T. R. Bernstein
134034f3ea
Automatic subtree watching only reacted to `CREATE`, so a directory moved in from elsewhere stayed unwatched. It is now handled like a created one. Items that already exist in such a directory never produce kernel events; they are reported with the same event kind and `synthesized` set to `true`, so consumers can treat them as newly appeared.
61 lines
2.8 KiB
Markdown
61 lines
2.8 KiB
Markdown
# Watching Directory Trees
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Monitor an entire directory hierarchy for filesystem events.
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## Overview
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The Linux inotify API watches individual directories — it does not descend into subdirectories automatically. The ``Inotify/Inotify`` actor offers two convenience methods that handle the recursion for you.
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### Recursive Watch
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Call ``Inotify/Inotify/addRecursiveWatch(forDirectory:mask:)`` to walk the directory tree once and install a watch on every subdirectory that exists at the time of the call:
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```swift
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let inotify = try Inotify()
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let descriptors = try await inotify.addRecursiveWatch(
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forDirectory: "/home/user/project",
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mask: [.create, .modify, .delete]
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)
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```
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The returned array contains one watch descriptor per directory. Subdirectories created **after** this call are not covered.
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### Automatic Subtree Watching
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When you also want future subdirectories to be picked up, use ``Inotify/Inotify/addWatchWithAutomaticSubtreeWatching(forDirectory:mask:)`` instead:
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```swift
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let descriptors = try await inotify.addWatchWithAutomaticSubtreeWatching(
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forDirectory: "/home/user/project",
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mask: [.create, .modify, .delete]
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)
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```
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Internally this listens for `CREATE` and `MOVED_TO` events carrying the ``InotifyEventMask/isDir`` flag and installs new watches with the same mask on the subdirectory and its subtree whenever one appears. Items that already exist inside such a subdirectory are reported with ``InotifyEvent/synthesized`` set to `true`, since the kernel never produces events for them; a synthesized event may duplicate a kernel event for the same item.
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When a directory is moved out of the watched tree, the watches on it and on its subdirectories are removed, so no events are reported under the stale path.
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### Excluding Directories
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When watching large trees you often want to skip certain subdirectories entirely — version-control metadata, build artefacts, dependency caches, and so on. Call ``Inotify/Inotify/exclude(names:)`` **before** adding a recursive or automatic-subtree watch:
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```swift
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let inotify = try Inotify()
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await inotify.exclude(names: ".git", "node_modules", ".build")
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try await inotify.addWatchWithAutomaticSubtreeWatching(
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forDirectory: "/home/user/project",
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mask: .allEvents
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)
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```
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Excluded names are matched against the last path component of each directory during resolution and are also filtered from the event stream, so you never receive events for items whose name is on the exclusion list.
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### Choosing the Right Method
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| Method | Covers existing subdirectories | Covers new subdirectories |
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|--------|:----:|:----:|
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| ``Inotify/Inotify/addWatch(path:mask:)`` | No | No |
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| ``Inotify/Inotify/addRecursiveWatch(forDirectory:mask:)`` | Yes | No |
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| ``Inotify/Inotify/addWatchWithAutomaticSubtreeWatching(forDirectory:mask:)`` | Yes | Yes |
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