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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.
 */

package org.apache.tomcat.jni;

/** Lock
 *
 * @author Mladen Turk
 */
public class Lock {

    /**
     * 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. */ public static final int APR_LOCK_FCNTL = 0; /** fcntl() */ public static final int APR_LOCK_FLOCK = 1; /** flock() */ public static final int APR_LOCK_SYSVSEM = 2; /** System V Semaphores */ public static final int APR_LOCK_PROC_PTHREAD = 3; /** POSIX pthread process-based locking */ public static final int APR_LOCK_POSIXSEM = 4; /** POSIX semaphore process-based locking */ public static final int APR_LOCK_DEFAULT = 5; /** Use the default process lock */ /** * Create and initialize a mutex that can be used to synchronize processes. *
Warning : Check APR_HAS_foo_SERIALIZE defines to see if the platform supports * APR_LOCK_foo. Only APR_LOCK_DEFAULT is portable. * @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 *
     *            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
     * 
* @param pool the pool from which to allocate the mutex. * @return Newly created mutex. */ public static native long create(String fname, int mech, long pool) throws Error; /** * Re-open a mutex in a child process. * This function must be called to maintain portability, even * if the underlying lock mechanism does not require it. * @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. * @return Newly opened mutex. */ public static native long childInit(String fname, long pool) throws Error; /** * 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. */ public static native int lock(long 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. */ public static native int trylock(long mutex); /** * Release the lock for the given mutex. * @param mutex the mutex from which to release the lock. */ public static native int unlock(long mutex); /** * Destroy the mutex and free the memory associated with the lock. * @param mutex the mutex to destroy. */ public static native int destroy(long mutex); /** * Return the name of the lockfile for the mutex, or NULL * if the mutex doesn't use a lock file */ public static native String lockfile(long mutex); /** * Display the name of the mutex, as it relates to the actual method used. * This matches the valid options for Apache's AcceptMutex directive * @param mutex the name of the mutex */ public static native String name(long mutex); /** * Display the name of the default mutex: APR_LOCK_DEFAULT */ public static native String defname(); }




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