Module io.helidon.config

Package io.helidon.config

Class FileSystemWatcher

java.lang.Object

io.helidon.config.FileSystemWatcher

All Implemented Interfaces:

ChangeWatcher<Path>

public final class FileSystemWatcher
extends Object
implements ChangeWatcher<Path>

This change watcher is backed by WatchService to fire a polling event with every change on monitored Path.

When a parent directory of the path is not available, or becomes unavailable later, a new attempt to register WatchService is scheduled again and again until the directory finally exists and the registration is successful.

This ChangeWatcher might be initialized with a custom executor or the Executors.newSingleThreadScheduledExecutor() is used if none is explicitly configured.

This watcher notifies with appropriate change event in the following cases:

• The watched directory is gone
• The watched directory appears
• A file in the watched directory is deleted, created or modified

A single file system watcher may be used to watch multiple targets. In such a case, if stop() is invoked, it stops watching all of these targets.

See Also:

• WatchService

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static final class	FileSystemWatcher.Builder	Fluent API builder for FileSystemWatcher.

Nested classes/interfaces inherited from interface io.helidon.config.spi.ChangeWatcher

ChangeWatcher.ChangeEvent<T>

Method Summary

Modifier and Type	Method	Description
static FileSystemWatcher.Builder	builder()	Fluent API builder for FileSystemWatcher.
static FileSystemWatcher	create()	Create a new file watcher with default configuration.
void	initWatchServiceModifiers(WatchEvent.Modifier... modifiers)	Add modifiers to be used when registering the WatchService.
void	start(Path target, Consumer<ChangeWatcher.ChangeEvent<Path>> listener)	Start watching a target for changes.
void	stop()	Stop watching all targets for changes.
Class<Path>	type()	Target supported by this change watcher.

Methods inherited from class java.lang.Object

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

Method Details

builder

public static FileSystemWatcher.Builder builder()

Fluent API builder for FileSystemWatcher.

Returns:

a new builder instance

create

public static FileSystemWatcher create()

Create a new file watcher with default configuration.

Returns:

a new file watcher

start

public void start(Path target,
 Consumer<ChangeWatcher.ChangeEvent<Path>> listener)

Description copied from interface: ChangeWatcher

Start watching a target for changes. If a change happens, notify the listener.

Specified by:

start in interface ChangeWatcher<Path>

Parameters:

target - target of this watcher, such as Path

listener - listener that handles reloading of the resource being watched

stop

public void stop()

Description copied from interface: ChangeWatcher

Stop watching all targets for changes.

Specified by:

stop in interface ChangeWatcher<Path>

type

public Class<Path> type()

Description copied from interface: ChangeWatcher

Target supported by this change watcher.

Specified by:

type in interface ChangeWatcher<Path>

Returns:

type supported

initWatchServiceModifiers

public void initWatchServiceModifiers(WatchEvent.Modifier... modifiers)

Add modifiers to be used when registering the WatchService. See Path.register.

Parameters:

modifiers - the modifiers to add