forked from rjeczalik/notify
/
watcher_kqueue.go
436 lines (412 loc) · 10.7 KB
/
watcher_kqueue.go
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// 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 dragonfly freebsd netbsd openbsd
package notify
import (
"os"
"path/filepath"
"strings"
"sync"
"syscall"
)
// newWatcher returns kqueue Watcher implementation.
func newWatcher(c chan<- EventInfo) watcher {
k := &kqueue{
idLkp: make(map[int]*watched, 0),
pthLkp: make(map[string]*watched, 0),
c: c,
s: make(chan struct{}, 1),
}
if err := k.init(); err != nil {
panic(err)
}
go k.monitor()
return k
}
// Close closes all still open file descriptors and kqueue.
func (k *kqueue) Close() (err error) {
// trigger event used to interrup Kevent call.
if _, err = syscall.Write(k.pipefds[1], []byte{0x00}); err != nil {
return
}
<-k.s
k.Lock()
var e error
for _, w := range k.idLkp {
if e = k.unwatch(w.p, w.fi); e != nil && err == nil {
dbgprintf("kqueue: unwatch %q failed: %q", w.p, e)
err = e
}
}
if e := error(syscall.Close(k.fd)); e != nil && err == nil {
dbgprintf("kqueue: closing kqueu fd failed: %q", e)
err = e
}
k.idLkp, k.pthLkp = nil, nil
k.Unlock()
return
}
// sendEvents sends reported events one by one through chan.
func (k *kqueue) sendEvents(evn []event) {
for i := range evn {
k.c <- &evn[i]
}
}
// encode converts requested events to kqueue representation.
func encode(e Event) (o uint32) {
o = uint32(e &^ Create)
if e&Write != 0 {
o = (o &^ uint32(Write)) | uint32(NoteWrite)
}
if e&Rename != 0 {
o = (o &^ uint32(Rename)) | uint32(NoteRename)
}
if e&Remove != 0 {
o = (o &^ uint32(Remove)) | uint32(NoteDelete)
}
return
}
// decode converts event received from kqueue to notify.Event
// representation taking into account requested events (w).
func decode(o uint32, w Event) (e Event) {
// TODO(someone) : fix me
if o&uint32(NoteWrite) != 0 {
if w&NoteWrite != 0 {
e |= NoteWrite
} else {
e |= Write
}
}
if o&uint32(NoteRename) != 0 {
if w&NoteRename != 0 {
e |= NoteRename
} else {
e |= Rename
}
}
if o&uint32(NoteDelete) != 0 {
if w&NoteDelete != 0 {
e |= NoteDelete
} else {
e |= Remove
}
}
e |= Event(o) & w
return
}
// del closes fd for watched and removes it from internal cache of monitored
// files/directories.
func (k *kqueue) del(w watched) {
syscall.Close(w.fd)
delete(k.idLkp, w.fd)
delete(k.pthLkp, w.p)
}
// monitor reads reported kqueue events and forwards them further after
// performing additional processing. If read event concerns directory,
// it generates Create/Remove event and sent them further instead of directory
// event. This event is detected based on reading contents of analyzed
// directory. If no changes in file list are detected, no event is send further.
// Reading directory structure is less accurate than kqueue and can lead
// to lack of detection of all events.
func (k *kqueue) monitor() {
var (
kevn [1]syscall.Kevent_t
n int
err error
)
for {
kevn[0] = syscall.Kevent_t{}
switch n, err = syscall.Kevent(k.fd, nil, kevn[:], nil); {
case err == syscall.EINTR:
case err != nil:
dbgprintf("kqueue: failed to read events: %q\n", err)
case int(kevn[0].Ident) == k.pipefds[0]:
k.s <- struct{}{}
return
case n > 0:
k.sendEvents(k.process(kevn[0]))
}
}
}
func (k *kqueue) dir(w watched, kevn syscall.Kevent_t, e Event) (evn []event) {
// If it's dir and delete we have to send it and continue, because
// other processing relies on opening (in this case not existing) dir.
// Events for contents of this dir are reported by kqueue.
// However events for rename must be generated for all monitored files
// inside of moved directory, because kqueue does not report it independently
// for each file descriptor being moved in result of move action on
// parent directory.
if (Event(kevn.Fflags) & (NoteDelete | NoteRename)) != 0 {
// Write is reported also for Remove on directory. Because of that
// we have to filter it out explicitly.
evn = append(evn, event{w.p,
e & ^Write & ^NoteWrite, Kevent{&kevn, w.fi}})
if Event(kevn.Fflags)&NoteRename != 0 {
for p, wt := range k.pthLkp {
// TODO: Change the way of storing paths in kqueue.
if strings.HasPrefix(p, w.p+string(os.PathSeparator)) {
if err := k.unwatch(p, wt.fi); err != nil && err != errNotWatched &&
!os.IsNotExist(err) {
dbgprintf("kqueue: failed stop watching moved file (%q): %q\n",
p, err)
}
if (w.eDir|w.eNonDir)&(NoteRename|Rename) != 0 {
evn = append(evn, event{
p, (w.eDir | w.eNonDir) & e &^ Write &^ NoteWrite,
Kevent{nil, wt.fi},
})
}
}
}
}
k.del(w)
return
}
if (Event(kevn.Fflags) & NoteWrite) != 0 {
switch err := k.walk(w.p, func(fi os.FileInfo) error {
p := filepath.Join(w.p, fi.Name())
switch err := k.singlewatch(p, w.eDir, false, fi); {
case os.IsNotExist(err) && ((w.eDir & Remove) != 0):
evn = append(evn, event{p, Remove, Kevent{nil, fi}})
case err == errAlreadyWatched:
case err != nil:
dbgprintf("kqueue: watching %q failed: %q", p, err)
case (w.eDir & Create) != 0:
evn = append(evn, event{p, Create, Kevent{nil, fi}})
}
return nil
}); {
// If file is already watched, kqueue will return remove event.
case os.IsNotExist(err):
return
case err != nil:
dbgprintf("kqueue: dir processing failed: %q", err)
default:
}
}
return
}
func (*kqueue) file(w watched, kevn syscall.Kevent_t, e Event) (evn []event) {
evn = append(evn, event{w.p, e, Kevent{&kevn, w.fi}})
return
}
// process event returned by Kevent call.
func (k *kqueue) process(kevn syscall.Kevent_t) (evn []event) {
k.Lock()
w := k.idLkp[int(kevn.Ident)]
if w == nil {
k.Unlock()
dbgprintf("kqueue: %v event for not registered fd", kevn)
return
}
e := decode(kevn.Fflags, w.eDir|w.eNonDir)
if w.fi.IsDir() {
evn = k.dir(*w, kevn, e)
} else {
evn = k.file(*w, kevn, e)
}
if (Event(kevn.Fflags) & (NoteDelete | NoteRename)) != 0 {
k.del(*w)
}
k.Unlock()
return
}
// kqueue is a type holding data for kqueue watcher.
type kqueue struct {
sync.Mutex
// fd is a kqueue file descriptor
fd int
// pipefds are file descriptors used to stop `Kevent` call.
pipefds [2]int
// idLkp is a data structure mapping file descriptors with data about watching
// represented by them files/directories.
idLkp map[int]*watched
// pthLkp is a data structure mapping file names with data about watching
// represented by them files/directories.
pthLkp map[string]*watched
// c is a channel used to pass events further.
c chan<- EventInfo
// s is a channel used to stop monitoring.
s chan struct{}
}
// watched is a data structure representing watched file/directory.
type watched struct {
// p is a path to watched file/directory.
p string
// fd is a file descriptor for watched file/directory.
fd int
// fi provides information about watched file/dir.
fi os.FileInfo
// eDir represents events watched directly.
eDir Event
// eNonDir represents events watched indirectly.
eNonDir Event
}
// init initializes kqueue.
func (k *kqueue) init() (err error) {
if k.fd, err = syscall.Kqueue(); err != nil {
return
}
// Creates pipe used to stop `Kevent` call by registering it,
// watching read end and writing to other end of it.
if err = syscall.Pipe(k.pipefds[:]); err != nil {
return
}
var kevn [1]syscall.Kevent_t
syscall.SetKevent(&kevn[0], k.pipefds[0], syscall.EVFILT_READ, syscall.EV_ADD)
_, err = syscall.Kevent(k.fd, kevn[:], nil, nil)
return
}
func (k *kqueue) watch(p string, e Event, fi os.FileInfo) error {
if err := k.singlewatch(p, e, true, fi); err != nil {
if err != errAlreadyWatched {
return nil
}
}
if fi.IsDir() {
err := k.walk(p, func(fi os.FileInfo) (err error) {
if err = k.singlewatch(filepath.Join(p, fi.Name()), e, false,
fi); err != nil {
if err != errAlreadyWatched {
return
}
}
return nil
})
if err != nil {
return err
}
}
return nil
}
// watch starts to watch given p file/directory.
func (k *kqueue) singlewatch(p string, e Event, direct bool,
fi os.FileInfo) error {
w, ok := k.pthLkp[p]
if !ok {
fd, err := syscall.Open(p, syscall.O_NONBLOCK|syscall.O_RDONLY, 0)
if err != nil {
return err
}
w = &watched{fd: fd, p: p, fi: fi}
}
if direct {
w.eDir |= e
} else {
w.eNonDir |= e
}
var kevn [1]syscall.Kevent_t
syscall.SetKevent(&kevn[0], w.fd, syscall.EVFILT_VNODE,
syscall.EV_ADD|syscall.EV_CLEAR)
kevn[0].Fflags = encode(w.eDir | w.eNonDir)
if _, err := syscall.Kevent(k.fd, kevn[:], nil, nil); err != nil {
return err
}
if !ok {
k.idLkp[w.fd], k.pthLkp[w.p] = w, w
return nil
}
return errAlreadyWatched
}
// unwatch stops watching p file/directory.
func (k *kqueue) singleunwatch(p string, direct bool) error {
w := k.pthLkp[p]
if w == nil {
return errNotWatched
}
if direct {
w.eDir = 0
} else {
w.eNonDir = 0
}
var kevn [1]syscall.Kevent_t
syscall.SetKevent(&kevn[0], w.fd, syscall.EVFILT_VNODE, syscall.EV_DELETE)
if _, err := syscall.Kevent(k.fd, kevn[:], nil, nil); err != nil {
return err
}
if w.eNonDir&w.eDir != 0 {
if err := k.singlewatch(p, w.eNonDir|w.eDir, w.eNonDir == 0,
w.fi); err != nil {
return err
}
} else {
k.del(*w)
}
return nil
}
// walk runs f func on each file/dir from p directory.
func (k *kqueue) walk(p string, f func(os.FileInfo) error) error {
fp, err := os.Open(p)
if err != nil {
return err
}
ls, err := fp.Readdir(0)
fp.Close()
if err != nil {
return err
}
for i := range ls {
if err := f(ls[i]); err != nil {
return err
}
}
return nil
}
func (k *kqueue) unwatch(p string, fi os.FileInfo) error {
if fi.IsDir() {
err := k.walk(p, func(fi os.FileInfo) error {
if !fi.IsDir() {
err := k.singleunwatch(filepath.Join(p, fi.Name()), false)
if err != errNotWatched {
return err
}
return nil
}
return nil
})
if err != nil {
return err
}
}
return k.singleunwatch(p, true)
}
// Watch implements Watcher interface.
func (k *kqueue) Watch(p string, e Event) error {
fi, err := os.Stat(p)
if err != nil {
return err
}
k.Lock()
err = k.watch(p, e, fi)
k.Unlock()
return nil
}
// Unwatch implements Watcher interface.
func (k *kqueue) Unwatch(p string) error {
fi, err := os.Stat(p)
if err != nil {
return err
}
k.Lock()
err = k.unwatch(p, fi)
k.Unlock()
return nil
}
// Rewatch implements Watcher interface.
//
// TODO(rjeczalik): This is a naive hack. Rewrite might help.
func (k *kqueue) Rewatch(p string, _, e Event) error {
fi, err := os.Stat(p)
if err != nil {
return err
}
k.Lock()
if err = k.unwatch(p, fi); err == nil {
// TODO(rjeczalik): If watch fails then we leave kqueue in inconsistent
// state. Handle? Panic? Native version of rewatch?
err = k.watch(p, e, fi)
}
k.Unlock()
return nil
}