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From tillrohrmann <...@git.apache.org>
Subject [GitHub] flink pull request #2435: [FLINK-4478] [flip-6] Add HeartbeatManager
Date Fri, 30 Sep 2016 14:24:36 GMT
Github user tillrohrmann commented on a diff in the pull request:

    https://github.com/apache/flink/pull/2435#discussion_r81348543
  
    --- Diff: flink-runtime/src/main/java/org/apache/flink/runtime/heartbeat/HeartbeatManagerImpl.java
---
    @@ -0,0 +1,328 @@
    +/*
    + * 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.flink.runtime.heartbeat;
    +
    +import org.apache.flink.runtime.clusterframework.types.ResourceID;
    +import org.apache.flink.runtime.concurrent.AcceptFunction;
    +import org.apache.flink.runtime.concurrent.Future;
    +import org.apache.flink.util.Preconditions;
    +import org.slf4j.Logger;
    +
    +import javax.annotation.concurrent.ThreadSafe;
    +import java.util.Collection;
    +import java.util.concurrent.ConcurrentHashMap;
    +import java.util.concurrent.Executor;
    +import java.util.concurrent.ScheduledExecutorService;
    +import java.util.concurrent.ScheduledFuture;
    +import java.util.concurrent.TimeUnit;
    +import java.util.concurrent.atomic.AtomicReference;
    +
    +/**
    + * Heartbeat manager implementation. The heartbeat manager maintains a map of heartbeat
monitors
    + * and resource IDs. Each monitor will be updated when a new heartbeat of the associated
machine has
    + * been received. If the monitor detects that a heartbeat has timed out, it will notify
the
    + * {@link HeartbeatListener} about it. A heartbeat times out iff no heartbeat signal
has been
    + * received within a given timeout interval.
    + *
    + * @param <I> Type of the incoming heartbeat payload
    + * @param <O> Type of the outgoing heartbeat payload
    + */
    +@ThreadSafe
    +public class HeartbeatManagerImpl<I, O> implements HeartbeatManager<I, O>,
HeartbeatTarget<I> {
    +
    +	/** Heartbeat timeout interval in milli seconds */
    +	private final long heartbeatTimeoutIntervalMs;
    +
    +	/** Resource ID which is used to mark one own's heartbeat signals */
    +	private final ResourceID ownResourceID;
    +
    +	/** Executor service used to run heartbeat timeout notifications */
    +	private final ScheduledExecutorService scheduledExecutorService;
    +
    +	protected final Logger log;
    +
    +	/** Map containing the heartbeat monitors associated with the respective resource ID
*/
    +	private final ConcurrentHashMap<ResourceID, HeartbeatManagerImpl.HeartbeatMonitor<O>>
heartbeatTargets;
    +
    +	/** Execution context used to run future callbacks */
    +	private final Executor executor;
    +
    +	/** Heartbeat listener with which the heartbeat manager has been associated */
    +	private HeartbeatListener<I, O> heartbeatListener;
    +
    +	/** Running state of the heartbeat manager */
    +	protected boolean stopped;
    +
    +	public HeartbeatManagerImpl(
    +		long heartbeatTimeoutIntervalMs,
    +		ResourceID ownResourceID,
    +		Executor executor,
    +		ScheduledExecutorService scheduledExecutorService,
    +		Logger log) {
    +		Preconditions.checkArgument(heartbeatTimeoutIntervalMs > 0L, "The heartbeat timeout
has to be larger than 0.");
    +
    +		this.heartbeatTimeoutIntervalMs = heartbeatTimeoutIntervalMs;
    +		this.ownResourceID = Preconditions.checkNotNull(ownResourceID);
    +		this.scheduledExecutorService = Preconditions.checkNotNull(scheduledExecutorService);
    +		this.log = Preconditions.checkNotNull(log);
    +		this.executor = Preconditions.checkNotNull(executor);
    +		this.heartbeatTargets = new ConcurrentHashMap<>(16);
    +
    +		stopped = true;
    +	}
    +
    +	//----------------------------------------------------------------------------------------------
    +	// Getters
    +	//----------------------------------------------------------------------------------------------
    +
    +	ResourceID getOwnResourceID() {
    +		return ownResourceID;
    +	}
    +
    +	Executor getExecutor() {
    +		return executor;
    +	}
    +
    +	HeartbeatListener<I, O> getHeartbeatListener() {
    +		return heartbeatListener;
    +	}
    +
    +	Collection<HeartbeatManagerImpl.HeartbeatMonitor<O>> getHeartbeatTargets()
{
    +		return heartbeatTargets.values();
    +	}
    +
    +	//----------------------------------------------------------------------------------------------
    +	// HeartbeatManager methods
    +	//----------------------------------------------------------------------------------------------
    +
    +	@Override
    +	public void monitorTarget(ResourceID resourceID, HeartbeatTarget<O> heartbeatTarget)
{
    +		if (!stopped) {
    +			if (heartbeatTargets.containsKey(resourceID)) {
    +				log.info("The target with resource ID {} is already been monitored.", resourceID);
    +			} else {
    +				HeartbeatManagerImpl.HeartbeatMonitor<O> heartbeatMonitor = new HeartbeatManagerImpl.HeartbeatMonitor<>(
    +					resourceID,
    +					heartbeatTarget,
    +					scheduledExecutorService,
    +					heartbeatListener,
    +					heartbeatTimeoutIntervalMs);
    +
    +				heartbeatTargets.put(
    +					resourceID,
    +					heartbeatMonitor);
    +
    +				// check if we have stopped in the meantime (concurrent stop operation)
    +				if (stopped) {
    +					heartbeatMonitor.cancel();
    +
    +					heartbeatTargets.remove(resourceID);
    +				}
    --- End diff --
    
    We have to check after we've put the element in the concurrent hash map, because the stop
operation can happen concurrently. If the stop took place after we've inserted it, then it
will be removed by the stop call. If the stop took place right before we've inserted the element,
then we have to clean it up ourselves.
    I tried to avoid locking in order to make access non-blocking.


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