/*
* Copyright (c) 2008-2017, Hazelcast, Inc. 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 com.hazelcast.map.impl.mapstore;
import com.hazelcast.core.IFunction;
import com.hazelcast.core.MapLoader;
import com.hazelcast.util.ExceptionUtil;
import com.hazelcast.util.IterableUtil;
import java.util.Collection;
import java.util.Map;
import java.util.concurrent.CountDownLatch;
/**
* MapLoader that pauses once while loading keys until resumed using {@link #resume()}
**/
class PausingMapLoader<K, V> implements MapLoader<K, V> {
private MapLoader<K, V> delegate;
private int pauseAt;
private int counter;
private CountDownLatch resumeLatch = new CountDownLatch(1);
private CountDownLatch pauseLatch = new CountDownLatch(1);
PausingMapLoader(MapLoader<K, V> delegate, int pauseAt) {
this.delegate = delegate;
this.pauseAt = pauseAt;
}
@Override
public V load(K key) {
return delegate.load(key);
}
@Override
public Map<K, V> loadAll(Collection<K> keys) {
return delegate.loadAll(keys);
}
@Override
public Iterable<K> loadAllKeys() {
Iterable<K> allKeys = delegate.loadAllKeys();
return IterableUtil.map(allKeys, new IFunction<K, K>() {
@Override
public K apply(K key) {
if (counter++ == pauseAt) {
pause();
}
return key;
}
});
}
private void pause() {
try {
pauseLatch.countDown();
resumeLatch.await();
} catch (InterruptedException e) {
ExceptionUtil.rethrow(e);
}
}
public void awaitPause() {
try {
pauseLatch.await();
} catch (InterruptedException e) {
ExceptionUtil.rethrow(e);
}
}
public void resume() {
resumeLatch.countDown();
}
}