/*
 * Copyright 2002-2017 the original author or authors.
 *
 * 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.
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package org.springframework.scheduling.concurrent;

import java.util.Date;
import java.util.concurrent.Delayed;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.ScheduledFuture;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;

import org.springframework.lang.Nullable;
import org.springframework.scheduling.Trigger;
import org.springframework.scheduling.support.DelegatingErrorHandlingRunnable;
import org.springframework.scheduling.support.SimpleTriggerContext;
import org.springframework.util.Assert;
import org.springframework.util.ErrorHandler;

Internal adapter that reschedules an underlying Runnable according to the next execution time suggested by a given Trigger.

Necessary because a native ScheduledExecutorService supports delay-driven execution only. The flexibility of the Trigger interface will be translated onto a delay for the next execution time (repeatedly).

Author:Juergen Hoeller, Mark Fisher
Since:3.0
/** * Internal adapter that reschedules an underlying {@link Runnable} according * to the next execution time suggested by a given {@link Trigger}. * * <p>Necessary because a native {@link ScheduledExecutorService} supports * delay-driven execution only. The flexibility of the {@link Trigger} interface * will be translated onto a delay for the next execution time (repeatedly). * * @author Juergen Hoeller * @author Mark Fisher * @since 3.0 */
class ReschedulingRunnable extends DelegatingErrorHandlingRunnable implements ScheduledFuture<Object> { private final Trigger trigger; private final SimpleTriggerContext triggerContext = new SimpleTriggerContext(); private final ScheduledExecutorService executor; @Nullable private ScheduledFuture<?> currentFuture; @Nullable private Date scheduledExecutionTime; private final Object triggerContextMonitor = new Object(); public ReschedulingRunnable( Runnable delegate, Trigger trigger, ScheduledExecutorService executor, ErrorHandler errorHandler) { super(delegate, errorHandler); this.trigger = trigger; this.executor = executor; } @Nullable public ScheduledFuture<?> schedule() { synchronized (this.triggerContextMonitor) { this.scheduledExecutionTime = this.trigger.nextExecutionTime(this.triggerContext); if (this.scheduledExecutionTime == null) { return null; } long initialDelay = this.scheduledExecutionTime.getTime() - System.currentTimeMillis(); this.currentFuture = this.executor.schedule(this, initialDelay, TimeUnit.MILLISECONDS); return this; } } private ScheduledFuture<?> obtainCurrentFuture() { Assert.state(this.currentFuture != null, "No scheduled future"); return this.currentFuture; } @Override public void run() { Date actualExecutionTime = new Date(); super.run(); Date completionTime = new Date(); synchronized (this.triggerContextMonitor) { Assert.state(this.scheduledExecutionTime != null, "No scheduled execution"); this.triggerContext.update(this.scheduledExecutionTime, actualExecutionTime, completionTime); if (!obtainCurrentFuture().isCancelled()) { schedule(); } } } @Override public boolean cancel(boolean mayInterruptIfRunning) { synchronized (this.triggerContextMonitor) { return obtainCurrentFuture().cancel(mayInterruptIfRunning); } } @Override public boolean isCancelled() { synchronized (this.triggerContextMonitor) { return obtainCurrentFuture().isCancelled(); } } @Override public boolean isDone() { synchronized (this.triggerContextMonitor) { return obtainCurrentFuture().isDone(); } } @Override public Object get() throws InterruptedException, ExecutionException { ScheduledFuture<?> curr; synchronized (this.triggerContextMonitor) { curr = obtainCurrentFuture(); } return curr.get(); } @Override public Object get(long timeout, TimeUnit unit) throws InterruptedException, ExecutionException, TimeoutException { ScheduledFuture<?> curr; synchronized (this.triggerContextMonitor) { curr = obtainCurrentFuture(); } return curr.get(timeout, unit); } @Override public long getDelay(TimeUnit unit) { ScheduledFuture<?> curr; synchronized (this.triggerContextMonitor) { curr = obtainCurrentFuture(); } return curr.getDelay(unit); } @Override public int compareTo(Delayed other) { if (this == other) { return 0; } long diff = getDelay(TimeUnit.MILLISECONDS) - other.getDelay(TimeUnit.MILLISECONDS); return (diff == 0 ? 0 : ((diff < 0)? -1 : 1)); } }