/*******************************************************************************
* Copyright (c) 2012-2017 Codenvy, S.A.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* Contributors:
* Codenvy, S.A. - initial API and implementation
*******************************************************************************/
package org.eclipse.che.commons.lang.concurrent;
import com.google.common.util.concurrent.Striped;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReadWriteLock;
/**
* Helper class to use striped locks in try-with-resources construction.
* </p>
* Examples of usage:
* <pre>{@code
* StripedLocks stripedLocks = new StripedLocks(16);
* try (Unlocker u = stripedLocks.writeLock(myKey)) {
* syncedObject.write();
* }
*
* try (Unlocker u = stripedLocks.readLock(myKey)) {
* syncedObject.read();
* }
*
* try (Unlocker u = stripedLocks.writeAllLock(myKey)) {
* for (ObjectToSync objectToSync : allObjectsToSync) {
* objectToSync.write();
* }
* }
* }</pre>
*
* @author Alexander Garagatyi
* @author Sergii Leschenko
* @author Yevhenii Voevodin
*/
public class StripedLocks {
private final Striped<ReadWriteLock> striped;
public StripedLocks(int stripesCount) {
striped = Striped.readWriteLock(stripesCount);
}
/**
* Acquire read lock for provided key.
*/
public Unlocker readLock(String key) {
Lock lock = striped.get(key).readLock();
lock.lock();
return new LockUnlocker(lock);
}
/**
* Acquire write lock for provided key.
*/
public Unlocker writeLock(String key) {
Lock lock = striped.get(key).writeLock();
lock.lock();
return new LockUnlocker(lock);
}
/**
* Acquire write lock for all possible keys.
*/
public Unlocker writeAllLock() {
Lock[] locks = getAllWriteLocks();
for (Lock lock : locks) {
lock.lock();
}
return new LocksUnlocker(locks);
}
private Lock[] getAllWriteLocks() {
Lock[] locks = new Lock[striped.size()];
for (int i = 0; i < striped.size(); i++) {
locks[i] = striped.getAt(i).writeLock();
}
return locks;
}
private static class LockUnlocker implements Unlocker {
private final Lock lock;
private LockUnlocker(Lock lock) {
this.lock = lock;
}
@Override
public void unlock() {
lock.unlock();
}
}
private static class LocksUnlocker implements Unlocker {
private final Lock[] locks;
private LocksUnlocker(Lock[] locks) {
this.locks = locks;
}
@Override
public void unlock() {
for (Lock lock : locks) {
lock.unlock();
}
}
}
}