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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_PROC_MUTEX_H
+#define APR_PROC_MUTEX_H
+
+/**
+ * @file apr_proc_mutex.h
+ * @brief APR Process Locking Routines
+ */
+
+#include "apr.h"
+#include "apr_pools.h"
+#include "apr_errno.h"
+#include "apr_perms_set.h"
+#include "apr_time.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif /* __cplusplus */
+
+/**
+ * @defgroup apr_proc_mutex Process Locking Routines
+ * @ingroup APR
+ * @{
+ */
+
+/**
+ * Enumerated potential types for APR process locking methods
+ * @warning Check APR_HAS_foo_SERIALIZE defines to see if the platform supports
+ * APR_LOCK_foo. Only APR_LOCK_DEFAULT is portable.
+ */
+typedef enum {
+ APR_LOCK_FCNTL, /**< fcntl() */
+ APR_LOCK_FLOCK, /**< flock() */
+ APR_LOCK_SYSVSEM, /**< System V Semaphores */
+ APR_LOCK_PROC_PTHREAD, /**< POSIX pthread process-based locking */
+ APR_LOCK_POSIXSEM, /**< POSIX semaphore process-based locking */
+ APR_LOCK_DEFAULT, /**< Use the default process lock */
+ APR_LOCK_DEFAULT_TIMED /**< Use the default process timed lock */
+} apr_lockmech_e;
+
+/** Opaque structure representing a process mutex. */
+typedef struct apr_proc_mutex_t apr_proc_mutex_t;
+
+/* Function definitions */
+
+/**
+ * Create and initialize a mutex that can be used to synchronize processes.
+ * @param mutex the memory address where the newly created mutex will be
+ * stored.
+ * @param fname A file name to use if the lock mechanism requires one. This
+ * argument should always be provided. The lock code itself will
+ * determine if it should be used.
+ * @param mech The mechanism to use for the interprocess lock, if any; one of
+ * <PRE>
+ * APR_LOCK_FCNTL
+ * APR_LOCK_FLOCK
+ * APR_LOCK_SYSVSEM
+ * APR_LOCK_POSIXSEM
+ * APR_LOCK_PROC_PTHREAD
+ * APR_LOCK_DEFAULT pick the default mechanism for the platform
+ * </PRE>
+ * @param pool the pool from which to allocate the mutex.
+ * @see apr_lockmech_e
+ * @warning Check APR_HAS_foo_SERIALIZE defines to see if the platform supports
+ * APR_LOCK_foo. Only APR_LOCK_DEFAULT is portable.
+ */
+APR_DECLARE(apr_status_t) apr_proc_mutex_create(apr_proc_mutex_t **mutex,
+ const char *fname,
+ apr_lockmech_e mech,
+ apr_pool_t *pool);
+
+/**
+ * Re-open a mutex in a child process.
+ * @param mutex The newly re-opened mutex structure.
+ * @param fname A file name to use if the mutex mechanism requires one. This
+ * argument should always be provided. The mutex code itself will
+ * determine if it should be used. This filename should be the
+ * same one that was passed to apr_proc_mutex_create().
+ * @param pool The pool to operate on.
+ * @remark This function must be called to maintain portability, even
+ * if the underlying lock mechanism does not require it.
+ */
+APR_DECLARE(apr_status_t) apr_proc_mutex_child_init(apr_proc_mutex_t **mutex,
+ const char *fname,
+ 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_proc_mutex_lock(apr_proc_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_proc_mutex_trylock(apr_proc_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 negative or nul timeout means immediate attempt, returning
+ * APR_TIMEUP without blocking if it the lock is already acquired.
+ */
+APR_DECLARE(apr_status_t) apr_proc_mutex_timedlock(apr_proc_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_proc_mutex_unlock(apr_proc_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_proc_mutex_destroy(apr_proc_mutex_t *mutex);
+
+/**
+ * Destroy the mutex and free the memory associated with the lock.
+ * @param mutex the mutex to destroy.
+ * @note This function is generally used to kill a cleanup on an already
+ * created mutex
+ */
+APR_DECLARE(apr_status_t) apr_proc_mutex_cleanup(void *mutex);
+
+/**
+ * Return the name of the lockfile for the mutex, or NULL
+ * if the mutex doesn't use a lock file
+ */
+
+APR_DECLARE(const char *) apr_proc_mutex_lockfile(apr_proc_mutex_t *mutex);
+
+/**
+ * Get the mechanism of the mutex, as it relates to the actual method
+ * used for the underlying apr_proc_mutex_t.
+ * @param mutex the mutex to get the mechanism from.
+ */
+APR_DECLARE(apr_lockmech_e) apr_proc_mutex_mech(apr_proc_mutex_t *mutex);
+
+/**
+ * Get the mechanism's name of the mutex, as it relates to the actual method
+ * used for the underlying apr_proc_mutex_t.
+ * @param mutex the mutex to get the mechanism's name from.
+ */
+APR_DECLARE(const char *) apr_proc_mutex_name(apr_proc_mutex_t *mutex);
+
+/**
+ * Display the name of the default mutex: APR_LOCK_DEFAULT
+ */
+APR_DECLARE(const char *) apr_proc_mutex_defname(void);
+
+/**
+ * Set mutex permissions.
+ */
+APR_PERMS_SET_IMPLEMENT(proc_mutex);
+
+/**
+ * Get the pool used by this proc_mutex.
+ * @return apr_pool_t the pool
+ */
+APR_POOL_DECLARE_ACCESSOR(proc_mutex);
+
+/** @} */
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* ! APR_PROC_MUTEX_H */