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   /*
    * Copyright 2012 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:
    *
    *   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 io.netty.channel;
  
  import io.netty.util.concurrent.EventExecutorGroup;
  import io.netty.util.concurrent.RejectedExecutionHandler;
  import io.netty.util.concurrent.RejectedExecutionHandlers;
  import io.netty.util.concurrent.SingleThreadEventExecutor;
  import io.netty.util.internal.SystemPropertyUtil;
  
  import java.util.concurrent.ThreadFactory;
  
  /**
   * Abstract base class for {@link EventLoop}'s that execute all its submitted tasks in a single thread.
   *
   */
  public abstract class SingleThreadEventLoop extends SingleThreadEventExecutor implements EventLoop {
  
      protected static final int DEFAULT_MAX_PENDING_TASKS = Math.max(16,
              SystemPropertyUtil.getInt("io.netty.eventLoop.maxPendingTasks", Integer.MAX_VALUE));
  
      /**
       * @see {@link SingleThreadEventExecutor#SingleThreadEventExecutor(EventExecutorGroup, ThreadFactory, boolean)}
       */
      protected SingleThreadEventLoop(EventLoopGroup parent, ThreadFactory threadFactory, boolean addTaskWakesUp) {
          this(parent, threadFactory, addTaskWakesUp, DEFAULT_MAX_PENDING_TASKS, RejectedExecutionHandlers.reject());
      }
  
      protected SingleThreadEventLoop(EventLoopGroup parent, ThreadFactory threadFactory,
                                      boolean addTaskWakesUp, int maxPendingTasks,
                                      RejectedExecutionHandler rejectedExecutionHandler) {
          super(parent, threadFactory, addTaskWakesUp, maxPendingTasks, rejectedExecutionHandler);
      }
  
      @Override
      public EventLoopGroup parent() {
          return (EventLoopGroup) super.parent();
      }
  
      @Override
      public EventLoop next() {
          return (EventLoop) super.next();
      }
  
      @Override
      public ChannelFuture register(Channel channel) {
          return register(channel, new DefaultChannelPromise(channel, this));
      }
  
      @Override
      public ChannelFuture register(final Channel channel, final ChannelPromise promise) {
          if (channel == null) {
              throw new NullPointerException("channel");
          }
          if (promise == null) {
              throw new NullPointerException("promise");
          }
  
          channel.unsafe().register(this, promise);
          return promise;
      }
  
      @Override
      protected boolean wakesUpForTask(Runnable task) {
          return !(task instanceof NonWakeupRunnable);
      }
  
      /**
       * Marker interface for {@link Runnable} that will not trigger an {@link #wakeup(boolean)} in all cases.
       */
      interface NonWakeupRunnable extends Runnable { }
  }