org.gradle.internal.filewatch.jdk7.WatchServiceFileWatcherBacking Maven / Gradle / Ivy

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/*
 * Copyright 2015 the original author or authors.
 *
 * 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 org.gradle.internal.filewatch.jdk7;

import com.google.common.base.Throwables;
import com.google.common.util.concurrent.FutureCallback;
import com.google.common.util.concurrent.Futures;
import com.google.common.util.concurrent.ListenableFuture;
import com.google.common.util.concurrent.ListeningExecutorService;
import com.google.common.util.concurrent.MoreExecutors;
import org.gradle.api.Action;
import org.gradle.api.internal.file.FileSystemSubset;
import org.gradle.internal.filewatch.FileWatcher;
import org.gradle.internal.filewatch.FileWatcherEvent;
import org.gradle.internal.filewatch.FileWatcherListener;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.IOException;
import java.lang.ref.SoftReference;
import java.nio.file.ClosedWatchServiceException;
import java.nio.file.WatchService;
import java.util.List;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.concurrent.atomic.AtomicReference;

public class WatchServiceFileWatcherBacking {

    private static final Logger LOGGER = LoggerFactory.getLogger(WatchServiceFileWatcherBacking.class);

    private final AtomicBoolean started = new AtomicBoolean();
    private final AtomicBoolean running = new AtomicBoolean();
    private final AtomicBoolean stopped = new AtomicBoolean();
    private final AtomicReference> pollerThreadReference = new AtomicReference>();

    private final Action onError;
    private final WatchServiceRegistrar watchServiceRegistrar;
    private final WatchService watchService;
    private final WatchServicePoller poller;

    private final FileWatcher fileWatcher = new FileWatcher() {
        @Override
        public boolean isRunning() {
            return running.get();
        }

        @Override
        public void watch(FileSystemSubset fileSystemSubset) throws IOException {
            WatchServiceFileWatcherBacking.this.watchServiceRegistrar.watch(fileSystemSubset);
        }

        @Override
        public void stop() {
            WatchServiceFileWatcherBacking.this.stop();
        }
    };

    WatchServiceFileWatcherBacking(Action onError, FileWatcherListener listener, WatchService watchService) throws IOException {
        this(onError, listener, watchService, new WatchServiceRegistrar(watchService, listener));
    }

    WatchServiceFileWatcherBacking(Action onError, FileWatcherListener listener, WatchService watchService, WatchServiceRegistrar watchServiceRegistrar) throws IOException {
        this.onError = onError;
        this.watchServiceRegistrar = watchServiceRegistrar;
        this.watchService = watchService;
        this.poller = new WatchServicePoller(watchService);
    }

    public FileWatcher start(ListeningExecutorService executorService) {
        if (started.compareAndSet(false, true)) {
            final ListenableFuture runLoopFuture = executorService.submit(new Runnable() {
                @Override
                public void run() {
                    if (!stopped.get()) {
                        pollerThreadReference.set(new SoftReference(Thread.currentThread()));
                        running.set(true);
                        try {
                            try {
                                pumpEvents();
                            } catch (InterruptedException e) {
                                Thread.currentThread().interrupt();
                            } catch (Throwable t) {
                                if (!(Throwables.getRootCause(t) instanceof InterruptedException)) {
                                    stop();
                                    onError.execute(t);
                                }
                            }
                        } finally {
                            stop();
                        }
                    }
                }
            });

            // This is necessary so that the watcher indicates its not running if the runnable gets cancelled
            Futures.addCallback(runLoopFuture, new FutureCallback