/**
    * 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.hadoop.hbase.ipc;
  
  import java.util.ArrayList;
  import java.util.List;
  import java.util.concurrent.BlockingQueue;
  import java.util.concurrent.LinkedBlockingQueue;
  
  import org.apache.commons.lang.ArrayUtils;
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.apache.hadoop.conf.Configuration;
  import org.apache.hadoop.hbase.Abortable;
  import org.apache.hadoop.hbase.HBaseInterfaceAudience;
  import org.apache.hadoop.hbase.classification.InterfaceAudience;
  import org.apache.hadoop.hbase.classification.InterfaceStability;
  import org.apache.hadoop.hbase.protobuf.generated.ClientProtos.Action;
  import org.apache.hadoop.hbase.protobuf.generated.ClientProtos.MultiRequest;
  import org.apache.hadoop.hbase.protobuf.generated.ClientProtos.MutateRequest;
  import org.apache.hadoop.hbase.protobuf.generated
    .RegionServerStatusProtos.ReportRegionStateTransitionRequest;
  import org.apache.hadoop.hbase.protobuf.generated.ClientProtos.RegionAction;
  import org.apache.hadoop.hbase.protobuf.generated.ClientProtos.ScanRequest;
  import org.apache.hadoop.hbase.protobuf.generated.RPCProtos.RequestHeader;
  import org.apache.hadoop.hbase.util.ReflectionUtils;
  
  import com.google.protobuf.Message;
  
  /**
   * RPC Executor that uses different queues for reads and writes.
   * With the options to use different queues/executors for gets and scans.
   * Each handler has its own queue and there is no stealing.
   */
  @InterfaceAudience.LimitedPrivate({HBaseInterfaceAudience.COPROC, HBaseInterfaceAudience.PHOENIX})
  @InterfaceStability.Evolving
  public class RWQueueRpcExecutor extends RpcExecutor {
    private static final Log LOG = LogFactory.getLog(RWQueueRpcExecutor.class);
  
    private final List<BlockingQueue<CallRunner>> queues;
    private final QueueBalancer writeBalancer;
    private final QueueBalancer readBalancer;
    private final QueueBalancer scanBalancer;
    private final int writeHandlersCount;
    private final int readHandlersCount;
    private final int scanHandlersCount;
    private final int numWriteQueues;
    private final int numReadQueues;
    private final int numScanQueues;
  
    public RWQueueRpcExecutor(final String name, final int handlerCount, final int numQueues,
        final float readShare, final int maxQueueLength,
        final Configuration conf, final Abortable abortable) {
      this(name, handlerCount, numQueues, readShare, maxQueueLength, 0,
        conf, abortable, LinkedBlockingQueue.class);
    }
  
    public RWQueueRpcExecutor(final String name, final int handlerCount, final int numQueues,
        final float readShare, final float scanShare, final int maxQueueLength) {
      this(name, handlerCount, numQueues, readShare, scanShare, maxQueueLength, null, null);
    }
  
    public RWQueueRpcExecutor(final String name, final int handlerCount, final int numQueues,
        final float readShare, final float scanShare, final int maxQueueLength,
        final Configuration conf, final Abortable abortable) {
      this(name, handlerCount, numQueues, readShare, scanShare, maxQueueLength,
        conf, abortable, LinkedBlockingQueue.class);
    }
  
    public RWQueueRpcExecutor(final String name, final int handlerCount, final int numQueues,
        final float readShare, final int maxQueueLength,
        final Configuration conf, final Abortable abortable,
        final Class<? extends BlockingQueue> readQueueClass, Object... readQueueInitArgs) {
      this(name, handlerCount, numQueues, readShare, 0, maxQueueLength, conf, abortable,
        readQueueClass, readQueueInitArgs);
    }
  
    public RWQueueRpcExecutor(final String name, final int handlerCount, final int numQueues,
        final float readShare, final float scanShare, final int maxQueueLength,
        final Configuration conf, final Abortable abortable,
        final Class<? extends BlockingQueue> readQueueClass, Object... readQueueInitArgs) {
      this(name, calcNumWriters(handlerCount, readShare), calcNumReaders(handlerCount, readShare),
        calcNumWriters(numQueues, readShare), calcNumReaders(numQueues, readShare), scanShare,
       LinkedBlockingQueue.class, new Object[] {maxQueueLength},
       readQueueClass, ArrayUtils.addAll(new Object[] {maxQueueLength}, readQueueInitArgs));
   }
 
   public RWQueueRpcExecutor(final String name, final int writeHandlers, final int readHandlers,
       final int numWriteQueues, final int numReadQueues,
       final Class<? extends BlockingQueue> writeQueueClass, Object[] writeQueueInitArgs,
       final Class<? extends BlockingQueue> readQueueClass, Object[] readQueueInitArgs) {
     this(name, writeHandlers, readHandlers, numWriteQueues, numReadQueues, 0,
       writeQueueClass, writeQueueInitArgs, readQueueClass, readQueueInitArgs);
   }
 
   public RWQueueRpcExecutor(final String name, int writeHandlers, int readHandlers,
       int numWriteQueues, int numReadQueues, float scanShare,
       final Class<? extends BlockingQueue> writeQueueClass, Object[] writeQueueInitArgs,
       final Class<? extends BlockingQueue> readQueueClass, Object[] readQueueInitArgs) {
     super(name, Math.max(writeHandlers, numWriteQueues) + Math.max(readHandlers, numReadQueues));
 
     int numScanQueues = Math.max(0, (int)Math.floor(numReadQueues * scanShare));
     int scanHandlers = Math.max(0, (int)Math.floor(readHandlers * scanShare));
     if ((numReadQueues - numScanQueues) > 0) {
       numReadQueues -= numScanQueues;
       readHandlers -= scanHandlers;
     } else {
       numScanQueues = 0;
       scanHandlers = 0;
     }
 
     this.writeHandlersCount = Math.max(writeHandlers, numWriteQueues);
     this.readHandlersCount = Math.max(readHandlers, numReadQueues);
     this.scanHandlersCount = Math.max(scanHandlers, numScanQueues);
     this.numWriteQueues = numWriteQueues;
     this.numReadQueues = numReadQueues;
     this.numScanQueues = numScanQueues;
     this.writeBalancer = getBalancer(numWriteQueues);
     this.readBalancer = getBalancer(numReadQueues);
     this.scanBalancer = getBalancer(numScanQueues);
 
     queues = new ArrayList<BlockingQueue<CallRunner>>(writeHandlersCount + readHandlersCount);
     LOG.debug(name + " writeQueues=" + numWriteQueues + " writeHandlers=" + writeHandlersCount +
               " readQueues=" + numReadQueues + " readHandlers=" + readHandlersCount +
               ((numScanQueues == 0) ? "" : " scanQueues=" + numScanQueues +
                 " scanHandlers=" + scanHandlersCount));
 
     for (int i = 0; i < numWriteQueues; ++i) {
       queues.add((BlockingQueue<CallRunner>)
         ReflectionUtils.newInstance(writeQueueClass, writeQueueInitArgs));
     }
 
     for (int i = 0; i < (numReadQueues + numScanQueues); ++i) {
       queues.add((BlockingQueue<CallRunner>)
         ReflectionUtils.newInstance(readQueueClass, readQueueInitArgs));
     }
   }
 
   @Override
   protected void startHandlers(final int port) {
     startHandlers(".write", writeHandlersCount, queues, 0, numWriteQueues, port);
     startHandlers(".read", readHandlersCount, queues, numWriteQueues, numReadQueues, port);
     startHandlers(".scan", scanHandlersCount, queues,
                   numWriteQueues + numReadQueues, numScanQueues, port);
   }
 
   @Override
   public void dispatch(final CallRunner callTask) throws InterruptedException {
     RpcServer.Call call = callTask.getCall();
     int queueIndex;
     if (isWriteRequest(call.getHeader(), call.param)) {
       queueIndex = writeBalancer.getNextQueue();
     } else if (numScanQueues > 0 && isScanRequest(call.getHeader(), call.param)) {
       queueIndex = numWriteQueues + numReadQueues + scanBalancer.getNextQueue();
     } else {
       queueIndex = numWriteQueues + readBalancer.getNextQueue();
     }
     queues.get(queueIndex).put(callTask);
   }
 
   private boolean isWriteRequest(final RequestHeader header, final Message param) {
     // TODO: Is there a better way to do this?
     if (param instanceof MultiRequest) {
       MultiRequest multi = (MultiRequest)param;
       for (RegionAction regionAction : multi.getRegionActionList()) {
         for (Action action: regionAction.getActionList()) {
           if (action.hasMutation()) {
             return true;
           }
         }
       }
     }
     if (param instanceof MutateRequest) {
       return true;
     }
     if (param instanceof ReportRegionStateTransitionRequest) {
       return true;
     }
     return false;
   }
 
   private boolean isScanRequest(final RequestHeader header, final Message param) {
     if (param instanceof ScanRequest) {
       // The first scan request will be executed as a "short read"
       ScanRequest request = (ScanRequest)param;
       return request.hasScannerId();
     }
     return false;
   }
 
   @Override
   public int getQueueLength() {
     int length = 0;
     for (final BlockingQueue<CallRunner> queue: queues) {
       length += queue.size();
     }
     return length;
   }
 
   @Override
   protected List<BlockingQueue<CallRunner>> getQueues() {
     return queues;
   }
 
   /*
    * Calculate the number of writers based on the "total count" and the read share.
    * You'll get at least one writer.
    */
   private static int calcNumWriters(final int count, final float readShare) {
     return Math.max(1, count - Math.max(1, (int)Math.round(count * readShare)));
   }
 
   /*
    * Calculate the number of readers based on the "total count" and the read share.
    * You'll get at least one reader.
    */
   private static int calcNumReaders(final int count, final float readShare) {
     return count - calcNumWriters(count, readShare);
   }
 }