Mercurial > hg > nginx
annotate src/core/ngx_rwlock.c @ 7660:d33e17499088
Version bump.
| author | Maxim Dounin <mdounin@mdounin.ru> |
|---|---|
| date | Tue, 26 May 2020 22:03:00 +0300 |
| parents | d1816a2696de |
| children | 7752d8523066 |
| rev | line source |
|---|---|
| 6101 | 1 |
| 2 /* | |
| 3 * Copyright (C) Ruslan Ermilov | |
| 4 * Copyright (C) Nginx, Inc. | |
| 5 */ | |
| 6 | |
| 7 | |
| 8 #include <ngx_config.h> | |
| 9 #include <ngx_core.h> | |
| 10 | |
| 11 | |
| 12 #if (NGX_HAVE_ATOMIC_OPS) | |
| 13 | |
| 14 | |
| 15 #define NGX_RWLOCK_SPIN 2048 | |
| 16 #define NGX_RWLOCK_WLOCK ((ngx_atomic_uint_t) -1) | |
| 17 | |
| 18 | |
| 19 void | |
| 20 ngx_rwlock_wlock(ngx_atomic_t *lock) | |
| 21 { | |
| 22 ngx_uint_t i, n; | |
| 23 | |
| 24 for ( ;; ) { | |
| 25 | |
| 26 if (*lock == 0 && ngx_atomic_cmp_set(lock, 0, NGX_RWLOCK_WLOCK)) { | |
| 27 return; | |
| 28 } | |
| 29 | |
| 30 if (ngx_ncpu > 1) { | |
| 31 | |
| 32 for (n = 1; n < NGX_RWLOCK_SPIN; n <<= 1) { | |
| 33 | |
| 34 for (i = 0; i < n; i++) { | |
| 35 ngx_cpu_pause(); | |
| 36 } | |
| 37 | |
| 38 if (*lock == 0 | |
| 39 && ngx_atomic_cmp_set(lock, 0, NGX_RWLOCK_WLOCK)) | |
| 40 { | |
| 41 return; | |
| 42 } | |
| 43 } | |
| 44 } | |
| 45 | |
| 46 ngx_sched_yield(); | |
| 47 } | |
| 48 } | |
| 49 | |
| 50 | |
| 51 void | |
| 52 ngx_rwlock_rlock(ngx_atomic_t *lock) | |
| 53 { | |
| 54 ngx_uint_t i, n; | |
| 55 ngx_atomic_uint_t readers; | |
| 56 | |
| 57 for ( ;; ) { | |
| 58 readers = *lock; | |
| 59 | |
| 60 if (readers != NGX_RWLOCK_WLOCK | |
| 61 && ngx_atomic_cmp_set(lock, readers, readers + 1)) | |
| 62 { | |
| 63 return; | |
| 64 } | |
| 65 | |
| 66 if (ngx_ncpu > 1) { | |
| 67 | |
| 68 for (n = 1; n < NGX_RWLOCK_SPIN; n <<= 1) { | |
| 69 | |
| 70 for (i = 0; i < n; i++) { | |
| 71 ngx_cpu_pause(); | |
| 72 } | |
| 73 | |
| 74 readers = *lock; | |
| 75 | |
| 76 if (readers != NGX_RWLOCK_WLOCK | |
| 77 && ngx_atomic_cmp_set(lock, readers, readers + 1)) | |
| 78 { | |
| 79 return; | |
| 80 } | |
| 81 } | |
| 82 } | |
| 83 | |
| 84 ngx_sched_yield(); | |
| 85 } | |
| 86 } | |
| 87 | |
| 88 | |
| 89 void | |
| 90 ngx_rwlock_unlock(ngx_atomic_t *lock) | |
| 91 { | |
| 92 ngx_atomic_uint_t readers; | |
| 93 | |
| 94 readers = *lock; | |
| 95 | |
| 96 if (readers == NGX_RWLOCK_WLOCK) { | |
|
7037
12efcdcb8a4b
Added memory barrier semantics to ngx_rwlock_unlock().
Ruslan Ermilov <ru@nginx.com>
parents:
6270
diff
changeset
|
97 (void) ngx_atomic_cmp_set(lock, NGX_RWLOCK_WLOCK, 0); |
| 6101 | 98 return; |
| 99 } | |
| 100 | |
| 101 for ( ;; ) { | |
| 102 | |
| 103 if (ngx_atomic_cmp_set(lock, readers, readers - 1)) { | |
| 104 return; | |
| 105 } | |
| 106 | |
| 107 readers = *lock; | |
| 108 } | |
| 109 } | |
| 110 | |
| 111 | |
|
7038
d1816a2696de
Introduced ngx_rwlock_downgrade().
Ruslan Ermilov <ru@nginx.com>
parents:
7037
diff
changeset
|
112 void |
|
d1816a2696de
Introduced ngx_rwlock_downgrade().
Ruslan Ermilov <ru@nginx.com>
parents:
7037
diff
changeset
|
113 ngx_rwlock_downgrade(ngx_atomic_t *lock) |
|
d1816a2696de
Introduced ngx_rwlock_downgrade().
Ruslan Ermilov <ru@nginx.com>
parents:
7037
diff
changeset
|
114 { |
|
d1816a2696de
Introduced ngx_rwlock_downgrade().
Ruslan Ermilov <ru@nginx.com>
parents:
7037
diff
changeset
|
115 if (*lock == NGX_RWLOCK_WLOCK) { |
|
d1816a2696de
Introduced ngx_rwlock_downgrade().
Ruslan Ermilov <ru@nginx.com>
parents:
7037
diff
changeset
|
116 *lock = 1; |
|
d1816a2696de
Introduced ngx_rwlock_downgrade().
Ruslan Ermilov <ru@nginx.com>
parents:
7037
diff
changeset
|
117 } |
|
d1816a2696de
Introduced ngx_rwlock_downgrade().
Ruslan Ermilov <ru@nginx.com>
parents:
7037
diff
changeset
|
118 } |
|
d1816a2696de
Introduced ngx_rwlock_downgrade().
Ruslan Ermilov <ru@nginx.com>
parents:
7037
diff
changeset
|
119 |
|
d1816a2696de
Introduced ngx_rwlock_downgrade().
Ruslan Ermilov <ru@nginx.com>
parents:
7037
diff
changeset
|
120 |
|
6103
79ddb0bdb273
Upstream: the "zone" directive.
Ruslan Ermilov <ru@nginx.com>
parents:
6101
diff
changeset
|
121 #else |
|
79ddb0bdb273
Upstream: the "zone" directive.
Ruslan Ermilov <ru@nginx.com>
parents:
6101
diff
changeset
|
122 |
|
6270
e769cc88f996
Core: read/write locks are also required by the Stream module.
Piotr Sikora <piotrsikora@google.com>
parents:
6103
diff
changeset
|
123 #if (NGX_HTTP_UPSTREAM_ZONE || NGX_STREAM_UPSTREAM_ZONE) |
|
6103
79ddb0bdb273
Upstream: the "zone" directive.
Ruslan Ermilov <ru@nginx.com>
parents:
6101
diff
changeset
|
124 |
|
79ddb0bdb273
Upstream: the "zone" directive.
Ruslan Ermilov <ru@nginx.com>
parents:
6101
diff
changeset
|
125 #error ngx_atomic_cmp_set() is not defined! |
|
79ddb0bdb273
Upstream: the "zone" directive.
Ruslan Ermilov <ru@nginx.com>
parents:
6101
diff
changeset
|
126 |
| 6101 | 127 #endif |
|
6103
79ddb0bdb273
Upstream: the "zone" directive.
Ruslan Ermilov <ru@nginx.com>
parents:
6101
diff
changeset
|
128 |
|
79ddb0bdb273
Upstream: the "zone" directive.
Ruslan Ermilov <ru@nginx.com>
parents:
6101
diff
changeset
|
129 #endif |