forked from zhurui/management
73 lines
3.0 KiB
Markdown
73 lines
3.0 KiB
Markdown
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# watchpack
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Wrapper library for directory and file watching.
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[](https://travis-ci.org/webpack/watchpack) [](https://ci.appveyor.com/project/sokra/watchpack/branch/master) [![Test coverage][coveralls-image]][coveralls-url]
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## Concept
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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.
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* The high level API requests `DirectoryWatchers` from a `WatcherManager`, which ensures that only a single `DirectoryWatcher` per directory is created.
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* A user-faced `Watcher` can be obtained from a `DirectoryWatcher` and provides a filtered view on the `DirectoryWatcher`.
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* Reference-counting is used on the `DirectoryWatcher` and `Watcher` to decide when to close them.
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* The real watchers (currently chokidar) are created by the `DirectoryWatcher`.
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* Files are never watched directly. This should keep the watcher count low.
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* Watching can be started in the past. This way watching can start after file reading.
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* Symlinks are not followed, instead the symlink is watched.
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## API
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``` javascript
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var Watchpack = require("watchpack");
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var wp = new Watchpack({
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// options:
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aggregateTimeout: 1000
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// fire "aggregated" event when after a change for 1000ms no additional change occurred
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// aggregated defaults to undefined, which doesn't fire an "aggregated" event
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poll: true
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// poll: true - use polling with the default interval
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// poll: 10000 - use polling with an interval of 10s
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// poll defaults to undefined, which prefer native watching methods
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// Note: enable polling when watching on a network path
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ignored: /node_modules/,
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// anymatch-compatible definition of files/paths to be ignored
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// see https://github.com/paulmillr/chokidar#path-filtering
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});
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// Watchpack.prototype.watch(string[] files, string[] directories, [number startTime])
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wp.watch(listOfFiles, listOfDirectories, Date.now() - 10000);
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// starts watching these files and directories
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// calling this again will override the files and directories
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wp.on("change", function(filePath, mtime) {
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// filePath: the changed file
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// mtime: last modified time for the changed file
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});
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wp.on("aggregated", function(changes) {
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// changes: an array of all changed files
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});
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// Watchpack.prototype.pause()
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wp.pause();
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// stops emitting events, but keeps watchers open
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// next "watch" call can reuse the watchers
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// Watchpack.prototype.close()
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wp.close();
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// stops emitting events and closes all watchers
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// Watchpack.prototype.getTimes()
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var fileTimes = wp.getTimes();
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// returns an object with all know change times for files
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// this include timestamps from files not directly watched
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// key: absolute path, value: timestamp as number
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```
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[coveralls-url]: https://coveralls.io/r/webpack/watchpack/
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[coveralls-image]: https://img.shields.io/coveralls/webpack/watchpack.svg
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