org.apache.hadoop.hbase.ipc.BalancedQueueRpcExecutor.java Source code

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Here is the source code for org.apache.hadoop.hbase.ipc.BalancedQueueRpcExecutor.java

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/**
 * 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.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);

    protected final List<BlockingQueue<CallRunner>> queues;
    private final QueueBalancer balancer;

    public BalancedQueueRpcExecutor(final String name, final int handlerCount, final int numQueues,
            final int maxQueueLength) {
        this(name, handlerCount, numQueues, maxQueueLength, null, null);
    }

    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);
    }

    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);
    }

    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), conf, abortable);
        queues = new ArrayList<BlockingQueue<CallRunner>>(numQueues);
        this.balancer = getBalancer(numQueues);
        initializeQueues(numQueues, queueClass, initargs);
        LOG.debug(name + " queues=" + numQueues + " handlerCount=" + handlerCount);
    }

    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);
    }

    @Override
    public int getQueueLength() {
        int length = 0;
        for (final BlockingQueue<CallRunner> queue : queues) {
            length += queue.size();
        }
        return length;
    }

    @Override
    public List<BlockingQueue<CallRunner>> getQueues() {
        return queues;
    }
}