001/*
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements.  See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership.  The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License.  You may obtain a copy of the License at
009 *
010 *     http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing, software
013 * distributed under the License is distributed on an "AS IS" BASIS,
014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015 * See the License for the specific language governing permissions and
016 * limitations under the License.
017 */
018package org.apache.hadoop.hbase.ipc;
019
020import java.util.concurrent.BlockingQueue;
021import org.apache.hadoop.conf.Configuration;
022import org.apache.hadoop.hbase.Abortable;
023import org.apache.hadoop.hbase.HBaseInterfaceAudience;
024import org.apache.hadoop.hbase.conf.ConfigurationObserver;
025import org.apache.yetus.audience.InterfaceAudience;
026import org.apache.yetus.audience.InterfaceStability;
027
028/**
029 * An {@link RpcExecutor} that will balance requests evenly across all its queues, but still remains
030 * efficient with a single queue via an inlinable queue balancing mechanism. Defaults to FIFO but
031 * you can pass an alternate queue class to use.
032 */
033@InterfaceAudience.LimitedPrivate({ HBaseInterfaceAudience.COPROC, HBaseInterfaceAudience.PHOENIX })
034@InterfaceStability.Evolving
035public class BalancedQueueRpcExecutor extends RpcExecutor {
036
037  private final QueueBalancer balancer;
038
039  public BalancedQueueRpcExecutor(final String name, final int handlerCount,
040    final int maxQueueLength, final PriorityFunction priority, final Configuration conf,
041    final Abortable abortable) {
042    this(name, handlerCount, conf.get(CALL_QUEUE_TYPE_CONF_KEY, CALL_QUEUE_TYPE_CONF_DEFAULT),
043      maxQueueLength, priority, conf, abortable);
044  }
045
046  public BalancedQueueRpcExecutor(final String name, final int handlerCount,
047    final String callQueueType, final int maxQueueLength, final PriorityFunction priority,
048    final Configuration conf, final Abortable abortable) {
049    super(name, handlerCount, callQueueType, maxQueueLength, priority, conf, abortable);
050    initializeQueues(this.numCallQueues);
051    this.balancer = getBalancer(name, conf, getQueues());
052  }
053
054  @Override
055  public boolean dispatch(final CallRunner callTask) {
056    int queueIndex = balancer.getNextQueue(callTask);
057    BlockingQueue<CallRunner> queue = queues.get(queueIndex);
058    // that means we can overflow by at most <num reader> size (5), that's ok
059    if (queue.size() >= currentQueueLimit) {
060      return false;
061    }
062    return queue.offer(callTask);
063  }
064
065  @Override
066  public void onConfigurationChange(Configuration conf) {
067    super.onConfigurationChange(conf);
068
069    if (balancer instanceof ConfigurationObserver) {
070      ((ConfigurationObserver) balancer).onConfigurationChange(conf);
071    }
072  }
073}