/*
    * Copyright 2013 The Netty Project
    *
    * The Netty Project 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:
    *
    *   https://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 io.netty.util.concurrent;
  
  import io.netty.util.internal.UnstableApi;
  import io.netty.util.internal.logging.InternalLogger;
  import io.netty.util.internal.logging.InternalLoggerFactory;
  
  import org.jetbrains.annotations.Async.Execute;
  
  import java.util.Collection;
  import java.util.Collections;
  import java.util.Iterator;
  import java.util.List;
  import java.util.concurrent.AbstractExecutorService;
  import java.util.concurrent.Callable;
  import java.util.concurrent.RunnableFuture;
  import java.util.concurrent.TimeUnit;
  
  /**
   * Abstract base class for {@link EventExecutor} implementations.
   */
  public abstract class AbstractEventExecutor extends AbstractExecutorService implements EventExecutor {
      private static final InternalLogger logger = InternalLoggerFactory.getInstance(AbstractEventExecutor.class);
  
      static final long DEFAULT_SHUTDOWN_QUIET_PERIOD = 2;
      static final long DEFAULT_SHUTDOWN_TIMEOUT = 15;
  
      private final EventExecutorGroup parent;
      private final Collection<EventExecutor> selfCollection = Collections.<EventExecutor>singleton(this);
  
      protected AbstractEventExecutor() {
          this(null);
      }
  
      protected AbstractEventExecutor(EventExecutorGroup parent) {
          this.parent = parent;
      }
  
      @Override
      public EventExecutorGroup parent() {
          return parent;
      }
  
      @Override
      public EventExecutor next() {
          return this;
      }
  
      @Override
      public Iterator<EventExecutor> iterator() {
          return selfCollection.iterator();
      }
  
      @Override
      public Future<?> shutdownGracefully() {
          return shutdownGracefully(DEFAULT_SHUTDOWN_QUIET_PERIOD, DEFAULT_SHUTDOWN_TIMEOUT, TimeUnit.SECONDS);
      }
  
      /**
       * @deprecated {@link #shutdownGracefully(long, long, TimeUnit)} or {@link #shutdownGracefully()} instead.
       */
      @Override
      @Deprecated
      public abstract void shutdown();
  
      /**
       * @deprecated {@link #shutdownGracefully(long, long, TimeUnit)} or {@link #shutdownGracefully()} instead.
       */
      @Override
      @Deprecated
      public List<Runnable> shutdownNow() {
          shutdown();
          return Collections.emptyList();
      }
  
      @Override
      public Future<?> submit(Runnable task) {
          return (Future<?>) super.submit(task);
      }
  
      @Override
      public <T> Future<T> submit(Runnable task, T result) {
          return (Future<T>) super.submit(task, result);
      }
  
     @Override
     public <T> Future<T> submit(Callable<T> task) {
         return (Future<T>) super.submit(task);
     }
 
     @Override
     protected final <T> RunnableFuture<T> newTaskFor(Runnable runnable, T value) {
         return new PromiseTask<T>(this, runnable, value);
     }
 
     @Override
     protected final <T> RunnableFuture<T> newTaskFor(Callable<T> callable) {
         return new PromiseTask<T>(this, callable);
     }
 
     @Override
     public ScheduledFuture<?> schedule(Runnable command, long delay,
                                        TimeUnit unit) {
         throw new UnsupportedOperationException();
     }
 
     @Override
     public <V> ScheduledFuture<V> schedule(Callable<V> callable, long delay, TimeUnit unit) {
         throw new UnsupportedOperationException();
     }
 
     @Override
     public ScheduledFuture<?> scheduleAtFixedRate(Runnable command, long initialDelay, long period, TimeUnit unit) {
         throw new UnsupportedOperationException();
     }
 
     @Override
     public ScheduledFuture<?> scheduleWithFixedDelay(Runnable command, long initialDelay, long delay, TimeUnit unit) {
         throw new UnsupportedOperationException();
     }
 
     /**
      * Try to execute the given {@link Runnable} and just log if it throws a {@link Throwable}.
      */
     protected static void safeExecute(Runnable task) {
         try {
             runTask(task);
         } catch (Throwable t) {
             logger.warn("A task raised an exception. Task: {}", task, t);
         }
     }
 
     protected static void runTask(@Execute Runnable task) {
         task.run();
     }
 
     /**
      * Like {@link #execute(Runnable)} but does not guarantee the task will be run until either
      * a non-lazy task is executed or the executor is shut down.
      * <p>
      * The default implementation just delegates to {@link #execute(Runnable)}.
      * </p>
      */
     @UnstableApi
     public void lazyExecute(Runnable task) {
         execute(task);
     }
 
     /**
      *  @deprecated override {@link SingleThreadEventExecutor#wakesUpForTask} to re-create this behaviour
      *
      */
     @Deprecated
     public interface LazyRunnable extends Runnable { }
 }