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.NamedLock;
029import org.eclipse.aether.named.NamedLockKey;
030import org.eclipse.aether.named.support.AdaptedSemaphoreNamedLock;
031import org.redisson.api.RSemaphore;
032
033/**
034 * Provider of {@link RedissonSemaphoreNamedLockFactory} using Redisson and {@link org.redisson.api.RSemaphore}.
035 */
036@Singleton
037@Named(RedissonSemaphoreNamedLockFactory.NAME)
038public class RedissonSemaphoreNamedLockFactory extends RedissonNamedLockFactorySupport {
039    public static final String NAME = "semaphore-redisson";
040
041    private static final String TYPED_NAME_PREFIX = NAME_PREFIX + NAME + ":";
042
043    private final ConcurrentMap<NamedLockKey, RSemaphore> semaphores;
044
045    public RedissonSemaphoreNamedLockFactory() {
046        this.semaphores = new ConcurrentHashMap<>();
047    }
048
049    @Override
050    protected AdaptedSemaphoreNamedLock createLock(final NamedLockKey key) {
051        RSemaphore semaphore = semaphores.computeIfAbsent(key, k -> {
052            RSemaphore result = redissonClient.getSemaphore(TYPED_NAME_PREFIX + k.name());
053            if (!result.trySetPermits(Integer.MAX_VALUE)) {
054                logger.warn("Failed to set permits on semaphore '{}'; it may be in a stale state", k.name());
055            }
056            return result;
057        });
058        return new AdaptedSemaphoreNamedLock(key, this, new RedissonSemaphore(semaphore));
059    }
060
061    @Override
062    protected void destroyLock(final NamedLock namedLock) {
063        if (namedLock instanceof AdaptedSemaphoreNamedLock) {
064            final NamedLockKey key = namedLock.key();
065            RSemaphore semaphore = semaphores.remove(key);
066            if (semaphore == null) {
067                throw new IllegalStateException("Semaphore expected, but does not exist: " + key);
068            }
069            /* There is no reasonable way to destroy the semaphore in Redis because we cannot know
070             * when the last process has stopped using it.
071             */
072        }
073    }
074
075    private static final class RedissonSemaphore implements AdaptedSemaphoreNamedLock.AdaptedSemaphore {
076        private final RSemaphore semaphore;
077
078        private RedissonSemaphore(final RSemaphore semaphore) {
079            this.semaphore = semaphore;
080        }
081
082        @Override
083        public boolean tryAcquire(final int perms, final long time, final TimeUnit unit) throws InterruptedException {
084            return semaphore.tryAcquire(perms, time, unit);
085        }
086
087        @Override
088        public void release(final int perms) {
089            semaphore.release(perms);
090        }
091    }
092}