watchpack

Wrapper library for directory and file watching.

Concept

watchpack high level API doesn't map directly to watchers. Instead a three level architecture ensures that for each directory only a single watcher exists.

• The high level API requests DirectoryWatchers from a WatcherManager, which ensures that only a single DirectoryWatcher per directory is created.
• A user-faced Watcher can be obtained from a DirectoryWatcher and provides a filtered view on the DirectoryWatcher.
• Reference-counting is used on the DirectoryWatcher and Watcher to decide when to close them.
• The real watchers are created by the DirectoryWatcher.
• Files are never watched directly. This should keep the watcher count low.
• Watching can be started in the past. This way watching can start after file reading.
• Symlinks are not followed, instead the symlink is watched.

API

var Watchpack = require("watchpack");

var wp = new Watchpack({
	// options:
	aggregateTimeout: 1000
	// fire "aggregated" event when after a change for 1000ms no additional change occurred
	// aggregated defaults to undefined, which doesn't fire an "aggregated" event

	poll: true
	// poll: true - use polling with the default interval
	// poll: 10000 - use polling with an interval of 10s
	// poll defaults to undefined, which prefer native watching methods
	// Note: enable polling when watching on a network path
	// When WATCHPACK_POLLING environment variable is set it will override this option
});

// Watchpack.prototype.watch(files: string[], directories: string[], startTime?: number)
wp.watch(listOfFiles, listOfDirectories, Date.now() - 10000);
// starts watching these files and directories
// calling this again will override the files and directories

wp.on("change", function(filePath, mtime) {
	// filePath: the changed file
	// mtime: last modified time for the changed file (null if file was removed)
	// for folders it's a time before that all changes in the directory happened
});

wp.on("aggregated", function(changes, removals) {
	// changes: a Set of all changed files
	// removals: a Set of all removed files
});

// Watchpack.prototype.pause()
wp.pause();
// stops emitting events, but keeps watchers open
// next "watch" call can reuse the watchers

// Watchpack.prototype.close()
wp.close();
// stops emitting events and closes all watchers

// Watchpack.prototype.getTimeInfoEntries()
var fileTimes = wp.getTimeInfoEntries();
// returns a Map with all known time info objects for files and directories
// this include info from files not directly watched
// key: absolute path, value: object with { safeTime, timestamp }
// safeTime: the time before that all changes happened
// timestamp: only for files, the mtime timestamp of the file

// (deprecated)
// Watchpack.prototype.getTimes()
var fileTimes = wp.getTimes();
// returns an object with all known change times for files
// this include timestamps from files not directly watched
// key: absolute path, value: timestamp as number