From 3d6987fbf52d71bea6ff0eb830f754d61e6c7e52 Mon Sep 17 00:00:00 2001 From: Martin Tournoij Date: Sun, 30 Oct 2022 11:47:55 +0100 Subject: [PATCH] Add AddWith() to pass options, allow controlling Windows buffer size (#521) This is similar to Add(), except that you can pass options. Ideally this should just be Add(), but that's not a compatible change, so we're stuck with this until we do a v2. There are quite a few enhancements that depend on *some* way to pass options; as an example I added WithBufferSize() to control the buffer size for (see #72) for the Windows backend, because that one is fairly trivial to implement: w, err := fsnotify.NewWatcher() err = w.AddWith("/path", fsnotify.WithBufferSize(65536*4)) Some other options we might want to add: err = w.AddWith("/path", fsnotify.WithEvents(fsnotify.Open | fsnotify.Close), // Filter events fsnotify.WithPoll(time.Second), // Use poll watcher fsnotify.WithFanotify(), // Prefer fanotify on Linux fsnotify.WithFollowLinks(true), // Control symlink follow behaviour fsnotify.WithDebounce(100*time.Milliseconds), // Automatically debounce duplicate events fsnotify.WithRetry(1*time.Second, 1*time.Minute), // Retry every second if the path disappears for a minute ) These are just some ideas, nothing fixed here yet. Some of these options are likely to change once I get around to actually working on it. This uses "functional options" so we can add more later. Options are passed to Add() rather than the Watcher itself, so the behaviour can be modified for every watch, rather than being global. This way you can do things like watch /nfs-drive with a poll backend, and use the regular OS backend for ~/dir, without having to create two watchers. This upgrades fairly nicely to v2 where we rename AddWith() to Add(): err = w.Add("/path", fsnotify.WithBufferSize(65536*4), fsnotify.WithEvents(fsnotify.Open | fsnotify.Close)) Folks will just have to s/fsnotify.AddWith/fsnotify.Add/, without having to change all the option names. Plus having a consistent prefix autocompletes nicely in editors. Fixes #72 --- backend_fen.go | 17 +++++++++++++-- backend_inotify.go | 19 ++++++++++++++--- backend_kqueue.go | 17 +++++++++++++-- backend_other.go | 15 ++++++++++++- backend_windows.go | 52 +++++++++++++++++++++++++++++++++------------- fsnotify.go | 30 ++++++++++++++++++++++++++ mkdoc.zsh | 16 +++++++++++++- 7 files changed, 142 insertions(+), 24 deletions(-) diff --git a/backend_fen.go b/backend_fen.go index 95fbe99a..1f4dcf77 100644 --- a/backend_fen.go +++ b/backend_fen.go @@ -105,7 +105,7 @@ type Watcher struct { // [ErrEventOverflow] is used to indicate there are too many events: // // - inotify: there are too many queued events (fs.inotify.max_queued_events sysctl) - // - windows: The buffer size is too small. + // - windows: The buffer size is too small; [WithBufferSize] can be used to increase it. // - kqueue, fen: not used. Errors chan error @@ -195,6 +195,8 @@ func (w *Watcher) Close() error { // // Returns [ErrClosed] if [Watcher.Close] was called. // +// See [AddWith] for a version that allows adding options. +// // # Watching directories // // All files in a directory are monitored, including new files that are created @@ -212,7 +214,16 @@ func (w *Watcher) Close() error { // // Instead, watch the parent directory and use Event.Name to filter out files // you're not interested in. There is an example of this in [cmd/fsnotify/file.go]. -func (w *Watcher) Add(name string) error { +func (w *Watcher) Add(name string) error { return w.AddWith(name) } + +// AddWith is like [Add], but allows adding options. When using Add() the +// defaults described below are used. +// +// Possible options are: +// +// - [WithBufferSize] sets the buffer size for the Windows backend; no-op on +// other platforms. The default is 64K (65536 bytes). +func (w *Watcher) AddWith(name string, opts ...addOpt) error { if w.isClosed() { return ErrClosed } @@ -220,6 +231,8 @@ func (w *Watcher) Add(name string) error { return nil } + _ = getOptions(opts...) + // Currently we resolve symlinks that were explicitly requested to be // watched. Otherwise we would use LStat here. stat, err := os.Stat(name) diff --git a/backend_inotify.go b/backend_inotify.go index a96c3adf..16ac36e1 100644 --- a/backend_inotify.go +++ b/backend_inotify.go @@ -108,7 +108,7 @@ type Watcher struct { // [ErrEventOverflow] is used to indicate there are too many events: // // - inotify: there are too many queued events (fs.inotify.max_queued_events sysctl) - // - windows: The buffer size is too small. + // - windows: The buffer size is too small; [WithBufferSize] can be used to increase it. // - kqueue, fen: not used. Errors chan error @@ -217,6 +217,8 @@ func (w *Watcher) Close() error { // // Returns [ErrClosed] if [Watcher.Close] was called. // +// See [AddWith] for a version that allows adding options. +// // # Watching directories // // All files in a directory are monitored, including new files that are created @@ -234,12 +236,23 @@ func (w *Watcher) Close() error { // // Instead, watch the parent directory and use Event.Name to filter out files // you're not interested in. There is an example of this in [cmd/fsnotify/file.go]. -func (w *Watcher) Add(name string) error { - name = filepath.Clean(name) +func (w *Watcher) Add(name string) error { return w.AddWith(name) } + +// AddWith is like [Add], but allows adding options. When using Add() the +// defaults described below are used. +// +// Possible options are: +// +// - [WithBufferSize] sets the buffer size for the Windows backend; no-op on +// other platforms. The default is 64K (65536 bytes). +func (w *Watcher) AddWith(name string, opts ...addOpt) error { if w.isClosed() { return ErrClosed } + name = filepath.Clean(name) + _ = getOptions(opts...) + var flags uint32 = unix.IN_MOVED_TO | unix.IN_MOVED_FROM | unix.IN_CREATE | unix.IN_ATTRIB | unix.IN_MODIFY | unix.IN_MOVE_SELF | unix.IN_DELETE | unix.IN_DELETE_SELF diff --git a/backend_kqueue.go b/backend_kqueue.go index cbe4778b..f9a0951f 100644 --- a/backend_kqueue.go +++ b/backend_kqueue.go @@ -106,7 +106,7 @@ type Watcher struct { // [ErrEventOverflow] is used to indicate there are too many events: // // - inotify: there are too many queued events (fs.inotify.max_queued_events sysctl) - // - windows: The buffer size is too small. + // - windows: The buffer size is too small; [WithBufferSize] can be used to increase it. // - kqueue, fen: not used. Errors chan error @@ -249,6 +249,8 @@ func (w *Watcher) Close() error { // // Returns [ErrClosed] if [Watcher.Close] was called. // +// See [AddWith] for a version that allows adding options. +// // # Watching directories // // All files in a directory are monitored, including new files that are created @@ -266,7 +268,18 @@ func (w *Watcher) Close() error { // // Instead, watch the parent directory and use Event.Name to filter out files // you're not interested in. There is an example of this in [cmd/fsnotify/file.go]. -func (w *Watcher) Add(name string) error { +func (w *Watcher) Add(name string) error { return w.AddWith(name) } + +// AddWith is like [Add], but allows adding options. When using Add() the +// defaults described below are used. +// +// Possible options are: +// +// - [WithBufferSize] sets the buffer size for the Windows backend; no-op on +// other platforms. The default is 64K (65536 bytes). +func (w *Watcher) AddWith(name string, opts ...addOpt) error { + _ = getOptions(opts...) + w.mu.Lock() w.userWatches[name] = struct{}{} w.mu.Unlock() diff --git a/backend_other.go b/backend_other.go index fc6bacae..60d57053 100644 --- a/backend_other.go +++ b/backend_other.go @@ -100,7 +100,7 @@ type Watcher struct { // [ErrEventOverflow] is used to indicate there are too many events: // // - inotify: there are too many queued events (fs.inotify.max_queued_events sysctl) - // - windows: The buffer size is too small. + // - windows: The buffer size is too small; [WithBufferSize] can be used to increase it. // - kqueue, fen: not used. Errors chan error } @@ -133,6 +133,8 @@ func (w *Watcher) WatchList() []string { return nil } // // Returns [ErrClosed] if [Watcher.Close] was called. // +// See [AddWith] for a version that allows adding options. +// // # Watching directories // // All files in a directory are monitored, including new files that are created @@ -152,6 +154,17 @@ func (w *Watcher) WatchList() []string { return nil } // you're not interested in. There is an example of this in [cmd/fsnotify/file.go]. func (w *Watcher) Add(name string) error { return nil } +// AddWith is like [Add], but allows adding options. When using Add() the +// defaults described below are used. +// +// Possible options are: +// +// - [WithBufferSize] sets the buffer size for the Windows backend; no-op on +// other platforms. The default is 64K (65536 bytes). +func (w *Watcher) AddWith(name string, opts ...addOpt) error { + return nil +} + // Remove stops monitoring the path for changes. // // Directories are always removed non-recursively. For example, if you added diff --git a/backend_windows.go b/backend_windows.go index ba5e9581..e99139e7 100644 --- a/backend_windows.go +++ b/backend_windows.go @@ -109,7 +109,7 @@ type Watcher struct { // [ErrEventOverflow] is used to indicate there are too many events: // // - inotify: there are too many queued events (fs.inotify.max_queued_events sysctl) - // - windows: The buffer size is too small. + // - windows: The buffer size is too small; [WithBufferSize] can be used to increase it. // - kqueue, fen: not used. Errors chan error @@ -204,6 +204,8 @@ func (w *Watcher) Close() error { // // Returns [ErrClosed] if [Watcher.Close] was called. // +// See [AddWith] for a version that allows adding options. +// // # Watching directories // // All files in a directory are monitored, including new files that are created @@ -221,16 +223,31 @@ func (w *Watcher) Close() error { // // Instead, watch the parent directory and use Event.Name to filter out files // you're not interested in. There is an example of this in [cmd/fsnotify/file.go]. -func (w *Watcher) Add(name string) error { +func (w *Watcher) Add(name string) error { return w.AddWith(name) } + +// AddWith is like [Add], but allows adding options. When using Add() the +// defaults described below are used. +// +// Possible options are: +// +// - [WithBufferSize] sets the buffer size for the Windows backend; no-op on +// other platforms. The default is 64K (65536 bytes). +func (w *Watcher) AddWith(name string, opts ...addOpt) error { if w.isClosed() { return ErrClosed } + with := getOptions(opts...) + if with.bufsize < 4096 { + return fmt.Errorf("fsnotify.WithBufferSize: buffer size cannot be smaller than 4096 bytes") + } + in := &input{ - op: opAddWatch, - path: filepath.Clean(name), - flags: sysFSALLEVENTS, - reply: make(chan error), + op: opAddWatch, + path: filepath.Clean(name), + flags: sysFSALLEVENTS, + reply: make(chan error), + bufsize: with.bufsize, } w.input <- in if err := w.wakeupReader(); err != nil { @@ -329,10 +346,11 @@ const ( ) type input struct { - op int - path string - flags uint32 - reply chan error + op int + path string + flags uint32 + bufsize int + reply chan error } type inode struct { @@ -348,7 +366,7 @@ type watch struct { mask uint64 // Directory itself is being watched with these notify flags names map[string]uint64 // Map of names being watched and their notify flags rename string // Remembers the old name while renaming a file - buf [65536]byte // 64K buffer + buf []byte // buffer, allocated later } type ( @@ -421,7 +439,7 @@ func (m watchMap) set(ino *inode, watch *watch) { } // Must run within the I/O thread. -func (w *Watcher) addWatch(pathname string, flags uint64) error { +func (w *Watcher) addWatch(pathname string, flags uint64, bufsize int) error { dir, err := w.getDir(pathname) if err != nil { return err @@ -444,6 +462,7 @@ func (w *Watcher) addWatch(pathname string, flags uint64) error { ino: ino, path: dir, names: make(map[string]uint64), + buf: make([]byte, bufsize), } w.mu.Lock() w.watches.set(ino, watchEntry) @@ -543,8 +562,11 @@ func (w *Watcher) startRead(watch *watch) error { return nil } - rdErr := windows.ReadDirectoryChanges(watch.ino.handle, &watch.buf[0], - uint32(unsafe.Sizeof(watch.buf)), false, mask, nil, &watch.ov, 0) + // We need to pass the array, rather than the slice. + hdr := (*reflect.SliceHeader)(unsafe.Pointer(&watch.buf)) + rdErr := windows.ReadDirectoryChanges(watch.ino.handle, + (*byte)(unsafe.Pointer(hdr.Data)), uint32(hdr.Len), + false, mask, nil, &watch.ov, 0) if rdErr != nil { err := os.NewSyscallError("ReadDirectoryChanges", rdErr) if rdErr == windows.ERROR_ACCESS_DENIED && watch.mask&provisional == 0 { @@ -603,7 +625,7 @@ func (w *Watcher) readEvents() { case in := <-w.input: switch in.op { case opAddWatch: - in.reply <- w.addWatch(in.path, uint64(in.flags)) + in.reply <- w.addWatch(in.path, uint64(in.flags), in.bufsize) case opRemoveWatch: in.reply <- w.remWatch(in.path) } diff --git a/fsnotify.go b/fsnotify.go index 4f7f445f..142169da 100644 --- a/fsnotify.go +++ b/fsnotify.go @@ -101,3 +101,33 @@ func (e Event) Has(op Op) bool { return e.Op.Has(op) } func (e Event) String() string { return fmt.Sprintf("%-13s %q", e.Op.String(), e.Name) } + +type ( + addOpt func(opt *withOpts) + withOpts struct { + bufsize int + } +) + +var defaultOpts = withOpts{ + bufsize: 65536, // 64K +} + +func getOptions(opts ...addOpt) withOpts { + with := defaultOpts + for _, o := range opts { + o(&with) + } + return with +} + +// WithBufferSize sets the buffer size for the Windows backend. This is a no-op +// for other backends. +// +// The default value is 64K (65536 bytes) which is the highest value that works +// on all filesystems and should be enough for most applications, but if you +// have a large burst of events it may not be enough. You can increase it if +// you're hitting "queue or buffer overflow" errors ([ErrEventOverflow]). +func WithBufferSize(bytes int) addOpt { + return func(opt *withOpts) { opt.bufsize = bytes } +} diff --git a/mkdoc.zsh b/mkdoc.zsh index 19aa1edf..02216e74 100755 --- a/mkdoc.zsh +++ b/mkdoc.zsh @@ -80,6 +80,8 @@ add=$(<