/*
    * Copyright 2014 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.epoll;
  
  import io.netty.channel.Channel;
  import io.netty.channel.ChannelFuture;
  import io.netty.channel.ChannelPromise;
  import io.netty.channel.EventLoop;
  import io.netty.channel.socket.ServerSocketChannel;
  import io.netty.channel.socket.SocketChannel;
  import io.netty.channel.unix.FileDescriptor;
  import io.netty.util.concurrent.GlobalEventExecutor;
  import io.netty.util.internal.OneTimeTask;
  
  import java.net.InetSocketAddress;
  import java.net.SocketAddress;
  import java.util.concurrent.Executor;
  
  /**
   * {@link SocketChannel} implementation that uses linux EPOLL Edge-Triggered Mode for
   * maximal performance.
   */
  public final class EpollSocketChannel extends AbstractEpollStreamChannel implements SocketChannel {
  
      private final EpollSocketChannelConfig config;
  
      private volatile InetSocketAddress local;
      private volatile InetSocketAddress remote;
  
      EpollSocketChannel(Channel parent, int fd, InetSocketAddress remote) {
          super(parent, fd);
          config = new EpollSocketChannelConfig(this);
          // Directly cache the remote and local addresses
          // See https://github.com/netty/netty/issues/2359
          this.remote = remote;
          local = Native.localAddress(fd);
      }
  
      public EpollSocketChannel() {
          super(Native.socketStreamFd());
          config = new EpollSocketChannelConfig(this);
      }
  
      /**
       * Creates a new {@link EpollSocketChannel} from an existing {@link FileDescriptor}.
       */
      public EpollSocketChannel(FileDescriptor fd) {
          super(fd);
          config = new EpollSocketChannelConfig(this);
  
          // As we create an EpollSocketChannel from a FileDescriptor we should try to obtain the remote and local
          // address from it. This is needed as the FileDescriptor may be bound/connected already.
          remote = Native.remoteAddress(fd.intValue());
          local = Native.localAddress(fd.intValue());
      }
  
      /**
       * Returns the {@code TCP_INFO} for the current socket. See <a href="http://linux.die.net/man/7/tcp">man 7 tcp</a>.
       */
      public EpollTcpInfo tcpInfo() {
          return tcpInfo(new EpollTcpInfo());
      }
  
      /**
       * Updates and returns the {@code TCP_INFO} for the current socket.
       * See <a href="http://linux.die.net/man/7/tcp">man 7 tcp</a>.
       */
      public EpollTcpInfo tcpInfo(EpollTcpInfo info) {
          Native.tcpInfo(fd().intValue(), info);
          return info;
      }
  
      @Override
      public InetSocketAddress remoteAddress() {
          return (InetSocketAddress) super.remoteAddress();
      }
  
      @Override
      public InetSocketAddress localAddress() {
          return (InetSocketAddress) super.localAddress();
      }
  
      @Override
      protected SocketAddress localAddress0() {
          return local;
      }
 
     @Override
     protected SocketAddress remoteAddress0() {
         if (remote == null) {
             // Remote address not know, try to get it now.
             InetSocketAddress address = Native.remoteAddress(fd().intValue());
             if (address != null) {
                 remote = address;
             }
             return address;
         }
         return remote;
     }
 
     @Override
     protected void doBind(SocketAddress local) throws Exception {
         InetSocketAddress localAddress = (InetSocketAddress) local;
         int fd = fd().intValue();
         Native.bind(fd, localAddress);
         this.local = Native.localAddress(fd);
     }
 
     @Override
     public EpollSocketChannelConfig config() {
         return config;
     }
 
     @Override
     public boolean isInputShutdown() {
         return isInputShutdown0();
     }
 
     @Override
     public boolean isOutputShutdown() {
         return isOutputShutdown0();
     }
 
     @Override
     public ChannelFuture shutdownOutput() {
         return shutdownOutput(newPromise());
     }
 
     @Override
     public ChannelFuture shutdownOutput(final ChannelPromise promise) {
         Executor closeExecutor = ((EpollSocketChannelUnsafe) unsafe()).closeExecutor();
         if (closeExecutor != null) {
             closeExecutor.execute(new OneTimeTask() {
                 @Override
                 public void run() {
                     shutdownOutput0(promise);
                 }
             });
         } else {
             EventLoop loop = eventLoop();
             if (loop.inEventLoop()) {
                 shutdownOutput0(promise);
             } else {
                 loop.execute(new OneTimeTask() {
                     @Override
                     public void run() {
                         shutdownOutput0(promise);
                     }
                 });
             }
         }
         return promise;
     }
 
     @Override
     public ServerSocketChannel parent() {
         return (ServerSocketChannel) super.parent();
     }
 
     @Override
     protected AbstractEpollUnsafe newUnsafe() {
         return new EpollSocketChannelUnsafe();
     }
 
     @Override
     protected boolean doConnect(SocketAddress remoteAddress, SocketAddress localAddress) throws Exception {
         if (localAddress != null) {
             checkResolvable((InetSocketAddress) localAddress);
         }
         checkResolvable((InetSocketAddress) remoteAddress);
         if (super.doConnect(remoteAddress, localAddress)) {
             int fd = fd().intValue();
             local = Native.localAddress(fd);
             remote = (InetSocketAddress) remoteAddress;
             return true;
         }
         return false;
     }
 
     private final class EpollSocketChannelUnsafe extends EpollStreamUnsafe {
         @Override
         protected Executor closeExecutor() {
             if (config().getSoLinger() > 0) {
                 return GlobalEventExecutor.INSTANCE;
             }
             return null;
         }
     }
 }