Implement magic references

Magic references are *intentionally* indistinguishable from ordinary
references for the Erlang software. Magic references do not change
the language, and are intended as a pure runtime internal optimization.

An ordinary reference is typically used as a key in some table. A
magic reference has a direct pointer to a reference counted magic
binary. This makes it possible to implement various things without
having to do lookups in a table, but instead access the data directly.
Besides very fast lookups this can also improve scalability by
removing a potentially contended table. A couple of examples of
planned future usage of magic references are ETS table identifiers,
and BIF timer identifiers.

Besides future optimizations using magic references it should also
be possible to replace the exposed magic binary cludge with magic
references. That is, magic binaries that are exposed as empty
binaries to the Erlang software.

1 files changed, 28 insertions, 44 deletions

diff --git a/erts/emulator/beam/io.c b/erts/emulator/beam/io.c
index 5446ebaab0..dad24d7ef6 100644
--- a/erts/emulator/beam/io.c
+++ b/erts/emulator/beam/io.c
@@ -1445,7 +1445,7 @@ finalize_force_imm_drv_call(ErtsTryImmDrvCallState *sp)
     erts_unblock_fpe(sp->fpe_was_unmasked);
 }
 
-#define ERTS_QUEUE_PORT_SCHED_OP_REPLY_SIZE (REF_THING_SIZE + 3)
+#define ERTS_QUEUE_PORT_SCHED_OP_REPLY_SIZE (ERTS_REF_THING_SIZE + 3)
 
 static ERTS_INLINE void
 queue_port_sched_op_reply(Process *rp,
@@ -1460,7 +1460,7 @@ queue_port_sched_op_reply(Process *rp,
 
     ref= make_internal_ref(hp);
     write_ref_thing(hp, ref_num[0], ref_num[1], ref_num[2]);
-    hp += REF_THING_SIZE;
+    hp += ERTS_REF_THING_SIZE;
 
     msg = TUPLE2(hp, ref, msg);
 
@@ -3099,7 +3099,7 @@ port_monitor(Port *prt, erts_aint32_t state, Eterm origin,
 
     ASSERT(is_pid(origin));
     ASSERT(is_atom(name) || is_port(name) || name == NIL);
-    ASSERT(is_internal_ref(ref));
+    ASSERT(is_internal_ordinary_ref(ref));
 
     if (!(state & ERTS_PORT_SFLGS_INVALID_LOOKUP)) {
         ErtsProcLocks p_locks = ERTS_PROC_LOCK_LINK;
@@ -3124,7 +3124,7 @@ static int
 port_sig_monitor(Port *prt, erts_aint32_t state, int op,
                  ErtsProc2PortSigData *sigdp)
 {
-    Eterm hp[REF_THING_SIZE];
+    Eterm hp[ERTS_REF_THING_SIZE];
     Eterm ref = make_internal_ref(&hp);
     write_ref_thing(hp, sigdp->ref[0], sigdp->ref[1], sigdp->ref[2]);
 
@@ -3245,7 +3245,7 @@ static int
 port_sig_demonitor(Port *prt, erts_aint32_t state, int op,
                    ErtsProc2PortSigData *sigdp)
 {
-    Eterm hp[REF_THING_SIZE];
+    Eterm hp[ERTS_REF_THING_SIZE];
     Eterm ref = make_internal_ref(&hp);
     write_ref_thing(hp, sigdp->u.demonitor.ref[0],
                     sigdp->u.demonitor.ref[1],
@@ -3302,10 +3302,10 @@ ErtsPortOpResult erts_port_demonitor(Process *origin, ErtsDemonitorMode mode,
     sigdp->u.demonitor.origin = origin->common.id;
     sigdp->u.demonitor.name = target->common.id;
     {
-        RefThing *reft = ref_thing_ptr(ref);
+	Uint32 *nums = internal_ref_numbers(ref);
         /* Start from 1 skip ref arity */
         sys_memcpy(sigdp->u.demonitor.ref,
-                   internal_thing_ref_numbers(reft),
+		   nums,
                    sizeof(sigdp->u.demonitor.ref));
     }
 
@@ -5413,7 +5413,7 @@ reply_io_bytes(void *vreq)
 	    rp_locks = ERTS_PROC_LOCK_MAIN;
 	}
 
-	hsz = 5 /* 4-tuple */ + REF_THING_SIZE;
+	hsz = 5 /* 4-tuple */ + ERTS_REF_THING_SIZE;
 
 	erts_bld_uint64(NULL, &hsz, in);
 	erts_bld_uint64(NULL, &hsz, out);
@@ -5422,7 +5422,7 @@ reply_io_bytes(void *vreq)
 
 	ref = make_internal_ref(hp);
 	write_ref_thing(hp, req->refn[0], req->refn[1], req->refn[2]);
-	hp += REF_THING_SIZE;
+	hp += ERTS_REF_THING_SIZE;
 
 	ein = erts_bld_uint64(&hp, NULL, in);
 	eout = erts_bld_uint64(&hp, NULL, out);
@@ -5451,7 +5451,7 @@ erts_request_io_bytes(Process *c_p)
     ErtsIOBytesReq *req = erts_alloc(ERTS_ALC_T_IOB_REQ,
 				     sizeof(ErtsIOBytesReq));
 
-    hp = HAlloc(c_p, REF_THING_SIZE);
+    hp = HAlloc(c_p, ERTS_REF_THING_SIZE);
     ref = erts_sched_make_ref_in_buffer(esdp, hp);
     refn = internal_ref_numbers(ref);
 
@@ -7609,20 +7609,16 @@ erl_drv_convert_time_unit(ErlDrvTime val,
 
 static void ref_to_driver_monitor(Eterm ref, ErlDrvMonitor *mon)
 {
-    RefThing *refp;
-    ASSERT(is_internal_ref(ref));
-    ERTS_CT_ASSERT(sizeof(RefThing) <= sizeof(ErlDrvMonitor));
-    refp = ref_thing_ptr(ref);
-    memset(mon,0,sizeof(ErlDrvMonitor));
-    memcpy(mon,refp,sizeof(RefThing));
+    ERTS_CT_ASSERT(sizeof(ErtsOIRefStorage) <= sizeof(ErlDrvMonitor));
+    erts_oiref_storage_save((ErtsOIRefStorage *) mon, ref);
 }
 
 
 static int do_driver_monitor_process(Port *prt,
-				     Eterm *buf,
 				     ErlDrvTermData process,
 				     ErlDrvMonitor *monitor)
 {
+    Eterm buf[ERTS_REF_THING_SIZE];
     Process *rp;
     Eterm ref;
 
@@ -7665,26 +7661,22 @@ int driver_monitor_process(ErlDrvPort drvport,
     /* Now (in SMP) we should have either the port lock (if we have a scheduler) or the port data lock
        (if we're a driver thread) */
     ERTS_SMP_LC_ASSERT((sched != NULL || prt->port_data_lock));
-    {
-	DeclareTmpHeapNoproc(buf,REF_THING_SIZE);
-	UseTmpHeapNoproc(REF_THING_SIZE);
-	ret = do_driver_monitor_process(prt,buf,process,monitor);
-	UnUseTmpHeapNoproc(REF_THING_SIZE);
-    }
+    ret = do_driver_monitor_process(prt,process,monitor);
     DRV_MONITOR_UNLOCK_PDL(prt);
     return ret;
 }
 
-static int do_driver_demonitor_process(Port *prt, Eterm *buf,
-				       const ErlDrvMonitor *monitor)
+static int do_driver_demonitor_process(Port *prt, const ErlDrvMonitor *monitor)
 {
+    Eterm heap[ERTS_REF_THING_SIZE];
+    Eterm *hp = &heap[0];
     Process *rp;
     Eterm ref;
     ErtsMonitor *mon;
     Eterm to;
 
-    memcpy(buf,monitor,sizeof(Eterm)*REF_THING_SIZE);
-    ref = make_internal_ref(buf);
+    ref = erts_oiref_storage_make_ref((ErtsOIRefStorage *) monitor, &hp),
+
     mon = erts_lookup_monitor(ERTS_P_MONITORS(prt), ref);
     if (mon == NULL) {
 	return 1;
@@ -7728,25 +7720,21 @@ int driver_demonitor_process(ErlDrvPort drvport,
     /* Now we should have either the port lock (if we have a scheduler) or the port data lock
        (if we're a driver thread) */
     ERTS_SMP_LC_ASSERT((sched != NULL || prt->port_data_lock));
-    {
-	DeclareTmpHeapNoproc(buf,REF_THING_SIZE);
-	UseTmpHeapNoproc(REF_THING_SIZE);
-	ret = do_driver_demonitor_process(prt,buf,monitor);
-	UnUseTmpHeapNoproc(REF_THING_SIZE);
-    }
+    ret = do_driver_demonitor_process(prt,monitor);
     DRV_MONITOR_UNLOCK_PDL(prt);
     return ret;
 }
 
-static ErlDrvTermData do_driver_get_monitored_process(Port *prt, Eterm *buf,
-					    const ErlDrvMonitor *monitor)
+static ErlDrvTermData do_driver_get_monitored_process(Port *prt,const ErlDrvMonitor *monitor)
 {
     Eterm ref;
     ErtsMonitor *mon;
     Eterm to;
+    Eterm heap[ERTS_REF_THING_SIZE];
+    Eterm *hp = &heap[0];
+
+    ref = erts_oiref_storage_make_ref((ErtsOIRefStorage *) monitor, &hp),
 
-    memcpy(buf,monitor,sizeof(Eterm)*REF_THING_SIZE);
-    ref = make_internal_ref(buf);
     mon = erts_lookup_monitor(ERTS_P_MONITORS(prt), ref);
     if (mon == NULL) {
 	return driver_term_nil;
@@ -7774,12 +7762,7 @@ ErlDrvTermData driver_get_monitored_process(ErlDrvPort drvport,
     /* Now we should have either the port lock (if we have a scheduler) or the port data lock
        (if we're a driver thread) */
     ERTS_SMP_LC_ASSERT((sched != NULL || prt->port_data_lock));
-    {
-	DeclareTmpHeapNoproc(buf,REF_THING_SIZE);
-	UseTmpHeapNoproc(REF_THING_SIZE);
-	ret = do_driver_get_monitored_process(prt,buf,monitor);
-	UnUseTmpHeapNoproc(REF_THING_SIZE);
-    }
+    ret = do_driver_get_monitored_process(prt,monitor);
     DRV_MONITOR_UNLOCK_PDL(prt);
     return ret;
 }
@@ -7788,7 +7771,8 @@ ErlDrvTermData driver_get_monitored_process(ErlDrvPort drvport,
 int driver_compare_monitors(const ErlDrvMonitor *monitor1,
 			    const ErlDrvMonitor *monitor2)
 {
-    return memcmp(monitor1,monitor2,sizeof(ErlDrvMonitor));
+    return erts_oiref_storage_cmp((ErtsOIRefStorage *) monitor1,
+				  (ErtsOIRefStorage *) monitor2);
 }
 
 void erts_fire_port_monitor(Port *prt, Eterm ref)