diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml index 90638be8..9728c7f5 100644 --- a/.github/workflows/build.yml +++ b/.github/workflows/build.yml @@ -26,9 +26,9 @@ jobs: export GOOS=${a%%/*} export GOARCH=${a#*/} - go test -c # Building for Android or iOS requires cgo if [ "$GOOS" != 'android' ] && [ "$GOOS" != 'ios' ]; then + go test -c go build ./cmd/fsnotify fi done diff --git a/.gitignore b/.gitignore index 1d89d85c..391cc076 100644 --- a/.gitignore +++ b/.gitignore @@ -4,3 +4,4 @@ # Output of go build ./cmd/fsnotify /fsnotify +/fsnotify.exe diff --git a/backend_other.go b/backend_other.go index e2b21427..bec67c52 100644 --- a/backend_other.go +++ b/backend_other.go @@ -8,8 +8,111 @@ import ( "runtime" ) -// Watcher watches a set of files, delivering events to a channel. -type Watcher struct{} +// Watcher watches a set of paths, delivering events on a channel. +// +// A watcher should not be copied (e.g. pass it by pointer, rather than by +// value). +// +// # Linux notes +// +// When a file is removed a Remove event won't be emitted until all file +// descriptors are closed, and deletes will always emit a Chmod. For example: +// +// fp := os.Open("file") +// os.Remove("file") // Triggers Chmod +// fp.Close() // Triggers Remove +// +// This is the event that inotify sends, so not much can be changed about this. +// +// The fs.inotify.max_user_watches sysctl variable specifies the upper limit +// for the number of watches per user, and fs.inotify.max_user_instances +// specifies the maximum number of inotify instances per user. Every Watcher you +// create is an "instance", and every path you add is a "watch". +// +// These are also exposed in /proc as /proc/sys/fs/inotify/max_user_watches and +// /proc/sys/fs/inotify/max_user_instances +// +// To increase them you can use sysctl or write the value to the /proc file: +// +// # Default values on Linux 5.18 +// sysctl fs.inotify.max_user_watches=124983 +// sysctl fs.inotify.max_user_instances=128 +// +// To make the changes persist on reboot edit /etc/sysctl.conf or +// /usr/lib/sysctl.d/50-default.conf (details differ per Linux distro; check +// your distro's documentation): +// +// fs.inotify.max_user_watches=124983 +// fs.inotify.max_user_instances=128 +// +// Reaching the limit will result in a "no space left on device" or "too many open +// files" error. +// +// # kqueue notes (macOS, BSD) +// +// kqueue requires opening a file descriptor for every file that's being watched; +// so if you're watching a directory with five files then that's six file +// descriptors. You will run in to your system's "max open files" limit faster on +// these platforms. +// +// The sysctl variables kern.maxfiles and kern.maxfilesperproc can be used to +// control the maximum number of open files, as well as /etc/login.conf on BSD +// systems. +// +// # macOS notes +// +// Spotlight indexing on macOS can result in multiple events (see [#15]). A +// temporary workaround is to add your folder(s) to the "Spotlight Privacy +// Settings" until we have a native FSEvents implementation (see [#11]). +// +// [#11]: https://github.com/fsnotify/fsnotify/issues/11 +// [#15]: https://github.com/fsnotify/fsnotify/issues/15 +type Watcher struct { + // Events sends the filesystem change events. + // + // fsnotify can send the following events; a "path" here can refer to a + // file, directory, symbolic link, or special file like a FIFO. + // + // fsnotify.Create A new path was created; this may be followed by one + // or more Write events if data also gets written to a + // file. + // + // fsnotify.Remove A path was removed. + // + // fsnotify.Rename A path was renamed. A rename is always sent with the + // old path as Event.Name, and a Create event will be + // sent with the new name. Renames are only sent for + // paths that are currently watched; e.g. moving an + // unmonitored file into a monitored directory will + // show up as just a Create. Similarly, renaming a file + // to outside a monitored directory will show up as + // only a Rename. + // + // fsnotify.Write A file or named pipe was written to. A Truncate will + // also trigger a Write. A single "write action" + // initiated by the user may show up as one or multiple + // writes, depending on when the system syncs things to + // disk. For example when compiling a large Go program + // you may get hundreds of Write events, so you + // probably want to wait until you've stopped receiving + // them (see the dedup example in cmd/fsnotify). + // + // fsnotify.Chmod Attributes were changed. On Linux this is also sent + // when a file is removed (or more accurately, when a + // link to an inode is removed). On kqueue it's sent + // and on kqueue when a file is truncated. On Windows + // it's never sent. + Events chan Event + + // Errors sends any errors. + // + // [ErrEventOverflow] is used to indicate ther are too many events: + // + // - inotify: there are too many queued events (fs.inotify.max_queued_events sysctl) + // - windows: The buffer size is too small. + // - kqueue, fen: not used. + Errors chan error +} // NewWatcher creates a new Watcher. func NewWatcher() (*Watcher, error) {