blazingcache.client.impl.LocalLockManager Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of blazingcache-core Show documentation
There is a newer version: 3.3.1
/*
 Licensed to Diennea S.r.l. under one
 or more contributor license agreements. See the NOTICE file
 distributed with this work for additional information
 regarding copyright ownership. Diennea S.r.l. 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 blazingcache.client.impl;

import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.concurrent.locks.ReentrantLock;
import java.util.concurrent.locks.ReentrantReadWriteLock;
import java.util.logging.Level;
import java.util.logging.Logger;

/**
 * Handle locks by key
 *
 * @author enrico.olivelli
 */
public class LocalLockManager {

    private static final Logger LOGGER = Logger.getLogger(LocalLockManager.class.getName());
    private static final boolean ENABLE_LOCAL_LOCKS = Boolean.parseBoolean(System.getProperty("blazingcache.client.enablelocallocks", "true"));

    private ReentrantReadWriteLock makeLock() {
        return new ReentrantReadWriteLock();
    }
    private final ReentrantLock generalLock = new ReentrantLock(true);
    private final Map liveLocks = new HashMap<>();
    private final Map locksCounter = new HashMap<>();

    private ReentrantReadWriteLock makeLockForKey(String key) {
        ReentrantReadWriteLock lock;
        generalLock.lock();
        try {
            lock = liveLocks.get(key);
            if (lock == null) {
                lock = makeLock();
                liveLocks.put(key, lock);
                locksCounter.put(key, new AtomicInteger(1));
            } else {
                locksCounter.get(key).incrementAndGet();
            }
        } finally {
            generalLock.unlock();
        }
        return lock;
    }

    private ReentrantReadWriteLock returnLockForKey(String key) throws IllegalStateException {
        ReentrantReadWriteLock lock;
        generalLock.lock();
        try {
            lock = liveLocks.get(key);
            if (lock == null) {
                LOGGER.log(Level.SEVERE, "no lock object exists for key {0}", key);
                throw new IllegalStateException("no lock object exists for key " + key);
            }
            int actualCount = locksCounter.get(key).decrementAndGet();
            if (actualCount == 0) {
                liveLocks.remove(key);
                locksCounter.remove(key);
            }
        } finally {
            generalLock.unlock();
        }
        return lock;
    }

    public ReentrantReadWriteLock acquireWriteLockForKey(String key) {
        if (!ENABLE_LOCAL_LOCKS) {
            return null;
        }
        ReentrantReadWriteLock lock = makeLockForKey(key);
        lock.writeLock().lock();
        return lock;
    }

    public void releaseWriteLockForKey(String key, ReentrantReadWriteLock lockStamp) {
        if (!ENABLE_LOCAL_LOCKS) {
            return;
        }
        ReentrantReadWriteLock lock = returnLockForKey(key);
        lock.writeLock().unlock();
    }

    public ReentrantReadWriteLock acquireReadLockForKey(String key) {
        if (!ENABLE_LOCAL_LOCKS) {
            return null;
        }
        ReentrantReadWriteLock lock = makeLockForKey(key);
        lock.readLock().lock();
        return lock;
    }

    public void releaseReadLockForKey(String key, ReentrantReadWriteLock lockStamp) {
        if (!ENABLE_LOCAL_LOCKS) {
            return;
        }
        ReentrantReadWriteLock lock = returnLockForKey(key);
        lock.readLock().unlock();
    }

}