                                               
                                                                    
                                                          




                                  
                                                 





                               





                                                                  



                                       
                                                            








































































































                                                                           

                    
                    
            





                                                               












































                                                                
                                                           











                                                                                   
                    





                                       



                                                                                         


                                                          
      




























                                                                      
                                                                    



















































































































































































































































































































                                                                               
                                                                             










                                                                           
                                                                    




















                                                      
/*
 * %CopyrightBegin%
 *
 * Copyright Ericsson AB 1996-2017. All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 * %CopyrightEnd%
 */

/*
 * distribution of erlang messages to other nodes.
 */


/* define this to get a lot of debug output */
/* #define ERTS_DIST_MSG_DBG */

#ifdef HAVE_CONFIG_H
#  include "config.h"
#endif

#define ERTS_WANT_EXTERNAL_TAGS

#include <stddef.h>
#include "sys.h"
#include "erl_vm.h"
#include "global.h"
#include "erl_process.h"
#include "error.h"
#include "dist.h"
#include "bif.h"
#include "external.h"
#include "erl_binary.h"
#include "erl_thr_progress.h"
#include "dtrace-wrapper.h"

#define DIST_CTL_DEFAULT_SIZE 64

/* Turn this on to get printouts of all distribution messages
 * which go on the line
 */
#if 0
#define ERTS_DIST_MSG_DBG
#endif
#if 0
#define ERTS_RAW_DIST_MSG_DBG
#endif

#if defined(ERTS_DIST_MSG_DBG) || defined(ERTS_RAW_DIST_MSG_DBG)
static void bw(byte *buf, ErlDrvSizeT sz)
{
    bin_write(ERTS_PRINT_STDERR, NULL, buf, sz);
}
#endif

#ifdef ERTS_DIST_MSG_DBG
static void
dist_msg_dbg(ErtsDistExternal *edep, char *what, byte *buf, int sz)
{
    ErtsHeapFactory factory;
    DeclareTmpHeapNoproc(ctl_default,DIST_CTL_DEFAULT_SIZE);
    Eterm* ctl = ctl_default;
    byte *extp = edep->extp;
    Eterm msg;
    Sint ctl_len;
    Sint size = ctl_len = erts_decode_dist_ext_size(edep);
    if (size < 0) {
	erts_fprintf(stderr,
		     "DIST MSG DEBUG: erts_decode_dist_ext_size(%s) failed:\n",
		     what);
	bw(buf, sz);
    }
    else {
	ErlHeapFragment *mbuf = new_message_buffer(size);
	erts_factory_static_init(&factory, ctl, ctl_len, &mbuf->off_heap);
	msg = erts_decode_dist_ext(&factory, edep);
	if (is_value(msg))
	    erts_fprintf(stderr, "    %s: %T\n", what, msg);
	else {
	    erts_fprintf(stderr,
			 "DIST MSG DEBUG: erts_decode_dist_ext(%s) failed:\n",
			 what);
	    bw(buf, sz);
	}
	free_message_buffer(mbuf);
	edep->extp = extp;
    }
}

#endif



#define PASS_THROUGH 'p'        /* This code should go */

int erts_is_alive; /* System must be blocked on change */
int erts_dist_buf_busy_limit;


/* distribution trap functions */
Export* dsend2_trap = NULL;
Export* dsend3_trap = NULL;
/*Export* dsend_nosuspend_trap = NULL;*/
Export* dlink_trap = NULL;
Export* dunlink_trap = NULL;
Export* dmonitor_node_trap = NULL;
Export* dgroup_leader_trap = NULL;
Export* dexit_trap = NULL;
Export* dmonitor_p_trap = NULL;

/* local variables */


/* forward declarations */

static void clear_dist_entry(DistEntry*);
static int dsig_send_ctl(ErtsDSigData* dsdp, Eterm ctl, int force_busy);
static void send_nodes_mon_msgs(Process *, Eterm, Eterm, Eterm, Eterm);
static void init_nodes_monitors(void);

static erts_smp_atomic_t no_caches;
static erts_smp_atomic_t no_nodes;

struct {
    Eterm reason;
    ErlHeapFragment *bp;
} nodedown;


static void
delete_cache(ErtsAtomCache *cache)
{
    if (cache) {
	erts_free(ERTS_ALC_T_DCACHE, (void *) cache);
	ASSERT(erts_smp_atomic_read_nob(&no_caches) > 0);
	erts_smp_atomic_dec_nob(&no_caches);
    }
}


static void
create_cache(DistEntry *dep)
{
    int i;
    ErtsAtomCache *cp;

    ERTS_SMP_LC_ASSERT(
	is_internal_port(dep->cid)
	&& erts_lc_is_port_locked(erts_port_lookup_raw(dep->cid)));
    ASSERT(!dep->cache);

    dep->cache = cp = (ErtsAtomCache*) erts_alloc(ERTS_ALC_T_DCACHE,
						  sizeof(ErtsAtomCache));
    erts_smp_atomic_inc_nob(&no_caches);
    for (i = 0; i < sizeof(cp->in_arr)/sizeof(cp->in_arr[0]); i++) {
	cp->in_arr[i] = THE_NON_VALUE;
	cp->out_arr[i] = THE_NON_VALUE;
    }
}

Uint erts_dist_cache_size(void)
{
    return (Uint) erts_smp_atomic_read_mb(&no_caches)*sizeof(ErtsAtomCache);
}

static ErtsProcList *
get_suspended_on_de(DistEntry *dep, Uint32 unset_qflgs)
{
    ERTS_SMP_LC_ASSERT(erts_smp_lc_mtx_is_locked(&dep->qlock));
    dep->qflgs &= ~unset_qflgs;
    if (dep->qflgs & ERTS_DE_QFLG_EXIT) {
	/* No resume when exit has been scheduled */
	return NULL;
    }
    else {
	ErtsProcList *suspended = dep->suspended;
	dep->suspended = NULL;
	erts_proclist_fetch(&suspended, NULL);
	return suspended;
    }
}

/*
** A full node name constists of a "n@h"
**
** n must be a valid node name: string of ([a-z][A-Z][0-9]_-)+
** 
** h is not checked at all, we assume that we have a properly
** configured machine where the networking is ok for the OS
**
** We do check that there is not a second @ in the string, since
** many distributed operations are guaranteed not to work then.
*/


static int is_node_name(char *ptr, int len)
{
   int c = '\0';		/* suppress use-before-set warning */
   int pos = 0;

   while (pos < len) {
      c = ptr[pos++];
      if (! ((c == '-') || (c == '_') ||
	     ((c >= 'a') && (c <= 'z')) ||
	     ((c >= 'A') && (c <= 'Z')) ||
	     ((c >= '0') && (c <= '9'))))
	 break;
   }

   /* Scanned past the host name: now we want to see a '@', and there
      should be text both before and after it. */
   if (c != '@' || pos < 2 || pos == len)
      return 0;

   while (pos < len) {
      c = ptr[pos++];
      if (c == '@')
	 return 0;
   }

   return 1;
}

int is_node_name_atom(Eterm a)
{
    int i;
    if(is_not_atom(a))
	return 0;
    i = atom_val(a);
    ASSERT((i > 0) && (i < atom_table_size()) &&  (atom_tab(i) != NULL));
    return is_node_name((char*)atom_tab(i)->name, atom_tab(i)->len);
}

typedef struct {
    DistEntry *dep;
    Eterm *lhp;
} NetExitsContext;

/* 
** This function is called when a distribution 
** port or process terminates
*/
static void doit_monitor_net_exits(ErtsMonitor *mon, void *vnecp)
{
    Process *rp;
    ErtsMonitor *rmon;
    DistEntry *dep = ((NetExitsContext *) vnecp)->dep;
    ErtsProcLocks rp_locks = ERTS_PROC_LOCK_LINK;

    rp = erts_pid2proc(NULL, 0, mon->pid, rp_locks);
    if (!rp)
	goto done;

    if (mon->type == MON_ORIGIN) {
	/* local pid is beeing monitored */
	rmon = erts_remove_monitor(&ERTS_P_MONITORS(rp), mon->ref);
	/* ASSERT(rmon != NULL); nope, can happen during process exit */
	if (rmon != NULL) {
	    erts_destroy_monitor(rmon);
	}
    } else {
	DeclareTmpHeapNoproc(lhp,3);
	Eterm watched;
	UseTmpHeapNoproc(3);
	ASSERT(mon->type == MON_TARGET);
	rmon = erts_remove_monitor(&ERTS_P_MONITORS(rp), mon->ref);
	/* ASSERT(rmon != NULL); can happen during process exit */
	if (rmon != NULL) {
	    ASSERT(is_atom(rmon->name) || is_nil(rmon->name));
	    watched = (is_atom(rmon->name)
		       ? TUPLE2(lhp, rmon->name, dep->sysname)
		       : rmon->pid);
#ifdef ERTS_SMP
	    rp_locks |= ERTS_PROC_LOCKS_MSG_SEND;
	    erts_smp_proc_lock(rp, ERTS_PROC_LOCKS_MSG_SEND);
#endif
	    erts_queue_monitor_message(rp, &rp_locks, mon->ref, am_process, 
				       watched, am_noconnection);
	    erts_destroy_monitor(rmon);
	}
	UnUseTmpHeapNoproc(3);
    }
    erts_smp_proc_unlock(rp, rp_locks);
 done:
    erts_destroy_monitor(mon);
}
	
typedef struct {
    NetExitsContext *necp;
    ErtsLink *lnk;
} LinkNetExitsContext;

/* 
** This is the function actually doing the job of sending exit messages
** for links in a dist entry upon net_exit (the node goes down), NB,
** only process links, not node monitors are handled here, 
** they reside in a separate tree....
*/
static void doit_link_net_exits_sub(ErtsLink *sublnk, void *vlnecp)
{
    ErtsLink *lnk = ((LinkNetExitsContext *) vlnecp)->lnk; /* the local pid */
    ErtsLink *rlnk;
    Process *rp;

    ASSERT(lnk->type == LINK_PID);
    if (is_internal_pid(lnk->pid)) {
	int xres;
	ErtsProcLocks rp_locks = ERTS_PROC_LOCK_LINK|ERTS_PROC_LOCKS_XSIG_SEND;

	rp = erts_pid2proc(NULL, 0, lnk->pid, rp_locks);
	if (!rp) {
	    goto done;
	}

	rlnk = erts_remove_link(&ERTS_P_LINKS(rp), sublnk->pid);
	xres = erts_send_exit_signal(NULL,
				     sublnk->pid,
				     rp,
				     &rp_locks,
				     am_noconnection,
				     NIL,
				     NULL,
				     0);

	if (rlnk) {
	    erts_destroy_link(rlnk);
	    if (xres >= 0 && IS_TRACED_FL(rp, F_TRACE_PROCS)) {
		/* We didn't exit the process and it is traced */
		trace_proc(NULL, 0, rp, am_getting_unlinked, sublnk->pid);
	    }
	}
	erts_smp_proc_unlock(rp, rp_locks);
    }
 done:
    erts_destroy_link(sublnk);

}
    




/* 
** This function is called when a distribution 
** port or process terminates, once for each link on the high level, 
** it in turn traverses the link subtree for the specific link node...
*/
static void doit_link_net_exits(ErtsLink *lnk, void *vnecp)
{
    LinkNetExitsContext lnec = {(NetExitsContext *) vnecp, lnk};
    ASSERT(lnk->type == LINK_PID);
    erts_sweep_links(ERTS_LINK_ROOT(lnk), &doit_link_net_exits_sub, (void *) &lnec);
#ifdef DEBUG
    ERTS_LINK_ROOT(lnk) = NULL;
#endif
    erts_destroy_link(lnk);
}


static void doit_node_link_net_exits(ErtsLink *lnk, void *vnecp)
{
    DistEntry *dep = ((NetExitsContext *) vnecp)->dep;
    Eterm name = dep->sysname;
    Process *rp;
    ErtsLink *rlnk;
    Uint i,n;
    ASSERT(lnk->type == LINK_NODE);
    if (is_internal_pid(lnk->pid)) {
	ErtsProcLocks rp_locks = ERTS_PROC_LOCK_LINK;
	ErlOffHeap *ohp;
	rp = erts_proc_lookup(lnk->pid);
	if (!rp)
	    goto done;
	erts_smp_proc_lock(rp, rp_locks);
        if (!ERTS_PROC_IS_EXITING(rp)) {
            rlnk = erts_remove_link(&ERTS_P_LINKS(rp), name);
            if (rlnk != NULL) {
                ASSERT(is_atom(rlnk->pid) && (rlnk->type == LINK_NODE));
                erts_destroy_link(rlnk);
            }
            n = ERTS_LINK_REFC(lnk);
            for (i = 0; i < n; ++i) {
                Eterm tup;
                Eterm *hp;
                ErtsMessage *msgp;

                msgp = erts_alloc_message_heap(rp, &rp_locks,
                                               3, &hp, &ohp);
                tup = TUPLE2(hp, am_nodedown, name);
                erts_queue_message(rp, rp_locks, msgp, tup, am_system);
            }
        }
	erts_smp_proc_unlock(rp, rp_locks);
    }
 done:
    erts_destroy_link(lnk);
}

static void
set_node_not_alive(void *unused)
{
    ErlHeapFragment *bp;
    Eterm nodename = erts_this_dist_entry->sysname;

    ASSERT(erts_smp_atomic_read_nob(&no_nodes) == 0);

    erts_smp_thr_progress_block();
    erts_set_this_node(am_Noname, 0);
    erts_is_alive = 0;
    send_nodes_mon_msgs(NULL, am_nodedown, nodename, am_visible, nodedown.reason);
    nodedown.reason = NIL;
    bp = nodedown.bp;
    nodedown.bp = NULL;
    erts_smp_thr_progress_unblock();
    if (bp)
	free_message_buffer(bp);
}

static ERTS_INLINE void
dec_no_nodes(void)
{
    erts_aint_t no = erts_smp_atomic_dec_read_mb(&no_nodes);
    ASSERT(no >= 0);
    ASSERT(erts_get_scheduler_id()); /* Need to be a scheduler */
    if (no == 0)
	erts_schedule_misc_aux_work(erts_get_scheduler_id(),
				    set_node_not_alive,
				    NULL);
}

static ERTS_INLINE void
inc_no_nodes(void)
{
#ifdef DEBUG
    erts_aint_t no = erts_smp_atomic_read_nob(&no_nodes);
    ASSERT(erts_is_alive ? no > 0 : no == 0);
#endif
    erts_smp_atomic_inc_mb(&no_nodes);
}
	
/*
 * proc is currently running or exiting process.
 */
int erts_do_net_exits(DistEntry *dep, Eterm reason)
{
    Eterm nodename;

    if (dep == erts_this_dist_entry) {  /* Net kernel has died (clean up!!) */
	DistEntry *tdep;
	int no_dist_port = 0;
	Eterm nd_reason = (reason == am_no_network
			   ? am_no_network
			   : am_net_kernel_terminated);
	erts_smp_rwmtx_rlock(&erts_dist_table_rwmtx);

	for (tdep = erts_hidden_dist_entries; tdep; tdep = tdep->next)
	    no_dist_port++;
	for (tdep = erts_visible_dist_entries; tdep; tdep = tdep->next)
	    no_dist_port++;

	/* KILL all port controllers */
	if (no_dist_port == 0)
	    erts_smp_rwmtx_runlock(&erts_dist_table_rwmtx);
	else {
	    Eterm def_buf[128];
	    int i = 0;
	    Eterm *dist_port;

	    if (no_dist_port <= sizeof(def_buf)/sizeof(def_buf[0]))
		dist_port = &def_buf[0];
	    else
		dist_port = erts_alloc(ERTS_ALC_T_TMP,
				       sizeof(Eterm)*no_dist_port);
	    for (tdep = erts_hidden_dist_entries; tdep; tdep = tdep->next) {
		ASSERT(is_internal_port(tdep->cid));
		dist_port[i++] = tdep->cid;
	    }
	    for (tdep = erts_visible_dist_entries; tdep; tdep = tdep->next) {
		ASSERT(is_internal_port(tdep->cid));
		dist_port[i++] = tdep->cid;
	    }
	    erts_smp_rwmtx_runlock(&erts_dist_table_rwmtx);

	    for (i = 0; i < no_dist_port; i++) {
		Port *prt = erts_port_lookup(dist_port[i],
					     ERTS_PORT_SFLGS_INVALID_LOOKUP);
		if (!prt)
		    continue;
		ASSERT(erts_atomic32_read_nob(&prt->state)
		       & ERTS_PORT_SFLG_DISTRIBUTION);

		erts_port_exit(NULL, ERTS_PORT_SIG_FLG_FORCE_SCHED,
			       prt, dist_port[i], nd_reason, NULL);
	    }

	    if (dist_port != &def_buf[0])
		erts_free(ERTS_ALC_T_TMP, dist_port);
	}

	/*
	 * When last dist port exits, node will be taken
	 * from alive to not alive.
	 */
	ASSERT(is_nil(nodedown.reason) && !nodedown.bp);
	if (is_immed(nd_reason))
	    nodedown.reason = nd_reason;
	else {
	    Eterm *hp;
	    Uint sz = size_object(nd_reason);
	    nodedown.bp = new_message_buffer(sz);
	    hp = nodedown.bp->mem;
	    nodedown.reason = copy_struct(nd_reason,
					  sz,
					  &hp,
					  &nodedown.bp->off_heap);
	}
    }
    else { /* Call from distribution port */
	NetExitsContext nec = {dep};
	ErtsLink *nlinks;
	ErtsLink *node_links;
	ErtsMonitor *monitors;
	Uint32 flags;

	erts_smp_atomic_set_mb(&dep->dist_cmd_scheduled, 1);
	erts_smp_de_rwlock(dep);

	ERTS_SMP_LC_ASSERT(is_internal_port(dep->cid)
			   && erts_lc_is_port_locked(erts_port_lookup_raw(dep->cid)));

	if (erts_port_task_is_scheduled(&dep->dist_cmd))
	    erts_port_task_abort(&dep->dist_cmd);

	if (dep->status & ERTS_DE_SFLG_EXITING) {
#ifdef DEBUG
	    erts_smp_mtx_lock(&dep->qlock);
	    ASSERT(dep->qflgs & ERTS_DE_QFLG_EXIT);
	    erts_smp_mtx_unlock(&dep->qlock);
#endif
	}
	else {
	    dep->status |= ERTS_DE_SFLG_EXITING;
	    erts_smp_mtx_lock(&dep->qlock);
	    ASSERT(!(dep->qflgs & ERTS_DE_QFLG_EXIT));
	    dep->qflgs |= ERTS_DE_QFLG_EXIT;
	    erts_smp_mtx_unlock(&dep->qlock);
	}

	erts_smp_de_links_lock(dep);
	monitors	= dep->monitors;
        nlinks		= dep->nlinks;
	node_links	= dep->node_links;
	dep->monitors	= NULL;
        dep->nlinks	= NULL;
	dep->node_links	= NULL;
	erts_smp_de_links_unlock(dep);

	nodename = dep->sysname;
	flags = dep->flags;

	erts_set_dist_entry_not_connected(dep);

	erts_smp_de_rwunlock(dep);

	erts_sweep_monitors(monitors, &doit_monitor_net_exits, (void *) &nec);
	erts_sweep_links(nlinks, &doit_link_net_exits, (void *) &nec);
	erts_sweep_links(node_links, &doit_node_link_net_exits, (void *) &nec);

	send_nodes_mon_msgs(NULL,
			    am_nodedown,
			    nodename,
			    flags & DFLAG_PUBLISHED ? am_visible : am_hidden,
			    reason == am_normal ? am_connection_closed : reason);

	clear_dist_entry(dep);

    }

    dec_no_nodes();

    return 1;
}

static Export*
trap_function(Eterm func, int arity)
{
    return erts_export_put(am_erlang, func, arity);
}

void init_dist(void)
{
    init_nodes_monitors();

    nodedown.reason = NIL;
    nodedown.bp = NULL;

    erts_smp_atomic_init_nob(&no_nodes, 0);
    erts_smp_atomic_init_nob(&no_caches, 0);

    /* Lookup/Install all references to trap functions */
    dsend2_trap = trap_function(am_dsend,2);
    dsend3_trap = trap_function(am_dsend,3);
    /*    dsend_nosuspend_trap = trap_function(am_dsend_nosuspend,2);*/
    dlink_trap = trap_function(am_dlink,1);
    dunlink_trap = trap_function(am_dunlink,1);
    dmonitor_node_trap = trap_function(am_dmonitor_node,3);
    dgroup_leader_trap = trap_function(am_dgroup_leader,2);
    dexit_trap = trap_function(am_dexit, 2);
    dmonitor_p_trap = trap_function(am_dmonitor_p, 2);
}

#define ErtsDistOutputBuf2Binary(OB) \
  ((Binary *) (((char *) (OB)) - offsetof(Binary, orig_bytes)))

static ERTS_INLINE ErtsDistOutputBuf *
alloc_dist_obuf(Uint size)
{
    ErtsDistOutputBuf *obuf;
    Uint obuf_size = sizeof(ErtsDistOutputBuf)+sizeof(byte)*(size-1);
    Binary *bin = erts_bin_drv_alloc(obuf_size);
    erts_refc_init(&bin->refc, 1);
    obuf = (ErtsDistOutputBuf *) &bin->orig_bytes[0];
#ifdef DEBUG
    obuf->dbg_pattern = ERTS_DIST_OUTPUT_BUF_DBG_PATTERN;
    ASSERT(bin == ErtsDistOutputBuf2Binary(obuf));
#endif
    return obuf;
}

static ERTS_INLINE void
free_dist_obuf(ErtsDistOutputBuf *obuf)
{
    Binary *bin = ErtsDistOutputBuf2Binary(obuf);
    ASSERT(obuf->dbg_pattern == ERTS_DIST_OUTPUT_BUF_DBG_PATTERN);
    if (erts_refc_dectest(&bin->refc, 0) == 0)
	erts_bin_free(bin);
}

static ERTS_INLINE Sint
size_obuf(ErtsDistOutputBuf *obuf)
{
    Binary *bin = ErtsDistOutputBuf2Binary(obuf);
    return bin->orig_size;
}

static void clear_dist_entry(DistEntry *dep)
{
    Sint obufsize = 0;
    ErtsAtomCache *cache;
    ErtsProcList *suspendees;
    ErtsDistOutputBuf *obuf;

    erts_smp_de_rwlock(dep);
    cache = dep->cache;
    dep->cache = NULL;

#ifdef DEBUG
    erts_smp_de_links_lock(dep);
    ASSERT(!dep->nlinks);
    ASSERT(!dep->node_links);
    ASSERT(!dep->monitors);
    erts_smp_de_links_unlock(dep);
#endif

    erts_smp_mtx_lock(&dep->qlock);

    if (!dep->out_queue.last)
	obuf = dep->finalized_out_queue.first;
    else {
	dep->out_queue.last->next = dep->finalized_out_queue.first;
	obuf = dep->out_queue.first;
    }

    dep->out_queue.first = NULL;
    dep->out_queue.last = NULL;
    dep->finalized_out_queue.first = NULL;
    dep->finalized_out_queue.last = NULL;
    dep->status = 0;
    suspendees = get_suspended_on_de(dep, ERTS_DE_QFLGS_ALL);

    erts_smp_mtx_unlock(&dep->qlock);
    erts_smp_atomic_set_nob(&dep->dist_cmd_scheduled, 0);
    dep->send = NULL;
    erts_smp_de_rwunlock(dep);

    erts_resume_processes(suspendees);

    delete_cache(cache);

    while (obuf) {
	ErtsDistOutputBuf *fobuf;
	fobuf = obuf;
	obuf = obuf->next;
	obufsize += size_obuf(fobuf);
	free_dist_obuf(fobuf);
    }

    if (obufsize) {
	erts_smp_mtx_lock(&dep->qlock);
	ASSERT(dep->qsize >= obufsize);
	dep->qsize -= obufsize;
	erts_smp_mtx_unlock(&dep->qlock);
    }
}

void erts_dsend_context_dtor(Binary* ctx_bin)
{
    ErtsSendContext* ctx = ERTS_MAGIC_BIN_DATA(ctx_bin);
    switch (ctx->dss.phase) {
    case ERTS_DSIG_SEND_PHASE_MSG_SIZE:
	DESTROY_SAVED_WSTACK(&ctx->dss.u.sc.wstack);
	break;
    case ERTS_DSIG_SEND_PHASE_MSG_ENCODE:
	DESTROY_SAVED_WSTACK(&ctx->dss.u.ec.wstack);
	break;
    default:;
    }
    if (ctx->dss.phase >= ERTS_DSIG_SEND_PHASE_ALLOC && ctx->dss.obuf) {
	free_dist_obuf(ctx->dss.obuf);
    }
    if (ctx->dep_to_deref)
	erts_deref_dist_entry(ctx->dep_to_deref);
}

Eterm erts_dsend_export_trap_context(Process* p, ErtsSendContext* ctx)
{
    struct exported_ctx {
	ErtsSendContext ctx;
	ErtsAtomCacheMap acm;
    };
    Binary* ctx_bin = erts_create_magic_binary(sizeof(struct exported_ctx),
					       erts_dsend_context_dtor);
    struct exported_ctx* dst = ERTS_MAGIC_BIN_DATA(ctx_bin);
    Eterm* hp = HAlloc(p, PROC_BIN_SIZE);

    sys_memcpy(&dst->ctx, ctx, sizeof(ErtsSendContext));
    ASSERT(ctx->dss.ctl == make_tuple(ctx->ctl_heap));
    dst->ctx.dss.ctl = make_tuple(dst->ctx.ctl_heap);
    if (ctx->dss.acmp) {
	sys_memcpy(&dst->acm, ctx->dss.acmp, sizeof(ErtsAtomCacheMap));
	dst->ctx.dss.acmp = &dst->acm;
    }
    return erts_mk_magic_binary_term(&hp, &MSO(p), ctx_bin);
}


/*
 * The erts_dsig_send_*() functions implemented below, sends asynchronous
 * distributed signals to other Erlang nodes. Before sending a distributed
 * signal, you need to prepare the operation by calling erts_dsig_prepare()
 * (see dist.h).
 *
 * Note that the distributed signal send operation is truly asynchronous,
 * and the signal is not guaranteed to reach the receiver if the connection
 * goes down before the signal has reached the receiver.
 */

/*
** Send a DOP_LINK link message
*/
int
erts_dsig_send_link(ErtsDSigData *dsdp, Eterm local, Eterm remote)
{
    DeclareTmpHeapNoproc(ctl_heap,4);
    Eterm ctl = TUPLE3(&ctl_heap[0], make_small(DOP_LINK), local, remote);
    int res;
    UseTmpHeapNoproc(4);

    res = dsig_send_ctl(dsdp, ctl, 0);
    UnUseTmpHeapNoproc(4);
    return res;
}

int
erts_dsig_send_unlink(ErtsDSigData *dsdp, Eterm local, Eterm remote)
{
    DeclareTmpHeapNoproc(ctl_heap,4);
    Eterm ctl = TUPLE3(&ctl_heap[0], make_small(DOP_UNLINK), local, remote);
    int res;

    UseTmpHeapNoproc(4);
    res = dsig_send_ctl(dsdp, ctl, 0);
    UnUseTmpHeapNoproc(4);
    return res;
}


/* A local process that's beeing monitored by a remote one exits. We send:
   {DOP_MONITOR_P_EXIT, Local pid or name, Remote pid, ref, reason},
   which is rather sad as only the ref is needed, no pid's... */
int
erts_dsig_send_m_exit(ErtsDSigData *dsdp, Eterm watcher, Eterm watched, 
			  Eterm ref, Eterm reason)
{
    Eterm ctl;
    DeclareTmpHeapNoproc(ctl_heap,6);
    int res;

    UseTmpHeapNoproc(6);

    ctl = TUPLE5(&ctl_heap[0], make_small(DOP_MONITOR_P_EXIT),
		 watched, watcher, ref, reason);

#ifdef DEBUG
    erts_smp_de_links_lock(dsdp->dep);
    ASSERT(!erts_lookup_monitor(dsdp->dep->monitors, ref));
    erts_smp_de_links_unlock(dsdp->dep);
#endif

    res = dsig_send_ctl(dsdp, ctl, 1);
    UnUseTmpHeapNoproc(6);
    return res;
}

/* We want to monitor a process (named or unnamed) on another node, we send:
   {DOP_MONITOR_P, Local pid, Remote pid or name, Ref}, which is exactly what's
   needed on the other side... */
int
erts_dsig_send_monitor(ErtsDSigData *dsdp, Eterm watcher, Eterm watched,
		       Eterm ref)
{
    Eterm ctl;
    DeclareTmpHeapNoproc(ctl_heap,5);
    int res;

    UseTmpHeapNoproc(5);
    ctl = TUPLE4(&ctl_heap[0],
		 make_small(DOP_MONITOR_P),
		 watcher, watched, ref);

    res = dsig_send_ctl(dsdp, ctl, 0);
    UnUseTmpHeapNoproc(5);
    return res;
}

/* A local process monitoring a remote one wants to stop monitoring, either 
   because of a demonitor bif call or because the local process died. We send
   {DOP_DEMONITOR_P, Local pid, Remote pid or name, ref}, which is once again
   rather redundant as only the ref will be needed on the other side... */
int
erts_dsig_send_demonitor(ErtsDSigData *dsdp, Eterm watcher,
			 Eterm watched, Eterm ref, int force)
{
    Eterm ctl;
    DeclareTmpHeapNoproc(ctl_heap,5);
    int res;

    UseTmpHeapNoproc(5);
    ctl = TUPLE4(&ctl_heap[0],
		 make_small(DOP_DEMONITOR_P),
		 watcher, watched, ref);

    res = dsig_send_ctl(dsdp, ctl, force);
    UnUseTmpHeapNoproc(5);
    return res;
}

int
erts_dsig_send_msg(Eterm remote, Eterm message, ErtsSendContext* ctx)
{
    Eterm ctl;
    Eterm token = NIL;
    Process *sender = ctx->dsd.proc;
    int res;
#ifdef USE_VM_PROBES
    Sint tok_label = 0;
    Sint tok_lastcnt = 0;
    Sint tok_serial = 0;
    Uint msize = 0;
    DTRACE_CHARBUF(node_name, 64);
    DTRACE_CHARBUF(sender_name, 64);
    DTRACE_CHARBUF(receiver_name, 64);
#endif

    if (have_seqtrace(SEQ_TRACE_TOKEN(sender))) {
	seq_trace_update_send(sender);
	token = SEQ_TRACE_TOKEN(sender);
	seq_trace_output(token, message, SEQ_TRACE_SEND, remote, sender);
    }
#ifdef USE_VM_PROBES
    *node_name = *sender_name = *receiver_name = '\0';
    if (DTRACE_ENABLED(message_send) || DTRACE_ENABLED(message_send_remote)) {
        erts_snprintf(node_name, sizeof(DTRACE_CHARBUF_NAME(node_name)),
                      "%T", ctx->dsd.dep->sysname);
        erts_snprintf(sender_name, sizeof(DTRACE_CHARBUF_NAME(sender_name)),
                      "%T", sender->common.id);
        erts_snprintf(receiver_name, sizeof(DTRACE_CHARBUF_NAME(receiver_name)),
                      "%T", remote);
        msize = size_object(message);
        if (have_seqtrace(token)) {
            tok_label = signed_val(SEQ_TRACE_T_LABEL(token));
            tok_lastcnt = signed_val(SEQ_TRACE_T_LASTCNT(token));
            tok_serial = signed_val(SEQ_TRACE_T_SERIAL(token));
        }
    }
#endif

    if (token != NIL)
	ctl = TUPLE4(&ctx->ctl_heap[0],
		     make_small(DOP_SEND_TT), am_Empty, remote, token);
    else
	ctl = TUPLE3(&ctx->ctl_heap[0], make_small(DOP_SEND), am_Empty, remote);
    DTRACE6(message_send, sender_name, receiver_name,
            msize, tok_label, tok_lastcnt, tok_serial);
    DTRACE7(message_send_remote, sender_name, node_name, receiver_name,
            msize, tok_label, tok_lastcnt, tok_serial);
    ctx->dss.ctl = ctl;
    ctx->dss.msg = message;
    ctx->dss.force_busy = 0;
    res = erts_dsig_send(&ctx->dsd, &ctx->dss);
    return res;
}

int
erts_dsig_send_reg_msg(Eterm remote_name, Eterm message,
		       ErtsSendContext* ctx)
{
    Eterm ctl;
    Eterm token = NIL;
    Process *sender = ctx->dsd.proc;
    int res;
#ifdef USE_VM_PROBES
    Sint tok_label = 0;
    Sint tok_lastcnt = 0;
    Sint tok_serial = 0;
    Uint32 msize = 0;
    DTRACE_CHARBUF(node_name, 64);
    DTRACE_CHARBUF(sender_name, 64);
    DTRACE_CHARBUF(receiver_name, 128);
#endif

    if (have_seqtrace(SEQ_TRACE_TOKEN(sender))) {
	seq_trace_update_send(sender);
	token = SEQ_TRACE_TOKEN(sender);
	seq_trace_output(token, message, SEQ_TRACE_SEND, remote_name, sender);
    }
#ifdef USE_VM_PROBES
    *node_name = *sender_name = *receiver_name = '\0';
    if (DTRACE_ENABLED(message_send) || DTRACE_ENABLED(message_send_remote)) {
        erts_snprintf(node_name, sizeof(DTRACE_CHARBUF_NAME(node_name)),
                      "%T", ctx->dsd.dep->sysname);
        erts_snprintf(sender_name, sizeof(DTRACE_CHARBUF_NAME(sender_name)),
                      "%T", sender->common.id);
        erts_snprintf(receiver_name, sizeof(DTRACE_CHARBUF_NAME(receiver_name)),
                      "{%T,%s}", remote_name, node_name);
        msize = size_object(message);
        if (have_seqtrace(token)) {
            tok_label = signed_val(SEQ_TRACE_T_LABEL(token));
            tok_lastcnt = signed_val(SEQ_TRACE_T_LASTCNT(token));
            tok_serial = signed_val(SEQ_TRACE_T_SERIAL(token));
        }
    }
#endif

    if (token != NIL)
	ctl = TUPLE5(&ctx->ctl_heap[0], make_small(DOP_REG_SEND_TT),
		     sender->common.id, am_Empty, remote_name, token);
    else
	ctl = TUPLE4(&ctx->ctl_heap[0], make_small(DOP_REG_SEND),
		     sender->common.id, am_Empty, remote_name);
    DTRACE6(message_send, sender_name, receiver_name,
            msize, tok_label, tok_lastcnt, tok_serial);
    DTRACE7(message_send_remote, sender_name, node_name, receiver_name,
            msize, tok_label, tok_lastcnt, tok_serial);
    ctx->dss.ctl = ctl;
    ctx->dss.msg = message;
    ctx->dss.force_busy = 0;
    res = erts_dsig_send(&ctx->dsd, &ctx->dss);
    return res;
}

/* local has died, deliver the exit signal to remote */
int
erts_dsig_send_exit_tt(ErtsDSigData *dsdp, Eterm local, Eterm remote, 
		       Eterm reason, Eterm token)
{
    Eterm ctl;
    DeclareTmpHeapNoproc(ctl_heap,6);
    int res;
#ifdef USE_VM_PROBES
    Process *sender = dsdp->proc;
    Sint tok_label = 0;
    Sint tok_lastcnt = 0;
    Sint tok_serial = 0;
    DTRACE_CHARBUF(node_name, 64);
    DTRACE_CHARBUF(sender_name, 64);
    DTRACE_CHARBUF(remote_name, 128);
    DTRACE_CHARBUF(reason_str, 128);
#endif

    UseTmpHeapNoproc(6);
    if (have_seqtrace(token)) {
	seq_trace_update_send(dsdp->proc);
	seq_trace_output_exit(token, reason, SEQ_TRACE_SEND, remote, local);
	ctl = TUPLE5(&ctl_heap[0],
		     make_small(DOP_EXIT_TT), local, remote, token, reason);
    } else {
	ctl = TUPLE4(&ctl_heap[0], make_small(DOP_EXIT), local, remote, reason);
    }
#ifdef USE_VM_PROBES
    *node_name = *sender_name = *remote_name = '\0';
    if (DTRACE_ENABLED(process_exit_signal_remote)) {
        erts_snprintf(node_name, sizeof(DTRACE_CHARBUF_NAME(node_name)),
                      "%T", dsdp->dep->sysname);
        erts_snprintf(sender_name, sizeof(DTRACE_CHARBUF_NAME(sender_name)),
                      "%T", sender->common.id);
        erts_snprintf(remote_name, sizeof(DTRACE_CHARBUF_NAME(remote_name)),
                      "{%T,%s}", remote, node_name);
        erts_snprintf(reason_str, sizeof(DTRACE_CHARBUF_NAME(reason_str)),
                      "%T", reason);
        if (have_seqtrace(token)) {
            tok_label = signed_val(SEQ_TRACE_T_LABEL(token));
            tok_lastcnt = signed_val(SEQ_TRACE_T_LASTCNT(token));
            tok_serial = signed_val(SEQ_TRACE_T_SERIAL(token));
        }
    }
#endif
    DTRACE7(process_exit_signal_remote, sender_name, node_name,
            remote_name, reason_str, tok_label, tok_lastcnt, tok_serial);
    /* forced, i.e ignore busy */
    res = dsig_send_ctl(dsdp, ctl, 1);
    UnUseTmpHeapNoproc(6);
    return res;
}

int
erts_dsig_send_exit(ErtsDSigData *dsdp, Eterm local, Eterm remote, Eterm reason)
{
    DeclareTmpHeapNoproc(ctl_heap,5);
    int res;
    Eterm ctl;

    UseTmpHeapNoproc(5);
    ctl = TUPLE4(&ctl_heap[0],
		 make_small(DOP_EXIT), local, remote, reason);
    /* forced, i.e ignore busy */
    res =  dsig_send_ctl(dsdp, ctl, 1);
    UnUseTmpHeapNoproc(5);
    return res;
}

int
erts_dsig_send_exit2(ErtsDSigData *dsdp, Eterm local, Eterm remote, Eterm reason)
{
    DeclareTmpHeapNoproc(ctl_heap,5);
    int res;
    Eterm ctl;

    UseTmpHeapNoproc(5);
    ctl = TUPLE4(&ctl_heap[0],
		 make_small(DOP_EXIT2), local, remote, reason);

    res = dsig_send_ctl(dsdp, ctl, 0);
    UnUseTmpHeapNoproc(5);
    return res;
}


int
erts_dsig_send_group_leader(ErtsDSigData *dsdp, Eterm leader, Eterm remote)
{
    DeclareTmpHeapNoproc(ctl_heap,4);
    int res;
    Eterm ctl;

    UseTmpHeapNoproc(4);
    ctl = TUPLE3(&ctl_heap[0],
		 make_small(DOP_GROUP_LEADER), leader, remote);

    res = dsig_send_ctl(dsdp, ctl, 0);
    UnUseTmpHeapNoproc(4);
    return res;
}

#if defined(PURIFY)
#  define PURIFY_MSG(msg) \
    purify_printf("%s, line %d: %s", __FILE__, __LINE__, msg)
#elif defined(VALGRIND)
#include <valgrind/valgrind.h>
#include <valgrind/memcheck.h>

#ifndef HAVE_VALGRIND_PRINTF_XML
#define VALGRIND_PRINTF_XML VALGRIND_PRINTF
#endif

#  define PURIFY_MSG(msg)                                                    \
    do {								     \
	char buf__[1]; size_t bufsz__ = sizeof(buf__);			     \
	if (erts_sys_getenv_raw("VALGRIND_LOG_XML", buf__, &bufsz__) >= 0) { \
	    VALGRIND_PRINTF_XML("<erlang_error_log>"			     \
			    "%s, line %d: %s</erlang_error_log>\n",	     \
			    __FILE__, __LINE__, msg);			     \
	} else {							     \
	    VALGRIND_PRINTF("%s, line %d: %s", __FILE__, __LINE__, msg);     \
	}								     \
    } while (0)
#else
#  define PURIFY_MSG(msg)
#endif

/*
** Input from distribution port.
**  Input follows the distribution protocol v4.5
**  
**   The protocol is a 4 byte header protocol
**   the DOP_DATA is stripped by driver_output
**
**   assert  hlen == 0 !!!
*/

int erts_net_message(Port *prt,
		     DistEntry *dep,
		     byte *hbuf,
		     ErlDrvSizeT hlen,
		     byte *buf,
		     ErlDrvSizeT len)
{
    ErtsDistExternal ede;
    byte *t;
    Sint ctl_len;
    Eterm arg;
    Eterm from, to;
    Eterm watcher, watched;
    Eterm ref;
    Eterm *tuple;
    Eterm reason;
    Process* rp;
    DeclareTmpHeapNoproc(ctl_default,DIST_CTL_DEFAULT_SIZE);
    Eterm* ctl = ctl_default;
    ErtsHeapFactory factory;
    Eterm* hp;
    Sint type;
    Eterm token;
    Eterm token_size;
    ErtsMonitor *mon;
    ErtsLink *lnk;
    Uint tuple_arity;
    int res;
#ifdef ERTS_DIST_MSG_DBG
    ErlDrvSizeT orig_len = len;
#endif

    UseTmpHeapNoproc(DIST_CTL_DEFAULT_SIZE);

    ERTS_SMP_CHK_NO_PROC_LOCKS;

    ERTS_SMP_LC_ASSERT(erts_lc_is_port_locked(prt));

    if (!erts_is_alive) {
	UnUseTmpHeapNoproc(DIST_CTL_DEFAULT_SIZE);
	return 0;
    }
    if (hlen != 0)
	goto data_error;
    if (len == 0) {  /* HANDLE TICK !!! */
	UnUseTmpHeapNoproc(DIST_CTL_DEFAULT_SIZE);
	return 0;
    }

#ifdef ERTS_RAW_DIST_MSG_DBG
    erts_fprintf(stderr, "<< ");
    bw(buf, len);
#endif

    if (dep->flags & DFLAG_DIST_HDR_ATOM_CACHE)
	t = buf;
    else {
	/* Skip PASS_THROUGH */
	t = buf+1;
	len--;
    }

    if (len == 0) {
	PURIFY_MSG("data error");
	goto data_error;
    }

    res = erts_prepare_dist_ext(&ede, t, len, dep, dep->cache);

    if (res >= 0)
	res = ctl_len = erts_decode_dist_ext_size(&ede);
    else {
#ifdef ERTS_DIST_MSG_DBG
	erts_fprintf(stderr, "DIST MSG DEBUG: erts_prepare_dist_ext() failed:\n");
	bw(buf, orig_len);
#endif
	ctl_len = 0;
    }

    if (res < 0) {
#ifdef ERTS_DIST_MSG_DBG
	erts_fprintf(stderr, "DIST MSG DEBUG: erts_decode_dist_ext_size(CTL) failed:\n");
	bw(buf, orig_len);
#endif
	PURIFY_MSG("data error");
	goto data_error;
    }

    if (ctl_len > DIST_CTL_DEFAULT_SIZE) {
	ctl = erts_alloc(ERTS_ALC_T_DCTRL_BUF, ctl_len * sizeof(Eterm));
    }
    hp = ctl;

    erts_factory_tmp_init(&factory, ctl, ctl_len, ERTS_ALC_T_DCTRL_BUF);
    arg = erts_decode_dist_ext(&factory, &ede);
    if (is_non_value(arg)) {
#ifdef ERTS_DIST_MSG_DBG
	erts_fprintf(stderr, "DIST MSG DEBUG: erts_decode_dist_ext(CTL) failed:\n");
	bw(buf, orig_len);
#endif
	PURIFY_MSG("data error");
	goto decode_error;
    }
    ctl_len = t - buf;

#ifdef ERTS_DIST_MSG_DBG
    erts_fprintf(stderr, "<<%s CTL: %T\n", len != orig_len ? "P" : " ", arg);
#endif

    if (is_not_tuple(arg) || 
	(tuple = tuple_val(arg), (tuple_arity = arityval(*tuple)) < 1) ||
	is_not_small(tuple[1])) {
 	goto invalid_message;
    }

    token_size = 0;

    switch (type = unsigned_val(tuple[1])) {
    case DOP_LINK:
	if (tuple_arity != 3) {
	    goto invalid_message;
	}
	from = tuple[2];
	to   = tuple[3];  /* local proc to link to */

	if (is_not_pid(from) || is_not_pid(to)) {
	    goto invalid_message;
	}

	rp = erts_pid2proc_opt(NULL, 0,
			       to, ERTS_PROC_LOCK_LINK,
			       ERTS_P2P_FLG_ALLOW_OTHER_X);
	if (!rp) {
	    /* This is tricky (we MUST force a distributed send) */
	    ErtsDSigData dsd;
	    int code;
	    code = erts_dsig_prepare(&dsd, dep, NULL, ERTS_DSP_NO_LOCK, 0);
	    if (code == ERTS_DSIG_PREP_CONNECTED) {
		code = erts_dsig_send_exit(&dsd, to, from, am_noproc);
		ASSERT(code == ERTS_DSIG_SEND_OK);
	    }
	    break;
	}

	erts_smp_de_links_lock(dep);
	res = erts_add_link(&ERTS_P_LINKS(rp), LINK_PID, from);

	if (res < 0) {
	    /* It was already there! Lets skip the rest... */
	    erts_smp_de_links_unlock(dep);
	    erts_smp_proc_unlock(rp, ERTS_PROC_LOCK_LINK);
	    break;
	}
	lnk = erts_add_or_lookup_link(&(dep->nlinks), LINK_PID, rp->common.id);
	erts_add_link(&(ERTS_LINK_ROOT(lnk)), LINK_PID, from);
	erts_smp_de_links_unlock(dep);

	if (IS_TRACED_FL(rp, F_TRACE_PROCS))
	    trace_proc(NULL, 0, rp, am_getting_linked, from);

	erts_smp_proc_unlock(rp, ERTS_PROC_LOCK_LINK);
	break;

    case DOP_UNLINK: {
	ErtsDistLinkData dld;
	if (tuple_arity != 3) {
	    goto invalid_message;
	}
	from = tuple[2];
	to = tuple[3];
	if (is_not_pid(from) || is_not_pid(to)) {
	    goto invalid_message;
	}
	
	rp = erts_pid2proc_opt(NULL, 0,
			       to, ERTS_PROC_LOCK_LINK,
			       ERTS_P2P_FLG_ALLOW_OTHER_X);
	if (!rp)
	    break;

	lnk = erts_remove_link(&ERTS_P_LINKS(rp), from);

	if (IS_TRACED_FL(rp, F_TRACE_PROCS) && lnk != NULL) {
	    trace_proc(NULL, 0, rp, am_getting_unlinked, from);
	}

	erts_smp_proc_unlock(rp, ERTS_PROC_LOCK_LINK);

	erts_remove_dist_link(&dld, to, from, dep);
	erts_destroy_dist_link(&dld);
	if (lnk)
	    erts_destroy_link(lnk);
	break;
    }
    
    case DOP_MONITOR_P: {
	/* A remote process wants to monitor us, we get:
	   {DOP_MONITOR_P, Remote pid, local pid or name, ref} */
	Eterm name;
	
	if (tuple_arity != 4) {
	    goto invalid_message;
	}

	watcher = tuple[2];
	watched = tuple[3];  /* local proc to monitor */
	ref     = tuple[4];

	if (is_not_ref(ref)) {
	    goto invalid_message;
	}

	if (is_atom(watched)) {
	    name = watched;
	    rp = erts_whereis_process(NULL, 0,
				      watched, ERTS_PROC_LOCK_LINK,
				      ERTS_P2P_FLG_ALLOW_OTHER_X);
	}
	else {
	    name = NIL;
	    rp = erts_pid2proc_opt(NULL, 0,
				   watched, ERTS_PROC_LOCK_LINK,
				   ERTS_P2P_FLG_ALLOW_OTHER_X);
	}

	if (!rp) {
	    ErtsDSigData dsd;
	    int code;
	    code = erts_dsig_prepare(&dsd, dep, NULL, ERTS_DSP_NO_LOCK, 0);
	    if (code == ERTS_DSIG_PREP_CONNECTED) {
		code = erts_dsig_send_m_exit(&dsd, watcher, watched, ref,
					     am_noproc);
		ASSERT(code == ERTS_DSIG_SEND_OK);
	    }
	}
	else {
	    if (is_atom(watched))
		watched = rp->common.id;
	    erts_smp_de_links_lock(dep);
	    erts_add_monitor(&(dep->monitors), MON_ORIGIN, ref, watched, name);
	    erts_add_monitor(&ERTS_P_MONITORS(rp), MON_TARGET, ref, watcher, name);
	    erts_smp_de_links_unlock(dep);
	    erts_smp_proc_unlock(rp, ERTS_PROC_LOCK_LINK);
	}

	break;
    }

    case DOP_DEMONITOR_P:
	/* A remote node informs us that a local pid in no longer monitored
	   We get {DOP_DEMONITOR_P, Remote pid, Local pid or name, ref},
	   We need only the ref of course */

	if (tuple_arity != 4) {
	    goto invalid_message;
	}
	/* watcher = tuple[2]; */
	/* watched = tuple[3]; May be an atom in case of monitor name */
	ref = tuple[4];

	if(is_not_ref(ref)) {
	    goto invalid_message;
	}

	erts_smp_de_links_lock(dep);
	mon = erts_remove_monitor(&(dep->monitors),ref);
	erts_smp_de_links_unlock(dep);
	/* ASSERT(mon != NULL); can happen in case of broken dist message */
	if (mon == NULL) {
	    break;
	}
	watched = mon->pid;
	erts_destroy_monitor(mon);
	rp = erts_pid2proc_opt(NULL, 0,
			       watched, ERTS_PROC_LOCK_LINK,
			       ERTS_P2P_FLG_ALLOW_OTHER_X);
	if (!rp) {
	    break;
	}
	mon = erts_remove_monitor(&ERTS_P_MONITORS(rp), ref);
	erts_smp_proc_unlock(rp, ERTS_PROC_LOCK_LINK);
	ASSERT(mon != NULL);
	if (mon == NULL) {
	    break;
	}
	erts_destroy_monitor(mon);
	break;

    case DOP_REG_SEND_TT:
	if (tuple_arity != 5) {
	    goto invalid_message;
	}

	token_size = size_object(tuple[5]);
	/* Fall through ... */
    case DOP_REG_SEND:
	/* {DOP_REG_SEND, From, Cookie, ToName} -- Message */
	/* {DOP_REG_SEND_TT, From, Cookie, ToName, TraceToken} -- Message */

	/*
	 * There is intentionally no testing of the cookie (it is always '')
	 * from R9B and onwards.
	 */
	if (type != DOP_REG_SEND_TT && tuple_arity != 4) {
	    goto invalid_message;
	}

#ifdef ERTS_DIST_MSG_DBG
	dist_msg_dbg(&ede, "MSG", buf, orig_len);
#endif

	from = tuple[2];
	to = tuple[4];
	if (is_not_pid(from) || is_not_atom(to)){
	    goto invalid_message;
	}
	rp = erts_whereis_process(NULL, 0, to, 0, 0);
	if (rp) {
	    Uint xsize = (type == DOP_REG_SEND
			  ? 0
			  : ERTS_HEAP_FRAG_SIZE(token_size));
	    ErtsProcLocks locks = 0;
	    ErtsDistExternal *ede_copy;

	    ede_copy = erts_make_dist_ext_copy(&ede, xsize);
	    if (type == DOP_REG_SEND) {
		token = NIL;
	    } else {
		ErlHeapFragment *heap_frag;
		ErlOffHeap *ohp;
		ASSERT(xsize);
		heap_frag = erts_dist_ext_trailer(ede_copy);
		ERTS_INIT_HEAP_FRAG(heap_frag, token_size, token_size);
		hp = heap_frag->mem;
		ohp = &heap_frag->off_heap;
		token = tuple[5];
		token = copy_struct(token, token_size, &hp, ohp);
	    }

	    erts_queue_dist_message(rp, locks, ede_copy, token, from);
	    if (locks)
		erts_smp_proc_unlock(rp, locks);
	}
	break;

    case DOP_SEND_TT:
	if (tuple_arity != 4) {
	    goto invalid_message;
	}
	
	token_size = size_object(tuple[4]);
	/* Fall through ... */
    case DOP_SEND:
	/*
	 * There is intentionally no testing of the cookie (it is always '')
	 * from R9B and onwards.
	 */
#ifdef ERTS_DIST_MSG_DBG
	dist_msg_dbg(&ede, "MSG", buf, orig_len);
#endif
	if (type != DOP_SEND_TT && tuple_arity != 3) {
	    goto invalid_message;
	}
	to = tuple[3];
	if (is_not_pid(to)) {
	    goto invalid_message;
	}
	rp = erts_proc_lookup(to);
	if (rp) {
	    Uint xsize = type == DOP_SEND ? 0 : ERTS_HEAP_FRAG_SIZE(token_size);
	    ErtsProcLocks locks = 0;
	    ErtsDistExternal *ede_copy;

	    ede_copy = erts_make_dist_ext_copy(&ede, xsize);
	    if (type == DOP_SEND) {
		token = NIL;
	    } else {
		ErlHeapFragment *heap_frag;
		ErlOffHeap *ohp;
		ASSERT(xsize);
		heap_frag = erts_dist_ext_trailer(ede_copy);
		ERTS_INIT_HEAP_FRAG(heap_frag, token_size, token_size);
		hp = heap_frag->mem;
		ohp = &heap_frag->off_heap;
		token = tuple[4];
		token = copy_struct(token, token_size, &hp, ohp);
	    }

	    erts_queue_dist_message(rp, locks, ede_copy, token, tuple[2]);
	    if (locks)
		erts_smp_proc_unlock(rp, locks);
	}
	break;

    case DOP_MONITOR_P_EXIT: {
	/* We are monitoring a process on the remote node which dies, we get
	   {DOP_MONITOR_P_EXIT, Remote pid or name, Local pid, ref, reason} */
	   

	DeclareTmpHeapNoproc(lhp,3);
	Eterm sysname;
	ErtsProcLocks rp_locks = ERTS_PROC_LOCKS_MSG_SEND|ERTS_PROC_LOCK_LINK;

	if (tuple_arity != 5) {
	    goto invalid_message;
	}

	/* watched = tuple[2]; */  /* remote proc which died */
	/* watcher = tuple[3]; */
	ref     = tuple[4];
	reason  = tuple[5];

	if(is_not_ref(ref)) {
	    goto invalid_message;
	}

	erts_smp_de_links_lock(dep);
	sysname = dep->sysname;
	mon = erts_remove_monitor(&(dep->monitors), ref);
	/*
	 * If demonitor was performed at the same time as the
	 * monitored process exits, monitoring side will have
	 * removed info about monitor. In this case, do nothing
	 * and everything will be as it should.
	 */
	erts_smp_de_links_unlock(dep);
	if (mon == NULL) {
	    break;
	}
	rp = erts_pid2proc(NULL, 0, mon->pid, rp_locks);

	erts_destroy_monitor(mon);
	if (rp == NULL) {
	    break;
	}

	mon = erts_remove_monitor(&ERTS_P_MONITORS(rp), ref);

	if (mon == NULL) {
	    erts_smp_proc_unlock(rp, rp_locks);
	    break;
	}
	UseTmpHeapNoproc(3);
	
	watched = (is_not_nil(mon->name)
		   ? TUPLE2(&lhp[0], mon->name, sysname)
		   : mon->pid);
	
	erts_queue_monitor_message(rp, &rp_locks,
				   ref, am_process, watched, reason);
	erts_smp_proc_unlock(rp, rp_locks);
	erts_destroy_monitor(mon);
	UnUseTmpHeapNoproc(3);
	break;
    }

    case DOP_EXIT_TT:
    case DOP_EXIT: {
	ErtsDistLinkData dld;
	ErtsProcLocks rp_locks = ERTS_PROC_LOCK_LINK|ERTS_PROC_LOCKS_XSIG_SEND;
	/* 'from', which 'to' is linked to, died */
	if (type == DOP_EXIT) {
	    if (tuple_arity != 4) {
		goto invalid_message;
	    }
	    
	    from = tuple[2];
	    to = tuple[3];
	    reason = tuple[4];
	    token = NIL;
	} else {
	    if (tuple_arity != 5) {
		goto invalid_message;
	    }
	    from = tuple[2];
	    to = tuple[3];
	    token = tuple[4];
	    reason = tuple[5];
	}
	if (is_not_pid(from) || is_not_internal_pid(to)) {
	    goto invalid_message;
	}

	rp = erts_pid2proc(NULL, 0, to, rp_locks);
	if (!rp)
	    lnk = NULL;
	else {
	    lnk = erts_remove_link(&ERTS_P_LINKS(rp), from);

	    /* If lnk == NULL, we have unlinked on this side, i.e.
	     * ignore exit.
	     */
	    if (lnk) {
		int xres;
#if 0
		/* Arndt: Maybe it should never be 'kill', but it can be,
		   namely when a linked process does exit(kill). Until we know
		   whether that is incorrect and what should happen instead,
		   we leave the assertion out. */
		ASSERT(reason != am_kill); /* should never be kill (killed) */
#endif
		xres = erts_send_exit_signal(NULL,
					     from,
					     rp,
					     &rp_locks, 
					     reason,
					     token,
					     NULL,
					     ERTS_XSIG_FLG_IGN_KILL);
		if (xres >= 0 && IS_TRACED_FL(rp, F_TRACE_PROCS)) {
		    /* We didn't exit the process and it is traced */
                    if (rp_locks & ERTS_PROC_LOCKS_XSIG_SEND) {
                        erts_smp_proc_unlock(rp, ERTS_PROC_LOCKS_XSIG_SEND);
                        rp_locks &= ~ERTS_PROC_LOCKS_XSIG_SEND;
                    }
		    trace_proc(NULL, 0, rp, am_getting_unlinked, from);
		}
	    }
	    erts_smp_proc_unlock(rp, rp_locks);
	}
	erts_remove_dist_link(&dld, to, from, dep);
	if (lnk)
	    erts_destroy_link(lnk);
	erts_destroy_dist_link(&dld);
	break;
    }
    case DOP_EXIT2_TT:
    case DOP_EXIT2: {
	ErtsProcLocks rp_locks = ERTS_PROC_LOCKS_XSIG_SEND;
	/* 'from' is send an exit signal to 'to' */
	if (type == DOP_EXIT2) {
	    if (tuple_arity != 4) {
		goto invalid_message;
	    }
	    from = tuple[2];
	    to = tuple[3];
	    reason = tuple[4];
	    token = NIL;
	} else {
	    if (tuple_arity != 5) {
		goto invalid_message;
	    }
	    from = tuple[2];
	    to = tuple[3];
	    token = tuple[4];
	    reason = tuple[5];
	}
	if (is_not_pid(from) || is_not_internal_pid(to)) {
	    goto invalid_message;
	}
	rp = erts_pid2proc(NULL, 0, to, rp_locks);
	if (rp) {
	    (void) erts_send_exit_signal(NULL,
					 from,
					 rp,
					 &rp_locks,
					 reason,
					 token,
					 NULL,
					 0);
	    erts_smp_proc_unlock(rp, rp_locks);
	}
	break;
    }
    case DOP_GROUP_LEADER:
	if (tuple_arity != 3) {
	    goto invalid_message;
	}
	from = tuple[2];   /* Group leader  */
	to = tuple[3];     /* new member */
	if (is_not_pid(from) || is_not_pid(to)) {
	    goto invalid_message;
	}

	rp = erts_pid2proc(NULL, 0, to, ERTS_PROC_LOCK_MAIN);
	if (!rp)
	    break;
	rp->group_leader = STORE_NC_IN_PROC(rp, from);
	erts_smp_proc_unlock(rp, ERTS_PROC_LOCK_MAIN);
	break;

    default: 
	goto invalid_message;
    }

    erts_factory_close(&factory);
    if (ctl != ctl_default) {
	erts_free(ERTS_ALC_T_DCTRL_BUF, (void *) ctl);
    }
    UnUseTmpHeapNoproc(DIST_CTL_DEFAULT_SIZE);
    ERTS_SMP_CHK_NO_PROC_LOCKS;
    return 0;
 invalid_message:
    {
	erts_dsprintf_buf_t *dsbufp = erts_create_logger_dsbuf();
	erts_dsprintf(dsbufp, "Invalid distribution message: %.200T", arg);
	erts_send_error_to_logger_nogl(dsbufp);
    }
decode_error:
    PURIFY_MSG("data error");
    erts_factory_close(&factory);
    if (ctl != ctl_default) {
	erts_free(ERTS_ALC_T_DCTRL_BUF, (void *) ctl);
    }
data_error:
    UnUseTmpHeapNoproc(DIST_CTL_DEFAULT_SIZE);
    erts_deliver_port_exit(prt, dep->cid, am_killed, 0, 1);
    ERTS_SMP_CHK_NO_PROC_LOCKS;
    return -1;
}

static int dsig_send_ctl(ErtsDSigData* dsdp, Eterm ctl, int force_busy)
{
    struct erts_dsig_send_context ctx;
    int ret;
    ctx.ctl = ctl;
    ctx.msg = THE_NON_VALUE;
    ctx.force_busy = force_busy;
    ctx.phase = ERTS_DSIG_SEND_PHASE_INIT;
#ifdef DEBUG
    ctx.reds = 1; /* provoke assert below (no reduction count without msg) */
#endif
    ret = erts_dsig_send(dsdp, &ctx);
    ASSERT(ret != ERTS_DSIG_SEND_CONTINUE);
    return ret;
}

int
erts_dsig_send(ErtsDSigData *dsdp, struct erts_dsig_send_context* ctx)
{
    int retval;
    Sint initial_reds = ctx->reds;
    Eterm cid;

    while (1) {
	switch (ctx->phase) {
	case ERTS_DSIG_SEND_PHASE_INIT:
	    ctx->flags = dsdp->dep->flags;
	    ctx->c_p = dsdp->proc;

	    if (!ctx->c_p || dsdp->no_suspend)
		ctx->force_busy = 1;

	    ERTS_SMP_LC_ASSERT(!ctx->c_p
			       || (ERTS_PROC_LOCK_MAIN
				   == erts_proc_lc_my_proc_locks(ctx->c_p)));

	    if (!erts_is_alive)
		return ERTS_DSIG_SEND_OK;

	    if (ctx->flags & DFLAG_DIST_HDR_ATOM_CACHE) {
		ctx->acmp = erts_get_atom_cache_map(ctx->c_p);
		ctx->pass_through_size = 0;
	    }
	    else {
		ctx->acmp = NULL;
		ctx->pass_through_size = 1;
	    }

    #ifdef ERTS_DIST_MSG_DBG
	    erts_fprintf(stderr, ">>%s CTL: %T\n", ctx->pass_through_size ? "P" : " ", ctx->ctl);
        if (is_value(ctx->msg))
            erts_fprintf(stderr, "    MSG: %T\n", ctx->msg);
    #endif

	    ctx->data_size = ctx->pass_through_size;
	    erts_reset_atom_cache_map(ctx->acmp);
	    erts_encode_dist_ext_size(ctx->ctl, ctx->flags, ctx->acmp, &ctx->data_size);

	    if (is_value(ctx->msg)) {
		ctx->u.sc.wstack.wstart = NULL;
		ctx->u.sc.flags = ctx->flags;
		ctx->u.sc.level = 0;
		ctx->phase = ERTS_DSIG_SEND_PHASE_MSG_SIZE;
	    } else {
		ctx->phase = ERTS_DSIG_SEND_PHASE_ALLOC;
	    }
	    break;

	case ERTS_DSIG_SEND_PHASE_MSG_SIZE:
	    if (erts_encode_dist_ext_size_int(ctx->msg, ctx, &ctx->data_size)) {
		retval = ERTS_DSIG_SEND_CONTINUE;
		goto done;
	    }

	    ctx->phase = ERTS_DSIG_SEND_PHASE_ALLOC;
	case ERTS_DSIG_SEND_PHASE_ALLOC:
	    erts_finalize_atom_cache_map(ctx->acmp, ctx->flags);

	    ctx->dhdr_ext_size = erts_encode_ext_dist_header_size(ctx->acmp);
	    ctx->data_size += ctx->dhdr_ext_size;

	    ctx->obuf = alloc_dist_obuf(ctx->data_size);
	    ctx->obuf->ext_endp = &ctx->obuf->data[0] + ctx->pass_through_size + ctx->dhdr_ext_size;

	    /* Encode internal version of dist header */
	    ctx->obuf->extp = erts_encode_ext_dist_header_setup(ctx->obuf->ext_endp, ctx->acmp);
	    /* Encode control message */
	    erts_encode_dist_ext(ctx->ctl, &ctx->obuf->ext_endp, ctx->flags, ctx->acmp, NULL, NULL);
	    if (is_value(ctx->msg)) {
		ctx->u.ec.flags = ctx->flags;
		ctx->u.ec.level = 0;
		ctx->u.ec.wstack.wstart = NULL;
		ctx->phase = ERTS_DSIG_SEND_PHASE_MSG_ENCODE;
	    } else {
		ctx->phase = ERTS_DSIG_SEND_PHASE_FIN;
	    }
	    break;

	case ERTS_DSIG_SEND_PHASE_MSG_ENCODE:
	    if (erts_encode_dist_ext(ctx->msg, &ctx->obuf->ext_endp, ctx->flags, ctx->acmp, &ctx->u.ec, &ctx->reds)) {
		retval = ERTS_DSIG_SEND_CONTINUE;
		goto done;
	    }

	    ctx->phase = ERTS_DSIG_SEND_PHASE_FIN;
	case ERTS_DSIG_SEND_PHASE_FIN: {
	    DistEntry *dep = dsdp->dep;
	    int suspended = 0;
	    int resume = 0;

	    ASSERT(ctx->obuf->extp < ctx->obuf->ext_endp);
	    ASSERT(&ctx->obuf->data[0] <= ctx->obuf->extp - ctx->pass_through_size);
	    ASSERT(ctx->obuf->ext_endp <= &ctx->obuf->data[0] + ctx->data_size);

	    ctx->data_size = ctx->obuf->ext_endp - ctx->obuf->extp;

	    /*
	     * Signal encoded; now verify that the connection still exists,
	     * and if so enqueue the signal and schedule it for send.
	     */
	    ctx->obuf->next = NULL;
	    erts_smp_de_rlock(dep);
	    cid = dep->cid;
	    if (cid != dsdp->cid
		|| dep->connection_id != dsdp->connection_id
		|| dep->status & ERTS_DE_SFLG_EXITING) {
		/* Not the same connection as when we started; drop message... */
		erts_smp_de_runlock(dep);
		free_dist_obuf(ctx->obuf);
	    }
	    else {
		ErtsProcList *plp = NULL;
		erts_smp_mtx_lock(&dep->qlock);
		dep->qsize += size_obuf(ctx->obuf);
		if (dep->qsize >= erts_dist_buf_busy_limit)
		    dep->qflgs |= ERTS_DE_QFLG_BUSY;
		if (!ctx->force_busy && (dep->qflgs & ERTS_DE_QFLG_BUSY)) {
		    erts_smp_mtx_unlock(&dep->qlock);

		    plp = erts_proclist_create(ctx->c_p);
		    erts_suspend(ctx->c_p, ERTS_PROC_LOCK_MAIN, NULL);
		    suspended = 1;
		    erts_smp_mtx_lock(&dep->qlock);
		}

		/* Enqueue obuf on dist entry */
		if (dep->out_queue.last)
		    dep->out_queue.last->next = ctx->obuf;
		else
		    dep->out_queue.first = ctx->obuf;
		dep->out_queue.last = ctx->obuf;

		if (!ctx->force_busy) {
		    if (!(dep->qflgs & ERTS_DE_QFLG_BUSY)) {
			if (suspended)
			    resume = 1; /* was busy when we started, but isn't now */
    #ifdef USE_VM_PROBES
			if (resume && DTRACE_ENABLED(dist_port_not_busy)) {
			    DTRACE_CHARBUF(port_str, 64);
			    DTRACE_CHARBUF(remote_str, 64);

			    erts_snprintf(port_str, sizeof(DTRACE_CHARBUF_NAME(port_str)),
					  "%T", cid);
			    erts_snprintf(remote_str, sizeof(DTRACE_CHARBUF_NAME(remote_str)),
					  "%T", dep->sysname);
			    DTRACE3(dist_port_not_busy, erts_this_node_sysname,
				    port_str, remote_str);
			}
    #endif
		    }
		    else {
			/* Enqueue suspended process on dist entry */
			ASSERT(plp);
			erts_proclist_store_last(&dep->suspended, plp);
		    }
		}

		erts_smp_mtx_unlock(&dep->qlock);
		erts_schedule_dist_command(NULL, dep);
		erts_smp_de_runlock(dep);

		if (resume) {
		    erts_resume(ctx->c_p, ERTS_PROC_LOCK_MAIN);
		    erts_proclist_destroy(plp);
		    /*
		     * Note that the calling process still have to yield as if it
		     * suspended. If not, the calling process could later be
		     * erroneously scheduled when it shouldn't be.
		     */
		}
	    }
	    ctx->obuf = NULL;

	    if (suspended) {
    #ifdef USE_VM_PROBES
		if (!resume && DTRACE_ENABLED(dist_port_busy)) {
		    DTRACE_CHARBUF(port_str, 64);
		    DTRACE_CHARBUF(remote_str, 64);
		    DTRACE_CHARBUF(pid_str, 16);

		    erts_snprintf(port_str, sizeof(DTRACE_CHARBUF_NAME(port_str)), "%T", cid);
		    erts_snprintf(remote_str, sizeof(DTRACE_CHARBUF_NAME(remote_str)),
				  "%T", dep->sysname);
		    erts_snprintf(pid_str, sizeof(DTRACE_CHARBUF_NAME(pid_str)),
				  "%T", ctx->c_p->common.id);
		    DTRACE4(dist_port_busy, erts_this_node_sysname,
			    port_str, remote_str, pid_str);
		}
    #endif
		if (!resume && erts_system_monitor_flags.busy_dist_port)
		    monitor_generic(ctx->c_p, am_busy_dist_port, cid);
		retval = ERTS_DSIG_SEND_YIELD;
	    } else {
		retval = ERTS_DSIG_SEND_OK;
	    }
	    goto done;
	}
	default:
	    erts_exit(ERTS_ABORT_EXIT, "dsig_send invalid phase (%d)\n", (int)ctx->phase);
	}
    }

done:
    if (ctx->msg && ctx->c_p) {
	BUMP_REDS(ctx->c_p, (initial_reds - ctx->reds) / TERM_TO_BINARY_LOOP_FACTOR);
    }
    return retval;
}

static Uint
dist_port_command(Port *prt, ErtsDistOutputBuf *obuf)
{
    int fpe_was_unmasked;
    Uint size = obuf->ext_endp - obuf->extp;

    ERTS_SMP_CHK_NO_PROC_LOCKS;
    ERTS_SMP_LC_ASSERT(erts_lc_is_port_locked(prt));

    if (size > (Uint) INT_MAX)
	erts_exit(ERTS_DUMP_EXIT,
		 "Absurdly large distribution output data buffer "
		 "(%beu bytes) passed.\n",
		 size);

#ifdef USE_VM_PROBES
    if (DTRACE_ENABLED(dist_output)) {
        DTRACE_CHARBUF(port_str, 64);
        DTRACE_CHARBUF(remote_str, 64);

        erts_snprintf(port_str, sizeof(DTRACE_CHARBUF_NAME(port_str)),
                      "%T", prt->common.id);
        erts_snprintf(remote_str, sizeof(DTRACE_CHARBUF_NAME(remote_str)),
                      "%T", prt->dist_entry->sysname);
        DTRACE4(dist_output, erts_this_node_sysname, port_str,
                remote_str, size);
    }
#endif
    prt->caller = NIL;
    fpe_was_unmasked = erts_block_fpe();
    (*prt->drv_ptr->output)((ErlDrvData) prt->drv_data,
			    (char*) obuf->extp,
			    (int) size);
    erts_unblock_fpe(fpe_was_unmasked);
    return size;
}

static Uint
dist_port_commandv(Port *prt, ErtsDistOutputBuf *obuf)
{
    int fpe_was_unmasked;
    Uint size = obuf->ext_endp - obuf->extp;
    SysIOVec iov[2];
    ErlDrvBinary* bv[2];
    ErlIOVec eiov;

    ERTS_SMP_CHK_NO_PROC_LOCKS;
    ERTS_SMP_LC_ASSERT(erts_lc_is_port_locked(prt));

    if (size > (Uint) INT_MAX)
	erts_exit(ERTS_DUMP_EXIT,
		 "Absurdly large distribution output data buffer "
		 "(%beu bytes) passed.\n",
		 size);

    iov[0].iov_base = NULL;
    iov[0].iov_len = 0;
    bv[0] = NULL;

    iov[1].iov_base = obuf->extp;
    iov[1].iov_len = size;
    bv[1] = Binary2ErlDrvBinary(ErtsDistOutputBuf2Binary(obuf));

    eiov.vsize = 2;
    eiov.size = size;
    eiov.iov = iov;
    eiov.binv = bv;

    ASSERT(prt->drv_ptr->outputv);

#ifdef USE_VM_PROBES
    if (DTRACE_ENABLED(dist_outputv)) {
        DTRACE_CHARBUF(port_str, 64);
        DTRACE_CHARBUF(remote_str, 64);

        erts_snprintf(port_str, sizeof(DTRACE_CHARBUF_NAME(port_str)),
                      "%T", prt->common.id);
        erts_snprintf(remote_str, sizeof(DTRACE_CHARBUF_NAME(remote_str)),
                      "%T", prt->dist_entry->sysname);
        DTRACE4(dist_outputv, erts_this_node_sysname, port_str,
                remote_str, size);
    }
#endif
    prt->caller = NIL;
    fpe_was_unmasked = erts_block_fpe();
    (*prt->drv_ptr->outputv)((ErlDrvData) prt->drv_data, &eiov);
    erts_unblock_fpe(fpe_was_unmasked);

    return size;
}


#if defined(ARCH_64)
#define ERTS_PORT_REDS_MASK__ 0x003fffffffffffffL
#elif defined(ARCH_32)
#define ERTS_PORT_REDS_MASK__ 0x003fffff
#else
#  error "Ohh come on ... !?!"
#endif

#define ERTS_PORT_REDS_DIST_CMD_START 5
#define ERTS_PORT_REDS_DIST_CMD_FINALIZE 3
#define ERTS_PORT_REDS_DIST_CMD_EXIT 200
#define ERTS_PORT_REDS_DIST_CMD_RESUMED 5
#define ERTS_PORT_REDS_DIST_CMD_DATA(SZ) \
  ((SZ) < (1 << 10) \
   ? ((Sint) 1) \
   : ((((Sint) (SZ)) >> 10) & ((Sint) ERTS_PORT_REDS_MASK__)))

int
erts_dist_command(Port *prt, int reds_limit)
{
    Sint reds = ERTS_PORT_REDS_DIST_CMD_START;
    Uint32 status;
    Uint32 flags;
    Sint obufsize = 0;
    ErtsDistOutputQueue oq, foq;
    DistEntry *dep = prt->dist_entry;
    Uint (*send)(Port *prt, ErtsDistOutputBuf *obuf);
    erts_aint32_t sched_flags;
    ErtsSchedulerData *esdp = erts_get_scheduler_data();

    ERTS_SMP_LC_ASSERT(erts_lc_is_port_locked(prt));

    erts_smp_refc_inc(&dep->refc, 1); /* Otherwise dist_entry might be
				     removed if port command fails */

    erts_smp_atomic_set_mb(&dep->dist_cmd_scheduled, 0);

    erts_smp_de_rlock(dep);
    flags = dep->flags;
    status = dep->status;
    send = dep->send;
    erts_smp_de_runlock(dep);

    if (status & ERTS_DE_SFLG_EXITING) {
	erts_deliver_port_exit(prt, prt->common.id, am_killed, 0, 1);
	erts_deref_dist_entry(dep);
	return reds + ERTS_PORT_REDS_DIST_CMD_EXIT;
    }

    ASSERT(send);

    /*
     * We need to remove both out queues from the
     * dist entry while passing it to port command;
     * otherwise, port command will free the buffers
     * in the queues on failure and we'll end up with
     * a mess.
     */

    erts_smp_mtx_lock(&dep->qlock);
    oq.first = dep->out_queue.first;
    oq.last = dep->out_queue.last;
    dep->out_queue.first = NULL;
    dep->out_queue.last = NULL;
    erts_smp_mtx_unlock(&dep->qlock);

    foq.first = dep->finalized_out_queue.first;
    foq.last = dep->finalized_out_queue.last;
    dep->finalized_out_queue.first = NULL;
    dep->finalized_out_queue.last = NULL;

    sched_flags = erts_smp_atomic32_read_nob(&prt->sched.flags);

    if (reds > reds_limit)
	goto preempted;

    if (!(sched_flags & ERTS_PTS_FLG_BUSY_PORT) && foq.first) {
	int preempt = 0;
	do {
	    Uint size;
	    ErtsDistOutputBuf *fob;

	    size = (*send)(prt, foq.first);
	    esdp->io.out += (Uint64) size;
#ifdef ERTS_RAW_DIST_MSG_DBG
	    erts_fprintf(stderr, ">> ");
	    bw(foq.first->extp, size);
#endif
	    reds += ERTS_PORT_REDS_DIST_CMD_DATA(size);
	    fob = foq.first;
	    obufsize += size_obuf(fob);
	    foq.first = foq.first->next;
	    free_dist_obuf(fob);
	    sched_flags = erts_smp_atomic32_read_nob(&prt->sched.flags);
	    preempt = reds > reds_limit || (sched_flags & ERTS_PTS_FLG_EXIT);
	    if (sched_flags & ERTS_PTS_FLG_BUSY_PORT)
		break;
	} while (foq.first && !preempt);
	if (!foq.first)
	    foq.last = NULL;
	if (preempt)
	    goto preempted;
    }

    if (sched_flags & ERTS_PTS_FLG_BUSY_PORT) {
	if (oq.first) {
	    ErtsDistOutputBuf *ob;
	    int preempt;
	finalize_only:
	    preempt = 0;
	    ob = oq.first;
	    ASSERT(ob);
	    do {
		ob->extp = erts_encode_ext_dist_header_finalize(ob->extp,
								dep->cache,
								flags);
		if (!(flags & DFLAG_DIST_HDR_ATOM_CACHE))
		    *--ob->extp = PASS_THROUGH; /* Old node; 'pass through'
						   needed */
		ASSERT(&ob->data[0] <= ob->extp && ob->extp < ob->ext_endp);
		reds += ERTS_PORT_REDS_DIST_CMD_FINALIZE;
		preempt = reds > reds_limit;
		if (preempt)
		    break;
		ob = ob->next;
	    } while (ob);
	    /*
	     * At least one buffer was finalized; if we got preempted,
	     * ob points to the last buffer that we finalized.
	     */
	    if (foq.last)
		foq.last->next = oq.first;
	    else
		foq.first = oq.first;
	    if (!preempt) {
		/* All buffers finalized */
		foq.last = oq.last;
		oq.first = oq.last = NULL;
	    }
	    else {
		/* Not all buffers finalized; split oq. */
		foq.last = ob;
		oq.first = ob->next;
		if (oq.first)
		    ob->next = NULL;
		else
		    oq.last = NULL;
	    }
	    if (preempt)
		goto preempted;
	}
    }
    else {
	int preempt = 0;
	while (oq.first && !preempt) {
	    ErtsDistOutputBuf *fob;
	    Uint size;
	    oq.first->extp
		= erts_encode_ext_dist_header_finalize(oq.first->extp,
						       dep->cache,
						       flags);
	    reds += ERTS_PORT_REDS_DIST_CMD_FINALIZE;
	    if (!(flags & DFLAG_DIST_HDR_ATOM_CACHE))
		*--oq.first->extp = PASS_THROUGH; /* Old node; 'pass through'
						     needed */
	    ASSERT(&oq.first->data[0] <= oq.first->extp
		   && oq.first->extp < oq.first->ext_endp);
	    size = (*send)(prt, oq.first);
	    esdp->io.out += (Uint64) size;
#ifdef ERTS_RAW_DIST_MSG_DBG
	    erts_fprintf(stderr, ">> ");
	    bw(oq.first->extp, size);
#endif
	    reds += ERTS_PORT_REDS_DIST_CMD_DATA(size);
	    fob = oq.first;
	    obufsize += size_obuf(fob);
	    oq.first = oq.first->next;
	    free_dist_obuf(fob);
	    sched_flags = erts_smp_atomic32_read_nob(&prt->sched.flags);
	    preempt = reds > reds_limit || (sched_flags & ERTS_PTS_FLG_EXIT);
	    if ((sched_flags & ERTS_PTS_FLG_BUSY_PORT) && oq.first && !preempt)
		goto finalize_only;
	}

	ASSERT(!oq.first || preempt);

	/*
	 * Preempt if not all buffers have been handled.
	 */
	if (preempt && oq.first)
	    goto preempted;

#ifdef DEBUG
	oq.last = NULL;
#endif
	ASSERT(!oq.first);
	ASSERT(!foq.first && !foq.last);

	/*
	 * Everything that was buffered when we started have now been
	 * written to the port. If port isn't busy but dist entry is
	 * and we havn't got too muched queued on dist entry, set
	 * dist entry in a non-busy state and resume suspended
	 * processes.
	 */
	erts_smp_mtx_lock(&dep->qlock);
	ASSERT(dep->qsize >= obufsize);
	dep->qsize -= obufsize;
	obufsize = 0;
	if (!(sched_flags & ERTS_PTS_FLG_BUSY_PORT)
	    && (dep->qflgs & ERTS_DE_QFLG_BUSY)
	    && dep->qsize < erts_dist_buf_busy_limit) {
	    ErtsProcList *suspendees;
	    int resumed;
	    suspendees = get_suspended_on_de(dep, ERTS_DE_QFLG_BUSY);
	    erts_smp_mtx_unlock(&dep->qlock);

	    resumed = erts_resume_processes(suspendees);
	    reds += resumed*ERTS_PORT_REDS_DIST_CMD_RESUMED;
	}
	else
	    erts_smp_mtx_unlock(&dep->qlock);
    }

    ASSERT(!oq.first && !oq.last);

 done:

    if (obufsize != 0) {
	ASSERT(obufsize > 0);
	erts_smp_mtx_lock(&dep->qlock);
	ASSERT(dep->qsize >= obufsize);
	dep->qsize -= obufsize;
	erts_smp_mtx_unlock(&dep->qlock);
    }

    ASSERT(foq.first || !foq.last);
    ASSERT(!foq.first || foq.last);
    ASSERT(!dep->finalized_out_queue.first);
    ASSERT(!dep->finalized_out_queue.last);

    if (foq.first) {
	dep->finalized_out_queue.first = foq.first;
	dep->finalized_out_queue.last = foq.last;
    }

     /* Avoid wrapping reduction counter... */
    if (reds > INT_MAX/2)
	reds = INT_MAX/2;

    erts_deref_dist_entry(dep);

    return reds;

 preempted:
    /*
     * Here we assume that state has been read
     * since last call to driver.
     */

    ASSERT(oq.first || !oq.last);
    ASSERT(!oq.first || oq.last);

    if (sched_flags & ERTS_PTS_FLG_EXIT) {
	/*
	 * Port died during port command; clean up 'oq'
	 * and 'foq'. Things buffered in dist entry after
	 * we begun processing the queues have already been
	 * cleaned up when port terminated.
	 */

	if (oq.first)
	    oq.last->next = foq.first;
	else
	    oq.first = foq.first;

	while (oq.first) {
	    ErtsDistOutputBuf *fob = oq.first;
	    oq.first = oq.first->next;
	    obufsize += size_obuf(fob);
	    free_dist_obuf(fob);
	}

	foq.first = NULL;
	foq.last = NULL;

#ifdef DEBUG
	erts_smp_mtx_lock(&dep->qlock);
	ASSERT(dep->qsize == obufsize);
	erts_smp_mtx_unlock(&dep->qlock);
#endif
    }
    else {
	if (oq.first) {
	    /*
	     * Unhandle buffers need to be put back first
	     * in out_queue.
	     */
	    erts_smp_mtx_lock(&dep->qlock);
	    dep->qsize -= obufsize;
	    obufsize = 0;
	    oq.last->next = dep->out_queue.first;
	    dep->out_queue.first = oq.first;
	    if (!dep->out_queue.last)
		dep->out_queue.last = oq.last;
	    erts_smp_mtx_unlock(&dep->qlock);
	}

	erts_schedule_dist_command(prt, NULL);
    }
    goto done;
}

void
erts_dist_port_not_busy(Port *prt)
{
#ifdef USE_VM_PROBES
    if (DTRACE_ENABLED(dist_port_not_busy)) {
        DTRACE_CHARBUF(port_str, 64);
        DTRACE_CHARBUF(remote_str, 64);

        erts_snprintf(port_str, sizeof(DTRACE_CHARBUF_NAME(port_str)),
                      "%T", prt->common.id);
        erts_snprintf(remote_str, sizeof(DTRACE_CHARBUF_NAME(remote_str)),
                      "%T", prt->dist_entry->sysname);
        DTRACE3(dist_port_not_busy, erts_this_node_sysname,
                port_str, remote_str);
    }
#endif
    erts_schedule_dist_command(prt, NULL);
}

void
erts_kill_dist_connection(DistEntry *dep, Uint32 connection_id)
{
    erts_smp_de_rwlock(dep);
    if (is_internal_port(dep->cid)
	&& connection_id == dep->connection_id
	&& !(dep->status & ERTS_DE_SFLG_EXITING)) {

	dep->status |= ERTS_DE_SFLG_EXITING;

	erts_smp_mtx_lock(&dep->qlock);
	ASSERT(!(dep->qflgs & ERTS_DE_QFLG_EXIT));
	dep->qflgs |= ERTS_DE_QFLG_EXIT;
	erts_smp_mtx_unlock(&dep->qlock);

	erts_schedule_dist_command(NULL, dep);
    }
    erts_smp_de_rwunlock(dep);
}

struct print_to_data {
    fmtfn_t to;
    void *arg;
};

static void doit_print_monitor_info(ErtsMonitor *mon, void *vptdp)
{
    fmtfn_t to = ((struct print_to_data *) vptdp)->to;
    void *arg = ((struct print_to_data *) vptdp)->arg;
    Process *rp;
    ErtsMonitor *rmon;
    rp = erts_proc_lookup(mon->pid);
    if (!rp || (rmon = erts_lookup_monitor(ERTS_P_MONITORS(rp), mon->ref)) == NULL) {
	erts_print(to, arg, "Warning, stray monitor for: %T\n", mon->pid);
    } else if (mon->type == MON_ORIGIN) {
	/* Local pid is being monitored */
	erts_print(to, arg, "Remotely monitored by: %T %T\n",
		   mon->pid, rmon->pid);
    } else {
	erts_print(to, arg, "Remote monitoring: %T ", mon->pid);
	if (is_not_atom(rmon->pid))
	    erts_print(to, arg, "%T\n", rmon->pid);
	else
	    erts_print(to, arg, "{%T, %T}\n",
		       rmon->name,
		       rmon->pid); /* which in this case is the 
				      remote system name... */
    }
}    

static void print_monitor_info(fmtfn_t to, void *arg, ErtsMonitor *mon)
{
    struct print_to_data ptd = {to, arg};
    erts_doforall_monitors(mon,&doit_print_monitor_info,&ptd);
}

typedef struct {
    struct print_to_data *ptdp;
    Eterm from;
} PrintLinkContext;

static void doit_print_link_info2(ErtsLink *lnk, void *vpplc)
{
    PrintLinkContext *pplc = (PrintLinkContext *) vpplc;
    erts_print(pplc->ptdp->to, pplc->ptdp->arg, "Remote link: %T %T\n",
	       pplc->from, lnk->pid);
}

static void doit_print_link_info(ErtsLink *lnk, void *vptdp)
{
    if (is_internal_pid(lnk->pid) && erts_proc_lookup(lnk->pid)) {
	PrintLinkContext plc = {(struct print_to_data *) vptdp, lnk->pid};
	erts_doforall_links(ERTS_LINK_ROOT(lnk), &doit_print_link_info2, &plc);
    } 
}

static void print_link_info(fmtfn_t to, void *arg, ErtsLink *lnk)
{
    struct print_to_data ptd = {to, arg};
    erts_doforall_links(lnk, &doit_print_link_info, (void *) &ptd);
}

typedef struct {
    struct print_to_data ptd;
    Eterm sysname;
} PrintNodeLinkContext;
    

static void doit_print_nodelink_info(ErtsLink *lnk, void *vpcontext)
{
    PrintNodeLinkContext *pcontext = vpcontext;

    if (is_internal_pid(lnk->pid) && erts_proc_lookup(lnk->pid))
	erts_print(pcontext->ptd.to, pcontext->ptd.arg,
		   "Remote monitoring: %T %T\n", lnk->pid, pcontext->sysname);
}

static void print_nodelink_info(fmtfn_t to, void *arg, ErtsLink *lnk, Eterm sysname)
{
    PrintNodeLinkContext context = {{to, arg}, sysname};
    erts_doforall_links(lnk, &doit_print_nodelink_info, &context);
}


static int
info_dist_entry(fmtfn_t to, void *arg, DistEntry *dep, int visible, int connected)
{

  if (visible && connected) {
      erts_print(to, arg, "=visible_node:");
  } else if (connected) {
      erts_print(to, arg, "=hidden_node:");
  } else {
      erts_print(to, arg, "=not_connected:");
  }
  erts_print(to, arg, "%d\n", dist_entry_channel_no(dep));

  if(connected && is_nil(dep->cid)) {
    erts_print(to, arg,
	       "Error: Not connected node still registered as connected:%T\n",
	       dep->sysname);
    return 0;
  }

  if(!connected && is_not_nil(dep->cid)) {
    erts_print(to, arg,
	       "Error: Connected node not registered as connected:%T\n",
	       dep->sysname);
    return 0;
  }

  erts_print(to, arg, "Name: %T", dep->sysname);
#ifdef DEBUG
  erts_print(to, arg, " (refc=%d)", erts_smp_refc_read(&dep->refc, 0));
#endif
  erts_print(to, arg, "\n");
  if (!connected && is_nil(dep->cid)) {
    if (dep->nlinks) {
      erts_print(to, arg, "Error: Got links to not connected node:%T\n",
		 dep->sysname);
    }
    return 0;
  }

  erts_print(to, arg, "Controller: %T\n", dep->cid, to);

  erts_print_node_info(to, arg, dep->sysname, NULL, NULL);
  print_monitor_info(to, arg, dep->monitors);
  print_link_info(to, arg, dep->nlinks);
  print_nodelink_info(to, arg, dep->node_links, dep->sysname);

  return 0;
    
}
int distribution_info(fmtfn_t to, void *arg)	/* Called by break handler */
{
    DistEntry *dep;

    erts_print(to, arg, "=node:%T\n", erts_this_dist_entry->sysname);
 
    if (erts_this_node->sysname == am_Noname) {
	erts_print(to, arg, "=no_distribution\n");
	return(0);
    }

#if 0
    if (!erts_visible_dist_entries && !erts_hidden_dist_entries) 
      erts_print(to, arg, "Alive but not holding any connections \n");
#endif

    for(dep = erts_visible_dist_entries; dep; dep = dep->next) {
      info_dist_entry(to, arg, dep, 1, 1);
    }

    for(dep = erts_hidden_dist_entries; dep; dep = dep->next) {
      info_dist_entry(to, arg, dep, 0, 1);
    }

    for (dep = erts_not_connected_dist_entries; dep; dep = dep->next) {
        if (dep != erts_this_dist_entry) {
            info_dist_entry(to, arg, dep, 0, 0);
        }
    }

    return(0);
}

/****************************************************************************
  DISTRIBUTION BIFS:

            setnode/2     -- start distribution
            setnode/3     -- set node controller

            node/1        -- return objects node name
            node/0        -- return this node name
            nodes/0       -- return a list of all (non hidden) nodes
            is_alive      -- return true if distribution is running else false
	    monitor_node  -- turn on/off node monitoring

            node controller only:
            dist_exit/3       -- send exit signals from remote to local process
            dist_link/2       -- link a remote process to a local
            dist_unlink/2     -- unlink a remote from a local
****************************************************************************/



/**********************************************************************
 ** Set the node name of current node fail if node already is set.
 ** setnode(name@host, Creation)
 ** loads functions pointer to trap_functions from module erlang.
 **    erlang:dsend/2
 **    erlang:dlink/1
 **    erlang:dunlink/1
 **    erlang:dmonitor_node/3
 **    erlang:dgroup_leader/2
 **    erlang:dexit/2
 **  -- are these needed ?
 **    dexit/1
 ***********************************************************************/

BIF_RETTYPE setnode_2(BIF_ALIST_2)
{
    Process *net_kernel;
    Uint creation;

    /* valid creation ? */
    if(!term_to_Uint(BIF_ARG_2, &creation))
	goto error;
    if(creation > 3)
	goto error;

    /* valid node name ? */
    if (!is_node_name_atom(BIF_ARG_1))
	goto error;

    if (BIF_ARG_1 == am_Noname) /* cant use this name !! */
	goto error;
    if (erts_is_alive)     /* must not be alive! */
	goto error;

    /* Check that all trap functions are defined !! */
    if (dsend2_trap->addressv[0] == NULL ||
	dsend3_trap->addressv[0] == NULL ||
	/*	dsend_nosuspend_trap->address == NULL ||*/
	dlink_trap->addressv[0] == NULL ||
	dunlink_trap->addressv[0] == NULL ||
	dmonitor_node_trap->addressv[0] == NULL ||
	dgroup_leader_trap->addressv[0] == NULL ||
	dmonitor_p_trap->addressv[0] == NULL ||
	dexit_trap->addressv[0] == NULL) {
	goto error;
    }

    net_kernel = erts_whereis_process(BIF_P, ERTS_PROC_LOCK_MAIN,
				      am_net_kernel, ERTS_PROC_LOCK_MAIN, 0);
    if (!net_kernel)
	goto error;

    /* By setting F_DISTRIBUTION on net_kernel,
     * do_net_exist will be called when net_kernel is terminated !! */
    net_kernel->flags |= F_DISTRIBUTION;

    if (net_kernel != BIF_P)
	erts_smp_proc_unlock(net_kernel, ERTS_PROC_LOCK_MAIN);

#ifdef DEBUG
    erts_smp_rwmtx_rlock(&erts_dist_table_rwmtx);
    ASSERT(!erts_visible_dist_entries && !erts_hidden_dist_entries);
    erts_smp_rwmtx_runlock(&erts_dist_table_rwmtx);
#endif

    erts_smp_proc_unlock(BIF_P, ERTS_PROC_LOCK_MAIN);
    erts_smp_thr_progress_block();
    inc_no_nodes();
    erts_set_this_node(BIF_ARG_1, (Uint32) creation);
    erts_is_alive = 1;
    send_nodes_mon_msgs(NULL, am_nodeup, BIF_ARG_1, am_visible, NIL);
    erts_smp_thr_progress_unblock();
    erts_smp_proc_lock(BIF_P, ERTS_PROC_LOCK_MAIN);

    BIF_RET(am_true);

 error:
    BIF_ERROR(BIF_P, BADARG);
}

/**********************************************************************
 ** Allocate a dist entry, set node name install the connection handler
 ** setnode_3({name@host, Creation}, Cid, {Type, Version, Initial, IC, OC})
 ** Type = flag field, where the flags are specified in dist.h
 ** Version = distribution version, >= 1
 ** IC = in_cookie (ignored)
 ** OC = out_cookie (ignored)
 **
 ** Note that in distribution protocols above 1, the Initial parameter
 ** is always NIL and the cookies are always the atom '', cookies are not
 ** sent in the distribution messages but are only used in 
 ** the handshake.
 **
 ***********************************************************************/

BIF_RETTYPE setnode_3(BIF_ALIST_3)
{
    BIF_RETTYPE ret;
    Uint flags;
    unsigned long version;
    Eterm ic, oc;
    Eterm *tp;
    DistEntry *dep = NULL;
    Port *pp = NULL;

    /* Prepare for success */
    ERTS_BIF_PREP_RET(ret, am_true);

    /*
     * Check and pick out arguments
     */

    if (!is_node_name_atom(BIF_ARG_1) ||
	is_not_internal_port(BIF_ARG_2) ||
	(erts_this_node->sysname == am_Noname)) {
	goto badarg;
    }

    if (!is_tuple(BIF_ARG_3))
	goto badarg;
    tp = tuple_val(BIF_ARG_3);
    if (*tp++ != make_arityval(4))
	goto badarg;
    if (!is_small(*tp))
	goto badarg;
    flags = unsigned_val(*tp++);
    if (!is_small(*tp) || (version = unsigned_val(*tp)) == 0)
	goto badarg;
    ic = *(++tp);
    oc = *(++tp);
    if (!is_atom(ic) || !is_atom(oc))
	goto badarg;

    /* DFLAG_EXTENDED_REFERENCES is compulsory from R9 and forward */
    if (!(DFLAG_EXTENDED_REFERENCES & flags)) {
	erts_dsprintf_buf_t *dsbufp = erts_create_logger_dsbuf();
	erts_dsprintf(dsbufp, "%T", BIF_P->common.id);
	if (BIF_P->common.u.alive.reg)
	    erts_dsprintf(dsbufp, " (%T)", BIF_P->common.u.alive.reg->name);
	erts_dsprintf(dsbufp,
		      " attempted to enable connection to node %T "
		      "which is not able to handle extended references.\n",
		      BIF_ARG_1);
	erts_send_error_to_logger(BIF_P->group_leader, dsbufp);
	goto badarg;
    }

    /*
     * Arguments seem to be in order.
     */

    /* get dist_entry */
    dep = erts_find_or_insert_dist_entry(BIF_ARG_1);
    if (dep == erts_this_dist_entry)
	goto badarg;
    else if (!dep)
	goto system_limit; /* Should never happen!!! */

    pp = erts_id2port_sflgs(BIF_ARG_2,
			    BIF_P,
			    ERTS_PROC_LOCK_MAIN,
			    ERTS_PORT_SFLGS_INVALID_LOOKUP);
    erts_smp_de_rwlock(dep);

    if (!pp || (erts_atomic32_read_nob(&pp->state)
		& ERTS_PORT_SFLG_EXITING))
	goto badarg;

    if ((pp->drv_ptr->flags & ERL_DRV_FLAG_SOFT_BUSY) == 0)
	goto badarg;

    if (dep->cid == BIF_ARG_2 && pp->dist_entry == dep)
	goto done; /* Already set */

    if (dep->status & ERTS_DE_SFLG_EXITING) {
	/* Suspend on dist entry waiting for the exit to finish */
	ErtsProcList *plp = erts_proclist_create(BIF_P);
	plp->next = NULL;
	erts_suspend(BIF_P, ERTS_PROC_LOCK_MAIN, NULL);
	erts_smp_mtx_lock(&dep->qlock);
	erts_proclist_store_last(&dep->suspended, plp);
	erts_smp_mtx_unlock(&dep->qlock);
	goto yield;
    }

    ASSERT(!(dep->status & ERTS_DE_SFLG_EXITING));

    if (pp->dist_entry || is_not_nil(dep->cid))
	goto badarg;

    erts_atomic32_read_bor_nob(&pp->state, ERTS_PORT_SFLG_DISTRIBUTION);

    /*
     * Dist-ports do not use the "busy port message queue" functionality, but
     * instead use "busy dist entry" functionality.
     */
    {
	ErlDrvSizeT disable = ERL_DRV_BUSY_MSGQ_DISABLED;
	erl_drv_busy_msgq_limits(ERTS_Port2ErlDrvPort(pp), &disable, NULL);
    }

    pp->dist_entry = dep;

    dep->version = version;
    dep->creation = 0;

    ASSERT(pp->drv_ptr->outputv || pp->drv_ptr->output);

#if 1
    dep->send = (pp->drv_ptr->outputv
		 ? dist_port_commandv
		 : dist_port_command);
#else
    dep->send = dist_port_command;
#endif
    ASSERT(dep->send);

#ifdef DEBUG
    erts_smp_mtx_lock(&dep->qlock);
    ASSERT(dep->qsize == 0);
    erts_smp_mtx_unlock(&dep->qlock);
#endif

    erts_set_dist_entry_connected(dep, BIF_ARG_2, flags);

    if (flags & DFLAG_DIST_HDR_ATOM_CACHE)
	create_cache(dep);

    erts_smp_de_rwunlock(dep);
    dep = NULL; /* inc of refc transferred to port (dist_entry field) */

    inc_no_nodes();

    send_nodes_mon_msgs(BIF_P,
			am_nodeup,
			BIF_ARG_1,
			flags & DFLAG_PUBLISHED ? am_visible : am_hidden,
			NIL);
 done:

    if (dep && dep != erts_this_dist_entry) {
	erts_smp_de_rwunlock(dep);
	erts_deref_dist_entry(dep);
    }

    if (pp)
	erts_port_release(pp);

    return ret;

 yield:
    ERTS_BIF_PREP_YIELD3(ret, bif_export[BIF_setnode_3], BIF_P,
			 BIF_ARG_1, BIF_ARG_2, BIF_ARG_3);
    goto done;

 badarg:
    ERTS_BIF_PREP_ERROR(ret, BIF_P, BADARG);
    goto done;

 system_limit:
    ERTS_BIF_PREP_ERROR(ret, BIF_P, SYSTEM_LIMIT);
    goto done;
}


/**********************************************************************/
/* dist_exit(Local, Term, Remote) -> Bool */

BIF_RETTYPE dist_exit_3(BIF_ALIST_3)
{
    Eterm local;
    Eterm remote;
    DistEntry *rdep;

    local = BIF_ARG_1;
    remote = BIF_ARG_3;

    /* Check that remote is a remote process */
    if (is_not_external_pid(remote))
	goto error;

    rdep = external_dist_entry(remote);
    
    if(rdep == erts_this_dist_entry)
	goto error;

    /* Check that local is local */
    if (is_internal_pid(local)) {
	Process *lp;
	ErtsProcLocks lp_locks;
	if (BIF_P->common.id == local) {
	    lp_locks = ERTS_PROC_LOCKS_ALL;
	    lp = BIF_P;
	    erts_smp_proc_lock(BIF_P, ERTS_PROC_LOCKS_ALL_MINOR);
	}
	else {
	    lp_locks = ERTS_PROC_LOCKS_XSIG_SEND;
	    lp = erts_pid2proc(BIF_P, ERTS_PROC_LOCK_MAIN,
			       local, lp_locks);
	    if (!lp) {
		BIF_RET(am_true); /* ignore */
	    }
	}
	
	(void) erts_send_exit_signal(BIF_P,
				     remote,
				     lp,
				     &lp_locks,
				     BIF_ARG_2,
				     NIL,
				     NULL,
				     0);
#ifdef ERTS_SMP
	if (lp == BIF_P)
	    lp_locks &= ~ERTS_PROC_LOCK_MAIN;
#endif
	erts_smp_proc_unlock(lp, lp_locks);
	if (lp == BIF_P) {
	    erts_aint32_t state = erts_smp_atomic32_read_acqb(&BIF_P->state);
	    /*
	     * We may have exited current process and may have to take action.
	     */
	    if (state & (ERTS_PSFLG_EXITING|ERTS_PSFLG_PENDING_EXIT)) {
#ifdef ERTS_SMP
		if (state & ERTS_PSFLG_PENDING_EXIT)
		    erts_handle_pending_exit(BIF_P, ERTS_PROC_LOCK_MAIN);
#endif
		ERTS_BIF_EXITED(BIF_P);
	    }
	}
    }
    else if (is_external_pid(local)
	     && external_dist_entry(local) == erts_this_dist_entry) {
	BIF_RET(am_true); /* ignore */
    }
    else
	goto error;
    BIF_RET(am_true);

 error:
    BIF_ERROR(BIF_P, BADARG);
}

/**********************************************************************/
/* node(Object) -> Node */

BIF_RETTYPE node_1(BIF_ALIST_1)
{ 
    if (is_not_node_container(BIF_ARG_1))
      BIF_ERROR(BIF_P, BADARG);
    BIF_RET(node_container_node_name(BIF_ARG_1));
}

/**********************************************************************/
/* node() -> Node */

BIF_RETTYPE node_0(BIF_ALIST_0)
{
    BIF_RET(erts_this_dist_entry->sysname);
}


/**********************************************************************/
/* nodes() -> [ Node ] */

#if 0 /* Done in erlang.erl instead. */
BIF_RETTYPE nodes_0(BIF_ALIST_0)
{
  return nodes_1(BIF_P, am_visible);
}
#endif


BIF_RETTYPE nodes_1(BIF_ALIST_1)
{
    Eterm result;
    int length;
    Eterm* hp;
    int not_connected = 0;
    int visible = 0;
    int hidden = 0;
    int this = 0;
    DeclareTmpHeap(buf,2,BIF_P); /* For one cons-cell */
    DistEntry *dep;
    Eterm arg_list = BIF_ARG_1;
#ifdef DEBUG
    Eterm* endp;
#endif

    UseTmpHeap(2,BIF_P);

    if (is_atom(BIF_ARG_1))
      arg_list = CONS(buf, BIF_ARG_1, NIL);

    while (is_list(arg_list)) {
      switch(CAR(list_val(arg_list))) {
      case am_visible:   visible = 1;                                 break;
      case am_hidden:    hidden = 1;                                  break;
      case am_known:     visible = hidden = not_connected = this = 1; break;
      case am_this:      this = 1;                                    break;
      case am_connected: visible = hidden = 1;                        break;
      default:           goto error;                                  break;
      }
      arg_list = CDR(list_val(arg_list));
    }

    if (is_not_nil(arg_list)) {
	goto error;
    }

    length = 0;

    erts_smp_rwmtx_rlock(&erts_dist_table_rwmtx);

    ASSERT(erts_no_of_not_connected_dist_entries > 0);
    ASSERT(erts_no_of_hidden_dist_entries >= 0);
    ASSERT(erts_no_of_visible_dist_entries >= 0);
    if(not_connected)
      length += (erts_no_of_not_connected_dist_entries - 1);
    if(hidden)
      length += erts_no_of_hidden_dist_entries;
    if(visible)
      length += erts_no_of_visible_dist_entries;
    if(this)
      length++;

    result = NIL;

    if (length == 0) {
	erts_smp_rwmtx_runlock(&erts_dist_table_rwmtx);
	goto done;
    }

    hp = HAlloc(BIF_P, 2*length);

#ifdef DEBUG
    endp = hp + length*2;
#endif
    if(not_connected)
      for(dep = erts_not_connected_dist_entries; dep; dep = dep->next) {
          if (dep != erts_this_dist_entry) {
            result = CONS(hp, dep->sysname, result);
            hp += 2;
          }
      }
    if(hidden)
      for(dep = erts_hidden_dist_entries; dep; dep = dep->next) {
	result = CONS(hp, dep->sysname, result);
	hp += 2;
      }
    if(visible)
      for(dep = erts_visible_dist_entries; dep; dep = dep->next) {
	result = CONS(hp, dep->sysname, result);
	hp += 2;
      }
    if(this) {
	result = CONS(hp, erts_this_dist_entry->sysname, result);
	hp += 2;
    }
    ASSERT(endp == hp);
    erts_smp_rwmtx_runlock(&erts_dist_table_rwmtx);

done:
    UnUseTmpHeap(2,BIF_P);
    BIF_RET(result);

error:
    UnUseTmpHeap(2,BIF_P);
    BIF_ERROR(BIF_P,BADARG);
}

/**********************************************************************/
/* is_alive() -> Bool */

BIF_RETTYPE is_alive_0(BIF_ALIST_0)
{
    Eterm res = erts_is_alive ? am_true : am_false;
    BIF_RET(res);
}

/**********************************************************************/
/* erlang:monitor_node(Node, Bool, Options) -> Bool */

static BIF_RETTYPE
monitor_node(Process* p, Eterm Node, Eterm Bool, Eterm Options)
{
    DistEntry *dep;
    ErtsLink *lnk;
    Eterm l;

    for (l = Options; l != NIL && is_list(l); l = CDR(list_val(l))) {
	Eterm t = CAR(list_val(l));
	/* allow_passive_connect the only available option right now */
	if (t != am_allow_passive_connect) {
	    BIF_ERROR(p, BADARG);
	}
    }
    if (l != NIL) {
	BIF_ERROR(p, BADARG);
    }

    if (is_not_atom(Node) ||
	((Bool != am_true) && (Bool != am_false)) ||
	((erts_this_node->sysname == am_Noname)
	 && (Node != erts_this_node->sysname))) {
	BIF_ERROR(p, BADARG);
    }
    dep = erts_sysname_to_connected_dist_entry(Node);
    if (!dep) {
    do_trap:
	BIF_TRAP3(dmonitor_node_trap, p, Node, Bool, Options);
    }
    if (dep == erts_this_dist_entry)
	goto done;

    erts_smp_proc_lock(p, ERTS_PROC_LOCK_LINK);
    erts_smp_de_rlock(dep);
    if (ERTS_DE_IS_NOT_CONNECTED(dep)) {
	erts_smp_proc_unlock(p, ERTS_PROC_LOCK_LINK);
	erts_smp_de_runlock(dep);
	goto do_trap;
    }
    erts_smp_de_links_lock(dep);
    erts_smp_de_runlock(dep);

    if (Bool == am_true) {
	ASSERT(dep->cid != NIL);
	lnk = erts_add_or_lookup_link(&(dep->node_links), LINK_NODE, 
				      p->common.id);
	++ERTS_LINK_REFC(lnk);
	lnk = erts_add_or_lookup_link(&ERTS_P_LINKS(p), LINK_NODE, Node);
	++ERTS_LINK_REFC(lnk);
    }
    else  {
	lnk = erts_lookup_link(dep->node_links, p->common.id);
	if (lnk != NULL) {
	    if ((--ERTS_LINK_REFC(lnk)) == 0) {
		erts_destroy_link(erts_remove_link(&(dep->node_links), 
						   p->common.id));
	    }
	}
	lnk = erts_lookup_link(ERTS_P_LINKS(p), Node);
	if (lnk != NULL) {
	    if ((--ERTS_LINK_REFC(lnk)) == 0) {
		erts_destroy_link(erts_remove_link(&ERTS_P_LINKS(p),
						   Node));
	    }
	}
    }

    erts_smp_de_links_unlock(dep);
    erts_smp_proc_unlock(p, ERTS_PROC_LOCK_LINK);

 done:
    erts_deref_dist_entry(dep);
    BIF_RET(am_true);
}

BIF_RETTYPE monitor_node_3(BIF_ALIST_3)
{
    BIF_RET(monitor_node(BIF_P, BIF_ARG_1, BIF_ARG_2, BIF_ARG_3));
}


/* monitor_node(Node, Bool) -> Bool */

BIF_RETTYPE monitor_node_2(BIF_ALIST_2)
{
    BIF_RET(monitor_node(BIF_P, BIF_ARG_1, BIF_ARG_2, NIL));
}

BIF_RETTYPE net_kernel_dflag_unicode_io_1(BIF_ALIST_1)
{
    DistEntry *de;
    Uint32 f;
    if (is_not_pid(BIF_ARG_1)) {
	BIF_ERROR(BIF_P,BADARG);
    }
    de = pid_dist_entry(BIF_ARG_1);
    ASSERT(de != NULL);
    if (de == erts_this_dist_entry) {
	BIF_RET(am_true);
    }
    erts_smp_de_rlock(de);
    f = de->flags;
    erts_smp_de_runlock(de);
    BIF_RET(((f & DFLAG_UNICODE_IO) ? am_true : am_false));
}
    
/*
 * The major part of the implementation of net_kernel:monitor_nodes/[1,2]
 * follows.
 *
 * Currently net_kernel:monitor_nodes/[1,2] calls process_flag/2 which in
 * turn calls erts_monitor_nodes(). If the process_flag() call fails (with
 * badarg), the code in net_kernel determines what type of error to return.
 * This in order to simplify the task of being backward compatible.
 */

#define ERTS_NODES_MON_OPT_TYPE_VISIBLE		(((Uint16) 1) << 0)
#define ERTS_NODES_MON_OPT_TYPE_HIDDEN		(((Uint16) 1) << 1)
#define ERTS_NODES_MON_OPT_DOWN_REASON		(((Uint16) 1) << 2)

#define ERTS_NODES_MON_OPT_TYPES \
  (ERTS_NODES_MON_OPT_TYPE_VISIBLE|ERTS_NODES_MON_OPT_TYPE_HIDDEN)

typedef struct ErtsNodesMonitor_ ErtsNodesMonitor;
struct ErtsNodesMonitor_ {
    ErtsNodesMonitor *prev;
    ErtsNodesMonitor *next;
    Process *proc;
    Uint16 opts;
    Uint16 no;
};

static erts_smp_mtx_t nodes_monitors_mtx;
static ErtsNodesMonitor *nodes_monitors;
static ErtsNodesMonitor *nodes_monitors_end;

/*
 * Nodes monitors are stored in a double linked list. 'nodes_monitors'
 * points to the beginning of the list and 'nodes_monitors_end' points
 * to the end of the list.
 *
 * There might be more than one entry per process in the list. If so,
 * they are located in sequence. The 'nodes_monitors' field of the
 * process struct refers to the first element in the sequence
 * corresponding to the process in question.
 */

static void
init_nodes_monitors(void)
{
    erts_smp_mtx_init(&nodes_monitors_mtx, "nodes_monitors");
    nodes_monitors = NULL;
    nodes_monitors_end = NULL;
}

static ERTS_INLINE Uint
nodes_mon_msg_sz(ErtsNodesMonitor *nmp, Eterm what, Eterm reason)
{
    Uint sz;
    if (!nmp->opts) {
	sz = 3;
    }
    else {
	sz = 0;

	if (nmp->opts & ERTS_NODES_MON_OPT_TYPES)
	    sz += 2 + 3;

	if (what == am_nodedown
	    && (nmp->opts & ERTS_NODES_MON_OPT_DOWN_REASON)) {
	    if (is_not_immed(reason))
		sz += size_object(reason);
	    sz += 2 + 3;
	}

	sz += 4;
    }
    return sz;
}

static ERTS_INLINE void
send_nodes_mon_msg(Process *rp,
		   ErtsProcLocks *rp_locksp,
		   ErtsNodesMonitor *nmp,
		   Eterm node,
		   Eterm what,
		   Eterm type,
		   Eterm reason,
		   Uint sz)
{
    Eterm msg;
    Eterm *hp;
    ErtsMessage *mp;
    ErlOffHeap *ohp;
#ifdef DEBUG
    Eterm *hend;
#endif

    mp = erts_alloc_message_heap(rp, rp_locksp, sz, &hp, &ohp);
#ifdef DEBUG
    hend = hp + sz;
#endif

    if (!nmp->opts) {
	msg = TUPLE2(hp, what, node);
#ifdef DEBUG
	hp += 3;
#endif
    }
    else {
	Eterm tup;
	Eterm info = NIL;

	if (nmp->opts & (ERTS_NODES_MON_OPT_TYPE_VISIBLE
			 | ERTS_NODES_MON_OPT_TYPE_HIDDEN)) {

	    tup = TUPLE2(hp, am_node_type, type);
	    hp += 3;
	    info = CONS(hp, tup, info);
	    hp += 2;
	}

	if (what == am_nodedown
	    && (nmp->opts & ERTS_NODES_MON_OPT_DOWN_REASON)) {
	    Eterm rsn_cpy;
	    
	    if (is_immed(reason))
		rsn_cpy = reason;
	    else {
		Eterm rsn_sz = size_object(reason);
		rsn_cpy = copy_struct(reason, rsn_sz, &hp, ohp);
	    }

	    tup = TUPLE2(hp, am_nodedown_reason, rsn_cpy);
	    hp += 3;
	    info = CONS(hp, tup, info);
	    hp += 2;
	}

	msg = TUPLE3(hp, what, node, info);
#ifdef DEBUG
	hp += 4;
#endif
    }

    ASSERT(hend == hp);
    erts_queue_message(rp, *rp_locksp, mp, msg, am_system);
}

static void
send_nodes_mon_msgs(Process *c_p, Eterm what, Eterm node, Eterm type, Eterm reason)
{
    ErtsNodesMonitor *nmp;
    ErtsProcLocks rp_locks = 0; /* Init to shut up false warning */
    Process *rp = NULL;

    ASSERT(is_immed(what));
    ASSERT(is_immed(node));
    ASSERT(is_immed(type));
#ifdef USE_VM_PROBES
    if (DTRACE_ENABLED(dist_monitor)) {
        DTRACE_CHARBUF(what_str, 12);
        DTRACE_CHARBUF(node_str, 64);
        DTRACE_CHARBUF(type_str, 12);
        DTRACE_CHARBUF(reason_str, 64);

        erts_snprintf(what_str, sizeof(DTRACE_CHARBUF_NAME(what_str)), "%T", what);
        erts_snprintf(node_str, sizeof(DTRACE_CHARBUF_NAME(node_str)), "%T", node);
        erts_snprintf(type_str, sizeof(DTRACE_CHARBUF_NAME(type_str)), "%T", type);
        erts_snprintf(reason_str, sizeof(DTRACE_CHARBUF_NAME(reason_str)), "%T", reason);
        DTRACE5(dist_monitor, erts_this_node_sysname,
                what_str, node_str, type_str, reason_str);
    }
#endif

    ERTS_SMP_LC_ASSERT(!c_p
		       || (erts_proc_lc_my_proc_locks(c_p)
			   == ERTS_PROC_LOCK_MAIN));
    erts_smp_mtx_lock(&nodes_monitors_mtx);

    for (nmp = nodes_monitors; nmp; nmp = nmp->next) {
	int i;
	Uint16 no;
	Uint sz;

	ASSERT(nmp->proc != NULL);

	if (!nmp->opts) {
	    if (type != am_visible)
		continue;
	}
	else {
	    switch (type) {
	    case am_hidden:
		if (!(nmp->opts & ERTS_NODES_MON_OPT_TYPE_HIDDEN))
		    continue;
		break;
	    case am_visible:
		if ((nmp->opts & ERTS_NODES_MON_OPT_TYPES)
		    && !(nmp->opts & ERTS_NODES_MON_OPT_TYPE_VISIBLE))
		    continue;
		break;
	    default:
		erts_exit(ERTS_ABORT_EXIT, "Bad node type found\n");
	    }
	}

	if (rp != nmp->proc) {
	    if (rp) {
		if (rp == c_p)
		    rp_locks &= ~ERTS_PROC_LOCK_MAIN;
		erts_smp_proc_unlock(rp, rp_locks);
	    }

	    rp = nmp->proc;
	    rp_locks = 0;
	    if (rp == c_p)
		rp_locks |= ERTS_PROC_LOCK_MAIN;
	}

	ASSERT(rp);

	sz = nodes_mon_msg_sz(nmp, what, reason);

	for (i = 0, no = nmp->no; i < no; i++)
	    send_nodes_mon_msg(rp,
			       &rp_locks,
			       nmp,
			       node,
			       what,
			       type,
			       reason,
			       sz);
    }

    if (rp) {
	if (rp == c_p)
	    rp_locks &= ~ERTS_PROC_LOCK_MAIN;
	erts_smp_proc_unlock(rp, rp_locks);
    }

    erts_smp_mtx_unlock(&nodes_monitors_mtx);
}

static Eterm
insert_nodes_monitor(Process *c_p, Uint32 opts)
{
    Uint16 no = 1;
    Eterm res = am_false;
    ErtsNodesMonitor *xnmp, *nmp;

    ERTS_SMP_LC_ASSERT(erts_smp_lc_mtx_is_locked(&nodes_monitors_mtx));
    ERTS_SMP_LC_ASSERT(erts_proc_lc_my_proc_locks(c_p) & ERTS_PROC_LOCK_MAIN);

    xnmp = c_p->nodes_monitors;
    if (xnmp) {
	ASSERT(!xnmp->prev || xnmp->prev->proc != c_p);

	while (1) {
	    ASSERT(xnmp->proc == c_p);
	    if (xnmp->opts == opts)
		break;
	    if (!xnmp->next || xnmp->next->proc != c_p)
		break;
	    xnmp = xnmp->next;
	}
	ASSERT(xnmp);
	ASSERT(xnmp->proc == c_p);
	ASSERT(xnmp->opts == opts
	       || !xnmp->next
	       || xnmp->next->proc != c_p);

	if (xnmp->opts != opts)
	    goto alloc_new;
	else {
	    res = am_true;
	    no = xnmp->no++;
	    if (!xnmp->no) {
		/*
		 * 'no' wrapped; transfer all prevous monitors to new
		 * element (which will be the next element in the list)
		 * and set this to one...
		 */
		xnmp->no = 1;
		goto alloc_new;
	    }
	}
    }
    else {
    alloc_new:
	nmp = erts_alloc(ERTS_ALC_T_NODES_MON, sizeof(ErtsNodesMonitor));
	nmp->proc = c_p;
	nmp->opts = opts;
	nmp->no = no;

	if (xnmp) {
	    ASSERT(nodes_monitors);
	    ASSERT(c_p->nodes_monitors);
	    nmp->next = xnmp->next;
	    nmp->prev = xnmp;
	    xnmp->next = nmp;
	    if (nmp->next) {
		ASSERT(nodes_monitors_end != xnmp);
		ASSERT(nmp->next->prev == xnmp);
		nmp->next->prev = nmp;
	    }
	    else {
		ASSERT(nodes_monitors_end == xnmp);
		nodes_monitors_end = nmp;
	    }
	}
	else {
	    ASSERT(!c_p->nodes_monitors);
	    c_p->nodes_monitors = nmp;
	    nmp->next = NULL;
	    nmp->prev = nodes_monitors_end;
	    if (nodes_monitors_end) {
		ASSERT(nodes_monitors);
		nodes_monitors_end->next = nmp;
	    }
	    else {
		ASSERT(!nodes_monitors);
		nodes_monitors = nmp;
	    }
	    nodes_monitors_end = nmp;
	}
    }
    return res;
}

static Eterm
remove_nodes_monitors(Process *c_p, Uint32 opts, int all)
{
    Eterm res = am_false;
    ErtsNodesMonitor *nmp;

    ERTS_SMP_LC_ASSERT(erts_smp_lc_mtx_is_locked(&nodes_monitors_mtx));
    ERTS_SMP_LC_ASSERT(erts_proc_lc_my_proc_locks(c_p) & ERTS_PROC_LOCK_MAIN);

    nmp = c_p->nodes_monitors;
    ASSERT(!nmp || !nmp->prev || nmp->prev->proc != c_p);

    while (nmp && nmp->proc == c_p) {
	if (!all && nmp->opts != opts)
	    nmp = nmp->next;
	else { /* if (all || nmp->opts == opts) */
	    ErtsNodesMonitor *free_nmp;
	    res = am_true;
	    if (nmp->prev) {
		ASSERT(nodes_monitors != nmp);
		nmp->prev->next = nmp->next;
	    }
	    else {
		ASSERT(nodes_monitors == nmp);
		nodes_monitors = nmp->next;
	    }
	    if (nmp->next) {
		ASSERT(nodes_monitors_end != nmp);
		nmp->next->prev = nmp->prev;
	    }
	    else {
		ASSERT(nodes_monitors_end == nmp);
		nodes_monitors_end = nmp->prev;
	    }
	    free_nmp = nmp;
	    nmp = nmp->next;
	    if (c_p->nodes_monitors == free_nmp)
		c_p->nodes_monitors = nmp && nmp->proc == c_p ? nmp : NULL;
	    erts_free(ERTS_ALC_T_NODES_MON, free_nmp);
	}
    }
    
    ASSERT(!all || !c_p->nodes_monitors);
    return res;
}

void
erts_delete_nodes_monitors(Process *c_p, ErtsProcLocks locks)
{
#if defined(ERTS_ENABLE_LOCK_CHECK) && defined(ERTS_SMP)
    if (c_p) {
	ErtsProcLocks might_unlock = locks & ~ERTS_PROC_LOCK_MAIN;
	if (might_unlock)
	    erts_proc_lc_might_unlock(c_p, might_unlock);
    }
#endif
    if (erts_smp_mtx_trylock(&nodes_monitors_mtx) == EBUSY) {
	ErtsProcLocks unlock_locks = locks & ~ERTS_PROC_LOCK_MAIN;
	if (c_p && unlock_locks)
	    erts_smp_proc_unlock(c_p, unlock_locks);
	erts_smp_mtx_lock(&nodes_monitors_mtx);
	if (c_p && unlock_locks)
	    erts_smp_proc_lock(c_p, unlock_locks);
    }
    remove_nodes_monitors(c_p, 0, 1);
    erts_smp_mtx_unlock(&nodes_monitors_mtx);
}

Eterm
erts_monitor_nodes(Process *c_p, Eterm on, Eterm olist)
{
    Eterm res;
    Eterm opts_list = olist;
    Uint16 opts = (Uint16) 0;

    ASSERT(c_p);
    ERTS_SMP_LC_ASSERT(erts_proc_lc_my_proc_locks(c_p) == ERTS_PROC_LOCK_MAIN);

    if (on != am_true && on != am_false)
	return THE_NON_VALUE;

    if (is_not_nil(opts_list)) {
	int all = 0, visible = 0, hidden = 0;

	while (is_list(opts_list)) {
	    Eterm *cp = list_val(opts_list);
	    Eterm opt = CAR(cp);
	    opts_list = CDR(cp);
	    if (opt == am_nodedown_reason)
		opts |= ERTS_NODES_MON_OPT_DOWN_REASON;
	    else if (is_tuple(opt)) {
		Eterm* tp = tuple_val(opt);
		if (arityval(tp[0]) != 2)
		    return THE_NON_VALUE;
		switch (tp[1]) {
		case am_node_type:
		    switch (tp[2]) {
		    case am_visible:
			if (hidden || all)
			    return THE_NON_VALUE;
			opts |= ERTS_NODES_MON_OPT_TYPE_VISIBLE;
			visible = 1;
			break;
		    case am_hidden:
			if (visible || all)
			    return THE_NON_VALUE;
			opts |= ERTS_NODES_MON_OPT_TYPE_HIDDEN;
			hidden = 1;
			break;
		    case am_all:
			if (visible || hidden)
			    return THE_NON_VALUE;
			opts |= ERTS_NODES_MON_OPT_TYPES;
			all = 1;
			break;
		    default:
			return THE_NON_VALUE;
		    }
		    break;
		default:
		    return THE_NON_VALUE;
		}
	    }
	    else {
		return THE_NON_VALUE;
	    }
	}

	if (is_not_nil(opts_list))
	    return THE_NON_VALUE;
    }

    erts_smp_mtx_lock(&nodes_monitors_mtx);

    if (on == am_true)
	res = insert_nodes_monitor(c_p, opts);
    else
	res = remove_nodes_monitors(c_p, opts, 0);

    erts_smp_mtx_unlock(&nodes_monitors_mtx);

    return res;
}

/*
 * Note, this function is only used for debuging.
 */

Eterm
erts_processes_monitoring_nodes(Process *c_p)
{
    ErtsNodesMonitor *nmp;
    Eterm res;
    Eterm *hp;
    Eterm **hpp;
    Uint sz;
    Uint *szp;
#ifdef DEBUG
    Eterm *hend;
#endif

    ASSERT(c_p);
    ERTS_SMP_LC_ASSERT(erts_proc_lc_my_proc_locks(c_p) == ERTS_PROC_LOCK_MAIN);
    erts_smp_mtx_lock(&nodes_monitors_mtx);

    sz = 0;
    szp = &sz;
    hpp = NULL;

 bld_result:
    res = NIL;

    for (nmp = nodes_monitors_end; nmp; nmp = nmp->prev) {
	Uint16 i;
	for (i = 0; i < nmp->no; i++) {
	    Eterm olist = NIL;
	    if (nmp->opts & ERTS_NODES_MON_OPT_TYPES) {
		Eterm type;
		switch (nmp->opts & ERTS_NODES_MON_OPT_TYPES) {
		case ERTS_NODES_MON_OPT_TYPES:        type = am_all;     break;
		case ERTS_NODES_MON_OPT_TYPE_VISIBLE: type = am_visible; break;
		case ERTS_NODES_MON_OPT_TYPE_HIDDEN:  type = am_hidden;  break;
		default: erts_exit(ERTS_ABORT_EXIT, "Bad node type found\n");
		}
		olist = erts_bld_cons(hpp, szp, 
				      erts_bld_tuple(hpp, szp, 2,
						     am_node_type,
						     type),
				      olist);
	    }
	    if (nmp->opts & ERTS_NODES_MON_OPT_DOWN_REASON)
		olist = erts_bld_cons(hpp, szp, am_nodedown_reason, olist);
	    res = erts_bld_cons(hpp, szp,
				erts_bld_tuple(hpp, szp, 2,
					       nmp->proc->common.id,
					       olist),
				res);
	}
    }

    if (!hpp) {
	hp = HAlloc(c_p, sz);
#ifdef DEBUG
	hend = hp + sz;
#endif
	hpp = &hp;
	szp = NULL;
	goto bld_result;
    }

    ASSERT(hp == hend);

    erts_smp_mtx_unlock(&nodes_monitors_mtx);

    return res;
}