MysqlQueryDecoder.java

/**
 * Copyright 2014 LinkedIn Corp. Licensed 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.
 */
package com.linkedin.proxy.netty;

import java.util.List;

import com.linkedin.proxy.query.MysqlQuery;
import com.linkedin.proxy.query.Query.QueryType;

import org.apache.log4j.Logger;

import io.netty.channel.ChannelHandlerContext;
import io.netty.handler.codec.MessageToMessageDecoder;
import io.netty.handler.codec.http.FullHttpRequest;
import io.netty.handler.codec.http.HttpMethod;

public class MysqlQueryDecoder extends MessageToMessageDecoder<FullHttpRequest>
{
  private static final Logger _LOG = Logger.getLogger(MysqlQueryDecoder.class);

  @Override
  protected void decode(ChannelHandlerContext ctx, FullHttpRequest msg, List<Object> out) throws Exception
  {
    MysqlQuery result = new MysqlQuery();

    try
    {
      HttpMethod met = msg.getMethod();
      String uri = msg.getUri();
      int s = 0;
      int e = uri.length();
      if(uri.charAt(0) == '/')
        s = 1;
      if(uri.charAt(e-1) == '/')
        e--;

      String parts[] = uri.substring(s, e).split("/");

      result.setDbName(parts[0]);
      result.setTableName(parts[1]);
      result.setKeyColName(parts[2]);
      result.setValueColName(parts[3]);

      if(met.equals(HttpMethod.PUT))
      {
        /*
         * If HttpRequest method is PUT, I interpret it as a WRITE query.
         * MysqlQuery instance's value is set as the value in the HttpRequest.
         */
        result.setKey(parts[4]);

        byte[] tempData = new byte[msg.content().readableBytes()];
        msg.content().readBytes(tempData);
        result.setValue(tempData);

        result.setType(QueryType.WRITE);
      }
      else if(met.equals(HttpMethod.GET))
      {
        /*
         * If HttpRequest method is GET, I interpret it as a READ query.
         * Once the query is processed, the result value (if any) is written to MysqlQuery.value.
         */
        result.setKey(parts[4]);
        result.setType(QueryType.READ);
      }
      else if(met.equals(HttpMethod.DELETE))
      {
        /*
         * If HttpRequest method is DELETE, I interpret it as a DELETE query.
         */
        result.setKey(parts[4]);
        result.setType(QueryType.DELETE);
      }
      else if(met.equals(HttpMethod.POST))
      {
        /*
         * If HttpRequest method is POST, I interpret it as a CREATE TABLE query.
         * I store size of the value column in MysqlQuery.Value.
         * I store byte array of the string representation.
         */
        result.setValue(parts[4].getBytes());
        result.setType(QueryType.CREATE);
      }
      else
      {
        result.setType(QueryType.INVALID);
        _LOG.error("Unhandled HttpMethod: " + met);
        _LOG.error("Type=" + QueryType.INVALID);
      }
    }
    catch(Exception e)
    {
      _LOG.error("Exception occured during HttpRequest processing", e);
      result.setType(QueryType.INVALID);
      _LOG.error("Type=" + QueryType.INVALID);
    }

    out.add(result);
  }
}