/*
 *  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.
 *
 * @deprecated The scope of the APR/Native Library will be reduced in Tomcat 9.1.x / Tomcat Native 2.x and has been
 *                 reduced in Tomcat 10.1.x / Tomcat Native 2.x onwards to only include those components required to
 *                 provide OpenSSL integration with the NIO and NIO2 connectors.
 */
@Deprecated
public class Lock {

    /*
     * Enumerated potential types for APR process locking methods <br><b>Warning :</b> Check APR_HAS_foo_SERIALIZE
     * defines to see if the platform supports APR_LOCK_foo. Only APR_LOCK_DEFAULT is portable.
     */

    /** fcntl() */
    public static final int APR_LOCK_FCNTL = 0;
    /** flock() */
    public static final int APR_LOCK_FLOCK = 1;
    /** System V Semaphores */
    public static final int APR_LOCK_SYSVSEM = 2;
    /** POSIX pthread process-based locking */
    public static final int APR_LOCK_PROC_PTHREAD = 3;
    /** POSIX semaphore process-based locking */
    public static final int APR_LOCK_POSIXSEM = 4;
    /** Use the default process lock */
    public static final int APR_LOCK_DEFAULT = 5;

    /**
     * Create and initialize a mutex that can be used to synchronize processes. <br>
     * <b>Warning :</b> 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
     *
     *                  <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.
     *
     * @return Newly created mutex.
     *
     * @throws Error An error occurred
     */
    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.
     *
     * @throws Error An error occurred
     */
    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.
     *
     * @return the operation status
     */
    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.
     *
     * @return the operation status
     */
    public static native int trylock(long mutex);

    /**
     * Release the lock for the given mutex.
     *
     * @param mutex the mutex from which to release the lock.
     *
     * @return the operation status
     */
    public static native int unlock(long mutex);

    /**
     * Destroy the mutex and free the memory associated with the lock.
     *
     * @param mutex the mutex to destroy.
     *
     * @return the operation status
     */
    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
     *
     * @param mutex the name of the mutex
     *
     * @return the name of the 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
     *
     * @return the name of the mutex
     */
    public static native String name(long mutex);

    /**
     * Display the name of the default mutex: APR_LOCK_DEFAULT
     *
     * @return the default name
     */
    public static native String defname();

}
