br.com.objectos.io.WatchServiceJava7 Maven / Gradle / Ivy

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/*
 * Copyright (C) 2011-2021 Objectos Software LTDA.
 *
 * 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 br.com.objectos.io;

import static br.com.objectos.collections.Collections.newGrowableMap;
import static br.com.objectos.collections.Collections.toImmutableSet;
import static br.com.objectos.lang.Lang.checkNotNull;

import br.com.objectos.collections.GrowableMap;
import br.com.objectos.collections.ImmutableMap;
import br.com.objectos.collections.ImmutableSet;
import br.com.objectos.lang.Lang;
import java.io.IOException;
import java.nio.file.FileSystem;
import java.nio.file.FileSystems;
import java.nio.file.WatchKey;
import java.util.Collection;
import java.util.EnumSet;
import java.util.Set;

final class WatchServiceJava7 implements WatchService {

  private final Set directories;

  private Worker worker;

  WatchServiceJava7(Set directories) {
    this.directories = directories;
  }

  @Override
  public final void onShutdownHook() throws Exception {
    stopService();
  }

  @Override
  public final synchronized void startService() throws IOException {
    FileSystem fs;
    fs = FileSystems.getDefault();

    java.nio.file.WatchService delegate;

    try {
      delegate = fs.newWatchService();
    } catch (IOException e) {
      throw e;
    }

    IOException ioException;
    ioException = null;

    GrowableMap keys;
    keys = newGrowableMap();

    for (WatchDirectoryJava7 option : directories) {
      try {
        WatchKey watchKey;
        watchKey = option.register(delegate);

        keys.put(watchKey, option);
      } catch (IOException e) {
        ioException = e;

        break;
      }
    }

    if (ioException != null) {
      ioException = Lang.close(ioException, delegate);

      throw ioException;
    }

    worker = new Worker(delegate, keys.toImmutableMap());

    worker.start();
  }

  @Override
  public final void stopService() throws IOException {
    worker.shutdown();
  }

  static class Builder implements WatchServiceBuilder {

    private final GrowableMap directories = newGrowableMap();

    public final WatchService build() {
      Collection values;
      values = directories.values();

      ImmutableSet set;
      set = toImmutableSet(values);

      return new WatchServiceJava7(set);
    }

    @Override
    public final void watchDirectory(
        Directory directory, WatchServiceListener listener, EventKind event) {
      checkNotNull(directory, "directory == null");

      if (directories.containsKey(directory)) {
        throw new IllegalArgumentException(directory.getPath() + " has already been registered");
      }

      checkNotNull(listener, "listener == null");
      checkNotNull(event, "event == null");

      EnumSet events;
      events = EnumSet.of(event);

      WatchDirectoryJava7 option;
      option = new WatchDirectoryJava7(directory, listener, events);

      directories.put(directory, option);
    }

  }

  private static class Worker extends Thread {

    private final java.nio.file.WatchService delegate;

    private final ImmutableMap keys;

    Worker(java.nio.file.WatchService delegate, ImmutableMap keys) {
      super("WatchService");

      this.delegate = delegate;
      this.keys = keys;
    }

    @Override
    public final void run() {
      while (!Thread.interrupted()) {
        try {
          WatchKey currentKey;
          currentKey = delegate.take();

          WatchDirectoryJava7 watchDirectory;
          watchDirectory = keys.get(currentKey);

          if (watchDirectory != null) {
            watchDirectory.consume(currentKey);
          }

          currentKey.reset();
        } catch (InterruptedException e) {
          return;
        }
      }
    }

    public final void shutdown() throws IOException {
      try {
        interrupt();
      } finally {
        delegate.close();
      }
    }

  }

}