/*
* 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.beam.sdk.testing;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.locks.LockSupport;
import org.apache.beam.sdk.util.Sleeper;
/**
* This class provides an expensive sleeper to deal with issues around Java's
* accuracy of {@link System#currentTimeMillis} and methods such as
* {@link Object#wait} and {@link Thread#sleep} which depend on it. This <a
* href="https://blogs.oracle.com/dholmes/entry/inside_the_hotspot_vm_clocks">
* article</a> goes into further detail about this issue.
*
* <p>This {@link Sleeper} uses {@link System#nanoTime}
* as the timing source and {@link LockSupport#parkNanos} as the wait method.
* Note that usage of this sleeper may impact performance because
* of the relatively more expensive methods being invoked when compared to
* {@link Thread#sleep}.
*/
public class SystemNanoTimeSleeper implements Sleeper {
public static final Sleeper INSTANCE = new SystemNanoTimeSleeper();
/** Limit visibility to prevent instantiation. */
private SystemNanoTimeSleeper() {
}
@Override
public void sleep(long millis) throws InterruptedException {
long currentTime;
long endTime = System.nanoTime() + TimeUnit.NANOSECONDS.convert(millis, TimeUnit.MILLISECONDS);
while ((currentTime = System.nanoTime()) < endTime) {
if (Thread.interrupted()) {
throw new InterruptedException();
}
LockSupport.parkNanos(endTime - currentTime);
}
if (Thread.interrupted()) {
throw new InterruptedException();
}
}
/**
* Causes the currently executing thread to sleep (temporarily cease
* execution) for the specified number of milliseconds. The thread does not
* lose ownership of any monitors.
*/
public static void sleepMillis(long millis) throws InterruptedException {
INSTANCE.sleep(millis);
}
}