| /* 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. |
| */ |
| |
| #include "apr_general.h" |
| #include "apr_lib.h" |
| #include "apr_strings.h" |
| #include "apr_portable.h" |
| #include "apr_arch_thread_rwlock.h" |
| #include "apr_arch_file_io.h" |
| #include <string.h> |
| |
| static apr_status_t thread_rwlock_cleanup(void *therwlock) |
| { |
| apr_thread_rwlock_t *rwlock = therwlock; |
| return apr_thread_rwlock_destroy(rwlock); |
| } |
| |
| |
| |
| APR_DECLARE(apr_status_t) apr_thread_rwlock_create(apr_thread_rwlock_t **rwlock, |
| apr_pool_t *pool) |
| { |
| apr_thread_rwlock_t *new_rwlock; |
| ULONG rc; |
| |
| new_rwlock = (apr_thread_rwlock_t *)apr_palloc(pool, sizeof(apr_thread_rwlock_t)); |
| new_rwlock->pool = pool; |
| new_rwlock->readers = 0; |
| |
| rc = DosCreateMutexSem(NULL, &(new_rwlock->write_lock), 0, FALSE); |
| |
| if (rc) |
| return APR_FROM_OS_ERROR(rc); |
| |
| rc = DosCreateEventSem(NULL, &(new_rwlock->read_done), 0, FALSE); |
| |
| if (rc) |
| return APR_FROM_OS_ERROR(rc); |
| |
| *rwlock = new_rwlock; |
| |
| if (!rc) |
| apr_pool_cleanup_register(pool, new_rwlock, thread_rwlock_cleanup, |
| apr_pool_cleanup_null); |
| |
| return APR_FROM_OS_ERROR(rc); |
| } |
| |
| |
| |
| APR_DECLARE(apr_status_t) apr_thread_rwlock_rdlock(apr_thread_rwlock_t *rwlock) |
| { |
| ULONG rc, posts; |
| |
| rc = DosRequestMutexSem(rwlock->write_lock, SEM_INDEFINITE_WAIT); |
| |
| if (rc) |
| return APR_FROM_OS_ERROR(rc); |
| |
| /* We've successfully acquired the writer mutex so we can't be locked |
| * for write which means it's ok to add a reader lock. The writer mutex |
| * doubles as race condition protection for the readers counter. |
| */ |
| rwlock->readers++; |
| DosResetEventSem(rwlock->read_done, &posts); |
| rc = DosReleaseMutexSem(rwlock->write_lock); |
| return APR_FROM_OS_ERROR(rc); |
| } |
| |
| |
| |
| APR_DECLARE(apr_status_t) apr_thread_rwlock_tryrdlock(apr_thread_rwlock_t *rwlock) |
| { |
| /* As above but with different wait time */ |
| ULONG rc, posts; |
| |
| rc = DosRequestMutexSem(rwlock->write_lock, SEM_IMMEDIATE_RETURN); |
| |
| if (rc) |
| return APR_FROM_OS_ERROR(rc); |
| |
| rwlock->readers++; |
| DosResetEventSem(rwlock->read_done, &posts); |
| rc = DosReleaseMutexSem(rwlock->write_lock); |
| return APR_FROM_OS_ERROR(rc); |
| } |
| |
| |
| |
| APR_DECLARE(apr_status_t) apr_thread_rwlock_wrlock(apr_thread_rwlock_t *rwlock) |
| { |
| ULONG rc; |
| |
| rc = DosRequestMutexSem(rwlock->write_lock, SEM_INDEFINITE_WAIT); |
| |
| if (rc) |
| return APR_FROM_OS_ERROR(rc); |
| |
| /* We've got the writer lock but we have to wait for all readers to |
| * unlock before it's ok to use it |
| */ |
| |
| if (rwlock->readers) { |
| rc = DosWaitEventSem(rwlock->read_done, SEM_INDEFINITE_WAIT); |
| |
| if (rc) |
| DosReleaseMutexSem(rwlock->write_lock); |
| } |
| |
| return APR_FROM_OS_ERROR(rc); |
| } |
| |
| |
| |
| APR_DECLARE(apr_status_t) apr_thread_rwlock_trywrlock(apr_thread_rwlock_t *rwlock) |
| { |
| ULONG rc; |
| |
| rc = DosRequestMutexSem(rwlock->write_lock, SEM_IMMEDIATE_RETURN); |
| |
| if (rc) |
| return APR_FROM_OS_ERROR(rc); |
| |
| /* We've got the writer lock but we have to wait for all readers to |
| * unlock before it's ok to use it |
| */ |
| |
| if (rwlock->readers) { |
| /* There are readers active, give up */ |
| DosReleaseMutexSem(rwlock->write_lock); |
| rc = ERROR_TIMEOUT; |
| } |
| |
| return APR_FROM_OS_ERROR(rc); |
| } |
| |
| |
| |
| APR_DECLARE(apr_status_t) apr_thread_rwlock_unlock(apr_thread_rwlock_t *rwlock) |
| { |
| ULONG rc; |
| |
| /* First, guess that we're unlocking a writer */ |
| rc = DosReleaseMutexSem(rwlock->write_lock); |
| |
| if (rc == ERROR_NOT_OWNER) { |
| /* Nope, we must have a read lock */ |
| if (rwlock->readers) { |
| DosEnterCritSec(); |
| rwlock->readers--; |
| |
| if (rwlock->readers == 0) { |
| DosPostEventSem(rwlock->read_done); |
| } |
| |
| DosExitCritSec(); |
| rc = 0; |
| } |
| } |
| |
| return APR_FROM_OS_ERROR(rc); |
| } |
| |
| |
| |
| APR_DECLARE(apr_status_t) apr_thread_rwlock_destroy(apr_thread_rwlock_t *rwlock) |
| { |
| ULONG rc; |
| |
| if (rwlock->write_lock == 0) |
| return APR_SUCCESS; |
| |
| while (DosReleaseMutexSem(rwlock->write_lock) == 0); |
| |
| rc = DosCloseMutexSem(rwlock->write_lock); |
| |
| if (!rc) { |
| rwlock->write_lock = 0; |
| DosCloseEventSem(rwlock->read_done); |
| return APR_SUCCESS; |
| } |
| |
| return APR_FROM_OS_ERROR(rc); |
| } |
| |
| APR_POOL_IMPLEMENT_ACCESSOR(thread_rwlock) |
| |