org.apache.wink.common.internal.utils.SimpleConcurrentMap Maven / Gradle / Ivy
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package org.apache.wink.common.internal.utils;
import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReadWriteLock;
import java.util.concurrent.locks.ReentrantReadWriteLock;
/**
*
* Concurrent implementation of the SimpleMap interface. The idea behind this
* implementation that get is called more frequently than put or clear,
* therefore ReentrantReadWriteLock is used: get is read operation, while put
* and clear are write operations.
*
* @param
* @param
* @see java.util.concurrent.locks.ReentrantReadWriteLock
*/
public class SimpleConcurrentMap implements SimpleMap {
private final Lock readersLock;
private final Lock writersLock;
private final Map map;
public SimpleConcurrentMap() {
this(new HashMap());
}
/**
* Provides the map implementation. Pay attention that get method is
* synchronized using the read lock, therefore it must not change the
* entire collection.
*
* @param map
*/
public SimpleConcurrentMap(Map map) {
this.map = map;
ReadWriteLock readWriteLock = new ReentrantReadWriteLock();
readersLock = readWriteLock.readLock();
writersLock = readWriteLock.writeLock();
}
public V get(K key) {
readersLock.lock();
try {
return map.get(key);
} finally {
readersLock.unlock();
}
}
public V put(K key, V val) {
writersLock.lock();
try {
return map.put(key, val);
} finally {
writersLock.unlock();
}
}
public void clear() {
writersLock.lock();
try {
map.clear();
} finally {
writersLock.unlock();
}
}
}