package org.eclipse.aether.named.providers;

/*
 * 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.
 */

import java.util.concurrent.Semaphore;
import java.util.concurrent.TimeUnit;

import javax.inject.Named;
import javax.inject.Singleton;

import org.eclipse.aether.named.support.AdaptedSemaphoreNamedLock;
import org.eclipse.aether.named.support.NamedLockFactorySupport;

/**
 * A JVM-local named lock factory that uses named {@link Semaphore}s.
 */
@Singleton
@Named( LocalSemaphoreNamedLockFactory.NAME )
public class LocalSemaphoreNamedLockFactory
    extends NamedLockFactorySupport
{
  public static final String NAME = "semaphore-local";

  @Override
  protected AdaptedSemaphoreNamedLock createLock( final String name )
  {
    return new AdaptedSemaphoreNamedLock( name, this, new JVMSemaphore() );
  }

  /**
   * Adapted JVM {@link java.util.concurrent.Semaphore}.
   */
  private static final class JVMSemaphore
      implements AdaptedSemaphoreNamedLock.AdaptedSemaphore
  {
    private final Semaphore semaphore;

    private JVMSemaphore()
    {
      this.semaphore = new Semaphore( Integer.MAX_VALUE );
    }

    @Override
    public boolean tryAcquire( final int perms, final long time, final TimeUnit unit ) throws InterruptedException
    {
      return semaphore.tryAcquire( perms, time, unit );
    }

    @Override
    public void release( final int perms )
    {
      semaphore.release( perms );
    }
  }
}
