--- /dev/null
+/* Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You 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.
+ */
+
+/*Read/Write locking implementation based on the MultiLock code from
+ * Stephen Beaulieu <hippo@be.com>
+ */
+
+#include "beos/apr_arch_thread_rwlock.h"
+#include "apr_strings.h"
+#include "apr_portable.h"
+
+#define BIG_NUM 100000
+
+static apr_status_t _thread_rw_cleanup(void * data)
+{
+ apr_thread_rwlock_t *mutex = (apr_thread_rwlock_t*)data;
+
+ if (mutex->ReadCount != 0) {
+ while (atomic_add(&mutex->ReadCount , -1) > 1){
+ release_sem (mutex->Read);
+ }
+ }
+ if (mutex->WriteCount != 0) {
+ while (atomic_add(&mutex->WriteCount , -1) > 1){
+ release_sem (mutex->Write);
+ }
+ }
+ if (mutex->LockCount != 0) {
+ while (atomic_add(&mutex->LockCount , -1) > 1){
+ release_sem (mutex->Lock);
+ }
+ }
+
+ delete_sem(mutex->Read);
+ delete_sem(mutex->Write);
+ delete_sem(mutex->Lock);
+ return APR_SUCCESS;
+}
+
+APR_DECLARE(apr_status_t) apr_thread_rwlock_create(apr_thread_rwlock_t **rwlock,
+ apr_pool_t *pool)
+{
+ apr_thread_rwlock_t *new;
+
+ new = (apr_thread_rwlock_t *)apr_pcalloc(pool, sizeof(apr_thread_rwlock_t));
+ if (new == NULL){
+ return APR_ENOMEM;
+ }
+
+ new->pool = pool;
+ /* we need to make 3 locks... */
+ new->ReadCount = 0;
+ new->WriteCount = 0;
+ new->LockCount = 0;
+ new->Read = create_sem(0, "APR_ReadLock");
+ new->Write = create_sem(0, "APR_WriteLock");
+ new->Lock = create_sem(0, "APR_Lock");
+
+ if (new->Lock < 0 || new->Read < 0 || new->Write < 0) {
+ _thread_rw_cleanup(new);
+ return -1;
+ }
+
+ apr_pool_cleanup_register(new->pool, (void *)new, _thread_rw_cleanup,
+ apr_pool_cleanup_null);
+ (*rwlock) = new;
+ return APR_SUCCESS;
+}
+
+APR_DECLARE(apr_status_t) apr_thread_rwlock_rdlock(apr_thread_rwlock_t *rwlock)
+{
+ int32 rv = APR_SUCCESS;
+
+ if (find_thread(NULL) == rwlock->writer) {
+ /* we're the writer - no problem */
+ rwlock->Nested++;
+ } else {
+ /* we're not the writer */
+ int32 r = atomic_add(&rwlock->ReadCount, 1);
+ if (r < 0) {
+ /* Oh dear, writer holds lock, wait for sem */
+ rv = acquire_sem_etc(rwlock->Read, 1, B_DO_NOT_RESCHEDULE,
+ B_INFINITE_TIMEOUT);
+ }
+ }
+
+ return rv;
+}
+
+APR_DECLARE(apr_status_t) apr_thread_rwlock_tryrdlock(apr_thread_rwlock_t *rwlock)
+{
+ return APR_ENOTIMPL;
+}
+
+APR_DECLARE(apr_status_t) apr_thread_rwlock_wrlock(apr_thread_rwlock_t *rwlock)
+{
+ int rv = APR_SUCCESS;
+
+ if (find_thread(NULL) == rwlock->writer) {
+ rwlock->Nested++;
+ } else {
+ /* we're not the writer... */
+ if (atomic_add(&rwlock->LockCount, 1) >= 1) {
+ /* we're locked - acquire the sem */
+ rv = acquire_sem_etc(rwlock->Lock, 1, B_DO_NOT_RESCHEDULE,
+ B_INFINITE_TIMEOUT);
+ }
+ if (rv == APR_SUCCESS) {
+ /* decrement the ReadCount to a large -ve number so that
+ * we block on new readers...
+ */
+ int32 readers = atomic_add(&rwlock->ReadCount, -BIG_NUM);
+ if (readers > 0) {
+ /* readers are holding the lock */
+ rv = acquire_sem_etc(rwlock->Write, readers, B_DO_NOT_RESCHEDULE,
+ B_INFINITE_TIMEOUT);
+ }
+ if (rv == APR_SUCCESS)
+ rwlock->writer = find_thread(NULL);
+ }
+ }
+
+ return rv;
+}
+
+APR_DECLARE(apr_status_t) apr_thread_rwlock_trywrlock(apr_thread_rwlock_t *rwlock)
+{
+ return APR_ENOTIMPL;
+}
+
+APR_DECLARE(apr_status_t) apr_thread_rwlock_unlock(apr_thread_rwlock_t *rwlock)
+{
+ apr_status_t rv = APR_SUCCESS;
+ int32 readers;
+
+ /* we know we hold the lock, so don't check it :) */
+ if (find_thread(NULL) == rwlock->writer) {
+ /* we know we hold the lock, so don't check it :) */
+ if (rwlock->Nested > 1) {
+ /* we're recursively locked */
+ rwlock->Nested--;
+ return APR_SUCCESS;
+ }
+ /* OK so we need to release the sem if we have it :) */
+ readers = atomic_add(&rwlock->ReadCount, BIG_NUM) + BIG_NUM;
+ if (readers > 0) {
+ rv = release_sem_etc(rwlock->Read, readers, B_DO_NOT_RESCHEDULE);
+ }
+ if (rv == APR_SUCCESS) {
+ rwlock->writer = -1;
+ if (atomic_add(&rwlock->LockCount, -1) > 1) {
+ rv = release_sem_etc(rwlock->Lock, 1, B_DO_NOT_RESCHEDULE);
+ }
+ }
+ } else {
+ /* We weren't the Writer, so just release the ReadCount... */
+ if (atomic_add(&rwlock->ReadCount, -1) < 0) {
+ /* we have a writer waiting for the lock, so release it */
+ rv = release_sem_etc(rwlock->Write, 1, B_DO_NOT_RESCHEDULE);
+ }
+ }
+
+ return rv;
+}
+
+APR_DECLARE(apr_status_t) apr_thread_rwlock_destroy(apr_thread_rwlock_t *rwlock)
+{
+ apr_status_t stat;
+ if ((stat = _thread_rw_cleanup(rwlock)) == APR_SUCCESS) {
+ apr_pool_cleanup_kill(rwlock->pool, rwlock, _thread_rw_cleanup);
+ return APR_SUCCESS;
+ }
+ return stat;
+}
+
+APR_POOL_IMPLEMENT_ACCESSOR(thread_rwlock)
+
Code Review / bottlenecks.git / blobdiff