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+/* 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.
+ */
+
+#ifndef APR_THREAD_MUTEX_H
+#define APR_THREAD_MUTEX_H
+
+/**
+ * @file apr_thread_mutex.h
+ * @brief APR Thread Mutex Routines
+ */
+
+#include "apr.h"
+#include "apr_errno.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif /* __cplusplus */
+
+#if APR_HAS_THREADS || defined(DOXYGEN)
+
+/**
+ * @defgroup apr_thread_mutex Thread Mutex Routines
+ * @ingroup APR
+ * @{
+ */
+
+/** Opaque thread-local mutex structure */
+typedef struct apr_thread_mutex_t apr_thread_mutex_t;
+
+#define APR_THREAD_MUTEX_DEFAULT 0x0 /**< platform-optimal lock behavior */
+#define APR_THREAD_MUTEX_NESTED 0x1 /**< enable nested (recursive) locks */
+#define APR_THREAD_MUTEX_UNNESTED 0x2 /**< disable nested locks */
+#define APR_THREAD_MUTEX_TIMED 0x4 /**< enable timed locks */
+
+/* Delayed the include to avoid a circular reference */
+#include "apr_pools.h"
+#include "apr_time.h"
+
+/**
+ * Create and initialize a mutex that can be used to synchronize threads.
+ * @param mutex the memory address where the newly created mutex will be
+ * stored.
+ * @param flags Or'ed value of:
+ * <PRE>
+ * APR_THREAD_MUTEX_DEFAULT platform-optimal lock behavior.
+ * APR_THREAD_MUTEX_NESTED enable nested (recursive) locks.
+ * APR_THREAD_MUTEX_UNNESTED disable nested locks (non-recursive).
+ * </PRE>
+ * @param pool the pool from which to allocate the mutex.
+ * @warning Be cautious in using APR_THREAD_MUTEX_DEFAULT. While this is the
+ * most optimal mutex based on a given platform's performance characteristics,
+ * it will behave as either a nested or an unnested lock.
+ */
+APR_DECLARE(apr_status_t) apr_thread_mutex_create(apr_thread_mutex_t **mutex,
+ unsigned int flags,
+ apr_pool_t *pool);
+/**
+ * Acquire the lock for the given mutex. If the mutex is already locked,
+ * the current thread will be put to sleep until the lock becomes available.
+ * @param mutex the mutex on which to acquire the lock.
+ */
+APR_DECLARE(apr_status_t) apr_thread_mutex_lock(apr_thread_mutex_t *mutex);
+
+/**
+ * Attempt to acquire the lock for the given mutex. If the mutex has already
+ * been acquired, the call returns immediately with APR_EBUSY. Note: it
+ * is important that the APR_STATUS_IS_EBUSY(s) macro be used to determine
+ * if the return value was APR_EBUSY, for portability reasons.
+ * @param mutex the mutex on which to attempt the lock acquiring.
+ */
+APR_DECLARE(apr_status_t) apr_thread_mutex_trylock(apr_thread_mutex_t *mutex);
+
+/**
+ * Attempt to acquire the lock for the given mutex until timeout expires.
+ * If the acquisition time outs, the call returns with APR_TIMEUP.
+ * @param mutex the mutex on which to attempt the lock acquiring.
+ * @param timeout the relative timeout (microseconds).
+ * @note A timeout negative or nul means immediate attempt, returning
+ * APR_TIMEUP without blocking if it the lock is already acquired.
+ */
+APR_DECLARE(apr_status_t) apr_thread_mutex_timedlock(apr_thread_mutex_t *mutex,
+ apr_interval_time_t timeout);
+
+/**
+ * Release the lock for the given mutex.
+ * @param mutex the mutex from which to release the lock.
+ */
+APR_DECLARE(apr_status_t) apr_thread_mutex_unlock(apr_thread_mutex_t *mutex);
+
+/**
+ * Destroy the mutex and free the memory associated with the lock.
+ * @param mutex the mutex to destroy.
+ */
+APR_DECLARE(apr_status_t) apr_thread_mutex_destroy(apr_thread_mutex_t *mutex);
+
+/**
+ * Get the pool used by this thread_mutex.
+ * @return apr_pool_t the pool
+ */
+APR_POOL_DECLARE_ACCESSOR(thread_mutex);
+
+#endif /* APR_HAS_THREADS */
+
+/** @} */
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* ! APR_THREAD_MUTEX_H */