/*
    * 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 org.jboss.netty.channel.socket.oio;
  
  import org.jboss.netty.channel.Channel;
  import org.jboss.netty.channel.ChannelFuture;
  import org.jboss.netty.channel.Channels;
  import org.jboss.netty.channel.socket.Worker;
  
  import java.io.IOException;
  import java.net.SocketTimeoutException;
  import java.util.Queue;
  import java.util.concurrent.ConcurrentLinkedQueue;
  
  import static org.jboss.netty.channel.Channels.*;
  
  /**
   * Abstract base class for Oio-Worker implementations
   *
   * @param <C> {@link AbstractOioChannel}
   */
  abstract class AbstractOioWorker<C extends AbstractOioChannel> implements Worker {
  
      private final Queue<Runnable> eventQueue = new ConcurrentLinkedQueue<Runnable>();
  
      protected final C channel;
  
      /**
       * If this worker has been started thread will be a reference to the thread
       * used when starting. i.e. the current thread when the run method is executed.
       */
      protected volatile Thread thread;
  
      private volatile boolean done;
  
      protected AbstractOioWorker(C channel) {
          this.channel = channel;
          channel.worker = this;
      }
  
      public void run() {
          thread = channel.workerThread = Thread.currentThread();
          while (channel.isOpen()) {
              synchronized (channel.interestOpsLock) {
                  while (!channel.isReadable()) {
                      try {
                          // notify() is not called at all.
                          // close() and setInterestOps() calls Thread.interrupt()
                          channel.interestOpsLock.wait();
                      } catch (InterruptedException e) {
                          if (!channel.isOpen()) {
                              break;
                          }
                      }
                  }
              }
  
              boolean cont = false;
              try {
                  cont = process();
              } catch (Throwable t) {
                  boolean readTimeout = t instanceof SocketTimeoutException;
                  if (!readTimeout && !channel.isSocketClosed()) {
                      fireExceptionCaught(channel, t);
                  }
                  if (readTimeout) {
                      // the readTimeout was triggered because of the SO_TIMEOUT,
                      // so  just continue with the loop here
                      cont = true;
                  }
              } finally {
                  processEventQueue();
              }
  
              if (!cont) {
                  break;
              }
          }
  
          synchronized (channel.interestOpsLock) {
              // Setting the workerThread to null will prevent any channel
              // operations from interrupting this thread from now on.
              //
              //
              // Do this while holding the lock to not race with close(...) or
              // setInterestOps(...)
             channel.workerThread = null;
         }
 
         // Clean up.
         close(channel, succeededFuture(channel), true);
 
         // Mark the worker event loop as done so we know that we need to run tasks directly and not queue them
         // See #287
         done = true;
 
         // just to make we don't have something left
         processEventQueue();
     }
 
     static boolean isIoThread(AbstractOioChannel channel) {
         return Thread.currentThread() == channel.workerThread;
     }
 
     public void executeInIoThread(Runnable task) {
         // check if the current thread is the worker thread
         //
         // Also check if the event loop of the worker is complete. If so we need to run the task now.
         // See #287
         if (Thread.currentThread() == thread || done) {
             task.run();
         } else {
             boolean added = eventQueue.offer(task);
 
             if (added) {
                 // as we set the SO_TIMEOUT to 1 second this task will get picked up in 1 second at latest
             }
         }
     }
 
     private void processEventQueue() {
         for (;;) {
             final Runnable task = eventQueue.poll();
             if (task == null) {
                 break;
             }
             task.run();
         }
     }
 
     /**
      * Process the incoming messages and also is responsible for call
      * {@link Channels#fireMessageReceived(Channel, Object)} once a message was processed without
      * errors.
      *
      * @return continue returns {@code true} as long as this worker should continue to try
      *         processing incoming messages
      * @throws IOException
      */
     abstract boolean process() throws IOException;
 
     static void setInterestOps(
             AbstractOioChannel channel, ChannelFuture future, int interestOps) {
         boolean iothread = isIoThread(channel);
 
         // Override OP_WRITE flag - a user cannot change this flag.
         interestOps &= ~Channel.OP_WRITE;
         interestOps |= channel.getInterestOps() & Channel.OP_WRITE;
 
         boolean changed = false;
         try {
             if (channel.getInterestOps() != interestOps) {
                 if ((interestOps & Channel.OP_READ) != 0) {
                     channel.setInterestOpsNow(Channel.OP_READ);
                 } else {
                     channel.setInterestOpsNow(Channel.OP_NONE);
                 }
                 changed = true;
             }
 
             future.setSuccess();
             if (changed) {
                 synchronized (channel.interestOpsLock) {
                     channel.setInterestOpsNow(interestOps);
 
                     // Notify the worker so it stops or continues reading.
                     Thread currentThread = Thread.currentThread();
                     Thread workerThread = channel.workerThread;
                     if (workerThread != null && currentThread != workerThread) {
                         workerThread.interrupt();
                     }
                 }
                 if (iothread) {
                     fireChannelInterestChanged(channel);
                 } else {
                     fireChannelInterestChangedLater(channel);
                 }
             }
         } catch (Throwable t) {
             future.setFailure(t);
             if (iothread) {
                 fireExceptionCaught(channel, t);
             } else {
                 fireExceptionCaughtLater(channel, t);
             }
         }
     }
 
     static void close(AbstractOioChannel channel, ChannelFuture future) {
         close(channel, future, isIoThread(channel));
     }
 
     private static void close(AbstractOioChannel channel, ChannelFuture future, boolean iothread) {
         boolean connected = channel.isConnected();
         boolean bound = channel.isBound();
 
         try {
             channel.closeSocket();
             if (channel.setClosed()) {
                 future.setSuccess();
                 if (connected) {
                     Thread currentThread = Thread.currentThread();
                     synchronized (channel.interestOpsLock) {
                         // We need to do this while hold the lock as otherwise
                         // we may race and so interrupt the workerThread even
                         // if we are in the workerThread now.
                         // This can happen if run() set channel.workerThread to null
                         // between workerThread != null and currentThread!= workerThread
                         Thread workerThread = channel.workerThread;
                         if (workerThread != null && currentThread != workerThread) {
                             workerThread.interrupt();
                         }
                     }
 
                     if (iothread) {
                         fireChannelDisconnected(channel);
                     } else {
                         fireChannelDisconnectedLater(channel);
                     }
                 }
                 if (bound) {
                     if (iothread) {
                         fireChannelUnbound(channel);
                     } else {
                         fireChannelUnboundLater(channel);
                     }
                 }
                 if (iothread) {
                     fireChannelClosed(channel);
                 } else {
                     fireChannelClosedLater(channel);
                 }
             } else {
                 future.setSuccess();
             }
         } catch (Throwable t) {
             future.setFailure(t);
             if (iothread) {
                 fireExceptionCaught(channel, t);
             } else {
                 fireExceptionCaughtLater(channel, t);
             }
         }
     }
 }