content: /*
   * 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.
   */
  
  package org.apache.spark.network.server;
  
  import io.netty.channel.ChannelHandlerContext;
  import io.netty.channel.SimpleChannelInboundHandler;
  import io.netty.handler.timeout.IdleState;
  import io.netty.handler.timeout.IdleStateEvent;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import org.apache.spark.network.client.TransportClient;
  import org.apache.spark.network.client.TransportResponseHandler;
  import org.apache.spark.network.protocol.Message;
  import org.apache.spark.network.protocol.RequestMessage;
  import org.apache.spark.network.protocol.ResponseMessage;
  import static org.apache.spark.network.util.NettyUtils.getRemoteAddress;
  
  /**
   * The single Transport-level Channel handler which is used for delegating requests to the
   * {@link TransportRequestHandler} and responses to the {@link TransportResponseHandler}.
   *
   * All channels created in the transport layer are bidirectional. When the Client initiates a Netty
   * Channel with a RequestMessage (which gets handled by the Server's RequestHandler), the Server
   * will produce a ResponseMessage (handled by the Client's ResponseHandler). However, the Server
   * also gets a handle on the same Channel, so it may then begin to send RequestMessages to the
   * Client.
   * This means that the Client also needs a RequestHandler and the Server needs a ResponseHandler,
   * for the Client's responses to the Server's requests.
   *
   * This class also handles timeouts from a {@link io.netty.handler.timeout.IdleStateHandler}.
   * We consider a connection timed out if there are outstanding fetch or RPC requests but no traffic
   * on the channel for at least `requestTimeoutMs`. Note that this is duplex traffic; we will not
   * timeout if the client is continuously sending but getting no responses, for simplicity.
   */
  public class TransportChannelHandler extends SimpleChannelInboundHandler<Message> {
    private static final Logger logger = LoggerFactory.getLogger(TransportChannelHandler.class);
  
    private final TransportClient client;
    private final TransportResponseHandler responseHandler;
    private final TransportRequestHandler requestHandler;
    private final long requestTimeoutNs;
    private final boolean closeIdleConnections;
  
    public TransportChannelHandler(
        TransportClient client,
        TransportResponseHandler responseHandler,
        TransportRequestHandler requestHandler,
        long requestTimeoutMs,
        boolean closeIdleConnections) {
      this.client = client;
      this.responseHandler = responseHandler;
      this.requestHandler = requestHandler;
      this.requestTimeoutNs = requestTimeoutMs * 1000L * 1000;
      this.closeIdleConnections = closeIdleConnections;
    }
  
    public TransportClient getClient() {
      return client;
    }
  
    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
      logger.warn("Exception in connection from " + getRemoteAddress(ctx.channel()),
        cause);
      requestHandler.exceptionCaught(cause);
      responseHandler.exceptionCaught(cause);
      ctx.close();
    }
  
    @Override
    public void channelActive(ChannelHandlerContext ctx) throws Exception {
      try {
        requestHandler.channelActive();
      } catch (RuntimeException e) {
        logger.error("Exception from request handler while registering channel", e);
      }
      try {
        responseHandler.channelActive();
      } catch (RuntimeException e) {
        logger.error("Exception from response handler while registering channel", e);
      }
      super.channelRegistered(ctx);
    }
  
    @Override
    public void channelInactive(ChannelHandlerContext ctx) throws Exception {
      try {
        requestHandler.channelInactive();
      } catch (RuntimeException e) {
        logger.error("Exception from request handler while unregistering channel", e);
      }
      try {
        responseHandler.channelInactive();
      } catch (RuntimeException e) {
        logger.error("Exception from response handler while unregistering channel", e);
      }
      super.channelUnregistered(ctx);
    }
  
    @Override
    public void channelRead0(ChannelHandlerContext ctx, Message request) throws Exception {
      if (request instanceof RequestMessage) {
        requestHandler.handle((RequestMessage) request);
      } else {
        responseHandler.handle((ResponseMessage) request);
      }
    }
  
    /** Triggered based on events from an {@link io.netty.handler.timeout.IdleStateHandler}. */
    @Override
    public void userEventTriggered(ChannelHandlerContext ctx, Object evt) throws Exception {
      if (evt instanceof IdleStateEvent) {
        IdleStateEvent e = (IdleStateEvent) evt;
        // See class comment for timeout semantics. In addition to ensuring we only timeout while
        // there are outstanding requests, we also do a secondary consistency check to ensure
        // there's no race between the idle timeout and incrementing the numOutstandingRequests
        // (see SPARK-7003).
        //
        // To avoid a race between TransportClientFactory.createClient() and this code which could
        // result in an inactive client being returned, this needs to run in a synchronized block.
        synchronized (this) {
          boolean isActuallyOverdue =
            System.nanoTime() - responseHandler.getTimeOfLastRequestNs() > requestTimeoutNs;
          if (e.state() == IdleState.ALL_IDLE && isActuallyOverdue) {
            if (responseHandler.numOutstandingRequests() > 0) {
              String address = getRemoteAddress(ctx.channel());
              logger.error("Connection to {} has been quiet for {} ms while there are outstanding " +
                "requests. Assuming connection is dead; please adjust spark.network.timeout if " +
                "this is wrong.", address, requestTimeoutNs / 1000 / 1000);
              client.timeOut();
              ctx.close();
            } else if (closeIdleConnections) {
              // While CloseIdleConnections is enable, we also close idle connection
              client.timeOut();
              ctx.close();
            }
          }
        }
      }
      ctx.fireUserEventTriggered(evt);
    }
  
    public TransportResponseHandler getResponseHandler() {
      return responseHandler;
    }
  
  }
  