1 /* Licensed to the Apache Software Foundation (ASF) under one or more
2 * contributor license agreements. See the NOTICE file distributed with
3 * this work for additional information regarding copyright ownership.
4 * The ASF licenses this file to You under the Apache License, Version 2.0
5 * (the "License"); you may not use this file except in compliance with
6 * the License. You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 /*Read/Write locking implementation based on the MultiLock code from
18 * Stephen Beaulieu <[email protected]>
19 */
20
21 #include "apr_arch_thread_mutex.h"
22 #include "apr_strings.h"
23 #include "apr_portable.h"
24
_thread_mutex_cleanup(void * data)25 static apr_status_t _thread_mutex_cleanup(void * data)
26 {
27 apr_thread_mutex_t *lock = (apr_thread_mutex_t*)data;
28 if (lock->LockCount != 0) {
29 /* we're still locked... */
30 while (atomic_add(&lock->LockCount , -1) > 1){
31 /* OK we had more than one person waiting on the lock so
32 * the sem is also locked. Release it until we have no more
33 * locks left.
34 */
35 release_sem (lock->Lock);
36 }
37 }
38 delete_sem(lock->Lock);
39 return APR_SUCCESS;
40 }
41
apr_thread_mutex_create(apr_thread_mutex_t ** mutex,unsigned int flags,apr_pool_t * pool)42 APR_DECLARE(apr_status_t) apr_thread_mutex_create(apr_thread_mutex_t **mutex,
43 unsigned int flags,
44 apr_pool_t *pool)
45 {
46 apr_thread_mutex_t *new_m;
47 apr_status_t stat = APR_SUCCESS;
48
49 new_m = (apr_thread_mutex_t *)apr_pcalloc(pool, sizeof(apr_thread_mutex_t));
50 if (new_m == NULL){
51 return APR_ENOMEM;
52 }
53
54 if ((stat = create_sem(0, "APR_Lock")) < B_NO_ERROR) {
55 _thread_mutex_cleanup(new_m);
56 return stat;
57 }
58 new_m->LockCount = 0;
59 new_m->Lock = stat;
60 new_m->pool = pool;
61
62 /* Optimal default is APR_THREAD_MUTEX_UNNESTED,
63 * no additional checks required for either flag.
64 */
65 new_m->nested = flags & APR_THREAD_MUTEX_NESTED;
66
67 apr_pool_cleanup_register(new_m->pool, (void *)new_m, _thread_mutex_cleanup,
68 apr_pool_cleanup_null);
69
70 (*mutex) = new_m;
71 return APR_SUCCESS;
72 }
73
74 #if APR_HAS_CREATE_LOCKS_NP
apr_thread_mutex_create_np(apr_thread_mutex_t ** mutex,const char * fname,apr_lockmech_e_np mech,apr_pool_t * pool)75 APR_DECLARE(apr_status_t) apr_thread_mutex_create_np(apr_thread_mutex_t **mutex,
76 const char *fname,
77 apr_lockmech_e_np mech,
78 apr_pool_t *pool)
79 {
80 return APR_ENOTIMPL;
81 }
82 #endif
83
apr_thread_mutex_lock(apr_thread_mutex_t * mutex)84 APR_DECLARE(apr_status_t) apr_thread_mutex_lock(apr_thread_mutex_t *mutex)
85 {
86 int32 stat;
87 thread_id me = find_thread(NULL);
88
89 if (mutex->nested && mutex->owner == me) {
90 mutex->owner_ref++;
91 return APR_SUCCESS;
92 }
93
94 if (atomic_add(&mutex->LockCount, 1) > 0) {
95 if ((stat = acquire_sem(mutex->Lock)) < B_NO_ERROR) {
96 /* Oh dear, acquire_sem failed!! */
97 atomic_add(&mutex->LockCount, -1);
98 return stat;
99 }
100 }
101
102 mutex->owner = me;
103 mutex->owner_ref = 1;
104
105 return APR_SUCCESS;
106 }
107
apr_thread_mutex_trylock(apr_thread_mutex_t * mutex)108 APR_DECLARE(apr_status_t) apr_thread_mutex_trylock(apr_thread_mutex_t *mutex)
109 {
110 return APR_ENOTIMPL;
111 }
112
apr_thread_mutex_unlock(apr_thread_mutex_t * mutex)113 APR_DECLARE(apr_status_t) apr_thread_mutex_unlock(apr_thread_mutex_t *mutex)
114 {
115 int32 stat;
116
117 if (mutex->nested && mutex->owner == find_thread(NULL)) {
118 mutex->owner_ref--;
119 if (mutex->owner_ref > 0)
120 return APR_SUCCESS;
121 }
122
123 if (atomic_add(&mutex->LockCount, -1) > 1) {
124 if ((stat = release_sem(mutex->Lock)) < B_NO_ERROR) {
125 atomic_add(&mutex->LockCount, 1);
126 return stat;
127 }
128 }
129
130 mutex->owner = -1;
131 mutex->owner_ref = 0;
132
133 return APR_SUCCESS;
134 }
135
apr_thread_mutex_destroy(apr_thread_mutex_t * mutex)136 APR_DECLARE(apr_status_t) apr_thread_mutex_destroy(apr_thread_mutex_t *mutex)
137 {
138 apr_status_t stat;
139 if ((stat = _thread_mutex_cleanup(mutex)) == APR_SUCCESS) {
140 apr_pool_cleanup_kill(mutex->pool, mutex, _thread_mutex_cleanup);
141 return APR_SUCCESS;
142 }
143 return stat;
144 }
145
146 APR_POOL_IMPLEMENT_ACCESSOR(thread_mutex)
147
148