001package org.eclipse.aether.named.providers;
002
003/*
004 * Licensed to the Apache Software Foundation (ASF) under one
005 * or more contributor license agreements.  See the NOTICE file
006 * distributed with this work for additional information
007 * regarding copyright ownership.  The ASF licenses this file
008 * to you under the Apache License, Version 2.0 (the
009 * "License"); you may not use this file except in compliance
010 * with the License.  You may obtain a copy of the License at
011 *
012 *  http://www.apache.org/licenses/LICENSE-2.0
013 *
014 * Unless required by applicable law or agreed to in writing,
015 * software distributed under the License is distributed on an
016 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
017 * KIND, either express or implied.  See the License for the
018 * specific language governing permissions and limitations
019 * under the License.
020 */
021
022import java.util.concurrent.Semaphore;
023import java.util.concurrent.TimeUnit;
024
025import javax.inject.Named;
026import javax.inject.Singleton;
027
028import org.eclipse.aether.named.support.AdaptedSemaphoreNamedLock;
029import org.eclipse.aether.named.support.NamedLockFactorySupport;
030
031/**
032 * A JVM-local named lock factory that uses named {@link Semaphore}s.
033 */
034@Singleton
035@Named( LocalSemaphoreNamedLockFactory.NAME )
036public class LocalSemaphoreNamedLockFactory
037    extends NamedLockFactorySupport
038{
039    public static final String NAME = "semaphore-local";
040
041    @Override
042    protected AdaptedSemaphoreNamedLock createLock( final String name )
043    {
044      Semaphore semaphore = new Semaphore( Integer.MAX_VALUE );
045      return new AdaptedSemaphoreNamedLock( name, this, new JVMSemaphore( semaphore ) );
046    }
047
048    /**
049     * Adapted JVM {@link java.util.concurrent.Semaphore}.
050     */
051    private static final class JVMSemaphore
052        implements AdaptedSemaphoreNamedLock.AdaptedSemaphore
053    {
054        private final Semaphore semaphore;
055
056        private JVMSemaphore( final Semaphore semaphore )
057        {
058          this.semaphore = semaphore;
059        }
060
061        @Override
062        public boolean tryAcquire( final int perms, final long time, final TimeUnit unit ) throws InterruptedException
063        {
064             return semaphore.tryAcquire( perms, time, unit );
065        }
066
067        @Override
068        public void release( final int perms )
069        {
070            semaphore.release( perms );
071        }
072    }
073}