Package org.syncany.operations.watch

Class RecursiveWatcher

java.lang.Object

org.syncany.operations.watch.RecursiveWatcher

Direct Known Subclasses:

DefaultRecursiveWatcher, WindowsRecursiveWatcher

public abstract class RecursiveWatcher
extends java.lang.Object

The recursive file watcher monitors a folder (and its sub-folders).

When a file event occurs, a timer is started to wait for the file operations to settle. It is reset whenever a new event occurs. When the timer times out, an event is thrown through the RecursiveWatcher.WatchListener.

This is an abstract class, using several template methods that are called in different lifecycle states: beforeStart(), beforePollEventLoop(), pollEvents(), and afterStop().

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static interface	RecursiveWatcher.WatchListener

Field Summary

Fields

Modifier and Type	Field	Description
protected java.util.List<java.nio.file.Path>	ignorePaths
protected static java.util.logging.Logger	logger
protected java.nio.file.Path	root

Constructor Summary

Constructors

Constructor	Description
RecursiveWatcher(java.nio.file.Path root, java.util.List<java.nio.file.Path> ignorePaths, int settleDelay, RecursiveWatcher.WatchListener listener)

Method Summary

Modifier and Type	Method	Description
protected abstract void	afterStop()	Called after the stop() method.
protected abstract void	beforePollEventLoop()	Called in the watch service polling thread, right before the pollEvents() loop.
protected abstract void	beforeStart()	Called before the start() method.
static RecursiveWatcher	createRecursiveWatcher(java.nio.file.Path root, java.util.List<java.nio.file.Path> ignorePaths, int settleDelay, RecursiveWatcher.WatchListener listener)	Creates a recursive watcher for the given root path.
protected abstract boolean	pollEvents()	Called in the watch service polling thread, inside of the pollEvents() loop.
void	start()	Starts the watcher service and registers watches in all of the sub-folders of the given root folder.
void	stop()	Stops the watch thread by interrupting it and subsequently calls the afterStop() template method (to be implemented by subclasses.
protected abstract void	watchEventsOccurred()	Called in the watch service polling thread, whenever a file system event occurs.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

logger

protected static final java.util.logging.Logger logger

root

protected java.nio.file.Path root

ignorePaths

protected java.util.List<java.nio.file.Path> ignorePaths

Constructor Detail

RecursiveWatcher

public RecursiveWatcher(java.nio.file.Path root,
                        java.util.List<java.nio.file.Path> ignorePaths,
                        int settleDelay,
                        RecursiveWatcher.WatchListener listener)

Method Detail

createRecursiveWatcher

public static RecursiveWatcher createRecursiveWatcher(java.nio.file.Path root,
                                                      java.util.List<java.nio.file.Path> ignorePaths,
                                                      int settleDelay,
                                                      RecursiveWatcher.WatchListener listener)

Creates a recursive watcher for the given root path. The returned watcher will ignore the ignore paths and fire an event through the RecursiveWatcher.WatchListener as soon as the settle delay (in ms) has passed.

The method returns a platform-specific recursive watcher: WindowsRecursiveWatcher for Windows and DefaultRecursiveWatcher for other operating systems.

start

public void start()
           throws java.lang.Exception

Starts the watcher service and registers watches in all of the sub-folders of the given root folder.

This method calls the beforeStart() method before everything else. Subclasses may execute their own commands there. Before the watch thread is started, beforePollEventLoop() is called. And in the watch thread loop, pollEvents() is called.

Important: This method returns immediately, even though the watches might not be in place yet. For large file trees, it might take several seconds until all directories are being monitored. For normal cases (1-100 folders), this should not take longer than a few milliseconds.

Throws:

java.lang.Exception

stop

public void stop()

Stops the watch thread by interrupting it and subsequently calls the afterStop() template method (to be implemented by subclasses.

beforeStart

protected abstract void beforeStart()
                             throws java.lang.Exception

Called before the start() method. This method is only called once.

Throws:

java.lang.Exception

beforePollEventLoop

protected abstract void beforePollEventLoop()

Called in the watch service polling thread, right before the pollEvents() loop. This method is only called once.

pollEvents

protected abstract boolean pollEvents()
                               throws java.lang.InterruptedException

Called in the watch service polling thread, inside of the pollEvents() loop. This method is called multiple times.

Throws:

java.lang.InterruptedException

watchEventsOccurred

protected abstract void watchEventsOccurred()

Called in the watch service polling thread, whenever a file system event occurs. This may be used by subclasses to (re-)set watches on folders. This method is called multiple times.

afterStop

protected abstract void afterStop()
                           throws java.io.IOException

Called after the stop() method. This method is only called once.

Throws:

java.io.IOException