/*

  * 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 org.apache.giraph.conf.ImmutableClassesGiraphConfiguration;

 import org.apache.giraph.comm.netty.InboundByteCounter;

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

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

 import org.apache.giraph.time.SystemTime;

 import org.apache.giraph.time.Time;

 import org.apache.giraph.time.Times;

 import org.apache.giraph.utils.ReflectionUtils;

 import org.apache.giraph.utils.RequestUtils;

 import org.apache.log4j.Logger;

 import io.netty.buffer.ByteBuf;

 import io.netty.channel.ChannelHandlerContext;

 import io.netty.channel.ChannelInboundHandlerAdapter;

 import io.netty.util.ReferenceCountUtil;

 /**

  * Decodes encoded requests from the client.

  */

 public class RequestDecoder extends ChannelInboundHandlerAdapter {

   /** Class logger */

   private static final Logger LOG =

       Logger.getLogger(RequestDecoder.class);

   /** Time class to use */

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

   /** Configuration */

   private final ImmutableClassesGiraphConfiguration conf;

   /** In bound byte counter to output */

   private final InboundByteCounter byteCounter;

   /** Start nanoseconds for the decoding time */

   private long startDecodingNanoseconds = -1;

   /**

    * Constructor.

    *

    * @param conf Configuration

    * @param byteCounter Keeps track of the decoded bytes

    */

   public RequestDecoder(ImmutableClassesGiraphConfiguration conf,

     InboundByteCounter byteCounter) {

     this.conf = conf;

     this.byteCounter = byteCounter;

   }

   @Override

   public void channelRead(ChannelHandlerContext ctx, Object msg)

     throws Exception {

     if (!(msg instanceof ByteBuf)) {

       throw new IllegalStateException("decode: Got illegal message " + msg);

     }

     // Output metrics every 1/2 minute

     String metrics = byteCounter.getMetricsWindow(30000);

     if (metrics != null) {

       if (LOG.isInfoEnabled()) {

         LOG.info("decode: Server window metrics " + metrics);

       }

     }

     if (LOG.isDebugEnabled()) {

       startDecodingNanoseconds = TIME.getNanoseconds();

     }

     // Decode the request

     ByteBuf buf = (ByteBuf) msg;

     int enumValue = buf.readByte();

     RequestType type = RequestType.values()[enumValue];

     Class<? extends WritableRequest> requestClass = type.getRequestClass();

     WritableRequest request =

         ReflectionUtils.newInstance(requestClass, conf);

     request = RequestUtils.decodeWritableRequest(buf, request);

     if (LOG.isDebugEnabled()) {

       LOG.debug("decode: Client " + request.getClientId() +

           ", requestId " + request.getRequestId() +

           ", " +  request.getType() + ", with size " +

           buf.writerIndex() + " took " +

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

     }

     ReferenceCountUtil.release(buf);

     // fire writableRequest object to upstream handlers

     ctx.fireChannelRead(request);

   }

 }