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 (currently chokidar) 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
ignored: /node_modules/,
// anymatch-compatible definition of files/paths to be ignored
// see https://github.com/paulmillr/chokidar#path-filtering
});
// Watchpack.prototype.watch(string[] files, string[] directories, [number startTime])
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
});
wp.on("aggregated", function(changes) {
// changes: an array of all changed 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.getTimes()
var fileTimes = wp.getTimes();
// returns an object with all know change times for files
// this include timestamps from files not directly watched
// key: absolute path, value: timestamp as number