com.liveramp.megadesk.base.state.MultiLock.java Source code

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Here is the source code for com.liveramp.megadesk.base.state.MultiLock.java

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/**
 *  Copyright 2014 LiveRamp
 *
 *  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 com.liveramp.megadesk.base.state;

import java.util.Collection;
import java.util.Iterator;
import java.util.Set;

import com.google.common.collect.ImmutableList;
import com.google.common.collect.Sets;

import com.liveramp.megadesk.core.state.Lock;

public class MultiLock implements Lock {

    private final Collection<Lock> locks;
    private final Set<Lock> acquiredLocks;

    public MultiLock(Collection<Lock> locks) {
        this.locks = ImmutableList.copyOf(locks);
        this.acquiredLocks = Sets.newHashSet();
    }

    @Override
    public void lock() {
        for (Lock lock : locks) {
            lockAndRemember(lock, acquiredLocks);
        }
    }

    @Override
    public boolean tryLock() {
        for (Lock lock : locks) {
            if (!tryLockAndRemember(lock, acquiredLocks)) {
                unlockAndRemember(acquiredLocks);
                return false;
            }
        }
        return true;
    }

    @Override
    public void unlock() {
        unlockAndRemember(acquiredLocks);
    }

    private static boolean tryLockAndRemember(Lock lock, Set<Lock> acquiredLocks) {
        boolean result = lock.tryLock();
        if (result) {
            acquiredLocks.add(lock);
        }
        return result;
    }

    private static void lockAndRemember(Lock lock, Set<Lock> acquiredLocks) {
        lock.lock();
        acquiredLocks.add(lock);
    }

    private static void unlockAndRemember(Set<Lock> acquiredLocks) {
        Iterator<Lock> lockIterator = acquiredLocks.iterator();
        while (lockIterator.hasNext()) {
            lockIterator.next().unlock();
            lockIterator.remove();
        }
    }
}