diff options
Diffstat (limited to 'vendor/github.com/rjeczalik/notify/watcher_fsevents.go')
-rw-r--r-- | vendor/github.com/rjeczalik/notify/watcher_fsevents.go | 319 |
1 files changed, 319 insertions, 0 deletions
diff --git a/vendor/github.com/rjeczalik/notify/watcher_fsevents.go b/vendor/github.com/rjeczalik/notify/watcher_fsevents.go new file mode 100644 index 000000000..9062c17c7 --- /dev/null +++ b/vendor/github.com/rjeczalik/notify/watcher_fsevents.go @@ -0,0 +1,319 @@ +// Copyright (c) 2014-2015 The Notify Authors. All rights reserved. +// Use of this source code is governed by the MIT license that can be +// found in the LICENSE file. + +// +build darwin,!kqueue + +package notify + +import ( + "errors" + "strings" + "sync/atomic" +) + +// TODO(rjeczalik): get rid of calls to canonical, it's tree responsibility + +const ( + failure = uint32(FSEventsMustScanSubDirs | FSEventsUserDropped | FSEventsKernelDropped) + filter = uint32(FSEventsCreated | FSEventsRemoved | FSEventsRenamed | + FSEventsModified | FSEventsInodeMetaMod) +) + +// FSEvent represents single file event. It is created out of values passed by +// FSEvents to FSEventStreamCallback function. +type FSEvent struct { + Path string // real path of the file or directory + ID uint64 // ID of the event (FSEventStreamEventId) + Flags uint32 // joint FSEvents* flags (FSEventStreamEventFlags) +} + +// splitflags separates event flags from single set into slice of flags. +func splitflags(set uint32) (e []uint32) { + for i := uint32(1); set != 0; i, set = i<<1, set>>1 { + if (set & 1) != 0 { + e = append(e, i) + } + } + return +} + +// watch represents a filesystem watchpoint. It is a higher level abstraction +// over FSEvents' stream, which implements filtering of file events based +// on path and event set. It emulates non-recursive watch-point by filtering out +// events which paths are more than 1 level deeper than the watched path. +type watch struct { + // prev stores last event set per path in order to filter out old flags + // for new events, which appratenly FSEvents likes to retain. It's a disgusting + // hack, it should be researched how to get rid of it. + prev map[string]uint32 + c chan<- EventInfo + stream *stream + path string + events uint32 + isrec int32 + flushed bool +} + +// Example format: +// +// ~ $ (trigger command) # (event set) -> (effective event set) +// +// Heuristics: +// +// 1. Create event is removed when it was present in previous event set. +// Example: +// +// ~ $ echo > file # Create|Write -> Create|Write +// ~ $ echo > file # Create|Write|InodeMetaMod -> Write|InodeMetaMod +// +// 2. Remove event is removed if it was present in previouse event set. +// Example: +// +// ~ $ touch file # Create -> Create +// ~ $ rm file # Create|Remove -> Remove +// ~ $ touch file # Create|Remove -> Create +// +// 3. Write event is removed if not followed by InodeMetaMod on existing +// file. Example: +// +// ~ $ echo > file # Create|Write -> Create|Write +// ~ $ chmod +x file # Create|Write|ChangeOwner -> ChangeOwner +// +// 4. Write&InodeMetaMod is removed when effective event set contain Remove event. +// Example: +// +// ~ $ echo > file # Write|InodeMetaMod -> Write|InodeMetaMod +// ~ $ rm file # Remove|Write|InodeMetaMod -> Remove +// +func (w *watch) strip(base string, set uint32) uint32 { + const ( + write = FSEventsModified | FSEventsInodeMetaMod + both = FSEventsCreated | FSEventsRemoved + ) + switch w.prev[base] { + case FSEventsCreated: + set &^= FSEventsCreated + if set&FSEventsRemoved != 0 { + w.prev[base] = FSEventsRemoved + set &^= write + } + case FSEventsRemoved: + set &^= FSEventsRemoved + if set&FSEventsCreated != 0 { + w.prev[base] = FSEventsCreated + } + default: + switch set & both { + case FSEventsCreated: + w.prev[base] = FSEventsCreated + case FSEventsRemoved: + w.prev[base] = FSEventsRemoved + set &^= write + } + } + dbgprintf("split()=%v\n", Event(set)) + return set +} + +// Dispatch is a stream function which forwards given file events for the watched +// path to underlying FileInfo channel. +func (w *watch) Dispatch(ev []FSEvent) { + events := atomic.LoadUint32(&w.events) + isrec := (atomic.LoadInt32(&w.isrec) == 1) + for i := range ev { + if ev[i].Flags&FSEventsHistoryDone != 0 { + w.flushed = true + continue + } + if !w.flushed { + continue + } + dbgprintf("%v (0x%x) (%s, i=%d, ID=%d, len=%d)\n", Event(ev[i].Flags), + ev[i].Flags, ev[i].Path, i, ev[i].ID, len(ev)) + if ev[i].Flags&failure != 0 { + // TODO(rjeczalik): missing error handling + continue + } + if !strings.HasPrefix(ev[i].Path, w.path) { + continue + } + n := len(w.path) + base := "" + if len(ev[i].Path) > n { + if ev[i].Path[n] != '/' { + continue + } + base = ev[i].Path[n+1:] + if !isrec && strings.IndexByte(base, '/') != -1 { + continue + } + } + // TODO(rjeczalik): get diff only from filtered events? + e := w.strip(string(base), ev[i].Flags) & events + if e == 0 { + continue + } + for _, e := range splitflags(e) { + dbgprintf("%d: single event: %v", ev[i].ID, Event(e)) + w.c <- &event{ + fse: ev[i], + event: Event(e), + } + } + } +} + +// Stop closes underlying FSEvents stream and stops dispatching events. +func (w *watch) Stop() { + w.stream.Stop() + // TODO(rjeczalik): make (*stream).Stop flush synchronously undelivered events, + // so the following hack can be removed. It should flush all the streams + // concurrently as we care not to block too much here. + atomic.StoreUint32(&w.events, 0) + atomic.StoreInt32(&w.isrec, 0) +} + +// fsevents implements Watcher and RecursiveWatcher interfaces backed by FSEvents +// framework. +type fsevents struct { + watches map[string]*watch + c chan<- EventInfo +} + +func newWatcher(c chan<- EventInfo) watcher { + return &fsevents{ + watches: make(map[string]*watch), + c: c, + } +} + +func (fse *fsevents) watch(path string, event Event, isrec int32) (err error) { + if path, err = canonical(path); err != nil { + return err + } + if _, ok := fse.watches[path]; ok { + return errAlreadyWatched + } + w := &watch{ + prev: make(map[string]uint32), + c: fse.c, + path: path, + events: uint32(event), + isrec: isrec, + } + w.stream = newStream(path, w.Dispatch) + if err = w.stream.Start(); err != nil { + return err + } + fse.watches[path] = w + return nil +} + +func (fse *fsevents) unwatch(path string) (err error) { + if path, err = canonical(path); err != nil { + return + } + w, ok := fse.watches[path] + if !ok { + return errNotWatched + } + w.stream.Stop() + delete(fse.watches, path) + return nil +} + +// Watch implements Watcher interface. It fails with non-nil error when setting +// the watch-point by FSEvents fails or with errAlreadyWatched error when +// the given path is already watched. +func (fse *fsevents) Watch(path string, event Event) error { + return fse.watch(path, event, 0) +} + +// Unwatch implements Watcher interface. It fails with errNotWatched when +// the given path is not being watched. +func (fse *fsevents) Unwatch(path string) error { + return fse.unwatch(path) +} + +// Rewatch implements Watcher interface. It fails with errNotWatched when +// the given path is not being watched or with errInvalidEventSet when oldevent +// does not match event set the watch-point currently holds. +func (fse *fsevents) Rewatch(path string, oldevent, newevent Event) error { + w, ok := fse.watches[path] + if !ok { + return errNotWatched + } + if !atomic.CompareAndSwapUint32(&w.events, uint32(oldevent), uint32(newevent)) { + return errInvalidEventSet + } + atomic.StoreInt32(&w.isrec, 0) + return nil +} + +// RecursiveWatch implements RecursiveWatcher interface. It fails with non-nil +// error when setting the watch-point by FSEvents fails or with errAlreadyWatched +// error when the given path is already watched. +func (fse *fsevents) RecursiveWatch(path string, event Event) error { + return fse.watch(path, event, 1) +} + +// RecursiveUnwatch implements RecursiveWatcher interface. It fails with +// errNotWatched when the given path is not being watched. +// +// TODO(rjeczalik): fail if w.isrec == 0? +func (fse *fsevents) RecursiveUnwatch(path string) error { + return fse.unwatch(path) +} + +// RecrusiveRewatch implements RecursiveWatcher interface. It fails: +// +// * with errNotWatched when the given path is not being watched +// * with errInvalidEventSet when oldevent does not match the current event set +// * with errAlreadyWatched when watch-point given by the oldpath was meant to +// be relocated to newpath, but the newpath is already watched +// * a non-nil error when setting the watch-point with FSEvents fails +// +// TODO(rjeczalik): Improve handling of watch-point relocation? See two TODOs +// that follows. +func (fse *fsevents) RecursiveRewatch(oldpath, newpath string, oldevent, newevent Event) error { + switch [2]bool{oldpath == newpath, oldevent == newevent} { + case [2]bool{true, true}: + w, ok := fse.watches[oldpath] + if !ok { + return errNotWatched + } + atomic.StoreInt32(&w.isrec, 1) + return nil + case [2]bool{true, false}: + w, ok := fse.watches[oldpath] + if !ok { + return errNotWatched + } + if !atomic.CompareAndSwapUint32(&w.events, uint32(oldevent), uint32(newevent)) { + return errors.New("invalid event state diff") + } + atomic.StoreInt32(&w.isrec, 1) + return nil + default: + // TODO(rjeczalik): rewatch newpath only if exists? + // TODO(rjeczalik): migrate w.prev to new watch? + if _, ok := fse.watches[newpath]; ok { + return errAlreadyWatched + } + if err := fse.Unwatch(oldpath); err != nil { + return err + } + // TODO(rjeczalik): revert unwatch if watch fails? + return fse.watch(newpath, newevent, 1) + } +} + +// Close unwatches all watch-points. +func (fse *fsevents) Close() error { + for _, w := range fse.watches { + w.Stop() + } + fse.watches = nil + return nil +} |