io.prestosql.jdbc.$internal.okio.Timeout Maven / Gradle / Ivy
/*
* Copyright (C) 2014 Square, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package io.prestosql.jdbc.$internal.okio;
import java.io.IOException;
import java.io.InterruptedIOException;
import java.util.concurrent.TimeUnit;
/**
* A policy on how much time to spend on a task before giving up. When a task
* times out, it is left in an unspecified state and should be abandoned. For
* example, if reading from a source times out, that source should be closed and
* the read should be retried later. If writing to a sink times out, the same
* rules apply: close the sink and retry later.
*
* Timeouts and Deadlines
* This class offers two complementary controls to define a timeout policy.
*
* Timeouts specify the maximum time to wait for a single
* operation to complete. Timeouts are typically used to detect problems like
* network partitions. For example, if a remote peer doesn't return any
* data for ten seconds, we may assume that the peer is unavailable.
*
*
Deadlines specify the maximum time to spend on a job,
* composed of one or more operations. Use deadlines to set an upper bound on
* the time invested on a job. For example, a battery-conscious app may limit
* how much time it spends pre-loading content.
*/
public class Timeout {
/**
* An empty timeout that neither tracks nor detects timeouts. Use this when
* timeouts aren't necessary, such as in implementations whose operations
* do not block.
*/
public static final Timeout NONE = new Timeout() {
@Override public Timeout timeout(long timeout, TimeUnit unit) {
return this;
}
@Override public Timeout deadlineNanoTime(long deadlineNanoTime) {
return this;
}
@Override public void throwIfReached() throws IOException {
}
};
/**
* True if {@code deadlineNanoTime} is defined. There is no equivalent to null
* or 0 for {@link System#nanoTime}.
*/
private boolean hasDeadline;
private long deadlineNanoTime;
private long timeoutNanos;
public Timeout() {
}
/**
* Wait at most {@code timeout} time before aborting an operation. Using a
* per-operation timeout means that as long as forward progress is being made,
* no sequence of operations will fail.
*
*
If {@code timeout == 0}, operations will run indefinitely. (Operating
* system timeouts may still apply.)
*/
public Timeout timeout(long timeout, TimeUnit unit) {
if (timeout < 0) throw new IllegalArgumentException("timeout < 0: " + timeout);
if (unit == null) throw new IllegalArgumentException("unit == null");
this.timeoutNanos = unit.toNanos(timeout);
return this;
}
/** Returns the timeout in nanoseconds, or {@code 0} for no timeout. */
public long timeoutNanos() {
return timeoutNanos;
}
/** Returns true if a deadline is enabled. */
public boolean hasDeadline() {
return hasDeadline;
}
/**
* Returns the {@linkplain System#nanoTime() nano time} when the deadline will
* be reached.
*
* @throws IllegalStateException if no deadline is set.
*/
public long deadlineNanoTime() {
if (!hasDeadline) throw new IllegalStateException("No deadline");
return deadlineNanoTime;
}
/**
* Sets the {@linkplain System#nanoTime() nano time} when the deadline will be
* reached. All operations must complete before this time. Use a deadline to
* set a maximum bound on the time spent on a sequence of operations.
*/
public Timeout deadlineNanoTime(long deadlineNanoTime) {
this.hasDeadline = true;
this.deadlineNanoTime = deadlineNanoTime;
return this;
}
/** Set a deadline of now plus {@code duration} time. */
public final Timeout deadline(long duration, TimeUnit unit) {
if (duration <= 0) throw new IllegalArgumentException("duration <= 0: " + duration);
if (unit == null) throw new IllegalArgumentException("unit == null");
return deadlineNanoTime(System.nanoTime() + unit.toNanos(duration));
}
/** Clears the timeout. Operating system timeouts may still apply. */
public Timeout clearTimeout() {
this.timeoutNanos = 0;
return this;
}
/** Clears the deadline. */
public Timeout clearDeadline() {
this.hasDeadline = false;
return this;
}
/**
* Throws an {@link InterruptedIOException} if the deadline has been reached or if the current
* thread has been interrupted. This method doesn't detect timeouts; that should be implemented to
* asynchronously abort an in-progress operation.
*/
public void throwIfReached() throws IOException {
if (Thread.interrupted()) {
throw new InterruptedIOException("thread interrupted");
}
if (hasDeadline && deadlineNanoTime - System.nanoTime() <= 0) {
throw new InterruptedIOException("deadline reached");
}
}
/**
* Waits on {@code monitor} until it is notified. Throws {@link InterruptedIOException} if either
* the thread is interrupted or if this timeout elapses before {@code monitor} is notified. The
* caller must be synchronized on {@code monitor}.
*
*
Here's a sample class that uses {@code waitUntilNotified()} to await a specific state. Note
* that the call is made within a loop to avoid unnecessary waiting and to mitigate spurious
* notifications.
{@code
*
* class Dice {
* Random random = new Random();
* int latestTotal;
*
* public synchronized void roll() {
* latestTotal = 2 + random.nextInt(6) + random.nextInt(6);
* System.out.println("Rolled " + latestTotal);
* notifyAll();
* }
*
* public void rollAtFixedRate(int period, TimeUnit timeUnit) {
* Executors.newScheduledThreadPool(0).scheduleAtFixedRate(new Runnable() {
* public void run() {
* roll();
* }
* }, 0, period, timeUnit);
* }
*
* public synchronized void awaitTotal(Timeout timeout, int total)
* throws InterruptedIOException {
* while (latestTotal != total) {
* timeout.waitUntilNotified(this);
* }
* }
* }
* }
*/
public final void waitUntilNotified(Object monitor) throws InterruptedIOException {
try {
boolean hasDeadline = hasDeadline();
long timeoutNanos = timeoutNanos();
if (!hasDeadline && timeoutNanos == 0L) {
monitor.wait(); // There is no timeout: wait forever.
return;
}
// Compute how long we'll wait.
long waitNanos;
long start = System.nanoTime();
if (hasDeadline && timeoutNanos != 0) {
long deadlineNanos = deadlineNanoTime() - start;
waitNanos = Math.min(timeoutNanos, deadlineNanos);
} else if (hasDeadline) {
waitNanos = deadlineNanoTime() - start;
} else {
waitNanos = timeoutNanos;
}
// Attempt to wait that long. This will break out early if the monitor is notified.
long elapsedNanos = 0L;
if (waitNanos > 0L) {
long waitMillis = waitNanos / 1000000L;
monitor.wait(waitMillis, (int) (waitNanos - waitMillis * 1000000L));
elapsedNanos = System.nanoTime() - start;
}
// Throw if the timeout elapsed before the monitor was notified.
if (elapsedNanos >= waitNanos) {
throw new InterruptedIOException("timeout");
}
} catch (InterruptedException e) {
throw new InterruptedIOException("interrupted");
}
}
}