test.utils/src/main/java/org/apache/clerezza/test/utils/LockingIteratorForTesting.java

/*
 * 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.clerezza.test.utils;

import org.apache.clerezza.Triple;

import java.util.Iterator;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantReadWriteLock;

/**
 * Wrapps an iterator<Triple> reading all elements to a cache on construction
 * and returning them from that cache.
 * @author reto
 */
class LockingIteratorForTesting implements Iterator<Triple> {

    private Iterator<Triple> base;
    private Lock readLock;
    private Lock writeLock;
    private ReentrantReadWriteLock lock;

    public LockingIteratorForTesting(Iterator<Triple> iterator, ReentrantReadWriteLock lock) {
        base = iterator;
        readLock = lock.readLock();
        writeLock = lock.writeLock();
        this.lock = lock;
    }

    @Override
    public boolean hasNext() {
        LockChecker.checkIfReadLocked(lock);
        readLock.lock();
        try {
            return base.hasNext();
        } finally {
            readLock.unlock();
        }
    }

    @Override
    public Triple next() {
        LockChecker.checkIfReadLocked(lock);
        readLock.lock();
        try {
            return base.next();
        } finally {
            readLock.unlock();
        }
    }

    @Override
    public void remove() {
        LockChecker.checkIfWriteLocked(lock);
        writeLock.lock();
        try {
            base.remove();
        } finally {
            writeLock.unlock();
        }
    }


}