org.imca_cat.pollingwatchservice.PathWatchService Maven / Gradle / Ivy
/*
* Copyright (c) 2013-2017 Cinchapi Inc.
*
* 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.imca_cat.pollingwatchservice;
import java.io.IOException;
import java.nio.file.ClosedWatchServiceException;
import java.nio.file.NotDirectoryException;
import java.nio.file.Path;
import java.nio.file.WatchEvent;
import java.nio.file.WatchKey;
import java.nio.file.WatchService;
/**
* A service for watching {@code Path} objects for changes.
*
* A {@code PathWatchService} is similar to a {@code WatchService} except that
* a {@code PathWatchService} must be started, it only watches {@code Path}
* instances (not {@code Watchable} instances), and instead of calling one of
* the {@code register} methods on a {@code Watchable}, we call one of the
* {@code register} methods on this interface.
*
* To use this service, create an instance, register directories to watch via
* the {@code register} methods, and start it via the {@code start} method.
* Registering directories to watch can be performed before and after starting
* the service. Retrieve changes via the {@code poll} or {@code take} methods,
* and close the service when done via the {@code close} method.
*
* Example:
*
*
* PathWatchService s = newPathWatchService();
* s.register(FileSystems.getDefault().getPath("/home/luke"),
* StandardWatchEventKinds.ENTRY_CREATE,
* StandardWatchEventKinds.ENTRY_DELETE,
* StandardWatchEventKinds.ENTRY_MODIFY);
* s.start();
* for (;;) {
* WatchKey k = s.take();
* ...
* }
*
*/
public interface PathWatchService extends WatchService {
/**
* Starts this service.
*
* @throws ClosedWatchServiceException if closed
* @throws IllegalStateException if already started
*/
public void start();
/**
* Registers the specified directory, using the specified {@code WatchEvent}
* kinds and no {@code WatchEvent} modifiers, with this watch service.
*
* This method is intended to be similar in behavior to
* {@link Path#register(WatchService, WatchEvent.Kind[])}.
*
* @param dir directory to watch; must not be a symbolic link
* @param kinds events to register for
*
* @throws ClosedWatchServiceException if this watch service is closed
* @throws NotDirectoryException if {@code dir} is not a directory
* @throws IOException if an I/O error occurs
*/
public WatchKey register(Path dir, WatchEvent.Kind... kinds)
throws IOException;
/**
* Registers the specified directory, using the specified {@code WatchEvent}
* kinds and modifiers, with this watch service.
*
* This method is intended to be similar in behavior to
* {@link Path#register(WatchService, WatchEvent.Kind[], WatchEvent.Modifier[])}
* .
*
* @param dir directory to watch; must not be a symbolic link
* @param kinds events to register for
* @param modifiers modifiers modifying how {@code dir} is registered
*
* @throws ClosedWatchServiceException if this watch service is closed
* @throws NotDirectoryException if {@code dir} is not a directory
* @throws IOException if an I/O error occurs
*/
public WatchKey register(Path dir, WatchEvent.Kind[] kinds,
WatchEvent.Modifier... modifiers) throws IOException;
}