/*
* 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.marmotta.commons.locking;
import com.google.common.cache.CacheBuilder;
import com.google.common.cache.CacheLoader;
import com.google.common.cache.LoadingCache;
import com.google.common.util.concurrent.Monitor;
import java.util.HashSet;
/**
* An implementation of dynamic name-based locks that allows more fine-grained locking methods based on a string name.
*
* @author Sebastian Schaffert (sschaffert@apache.org)
*/
public class ObjectLocks {
private LoadingCache<Object,Monitor> stringLocks;
public ObjectLocks() {
stringLocks = CacheBuilder.newBuilder().build(new LockCacheLoader());
}
public void lock(Object name) {
Monitor lock;
synchronized (stringLocks) {
lock = stringLocks.getUnchecked(name);
}
lock.enter();
}
public void unlock(Object name) {
Monitor lock;
synchronized (stringLocks) {
lock = stringLocks.getUnchecked(name);
}
lock.leave();
}
public boolean tryLock(Object name) {
Monitor lock;
synchronized (stringLocks) {
lock = stringLocks.getUnchecked(name);
}
return lock.tryEnter();
}
/**
* A simple Guava cache loader implementation for generating object-based locks
*/
private static class LockCacheLoader extends CacheLoader<Object,Monitor> {
@Override
public Monitor load(Object key) throws Exception {
return new Monitor();
}
}
}