org.apache.flink.runtime.operators.sort.ThreadBase Maven / Gradle / Ivy
/*
* 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.operators.sort;
import javax.annotation.Nullable;
import java.io.IOException;
import static org.apache.flink.util.Preconditions.checkNotNull;
/**
* Base class for all working threads in this sort-merger. The specific threads for reading,
* sorting, spilling, merging, etc... extend this subclass.
*
* The threads are designed to terminate themselves when the task they are set up to do is
* completed. Further more, they terminate immediately when the shutdown()
method is
* called.
*/
abstract class ThreadBase extends Thread
implements Thread.UncaughtExceptionHandler, StageRunner {
/** The queue of empty buffer that can be used for reading; */
protected final StageMessageDispatcher dispatcher;
/** The exception handler for any problems. */
private final ExceptionHandler exceptionHandler;
/** The flag marking this thread as alive. */
private volatile boolean alive;
/**
* Creates a new thread.
*
* @param exceptionHandler The exception handler to call for all exceptions.
* @param name The name of the thread.
* @param queues The queues used to pass buffers between the threads.
*/
protected ThreadBase(
@Nullable ExceptionHandler exceptionHandler,
String name,
StageMessageDispatcher queues) {
// thread setup
super(checkNotNull(name));
this.setDaemon(true);
// exception handling
this.exceptionHandler = exceptionHandler;
this.setUncaughtExceptionHandler(this);
this.dispatcher = checkNotNull(queues);
this.alive = true;
}
/** Implements exception handling and delegates to go(). */
public void run() {
try {
go();
} catch (Throwable t) {
internalHandleException(
new IOException(
"Thread '"
+ getName()
+ "' terminated due to an exception: "
+ t.getMessage(),
t));
}
}
/**
* Equivalent to the run() method.
*
* @throws IOException Exceptions that prohibit correct completion of the work may be thrown by
* the thread.
*/
protected abstract void go() throws IOException, InterruptedException;
/**
* Checks whether this thread is still alive.
*
* @return true, if the thread is alive, false otherwise.
*/
protected boolean isRunning() {
return this.alive;
}
@Override
public void close() throws InterruptedException {
this.alive = false;
this.interrupt();
this.join();
}
/**
* Internally handles an exception and makes sure that this method returns without a problem.
*
* @param ioex The exception to handle.
*/
protected final void internalHandleException(IOException ioex) {
if (!isRunning()) {
// discard any exception that occurs when after the thread is killed.
return;
}
if (this.exceptionHandler != null) {
try {
this.exceptionHandler.handleException(ioex);
} catch (Throwable ignored) {
}
}
}
/* (non-Javadoc)
* @see java.lang.Thread.UncaughtExceptionHandler#uncaughtException(java.lang.Thread, java.lang.Throwable)
*/
@Override
public void uncaughtException(Thread t, Throwable e) {
internalHandleException(
new IOException(
"Thread '"
+ t.getName()
+ "' terminated due to an uncaught exception: "
+ e.getMessage(),
e));
}
}