/**
    * 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.concurrent.BlockingQueue;
  import java.util.concurrent.LinkedBlockingQueue;
  
  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.util.ReflectionUtils;
  
  /**
   * An {@link RpcExecutor} that will balance requests evenly across all its queues, but still remains
   * efficient with a single queue via an inlinable queue balancing mechanism. Defaults to FIFO but
   * you can pass an alternate queue class to use.
   */
  @InterfaceAudience.LimitedPrivate({ HBaseInterfaceAudience.COPROC, HBaseInterfaceAudience.PHOENIX })
  @InterfaceStability.Evolving
  public class BalancedQueueRpcExecutor extends RpcExecutor {
    private static final Log LOG = LogFactory.getLog(BalancedQueueRpcExecutor.class);
  
    private final QueueBalancer balancer;
  
    public BalancedQueueRpcExecutor(final String name, final int handlerCount,
        final int maxQueueLength, final PriorityFunction priority, final Configuration conf,
        final Abortable abortable) {
      this(name, handlerCount, conf.get(CALL_QUEUE_TYPE_CONF_KEY, CALL_QUEUE_TYPE_CONF_DEFAULT),
          maxQueueLength, priority, conf, abortable);
    }
  
    public BalancedQueueRpcExecutor(final String name, final int handlerCount,
        final String callQueueType, final int maxQueueLength, final PriorityFunction priority,
        final Configuration conf, final Abortable abortable) {
      super(name, handlerCount, callQueueType, maxQueueLength, priority, conf, abortable);
      this.balancer = getBalancer(this.numCallQueues);
      initializeQueues(this.numCallQueues);
    }
  
    @Deprecated
    public BalancedQueueRpcExecutor(final String name, final int handlerCount, final int numQueues,
        final int maxQueueLength) {
      this(name, handlerCount, numQueues, maxQueueLength, null, null);
    }
  
    @Deprecated
    public BalancedQueueRpcExecutor(final String name, final int handlerCount, final int numQueues,
        final int maxQueueLength, final Configuration conf, final Abortable abortable) {
      this(name, handlerCount, numQueues, conf, abortable, LinkedBlockingQueue.class, maxQueueLength);
    }
  
    @Deprecated
    public BalancedQueueRpcExecutor(final String name, final int handlerCount, final int numQueues,
        final Class<? extends BlockingQueue> queueClass, Object... initargs) {
      this(name, handlerCount, numQueues, null, null,  queueClass, initargs);
    }
  
    @Deprecated
    public BalancedQueueRpcExecutor(final String name, final int handlerCount, final int numQueues,
        final Configuration conf, final Abortable abortable,
        final Class<? extends BlockingQueue> queueClass, Object... initargs) {
      super(name, Math.max(handlerCount, numQueues), numQueues, conf, abortable);
      this.balancer = getBalancer(numQueues);
      initializeQueues(numQueues, queueClass, initargs);
      LOG.debug(name + " queues=" + numQueues + " handlerCount=" + handlerCount);
    }
  
    @Deprecated
    protected void initializeQueues(final int numQueues,
        final Class<? extends BlockingQueue> queueClass, Object... initargs) {
      if (initargs.length > 0) {
        currentQueueLimit = (int) initargs[0];
        initargs[0] = Math.max((int) initargs[0], DEFAULT_CALL_QUEUE_SIZE_HARD_LIMIT);
      }
      for (int i = 0; i < numQueues; ++i) {
        queues.add((BlockingQueue<CallRunner>) ReflectionUtils.newInstance(queueClass, initargs));
      }
    }
  
    @Override
   public boolean dispatch(final CallRunner callTask) throws InterruptedException {
     int queueIndex = balancer.getNextQueue();
     BlockingQueue<CallRunner> queue = queues.get(queueIndex);
     // that means we can overflow by at most <num reader> size (5), that's ok
     if (queue.size() >= currentQueueLimit) {
       return false;
     }
     return queue.offer(callTask);
   }
 }