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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 org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hbase.DaemonThreadFactory;
import java.io.IOException;
import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicInteger;
/**
* A very simple {@code }RpcScheduler} that serves incoming requests in order.
*
* This can be used for HMaster, where no prioritization is needed.
*/
public class FifoRpcScheduler extends RpcScheduler {
private static final Log LOG = LogFactory.getLog(FifoRpcScheduler.class);
private final int handlerCount;
private final int maxQueueLength;
private final AtomicInteger queueSize = new AtomicInteger(0);
private ThreadPoolExecutor executor;
public FifoRpcScheduler(Configuration conf, int handlerCount) {
this.handlerCount = handlerCount;
this.maxQueueLength = conf.getInt(RpcScheduler.IPC_SERVER_MAX_CALLQUEUE_LENGTH,
handlerCount * RpcServer.DEFAULT_MAX_CALLQUEUE_LENGTH_PER_HANDLER);
LOG.info("Using " + this.getClass().getSimpleName() + " as user call queue; handlerCount=" +
handlerCount + "; maxQueueLength=" + maxQueueLength);
}
@Override
public void init(Context context) {
// no-op
}
@Override
public void start() {
this.executor = new ThreadPoolExecutor(
handlerCount,
handlerCount,
60,
TimeUnit.SECONDS,
new ArrayBlockingQueue<Runnable>(maxQueueLength),
new DaemonThreadFactory("FifoRpcScheduler.handler"),
new ThreadPoolExecutor.CallerRunsPolicy());
}
@Override
public void stop() {
this.executor.shutdown();
}
@Override
public boolean dispatch(final CallRunner task) throws IOException, InterruptedException {
// Executors provide no offer, so make our own.
int queued = queueSize.getAndIncrement();
if (maxQueueLength > 0 && queued >= maxQueueLength) {
queueSize.decrementAndGet();
return false;
}
executor.submit(new Runnable() {
@Override
public void run() {
task.setStatus(RpcServer.getStatus());
task.run();
queueSize.decrementAndGet();
}
});
return true;
}
@Override
public int getGeneralQueueLength() {
return executor.getQueue().size();
}
@Override
public int getPriorityQueueLength() {
return 0;
}
@Override
public int getReplicationQueueLength() {
return 0;
}
@Override
public int getActiveRpcHandlerCount() {
return executor.getActiveCount();
}
@Override
public long getNumGeneralCallsDropped() {
return 0;
}
@Override
public long getNumLifoModeSwitches() {
return 0;
}
}