Struct FileWatcher 

pub struct FileWatcher { /* private fields */ }

Watches a set of files and resolves whenever something changes in their directories.

Reacting to the filesystem (rather than a SIGHUP/SIGUSR1) is what lets cert-manager, Kubernetes secret mounts, and mv-into-place rotate files with no extra signalling: they rewrite the file and the watcher fires.

Watches each file’s parent directory, not the file itself. Editors, cert-manager, and K8s secret mounts replace files by atomic rename or symlink swap, which changes the inode (and, for the K8s ..data symlink, fires on the directory without ever naming the file), so a watch set directly on the path would be missed.

Implementations

impl FileWatcher

pub fn new(paths: &[PathBuf]) -> Result<Self>

Start watching the parent directories of paths. Errors if the OS watcher can’t be created or a directory can’t be watched (e.g. the inotify instance/watch limit is hit). notify already falls back to a built-in poll watcher on platforms without a native backend, so there’s no manual polling here.

pub async fn changed(&mut self)

Resolve once the OS reports activity in a watched directory. The caller reloads on return; reloads are idempotent, so the coarse “something changed” granularity at worst costs an occasional redundant reload.