001/*
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements.  See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership.  The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License.  You may obtain a copy of the License at
009 *
010 *   http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing,
013 * software distributed under the License is distributed on an
014 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
015 * KIND, either express or implied.  See the License for the
016 * specific language governing permissions and limitations
017 * under the License.
018 */
019package org.eclipse.aether.named.redisson;
020
021import javax.inject.Named;
022import javax.inject.Singleton;
023
024import java.util.concurrent.ConcurrentHashMap;
025import java.util.concurrent.ConcurrentMap;
026import java.util.concurrent.TimeUnit;
027
028import org.eclipse.aether.named.support.AdaptedSemaphoreNamedLock;
029import org.redisson.api.RSemaphore;
030
031/**
032 * Provider of {@link RedissonSemaphoreNamedLockFactory} using Redisson and {@link org.redisson.api.RSemaphore}.
033 */
034@Singleton
035@Named(RedissonSemaphoreNamedLockFactory.NAME)
036public class RedissonSemaphoreNamedLockFactory extends RedissonNamedLockFactorySupport {
037    public static final String NAME = "semaphore-redisson";
038
039    private static final String TYPED_NAME_PREFIX = NAME_PREFIX + NAME + ":";
040
041    private final ConcurrentMap<String, RSemaphore> semaphores;
042
043    public RedissonSemaphoreNamedLockFactory() {
044        this.semaphores = new ConcurrentHashMap<>();
045    }
046
047    @Override
048    protected AdaptedSemaphoreNamedLock createLock(final String name) {
049        RSemaphore semaphore = semaphores.computeIfAbsent(name, k -> {
050            RSemaphore result = redissonClient.getSemaphore(TYPED_NAME_PREFIX + k);
051            result.trySetPermits(Integer.MAX_VALUE);
052            return result;
053        });
054        return new AdaptedSemaphoreNamedLock(name, this, new RedissonSemaphore(semaphore));
055    }
056
057    @Override
058    protected void destroyLock(final String name) {
059        RSemaphore semaphore = semaphores.remove(name);
060        if (semaphore == null) {
061            throw new IllegalStateException("Semaphore expected, but does not exist: " + name);
062        }
063        /* Threre is no reasonable way to destroy the semaphore in Redis because we cannot know
064         * when the last process has stopped using it.
065         */
066    }
067
068    private static final class RedissonSemaphore implements AdaptedSemaphoreNamedLock.AdaptedSemaphore {
069        private final RSemaphore semaphore;
070
071        private RedissonSemaphore(final RSemaphore semaphore) {
072            this.semaphore = semaphore;
073        }
074
075        @Override
076        public boolean tryAcquire(final int perms, final long time, final TimeUnit unit) throws InterruptedException {
077            return semaphore.tryAcquire(perms, time, unit);
078        }
079
080        @Override
081        public void release(final int perms) {
082            semaphore.release(perms);
083        }
084    }
085}