org.skife.clocked.ClockedExecutorService Maven / Gradle / Ivy

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/*
 * 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.skife.clocked;

import java.io.Closeable;
import java.util.List;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.Future;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.ScheduledFuture;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;

/**
 * NOT INTENDED FOR USE OUTSIDE CAREFULLY CONTROLLED TESTS
 * 
 * ScheduledExecutorService implementation designed for deterministic testing. It runs off an
 * internal clock which must be manually advanced via the {@see ClockedExecutorService#advance}
 * method.
 * 
 * 
 * Additionally, for recurring scheduled tasks, there is a guarantee that the task will nly
 * be called once for each call to advance(...). This is important to note as it
 * rather violates the normal contracts, but is very useful for testing.
 * 
 */
public class ClockedExecutorService extends ThreadPoolExecutor implements ScheduledExecutorService, Closeable
{
    private final Clock clock;
    private final Scheduler scheduler;

    public ClockedExecutorService(final int corePoolSize)
    {
        super(corePoolSize, corePoolSize, 365L, TimeUnit.DAYS, new LinkedBlockingQueue());
        this.clock = new Clock();
        this.scheduler = new Scheduler(clock);
    }

    public ClockedExecutorService()
    {
        this(1);
    }

    public Future advance(long time, TimeUnit unit) throws ExecutionException, InterruptedException
    {
        synchronized (scheduler) {
            List> runnables = scheduler.advance(unit.toMillis(time));
            for (ScheduledFutureTask runnable : runnables) {
                this.submit(runnable);
            }
            return new CompositeFuture(runnables);
        }
    }

    @Override
    public ScheduledFuture schedule(final Runnable command, final long delay, final TimeUnit unit)
    {
        synchronized (scheduler) {
            return scheduler.add(new ScheduledFutureTask