io.grpc.internal.Rescheduler Maven / Gradle / Ivy
/*
* Copyright 2018 The gRPC 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.
*/
package io.grpc.internal;
import com.google.common.annotations.VisibleForTesting;
import com.google.common.base.Stopwatch;
import java.util.concurrent.Executor;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.ScheduledFuture;
import java.util.concurrent.TimeUnit;
/**
* Reschedules a runnable lazily.
*/
final class Rescheduler {
// deps
private final ScheduledExecutorService scheduler;
private final Executor serializingExecutor;
private final Runnable runnable;
// state
private final Stopwatch stopwatch;
private long runAtNanos;
private boolean enabled;
private ScheduledFuture wakeUp;
Rescheduler(
Runnable r,
Executor serializingExecutor,
ScheduledExecutorService scheduler,
Stopwatch stopwatch) {
this.runnable = r;
this.serializingExecutor = serializingExecutor;
this.scheduler = scheduler;
this.stopwatch = stopwatch;
stopwatch.start();
}
/* must be called from the {@link #serializingExecutor} originally passed in. */
void reschedule(long delay, TimeUnit timeUnit) {
long delayNanos = timeUnit.toNanos(delay);
long newRunAtNanos = nanoTime() + delayNanos;
enabled = true;
if (newRunAtNanos - runAtNanos < 0 || wakeUp == null) {
if (wakeUp != null) {
wakeUp.cancel(false);
}
wakeUp = scheduler.schedule(new FutureRunnable(), delayNanos, TimeUnit.NANOSECONDS);
}
runAtNanos = newRunAtNanos;
}
// must be called from channel executor
void cancel(boolean permanent) {
enabled = false;
if (permanent && wakeUp != null) {
wakeUp.cancel(false);
wakeUp = null;
}
}
private final class FutureRunnable implements Runnable {
@Override
public void run() {
Rescheduler.this.serializingExecutor.execute(new ChannelFutureRunnable());
}
private boolean isEnabled() {
return Rescheduler.this.enabled;
}
}
private final class ChannelFutureRunnable implements Runnable {
@Override
public void run() {
if (!enabled) {
wakeUp = null;
return;
}
long now = nanoTime();
if (runAtNanos - now > 0) {
wakeUp = scheduler.schedule(
new FutureRunnable(), runAtNanos - now, TimeUnit.NANOSECONDS);
} else {
enabled = false;
wakeUp = null;
runnable.run();
}
}
}
@VisibleForTesting
static boolean isEnabled(Runnable r) {
return ((FutureRunnable) r).isEnabled();
}
private long nanoTime() {
return stopwatch.elapsed(TimeUnit.NANOSECONDS);
}
}