/*

  * 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.giraph.comm.netty.handler;

 import io.netty.buffer.ByteBufOutputStream;

 import org.apache.giraph.comm.requests.WritableRequest;

 import org.apache.giraph.conf.GiraphConfiguration;

 import org.apache.giraph.conf.GiraphConstants;

 import org.apache.giraph.time.SystemTime;

 import org.apache.giraph.time.Time;

 import org.apache.giraph.time.Times;

 import org.apache.log4j.Logger;

 import io.netty.buffer.ByteBuf;

 import io.netty.channel.ChannelHandlerContext;

 import io.netty.channel.ChannelOutboundHandlerAdapter;

 import io.netty.channel.ChannelPromise;

 import static org.apache.giraph.utils.ByteUtils.SIZE_OF_BYTE;

 import static org.apache.giraph.utils.ByteUtils.SIZE_OF_INT;

 /**

  * Requests have a request type and an encoded request.

  */

 public class RequestEncoder extends ChannelOutboundHandlerAdapter {

   /** Class logger */

   private static final Logger LOG = Logger.getLogger(RequestEncoder.class);

   /** Time class to use */

   private static final Time TIME = SystemTime.get();

   /** Buffer starting size */

   private final int bufferStartingSize;

   /** Start nanoseconds for the encoding time */

   private long startEncodingNanoseconds = -1;

   /**

    * Constructor.

    *

    * @param conf Giraph configuration

    */

   public RequestEncoder(GiraphConfiguration conf) {

     bufferStartingSize =

         GiraphConstants.NETTY_REQUEST_ENCODER_BUFFER_SIZE.get(conf);

   }

   @Override

   public void write(ChannelHandlerContext ctx, Object msg,

     ChannelPromise promise) throws Exception {

     if (!(msg instanceof WritableRequest)) {

       throw new IllegalArgumentException(

           "encode: Got a message of type " + msg.getClass());

     }

     // Encode the request

     if (LOG.isDebugEnabled()) {

       startEncodingNanoseconds = TIME.getNanoseconds();

     }

     ByteBuf buf;

     WritableRequest request = (WritableRequest) msg;

     int requestSize = request.getSerializedSize();

     if (requestSize == WritableRequest.UNKNOWN_SIZE) {

       buf = ctx.alloc().buffer(bufferStartingSize);

     } else {

       requestSize +=  SIZE_OF_INT + SIZE_OF_BYTE;

       buf = ctx.alloc().buffer(requestSize);

     }

     ByteBufOutputStream output = new ByteBufOutputStream(buf);

     // This will later be filled with the correct size of serialized request

     output.writeInt(0);

     output.writeByte(request.getType().ordinal());

     try {

       request.write(output);

     } catch (IndexOutOfBoundsException e) {

       LOG.error("write: Most likely the size of request was not properly " +

           "specified (this buffer is too small) - see getSerializedSize() " +

           "in " + request.getType().getRequestClass());

       throw new IllegalStateException(e);

     }

     output.flush();

     output.close();

     // Set the correct size at the end

     buf.setInt(0, buf.writerIndex() - SIZE_OF_INT);

     if (LOG.isDebugEnabled()) {

       LOG.debug("write: Client " + request.getClientId() + ", " +

           "requestId " + request.getRequestId() +

           ", size = " + buf.readableBytes() + ", " +

           request.getType() + " took " +

           Times.getNanosSince(TIME, startEncodingNanoseconds) + " ns");

     }

     ctx.write(buf, promise);

   }

 }