maven-resolver-named-locks/src/main/java/org/eclipse/aether/named/providers/LocalSemaphoreNamedLockFactory.java

/*
 * 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.eclipse.aether.named.providers;

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

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

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) {
        Semaphore semaphore = new Semaphore(Integer.MAX_VALUE);
        return new AdaptedSemaphoreNamedLock(name, this, new JVMSemaphore(semaphore));
    }

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

        private JVMSemaphore(final Semaphore semaphore) {
            this.semaphore = semaphore;
        }

        @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);
        }
    }
}