
org.jboss.threads.LimitedExecutor Maven / Gradle / Ivy
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* JBoss, Home of Professional Open Source.
* Copyright 2017 Red Hat, Inc., and individual contributors
* as indicated by the @author tags.
*
* Licensed 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.jboss.threads;
import java.util.ArrayDeque;
import java.util.concurrent.Executor;
import java.util.concurrent.RejectedExecutionException;
import org.wildfly.common.Assert;
/**
* An executor for long-running tasks which limits the total concurrency over a delegate thread pool.
*
* @author David M. Lloyd
*/
public class LimitedExecutor implements Executor {
private final Executor executor;
private final Thread.UncaughtExceptionHandler handler;
private final int concurrencyLimit;
private final Runner runner;
public LimitedExecutor(final Executor executor, final Thread.UncaughtExceptionHandler handler, final int concurrencyLimit) {
this.executor = executor;
this.handler = handler;
this.concurrencyLimit = concurrencyLimit;
this.runner = new Runner();
}
public LimitedExecutor(final Executor executor, final int concurrencyLimit) {
this(executor, null, concurrencyLimit);
}
public void execute(final Runnable command) throws RejectedExecutionException {
Assert.checkNotNullParam("command", command);
runner.add(command);
}
@SuppressWarnings("serial")
class Runner extends ArrayDeque implements Runnable {
private int runCount;
public synchronized boolean add(final Runnable runnable) {
int runCount = this.runCount;
if (runCount < concurrencyLimit) {
executor.execute(this);
this.runCount = runCount + 1;
}
return super.add(runnable);
}
public void run() {
Runnable task;
for (;;) {
synchronized (this) {
task = poll();
if (task == null) {
runCount--;
return;
}
}
try {
task.run();
} catch (Throwable t) {
final Thread.UncaughtExceptionHandler handler = LimitedExecutor.this.handler;
if (handler != null) try {
handler.uncaughtException(Thread.currentThread(), t);
} catch (Throwable ignored) {}
}
}
}
public String toString() {
return String.format("Task runner for %s", LimitedExecutor.this);
}
}
public String toString() {
return String.format("Limited executor (%d tasks) over %s", Integer.valueOf(concurrencyLimit), executor);
}
}
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