package org.eclipse.aether.named.redisson;
   
   /*
    * 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 org.eclipse.aether.named.support.AdaptedSemaphoreNamedLock;
  import org.redisson.api.RSemaphore;
  
  import javax.inject.Named;
  import javax.inject.Singleton;
  import java.util.concurrent.ConcurrentHashMap;
  import java.util.concurrent.ConcurrentMap;
  import java.util.concurrent.TimeUnit;
  
  /**
   * Provider of {@link RedissonSemaphoreNamedLockFactory} using Redisson and {@link org.redisson.api.RSemaphore}.
   */
  @Singleton
  @Named( RedissonSemaphoreNamedLockFactory.NAME )
  public class RedissonSemaphoreNamedLockFactory
      extends RedissonNamedLockFactorySupport
  {
      public static final String NAME = "semaphore-redisson";
  
      private static final String TYPED_NAME_PREFIX = NAME_PREFIX + NAME + ":";
  
      private final ConcurrentMap<String, RSemaphore> semaphores;
  
      public RedissonSemaphoreNamedLockFactory()
      {
          this.semaphores = new ConcurrentHashMap<>();
      }
  
      @Override
      protected AdaptedSemaphoreNamedLock createLock( final String name )
      {
          RSemaphore semaphore = semaphores.computeIfAbsent( name, k ->
          {
              RSemaphore result = redissonClient.getSemaphore( TYPED_NAME_PREFIX + k );
              result.trySetPermits( Integer.MAX_VALUE );
              return result;
          } );
          return new AdaptedSemaphoreNamedLock( name, this, new RedissonSemaphore( semaphore ) );
      }
  
      @Override
      protected void destroyLock( final String name )
      {
          RSemaphore semaphore = semaphores.remove( name );
          if ( semaphore == null )
          {
              throw new IllegalStateException( "Semaphore expected but does not exist: " + name );
          }
          /* Threre is no reasonable way to destroy the semaphore in Redis because we cannot know
           * when the last process has stopped using it.
           */
      }
  
      private static final class RedissonSemaphore implements AdaptedSemaphoreNamedLock.AdaptedSemaphore
      {
          private final RSemaphore semaphore;
  
          private RedissonSemaphore( final RSemaphore 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 );
          }
      }
  }