org.gridgain.client.util.GridClientStripedLock Maven / Gradle / Ivy

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/* 
 Copyright (C) GridGain Systems. All Rights Reserved.
 
 Licensed 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.gridgain.client.util;

import java.util.concurrent.locks.*;

/**
 * This is an utility class for 'splitting' locking of some
 * {@code int}- or {@code long}-keyed resources.
 *
 * Map {@code int} and {@code long} values to some number of locks,
 * and supply convenience methods to obtain and release these locks using key values.
 */
public class GridClientStripedLock {
    /** Array of underlying locks. */
    private final Lock[] locks;

    /**
     * Creates new instance with the given concurrency level (number of locks).
     *
     * @param concurrencyLevel Concurrency level.
     */
    public GridClientStripedLock(int concurrencyLevel) {
        locks = new Lock[concurrencyLevel];

        for (int i = 0; i < concurrencyLevel; i++)
            locks[i] = new ReentrantLock();
    }

    /**
     * Gets concurrency level.
     *
     * @return Concurrency level.
     */
    public int concurrencyLevel() {
        return locks.length;
    }

    /**
     * Returns {@link Lock} object for the given key.
     * @param key Key.
     * @return Lock.
     */
    public Lock getLock(int key) {
        return locks[GridClientUtils.safeAbs(key) % locks.length];
    }

    /**
     * Returns {@link Lock} object for the given key.
     * @param key Key.
     * @return Lock.
     */
    public Lock getLock(long key) {
        return locks[GridClientUtils.safeAbs((int)(key % locks.length))];
    }

    /**
     * Returns lock for object.
     *
     * @param o Object.
     * @return Lock.
     */
    public Lock getLock(Object o) {
        return o == null ? locks[0] : getLock(o.hashCode());
    }

    /**
     * Locks given key.
     *
     * @param key Key.
     */
    public void lock(int key) {
        getLock(key).lock();
    }

    /**
     * Unlocks given key.
     *
     * @param key Key.
     */
    public void unlock(int key) {
        getLock(key).unlock();
    }

    /**
     * Locks given key.
     *
     * @param key Key.
     */
    public void lock(long key) {
        getLock(key).lock();
    }

    /**
     * Unlocks given key.
     *
     * @param key Key.
     */
    public void unlock(long key) {
        getLock(key).unlock();
    }

    /**
     * Locks an object.
     *
     * @param o Object.
     */
    public void lock(Object o) {
        getLock(o).lock();
    }

    /**
     * Unlocks an object.
     *
     * @param o Object.
     */
    public void unlock(Object o) {
        getLock(o).unlock();
    }
}