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/*
* SPDX-License-Identifier: Apache-2.0
*
* The OpenSearch Contributors require contributions made to
* this file be licensed under the Apache-2.0 license or a
* compatible open source license.
*/
/*
* Licensed to Elasticsearch under one or more contributor
* license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright
* ownership. Elasticsearch 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.
*/
/*
* Modifications Copyright OpenSearch Contributors. See
* GitHub history for details.
*/
package org.opensearch.common.util.concurrent;
import org.apache.logging.log4j.Logger;
import org.apache.logging.log4j.message.ParameterizedMessage;
import org.opensearch.common.unit.TimeValue;
import org.opensearch.threadpool.Scheduler;
import org.opensearch.threadpool.ThreadPool;
import java.io.Closeable;
import java.util.Objects;
import java.util.concurrent.atomic.AtomicBoolean;
/**
* A base class for tasks that need to repeat.
*
* @opensearch.internal
*/
public abstract class AbstractAsyncTask implements Runnable, Closeable {
private final Logger logger;
private final ThreadPool threadPool;
private final AtomicBoolean closed = new AtomicBoolean(false);
private final boolean autoReschedule;
private volatile Scheduler.Cancellable cancellable;
private volatile boolean isScheduledOrRunning;
private volatile Exception lastThrownException;
private volatile TimeValue interval;
protected AbstractAsyncTask(Logger logger, ThreadPool threadPool, TimeValue interval, boolean autoReschedule) {
this.logger = logger;
this.threadPool = threadPool;
this.interval = interval;
this.autoReschedule = autoReschedule;
}
/**
* Change the interval between runs.
* If a future run is scheduled then this will reschedule it.
* @param interval The new interval between runs.
*/
public synchronized void setInterval(TimeValue interval) {
this.interval = interval;
if (cancellable != null) {
rescheduleIfNecessary();
}
}
public TimeValue getInterval() {
return interval;
}
/**
* Test any external conditions that determine whether the task
* should be scheduled. This method does *not* need to test if
* the task is closed, as being closed automatically prevents
* scheduling.
* @return Should the task be scheduled to run?
*/
protected abstract boolean mustReschedule();
/**
* Schedule the task to run after the configured interval if it
* is not closed and any further conditions imposed by derived
* classes are met. Any previously scheduled invocation is
* cancelled.
*/
public synchronized void rescheduleIfNecessary() {
if (isClosed()) {
return;
}
if (cancellable != null) {
cancellable.cancel();
}
if (interval.millis() > 0 && mustReschedule()) {
if (logger.isTraceEnabled()) {
logger.trace("scheduling {} every {}", toString(), interval);
}
cancellable = threadPool.schedule(this, interval, getThreadPool());
isScheduledOrRunning = true;
} else {
logger.trace("scheduled {} disabled", toString());
cancellable = null;
isScheduledOrRunning = false;
}
}
public boolean isScheduled() {
// Currently running counts as scheduled to avoid an oscillating return value
// from this method when a task is repeatedly running and rescheduling itself.
return isScheduledOrRunning;
}
/**
* Cancel any scheduled run, but do not prevent subsequent restarts.
*/
public synchronized void cancel() {
if (cancellable != null) {
cancellable.cancel();
cancellable = null;
}
isScheduledOrRunning = false;
}
/**
* Cancel any scheduled run
*/
@Override
public synchronized void close() {
if (closed.compareAndSet(false, true)) {
cancel();
}
}
public boolean isClosed() {
return this.closed.get();
}
@Override
public final void run() {
synchronized (this) {
if (isClosed()) {
return;
}
cancellable = null;
isScheduledOrRunning = autoReschedule;
}
try {
runInternal();
} catch (Exception ex) {
if (lastThrownException == null || sameException(lastThrownException, ex) == false) {
// prevent the annoying fact of logging the same stuff all the time with an interval of 1 sec will spam all your logs
logger.warn(
() -> new ParameterizedMessage(
"failed to run task {} - suppressing re-occurring exceptions unless the exception changes",
toString()
),
ex
);
lastThrownException = ex;
}
} finally {
if (autoReschedule) {
rescheduleIfNecessary();
}
}
}
private static boolean sameException(Exception left, Exception right) {
if (left.getClass() == right.getClass()) {
if (Objects.equals(left.getMessage(), right.getMessage())) {
StackTraceElement[] stackTraceLeft = left.getStackTrace();
StackTraceElement[] stackTraceRight = right.getStackTrace();
if (stackTraceLeft.length == stackTraceRight.length) {
for (int i = 0; i < stackTraceLeft.length; i++) {
if (stackTraceLeft[i].equals(stackTraceRight[i]) == false) {
return false;
}
}
return true;
}
}
}
return false;
}
protected abstract void runInternal();
/**
* Use the same threadpool by default.
* Derived classes can change this if required.
*/
protected String getThreadPool() {
return ThreadPool.Names.SAME;
}
}