Package com.inductiveautomation.perspective.gateway.files

Class FileWatcher

java.lang.Object

com.inductiveautomation.ignition.common.lifecycle.AbstractLifecycle

com.inductiveautomation.perspective.gateway.files.FileWatcher

All Implemented Interfaces:

Lifecycle

public class FileWatcher
extends AbstractLifecycle

Creates a WatchService from the injected FileSystem and registers it to the injected Path to watch. When started, instances of this class will schedule polling tasks on the injected SchedulerAbstraction to check whether or not the directory represented by the injected path to watch exists and is a valid directory and if so, will start watching that directory and will call the injected listener with a FileWatcher.FileWatchEventType.REGISTER event type and a null path, else it will continue polling until the directory is created or it is shut down. Once the directory is being watched, if a file was created, modified, or deleted in the watched directory in between each poll cycle, then the respective FileWatcher.FileWatchEventType will be passed to the injected listener along with the full path to the file for each watch event which occurred for that poll cycle. If there is an overflow of events from the FileSystem, the injected listener will be called with a FileWatcher.FileWatchEventType.OVERFLOW event type and a null path. This watcher handles the case where the path to watch is deleted while it is being watched. In this case, it falls back to the above mentioned behavior when the watcher is started up and the path to watch does not represent a directory or does not exist. If the path to watch is re-created as a valid directory, the watcher will resume watching the path for changes and will notify the listener with a FileWatcher.FileWatchEventType.REGISTER event type and a null path.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static enum	FileWatcher.FileWatchEventType	Represents the types of file watch events which may occur

Constructor Summary

Constructors

Constructor	Description
FileWatcher(FileSystem fileSystem, Path pathToWatch, SchedulerAbstraction scheduler, BiConsumer<FileWatcher.FileWatchEventType,Path> listener)	The primary constructor for creating instances of the FileWatcher.

Method Summary

Modifier and Type	Method	Description
protected void	onShutdown()
protected void	onStartup()

Methods inherited from class com.inductiveautomation.ignition.common.lifecycle.AbstractLifecycle

isRunning, shutdown, startup

Methods inherited from class java.lang.Object

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

Constructor Details

FileWatcher

public FileWatcher(@Nonnull
 FileSystem fileSystem,
 @Nonnull
 Path pathToWatch,
 @Nonnull
 SchedulerAbstraction scheduler,
 @Nonnull
 BiConsumer<FileWatcher.FileWatchEventType,Path> listener)

The primary constructor for creating instances of the FileWatcher.

Parameters:

fileSystem - The FileSystem which has the injected path which will be watched

pathToWatch - The Path to watch

scheduler - The SchedulerAbstraction used to schedule polling tasks

listener - The BiConsumer listener which will be called when the watcher is registered with the path to watch and for any watch events which occur in the watched path per poll cycle

Method Details

onStartup

protected void onStartup()

Specified by:

onStartup in class AbstractLifecycle

onShutdown

protected void onShutdown()

Specified by:

onShutdown in class AbstractLifecycle