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- /*
- * Copyright (C) 2010, Google Inc.
- * and other copyright owners as documented in the project's IP log.
- *
- * This program and the accompanying materials are made available
- * under the terms of the Eclipse Distribution License v1.0 which
- * accompanies this distribution, is reproduced below, and is
- * available at http://www.eclipse.org/org/documents/edl-v10.php
- *
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or
- * without modification, are permitted provided that the following
- * conditions are met:
- *
- * - Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- *
- * - Redistributions in binary form must reproduce the above
- * copyright notice, this list of conditions and the following
- * disclaimer in the documentation and/or other materials provided
- * with the distribution.
- *
- * - Neither the name of the Eclipse Foundation, Inc. nor the
- * names of its contributors may be used to endorse or promote
- * products derived from this software without specific prior
- * written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
- * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
- * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
- * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
- * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
- * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
- * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
- * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
- * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
- * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
- * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
- * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- */
-
- package org.eclipse.jgit.lib;
-
- import java.util.concurrent.Semaphore;
- import java.util.concurrent.atomic.AtomicInteger;
- import java.util.concurrent.locks.ReentrantLock;
-
- /**
- * Wrapper around the general {@link ProgressMonitor} to make it thread safe.
- *
- * Updates to the underlying ProgressMonitor are made only from the thread that
- * allocated this wrapper. Callers are responsible for ensuring the allocating
- * thread uses {@link #pollForUpdates()} or {@link #waitForCompletion()} to
- * update the underlying ProgressMonitor.
- *
- * Only {@link #update(int)}, {@link #isCancelled()}, and {@link #endWorker()}
- * may be invoked from a worker thread. All other methods of the ProgressMonitor
- * interface can only be called from the thread that allocates this wrapper.
- */
- public class ThreadSafeProgressMonitor implements ProgressMonitor {
- private final ProgressMonitor pm;
-
- private final ReentrantLock lock;
-
- private final Thread mainThread;
-
- private final AtomicInteger workers;
-
- private final AtomicInteger pendingUpdates;
-
- private final Semaphore process;
-
- /**
- * Wrap a ProgressMonitor to be thread safe.
- *
- * @param pm
- * the underlying monitor to receive events.
- */
- public ThreadSafeProgressMonitor(ProgressMonitor pm) {
- this.pm = pm;
- this.lock = new ReentrantLock();
- this.mainThread = Thread.currentThread();
- this.workers = new AtomicInteger(0);
- this.pendingUpdates = new AtomicInteger(0);
- this.process = new Semaphore(0);
- }
-
- public void start(int totalTasks) {
- if (!isMainThread())
- throw new IllegalStateException();
- pm.start(totalTasks);
- }
-
- public void beginTask(String title, int totalWork) {
- if (!isMainThread())
- throw new IllegalStateException();
- pm.beginTask(title, totalWork);
- }
-
- /** Notify the monitor a worker is starting. */
- public void startWorker() {
- startWorkers(1);
- }
-
- /**
- * Notify the monitor of workers starting.
- *
- * @param count
- * the number of worker threads that are starting.
- */
- public void startWorkers(int count) {
- workers.addAndGet(count);
- }
-
- /** Notify the monitor a worker is finished. */
- public void endWorker() {
- if (workers.decrementAndGet() == 0)
- process.release();
- }
-
- /**
- * Non-blocking poll for pending updates.
- *
- * This method can only be invoked by the same thread that allocated this
- * ThreadSafeProgressMonior.
- */
- public void pollForUpdates() {
- assert isMainThread();
- doUpdates();
- }
-
- /**
- * Process pending updates and wait for workers to finish.
- *
- * This method can only be invoked by the same thread that allocated this
- * ThreadSafeProgressMonior.
- *
- * @throws InterruptedException
- * if the main thread is interrupted while waiting for
- * completion of workers.
- */
- public void waitForCompletion() throws InterruptedException {
- assert isMainThread();
- while (0 < workers.get()) {
- doUpdates();
- process.acquire();
- }
- doUpdates();
- }
-
- private void doUpdates() {
- int cnt = pendingUpdates.getAndSet(0);
- if (0 < cnt)
- pm.update(cnt);
- }
-
- public void update(int completed) {
- int old = pendingUpdates.getAndAdd(completed);
- if (isMainThread())
- doUpdates();
- else if (old == 0)
- process.release();
- }
-
- public boolean isCancelled() {
- lock.lock();
- try {
- return pm.isCancelled();
- } finally {
- lock.unlock();
- }
- }
-
- public void endTask() {
- if (!isMainThread())
- throw new IllegalStateException();
- pm.endTask();
- }
-
- private boolean isMainThread() {
- return Thread.currentThread() == mainThread;
- }
- }
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