1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
|
/*
* %CopyrightBegin%
*
* Copyright Ericsson AB 2012. All Rights Reserved.
*
* The contents of this file are subject to the Erlang Public License,
* Version 1.1, (the "License"); you may not use this file except in
* compliance with the License. You should have received a copy of the
* Erlang Public License along with this software. If not, it can be
* retrieved online at http://www.erlang.org/.
*
* Software distributed under the License is distributed on an "AS IS"
* basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
* the License for the specific language governing rights and limitations
* under the License.
*
* %CopyrightEnd%
*/
#ifdef HAVE_CONFIG_H
# include "config.h"
#endif
#include "code_ix.h"
#include "global.h"
#include "beam_catches.h"
#if 0
# define CIX_TRACE(text) erts_fprintf(stderr, "CIX_TRACE: " text " act=%u load=%u\r\n", erts_active_code_ix(), erts_staging_code_ix())
#else
# define CIX_TRACE(text)
#endif
erts_smp_atomic32_t the_active_code_index;
erts_smp_atomic32_t the_staging_code_index;
static int is_code_write_locked = 0;
struct code_write_queue_item {
Process *p;
struct code_write_queue_item* next;
};
static struct code_write_queue_item* code_write_queue = NULL;
static erts_smp_mtx_t code_write_permission_mtx;
#ifdef ERTS_ENABLE_LOCK_CHECK
static erts_tsd_key_t has_code_write_permission;
#endif
void erts_code_ix_init(void)
{
/* We start emulator by initializing preloaded modules
* single threaded with active and staging set both to zero.
* Preloading is finished by a commit that will set things straight.
*/
erts_smp_atomic32_init_nob(&the_active_code_index, 0);
erts_smp_atomic32_init_nob(&the_staging_code_index, 0);
erts_smp_mtx_init(&code_write_permission_mtx, "code_write_permission");
#ifdef ERTS_ENABLE_LOCK_CHECK
erts_tsd_key_create(&has_code_write_permission);
#endif
CIX_TRACE("init");
}
void erts_start_staging_code_ix(void)
{
beam_catches_start_staging();
export_start_staging();
module_start_staging();
erts_start_staging_ranges();
CIX_TRACE("start");
}
void erts_end_staging_code_ix(void)
{
beam_catches_end_staging(1);
export_end_staging(1);
module_end_staging(1);
erts_end_staging_ranges(1);
CIX_TRACE("end");
}
void erts_commit_staging_code_ix(void)
{
ErtsCodeIndex ix;
/* We need to this lock as we are now making the staging export table active */
export_staging_lock();
ix = erts_staging_code_ix();
erts_smp_atomic32_set_nob(&the_active_code_index, ix);
ix = (ix + 1) % ERTS_NUM_CODE_IX;
erts_smp_atomic32_set_nob(&the_staging_code_index, ix);
export_staging_unlock();
CIX_TRACE("activate");
}
void erts_abort_staging_code_ix(void)
{
beam_catches_end_staging(0);
export_end_staging(0);
module_end_staging(0);
erts_end_staging_ranges(0);
CIX_TRACE("abort");
}
/*
* Calller _must_ yield if we return 0
*/
int erts_try_seize_code_write_permission(Process* c_p)
{
int success;
#ifdef ERTS_SMP
ASSERT(!erts_smp_thr_progress_is_blocking()); /* to avoid deadlock */
#endif
erts_smp_mtx_lock(&code_write_permission_mtx);
success = !is_code_write_locked;
if (success) {
is_code_write_locked = 1;
#ifdef ERTS_ENABLE_LOCK_CHECK
erts_tsd_set(has_code_write_permission, (void *) 1);
#endif
}
else { /* Already locked */
struct code_write_queue_item* qitem;
ERTS_SMP_LC_ASSERT(!erts_tsd_get(has_code_write_permission));
qitem = erts_alloc(ERTS_ALC_T_CODE_IX_LOCK_Q, sizeof(*qitem));
qitem->p = c_p;
erts_smp_proc_inc_refc(c_p);
qitem->next = code_write_queue;
code_write_queue = qitem;
erts_suspend(c_p, ERTS_PROC_LOCK_MAIN, NULL);
}
erts_smp_mtx_unlock(&code_write_permission_mtx);
return success;
}
void erts_release_code_write_permission(void)
{
erts_smp_mtx_lock(&code_write_permission_mtx);
ERTS_SMP_LC_ASSERT(erts_has_code_write_permission());
while (code_write_queue != NULL) { /* unleash the entire herd */
struct code_write_queue_item* qitem = code_write_queue;
erts_smp_proc_lock(qitem->p, ERTS_PROC_LOCK_STATUS);
if (!ERTS_PROC_IS_EXITING(qitem->p)) {
erts_resume(qitem->p, ERTS_PROC_LOCK_STATUS);
}
erts_smp_proc_unlock(qitem->p, ERTS_PROC_LOCK_STATUS);
code_write_queue = qitem->next;
erts_smp_proc_dec_refc(qitem->p);
erts_free(ERTS_ALC_T_CODE_IX_LOCK_Q, qitem);
}
is_code_write_locked = 0;
#ifdef ERTS_ENABLE_LOCK_CHECK
erts_tsd_set(has_code_write_permission, (void *) 0);
#endif
erts_smp_mtx_unlock(&code_write_permission_mtx);
}
#ifdef ERTS_ENABLE_LOCK_CHECK
int erts_has_code_write_permission(void)
{
return is_code_write_locked && erts_tsd_get(has_code_write_permission);
}
#endif
|
