| /* |
| * Copyright (c) 2008, 2009, Oracle and/or its affiliates. All rights reserved. |
| * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| * |
| * This code is free software; you can redistribute it and/or modify it |
| * under the terms of the GNU General Public License version 2 only, as |
| * published by the Free Software Foundation. Oracle designates this |
| * particular file as subject to the "Classpath" exception as provided |
| * by Oracle in the LICENSE file that accompanied this code. |
| * |
| * This code is distributed in the hope that it will be useful, but WITHOUT |
| * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| * version 2 for more details (a copy is included in the LICENSE file that |
| * accompanied this code). |
| * |
| * You should have received a copy of the GNU General Public License version |
| * 2 along with this work; if not, write to the Free Software Foundation, |
| * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| * |
| * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| * or visit www.oracle.com if you need additional information or have any |
| * questions. |
| */ |
| |
| package sun.nio.ch; |
| |
| import java.nio.channels.*; |
| import java.util.concurrent.*; |
| import java.io.IOException; |
| |
| /** |
| * A Future for a pending I/O operation. A PendingFuture allows for the |
| * attachment of an additional arbitrary context object and a timer task. |
| */ |
| |
| final class PendingFuture<V,A> implements Future<V> { |
| private static final CancellationException CANCELLED = |
| new CancellationException(); |
| |
| private final AsynchronousChannel channel; |
| private final CompletionHandler<V,? super A> handler; |
| private final A attachment; |
| |
| // true if result (or exception) is available |
| private volatile boolean haveResult; |
| private volatile V result; |
| private volatile Throwable exc; |
| |
| // latch for waiting (created lazily if needed) |
| private CountDownLatch latch; |
| |
| // optional timer task that is cancelled when result becomes available |
| private Future<?> timeoutTask; |
| |
| // optional context object |
| private volatile Object context; |
| |
| PendingFuture(AsynchronousChannel channel, |
| CompletionHandler<V,? super A> handler, |
| A attachment, |
| Object context) |
| { |
| this.channel = channel; |
| this.handler = handler; |
| this.attachment = attachment; |
| this.context = context; |
| } |
| |
| PendingFuture(AsynchronousChannel channel, |
| CompletionHandler<V,? super A> handler, |
| A attachment) |
| { |
| this.channel = channel; |
| this.handler = handler; |
| this.attachment = attachment; |
| } |
| |
| PendingFuture(AsynchronousChannel channel) { |
| this(channel, null, null); |
| } |
| |
| PendingFuture(AsynchronousChannel channel, Object context) { |
| this(channel, null, null, context); |
| } |
| |
| AsynchronousChannel channel() { |
| return channel; |
| } |
| |
| CompletionHandler<V,? super A> handler() { |
| return handler; |
| } |
| |
| A attachment() { |
| return attachment; |
| } |
| |
| void setContext(Object context) { |
| this.context = context; |
| } |
| |
| Object getContext() { |
| return context; |
| } |
| |
| void setTimeoutTask(Future<?> task) { |
| synchronized (this) { |
| if (haveResult) { |
| task.cancel(false); |
| } else { |
| this.timeoutTask = task; |
| } |
| } |
| } |
| |
| // creates latch if required; return true if caller needs to wait |
| private boolean prepareForWait() { |
| synchronized (this) { |
| if (haveResult) { |
| return false; |
| } else { |
| if (latch == null) |
| latch = new CountDownLatch(1); |
| return true; |
| } |
| } |
| } |
| |
| /** |
| * Sets the result, or a no-op if the result or exception is already set. |
| */ |
| void setResult(V res) { |
| synchronized (this) { |
| if (haveResult) |
| return; |
| result = res; |
| haveResult = true; |
| if (timeoutTask != null) |
| timeoutTask.cancel(false); |
| if (latch != null) |
| latch.countDown(); |
| } |
| } |
| |
| /** |
| * Sets the result, or a no-op if the result or exception is already set. |
| */ |
| void setFailure(Throwable x) { |
| if (!(x instanceof IOException) && !(x instanceof SecurityException)) |
| x = new IOException(x); |
| synchronized (this) { |
| if (haveResult) |
| return; |
| exc = x; |
| haveResult = true; |
| if (timeoutTask != null) |
| timeoutTask.cancel(false); |
| if (latch != null) |
| latch.countDown(); |
| } |
| } |
| |
| /** |
| * Sets the result |
| */ |
| void setResult(V res, Throwable x) { |
| if (x == null) { |
| setResult(res); |
| } else { |
| setFailure(x); |
| } |
| } |
| |
| @Override |
| public V get() throws ExecutionException, InterruptedException { |
| if (!haveResult) { |
| boolean needToWait = prepareForWait(); |
| if (needToWait) |
| latch.await(); |
| } |
| if (exc != null) { |
| if (exc == CANCELLED) |
| throw new CancellationException(); |
| throw new ExecutionException(exc); |
| } |
| return result; |
| } |
| |
| @Override |
| public V get(long timeout, TimeUnit unit) |
| throws ExecutionException, InterruptedException, TimeoutException |
| { |
| if (!haveResult) { |
| boolean needToWait = prepareForWait(); |
| if (needToWait) |
| if (!latch.await(timeout, unit)) throw new TimeoutException(); |
| } |
| if (exc != null) { |
| if (exc == CANCELLED) |
| throw new CancellationException(); |
| throw new ExecutionException(exc); |
| } |
| return result; |
| } |
| |
| Throwable exception() { |
| return (exc != CANCELLED) ? exc : null; |
| } |
| |
| V value() { |
| return result; |
| } |
| |
| @Override |
| public boolean isCancelled() { |
| return (exc == CANCELLED); |
| } |
| |
| @Override |
| public boolean isDone() { |
| return haveResult; |
| } |
| |
| @Override |
| public boolean cancel(boolean mayInterruptIfRunning) { |
| synchronized (this) { |
| if (haveResult) |
| return false; // already completed |
| |
| // notify channel |
| if (channel() instanceof Cancellable) |
| ((Cancellable)channel()).onCancel(this); |
| |
| // set result and cancel timer |
| exc = CANCELLED; |
| haveResult = true; |
| if (timeoutTask != null) |
| timeoutTask.cancel(false); |
| } |
| |
| // close channel if forceful cancel |
| if (mayInterruptIfRunning) { |
| try { |
| channel().close(); |
| } catch (IOException ignore) { } |
| } |
| |
| // release waiters |
| if (latch != null) |
| latch.countDown(); |
| return true; |
| } |
| } |