diff options
Diffstat (limited to 'locks/beos/thread_rwlock.c')
| -rw-r--r-- | locks/beos/thread_rwlock.c | 190 |
1 files changed, 190 insertions, 0 deletions
diff --git a/locks/beos/thread_rwlock.c b/locks/beos/thread_rwlock.c new file mode 100644 index 0000000..a540b44 --- /dev/null +++ b/locks/beos/thread_rwlock.c @@ -0,0 +1,190 @@ +/* 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 "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) + |