134 lines
6 KiB
Markdown
134 lines
6 KiB
Markdown
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# watchpack
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Wrapper library for directory and file watching.
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[](https://github.com/webpack/watchpack/actions/workflows/test.yml)
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[](https://codecov.io/gh/webpack/watchpack)
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[](https://www.npmjs.com/package/watchpack)
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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 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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// When WATCHPACK_POLLING environment variable is set it will override this option
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followSymlinks: true,
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// true: follows symlinks and watches symlinks and real files
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// (This makes sense when symlinks has not been resolved yet, comes with a performance hit)
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// false (default): watches only specified item they may be real files or symlinks
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// (This makes sense when symlinks has already been resolved)
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ignored: "**/.git"
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// ignored: "string" - a glob pattern for files or folders that should not be watched
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// ignored: ["string", "string"] - multiple glob patterns that should be ignored
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// ignored: /regexp/ - a regular expression for files or folders that should not be watched
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// ignored: (entry) => boolean - an arbitrary function which must return truthy to ignore an entry
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// For all cases expect the arbitrary function the path will have path separator normalized to '/'.
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// All subdirectories are ignored too
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});
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// Watchpack.prototype.watch({
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// files: Iterable<string>,
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// directories: Iterable<string>,
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// missing: Iterable<string>,
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// startTime?: number
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// })
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wp.watch({
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files: listOfFiles,
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directories: listOfDirectories,
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missing: listOfNotExistingItems,
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startTime: Date.now() - 10000
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});
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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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// files: can be files or directories, for files: content and existence changes are tracked
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// for directories: only existence and timestamp changes are tracked
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// directories: only directories, directory content (and content of children, ...) and
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// existence changes are tracked.
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// assumed to exist, when directory is not found without further information a remove event is emitted
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// missing: can be files or directorees,
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// only existence changes are tracked
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// expected to not exist, no remove event is emitted when not found initially
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// files and directories are assumed to exist, when they are not found without further information a remove event is emitted
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// missing is assumed to not exist and no remove event is emitted
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wp.on("change", function(filePath, mtime, explanation) {
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// filePath: the changed file
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// mtime: last modified time for the changed file
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// explanation: textual information how this change was detected
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});
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wp.on("remove", function(filePath, explanation) {
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// filePath: the removed file or directory
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// explanation: textual information how this change was detected
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});
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wp.on("aggregated", function(changes, removals) {
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// changes: a Set of all changed files
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// removals: a Set of all removed files
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// watchpack gives up ownership on these Sets.
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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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// The watcher will keep aggregating events
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// which can be received with getAggregated()
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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.getAggregated(): { changes: Set<string>, removals: Set<string> }
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const { changes, removals } = wp.getAggregated();
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// returns the current aggregated info and removes that from the watcher
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// The next aggregated event won't include that info and will only emitted
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// when futher changes happen
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// Can also be used when paused.
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// Watchpack.prototype.collectTimeInfoEntries(fileInfoEntries: Map<string, Entry>, directoryInfoEntries: Map<string, Entry>)
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wp.collectTimeInfoEntries(fileInfoEntries, directoryInfoEntries);
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// collects time info objects for all known files and directories
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// this include info from files not directly watched
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// key: absolute path, value: object with { safeTime, timestamp }
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// safeTime: a point in time at which it is safe to say all changes happened before that
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// timestamp: only for files, the mtime timestamp of the file
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// Watchpack.prototype.getTimeInfoEntries()
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var fileTimes = wp.getTimeInfoEntries();
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// returns a Map with all known time info objects for files and directories
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// similar to collectTimeInfoEntries but returns a single map with all entries
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// (deprecated)
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// Watchpack.prototype.getTimes()
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var fileTimes = wp.getTimes();
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// returns an object with all known 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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