| // |
| // ======================================================================== |
| // Copyright (c) 1995-2017 Mort Bay Consulting Pty. Ltd. |
| // ------------------------------------------------------------------------ |
| // 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.IOException; |
| import java.io.InterruptedIOException; |
| import java.util.concurrent.CancellationException; |
| import java.util.concurrent.CountDownLatch; |
| import java.util.concurrent.atomic.AtomicReference; |
| |
| import org.eclipse.jetty.util.log.Log; |
| import org.eclipse.jetty.util.log.Logger; |
| import org.eclipse.jetty.util.thread.NonBlockingThread; |
| |
| /* ------------------------------------------------------------ */ |
| /** |
| * An implementation of Callback that blocks until success or failure. |
| */ |
| public class BlockingCallback implements Callback |
| { |
| private static final Logger LOG = Log.getLogger(BlockingCallback.class); |
| |
| private static Throwable SUCCEEDED = new ConstantThrowable("SUCCEEDED"); |
| |
| private final CountDownLatch _latch = new CountDownLatch(1); |
| private final AtomicReference<Throwable> _state = new AtomicReference<>(); |
| |
| public BlockingCallback() |
| {} |
| |
| @Override |
| public void succeeded() |
| { |
| if (_state.compareAndSet(null,SUCCEEDED)) |
| _latch.countDown(); |
| } |
| |
| @Override |
| public void failed(Throwable cause) |
| { |
| if (_state.compareAndSet(null,cause)) |
| _latch.countDown(); |
| } |
| |
| /** 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 |
| { |
| if (NonBlockingThread.isNonBlockingThread()) |
| LOG.warn("Blocking a NonBlockingThread: ",new Throwable()); |
| |
| try |
| { |
| _latch.await(); |
| Throwable state=_state.get(); |
| if (state==SUCCEEDED) |
| return; |
| if (state instanceof IOException) |
| throw (IOException) state; |
| if (state instanceof CancellationException) |
| throw (CancellationException) state; |
| throw new IOException(state); |
| } |
| catch (final InterruptedException e) |
| { |
| throw new InterruptedIOException(){{initCause(e);}}; |
| } |
| finally |
| { |
| _state.set(null); |
| } |
| } |
| |
| |
| @Override |
| public String toString() |
| { |
| return String.format("%s@%x{%s}",BlockingCallback.class.getSimpleName(),hashCode(),_state.get()); |
| } |
| |
| } |