org.eclipse.jetty.util.SharedBlockingCallback Maven / Gradle / Ivy
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//
// ========================================================================
// Copyright (c) 1995-2022 Mort Bay Consulting Pty Ltd and others.
// ------------------------------------------------------------------------
// All rights reserved. This program and the accompanying materials
// are made available under the terms of the Eclipse Public License v1.0
// and Apache License v2.0 which accompanies this distribution.
//
// The Eclipse Public License is available at
// http://www.eclipse.org/legal/epl-v10.html
//
// The Apache License v2.0 is available at
// http://www.opensource.org/licenses/apache2.0.php
//
// You may elect to redistribute this code under either of these licenses.
// ========================================================================
//
package org.eclipse.jetty.util;
import java.io.Closeable;
import java.io.IOException;
import java.io.InterruptedIOException;
import java.util.Objects;
import java.util.concurrent.CancellationException;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;
import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.ReentrantLock;
import org.eclipse.jetty.util.log.Log;
import org.eclipse.jetty.util.log.Logger;
/**
* Provides a reusable {@link Callback} that can block the thread
* while waiting to be completed.
*
* A typical usage pattern is:
*
* void someBlockingCall(Object... args) throws IOException
* {
* try(Blocker blocker = sharedBlockingCallback.acquire())
* {
* someAsyncCall(args, blocker);
* blocker.block();
* }
* }
*
*
* @deprecated The Eclipse Jetty and Apache Felix Http Jetty packages are no longer supported.
*/
@Deprecated(since = "2021-05-27")
public class SharedBlockingCallback {
private static final Logger LOG = Log.getLogger(SharedBlockingCallback.class);
private static final Throwable IDLE = new ConstantThrowable("IDLE");
private static final Throwable SUCCEEDED = new ConstantThrowable("SUCCEEDED");
private static final Throwable FAILED = new ConstantThrowable("FAILED");
private final ReentrantLock _lock = new ReentrantLock();
private final Condition _idle = _lock.newCondition();
private final Condition _complete = _lock.newCondition();
private Blocker _blocker = new Blocker();
@Deprecated
protected long getIdleTimeout() {
return -1;
}
public Blocker acquire() throws IOException {
long idle = getIdleTimeout();
_lock.lock();
try {
while (_blocker._state != IDLE) {
if (idle > 0 && (idle < Long.MAX_VALUE / 2)) {
// Wait a little bit longer than the blocker might block
if (!_idle.await(idle * 2, TimeUnit.MILLISECONDS))
throw new IOException(new TimeoutException());
} else
_idle.await();
}
_blocker._state = null;
return _blocker;
} catch (InterruptedException x) {
throw new InterruptedIOException();
} finally {
_lock.unlock();
}
}
public boolean fail(Throwable cause) {
Objects.requireNonNull(cause);
_lock.lock();
try {
if (_blocker._state == null) {
_blocker._state = new BlockerFailedException(cause);
_complete.signalAll();
return true;
}
} finally {
_lock.unlock();
}
return false;
}
protected void notComplete(Blocker blocker) {
LOG.warn("Blocker not complete {}", blocker);
if (LOG.isDebugEnabled())
LOG.debug(new Throwable());
}
/**
* A Closeable Callback.
* Uses the auto close mechanism to check block has been called OK.
* Implements {@link Callback} because calls to this
* callback do not blocak, rather they wakeup the thread that is blocked
* in {@link #block()}
*
* @deprecated The Eclipse Jetty and Apache Felix Http Jetty packages are no longer supported.
*/
@Deprecated(since = "2021-05-27")
public class Blocker implements Callback, Closeable {
private Throwable _state = IDLE;
protected Blocker() {
}
@Override
public InvocationType getInvocationType() {
return InvocationType.NON_BLOCKING;
}
@Override
public void succeeded() {
_lock.lock();
try {
if (_state == null) {
_state = SUCCEEDED;
_complete.signalAll();
} else {
LOG.warn("Succeeded after {}", _state.toString());
if (LOG.isDebugEnabled())
LOG.debug(_state);
}
} finally {
_lock.unlock();
}
}
@Override
public void failed(Throwable cause) {
_lock.lock();
try {
if (_state == null) {
if (cause == null)
_state = FAILED;
else if (cause instanceof BlockerTimeoutException)
// Not this blockers timeout
_state = new IOException(cause);
else
_state = cause;
_complete.signalAll();
} else if (_state instanceof BlockerTimeoutException || _state instanceof BlockerFailedException) {
// Failure arrived late, block() already
// modified the state, nothing more to do.
if (LOG.isDebugEnabled())
LOG.debug("Failed after {}", _state);
} else {
LOG.warn("Failed after {}: {}", _state, cause);
if (LOG.isDebugEnabled()) {
LOG.debug(_state);
LOG.debug(cause);
}
}
} finally {
_lock.unlock();
}
}
/**
* Block until the Callback has succeeded or failed and after the return leave in the state to allow reuse. This is useful for code that wants to
* repeatable use a FutureCallback to convert an asynchronous API to a blocking API.
*
* @throws IOException if exception was caught during blocking, or callback was cancelled
*/
public void block() throws IOException {
long idle = getIdleTimeout();
_lock.lock();
try {
while (_state == null) {
if (idle > 0) {
// Waiting here may compete with the idle timeout mechanism,
// so here we wait a little bit longer to favor the normal
// idle timeout mechanism that will call failed(Throwable).
long excess = Math.min(idle / 2, 1000);
if (!_complete.await(idle + excess, TimeUnit.MILLISECONDS)) {
// Method failed(Throwable) has not been called yet,
// so we will synthesize a special TimeoutException.
_state = new BlockerTimeoutException();
}
} else {
_complete.await();
}
}
if (_state == SUCCEEDED)
return;
if (_state == IDLE)
throw new IllegalStateException("IDLE");
if (_state instanceof IOException)
throw (IOException) _state;
if (_state instanceof CancellationException)
throw (CancellationException) _state;
if (_state instanceof RuntimeException)
throw (RuntimeException) _state;
if (_state instanceof Error)
throw (Error) _state;
throw new IOException(_state);
} catch (final InterruptedException e) {
_state = e;
throw new InterruptedIOException();
} finally {
_lock.unlock();
}
}
/**
* Check the Callback has succeeded or failed and after the return leave in the state to allow reuse.
*/
@Override
public void close() {
_lock.lock();
try {
if (_state == IDLE)
throw new IllegalStateException("IDLE");
if (_state == null)
notComplete(this);
} finally {
try {
// If we have a failure
if (_state != null && _state != SUCCEEDED)
// create a new Blocker
_blocker = new Blocker();
else
// else reuse Blocker
_state = IDLE;
_idle.signalAll();
_complete.signalAll();
} finally {
_lock.unlock();
}
}
}
@Override
public String toString() {
_lock.lock();
try {
return String.format("%s@%x{%s}", Blocker.class.getSimpleName(), hashCode(), _state);
} finally {
_lock.unlock();
}
}
}
// @deprecated The Eclipse Jetty and Apache Felix Http Jetty packages are no longer supported.
@Deprecated(since = "2021-05-27")
private static class BlockerTimeoutException extends TimeoutException {
}
// @deprecated The Eclipse Jetty and Apache Felix Http Jetty packages are no longer supported.
@Deprecated(since = "2021-05-27")
private static class BlockerFailedException extends Exception {
public BlockerFailedException(Throwable cause) {
super(cause);
}
}
}