notify_win/

lib.rs

//! Windows file system notification library
//!
//! Fork of [notify](https://github.com/notify-rs/notify)
//!
//! # Installation
//!
//! ```toml
//! [dependencies]
//! notify-win = "0.1.0"
//! ```
//!
//! ## Features
//!
//! List of compilation features, see below for details
//!
//! - `serde` for serialization of events
//! - `serialization-compat-6` restores the serialization behavior of notify 6, off by default
//!
//! ### Serde
//!
//! Events are serializable via [serde](https://serde.rs) if the `serde` feature is enabled:
//!
//! ```toml
//! notify-win = { version = "0.1.0", features = ["serde"] }
//! ```
//!
//! # Known Problems
//!
//! ### Network filesystems
//!
//! Network mounted filesystems like NFS may not emit any events for notify to listen to.
//! This applies especially to WSL programs watching windows paths.
//!
//! A workaround is the [`PollWatcher`] backend.
//!
//! ### Editor Behaviour
//!
//! If you rely on precise events (Write/Delete/Create..), you will notice that the actual events
//! can differ a lot between file editors. Some truncate the file on save, some create a new one and replace the old one.
//!
//! ### Parent folder deletion
//!
//! If you want to receive an event for a deletion of folder `b` for the path `/a/b/..`, you will have to watch its parent `/a`.
//!
//! ### Pseudo Filesystems like /proc, /sys
//!
//! Some filesystems like `/proc` and `/sys` on *nix do not emit change events or use correct file change dates.
//! To circumvent that problem you can use the [`PollWatcher`] with the `compare_contents` option.
//!
//! Note that the [`PollWatcher`] is not restricted by this limitation, so it may be an alternative if your users can't increase the limit.
//!
//! ### Watching large directories
//!
//! When watching a very large amount of files, notify may fail to receive all events.
//!
//! ```rust
//! use notify_win::{Event, RecursiveMode, Result, Watcher};
//! use std::sync::mpsc;
//!
//! fn main() -> Result<()> {
//!     let (tx, rx) = mpsc::channel::<Result<Event>>();
//!
//!     // Use recommended_watcher() to automatically select the best implementation
//!     // for your platform. The `EventHandler` passed to this constructor can be a
//!     // closure, a `std::sync::mpsc::Sender`, a `crossbeam_channel::Sender`, or
//!     // another type the trait is implemented for.
//!     let mut watcher = notify_win::recommended_watcher(tx)?;
//!
//!     // Add a path to be watched. All files and directories at that path and
//!     // below will be monitored for changes.
//! #     { // "." doesn't exist on BSD for some reason in CI
//!     watcher.watch(Path::new("."), RecursiveMode::Recursive)?;
//! #     }
//! #     #[cfg(any())]
//! #     { // don't run this in doctests, it blocks forever
//!     // Block forever, printing out events as they come in
//!     for res in rx {
//!         match res {
//!             Ok(event) => println!("event: {:?}", event),
//!             Err(e) => println!("watch error: {:?}", e),
//!         }
//!     }
//! #     }
//!
//!     Ok(())
//! }
//! ```
//!
//! ## With different configurations
//!
//! It is possible to create several watchers with different configurations or implementations that
//! all call the same event function. This can accommodate advanced behaviour or work around limits.
//!
//! ```rust
//! # use notify_win::{RecursiveMode, Result, Watcher};
//! # use std::path::Path;
//! #
//! # fn main() -> Result<()> {
//!       fn event_fn(res: Result<notify_win::Event>) {
//!           match res {
//!              Ok(event) => println!("event: {:?}", event),
//!              Err(e) => println!("watch error: {:?}", e),
//!           }
//!       }
//!
//!       let mut watcher1 = notify_win::recommended_watcher(event_fn)?;
//!       // we will just use the same watcher kind again here
//!       let mut watcher2 = notify_win::recommended_watcher(event_fn)?;
//! #     { // "." doesn't exist on BSD for some reason in CI
//! #     watcher1.watch(Path::new("."), RecursiveMode::Recursive)?;
//! #     watcher2.watch(Path::new("."), RecursiveMode::Recursive)?;
//! #     }
//!       // dropping the watcher1/2 here (no loop etc) will end the program
//! #
//! #     Ok(())
//! # }
//! ```

#![deny(missing_docs)]

pub use config::{Config, RecursiveMode};
pub use error::{Error, ErrorKind, Result};
pub use notify_win_types::event::{self, Event, EventKind};
use std::path::Path;

pub(crate) type Receiver<T> = std::sync::mpsc::Receiver<T>;
pub(crate) type Sender<T> = std::sync::mpsc::Sender<T>;
pub(crate) type BoundSender<T> = std::sync::mpsc::SyncSender<T>;

mod config;
mod error;

pub mod null;
pub mod poll;
pub mod windows;

#[inline]
pub(crate) fn unbounded<T>() -> (Sender<T>, Receiver<T>) {
    std::sync::mpsc::channel()
}

#[inline]
pub(crate) fn bounded<T>(cap: usize) -> (BoundSender<T>, Receiver<T>) {
    std::sync::mpsc::sync_channel(cap)
}

pub use null::NullWatcher;
pub use poll::PollWatcher;
pub use windows::ReadDirectoryChangesWatcher;

/// The set of requirements for watcher event handling functions.
///
/// # Example implementation
///
/// ```no_run
/// use notify_win::{Event, Result, EventHandler};
///
/// /// Prints received events
/// struct EventPrinter;
///
/// impl EventHandler for EventPrinter {
///     fn handle_event(&mut self, event: Result<Event>) {
///         if let Ok(event) = event {
///             println!("Event: {:?}", event);
///         }
///     }
/// }
/// ```
pub trait EventHandler: Send + 'static {
    /// Handles an event.
    fn handle_event(&mut self, event: Result<Event>);
}

impl<F> EventHandler for F
where
    F: FnMut(Result<Event>) + Send + 'static,
{
    fn handle_event(&mut self, event: Result<Event>) {
        (self)(event);
    }
}

#[cfg(feature = "crossbeam-channel")]
impl EventHandler for crossbeam_channel::Sender<Result<Event>> {
    fn handle_event(&mut self, event: Result<Event>) {
        let _ = self.send(event);
    }
}

impl EventHandler for std::sync::mpsc::Sender<Result<Event>> {
    fn handle_event(&mut self, event: Result<Event>) {
        let _ = self.send(event);
    }
}

/// Watcher kind enumeration
#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
#[non_exhaustive]
pub enum WatcherKind {
    /// Polling based backend (fallback)
    PollWatcher,
    /// Windows backend
    ReadDirectoryChangesWatcher,
    /// Fake watcher for testing
    NullWatcher,
}

/// Type that can deliver file activity notifications
///
/// `Watcher` is implemented per platform using the best implementation available on that platform.
/// In addition to such event driven implementations, a polling implementation is also provided
/// that should work on any platform.
pub trait Watcher {
    /// Create a new watcher with an initial Config.
    fn new<F: EventHandler>(event_handler: F, config: config::Config) -> Result<Self>
    where
        Self: Sized;
    /// Begin watching a new path.
    ///
    /// If the `path` is a directory, `recursive_mode` will be evaluated. If `recursive_mode` is
    /// `RecursiveMode::Recursive` events will be delivered for all files in that tree. Otherwise
    /// only the directory and its immediate children will be watched.
    ///
    /// If the `path` is a file, `recursive_mode` will be ignored and events will be delivered only
    /// for the file.
    ///
    /// On some platforms, if the `path` is renamed or removed while being watched, behaviour may
    /// be unexpected. See discussions in [#165] and [#166]. If less surprising behaviour is wanted
    /// one may non-recursively watch the _parent_ directory as well and manage related events.
    fn watch(&mut self, path: &Path, recursive_mode: RecursiveMode) -> Result<()>;

    /// Stop watching a path.
    ///
    /// # Errors
    ///
    /// Returns an error in the case that `path` has not been watched or if removing the watch
    /// fails.
    fn unwatch(&mut self, path: &Path) -> Result<()>;

    /// Configure the watcher at runtime.
    ///
    /// See the [`Config`](config/struct.Config.html) struct for all configuration options.
    ///
    /// # Returns
    ///
    /// - `Ok(true)` on success.
    /// - `Ok(false)` if the watcher does not support or implement the option.
    /// - `Err(notify_win::Error)` on failure.
    fn configure(&mut self, _option: Config) -> Result<bool> {
        Ok(false)
    }

    /// Returns the watcher kind, allowing to perform backend-specific tasks
    fn kind() -> WatcherKind
    where
        Self: Sized;
}

/// The recommended [`Watcher`] implementation for the current platform
pub type RecommendedWatcher = ReadDirectoryChangesWatcher;

/// Convenience method for creating the [`RecommendedWatcher`] for the current platform.
pub fn recommended_watcher<F>(event_handler: F) -> Result<RecommendedWatcher>
where
    F: EventHandler,
{
    // All recommended watchers currently implement `new`, so just call that.
    RecommendedWatcher::new(event_handler, Config::default())
}

#[cfg(test)]
mod tests {
    use std::{fs, time::Duration};

    use tempfile::tempdir;

    use super::*;

    #[test]
    fn test_object_safe() {
        let _watcher: &dyn Watcher = &NullWatcher;
    }

    #[test]
    fn test_debug_impl() {
        macro_rules! assert_debug_impl {
            ($t:ty) => {{
                trait NeedsDebug: std::fmt::Debug {}
                impl NeedsDebug for $t {}
            }};
        }

        assert_debug_impl!(Config);
        assert_debug_impl!(Error);
        assert_debug_impl!(ErrorKind);
        assert_debug_impl!(NullWatcher);
        assert_debug_impl!(PollWatcher);
        assert_debug_impl!(RecommendedWatcher);
        assert_debug_impl!(RecursiveMode);
        assert_debug_impl!(WatcherKind);
    }

    #[test]
    fn integration() -> std::result::Result<(), Box<dyn std::error::Error>> {
        let dir = tempdir()?;

        let (tx, rx) = std::sync::mpsc::channel();

        let mut watcher = RecommendedWatcher::new(tx, Config::default())?;

        watcher.watch(dir.path(), RecursiveMode::Recursive)?;

        let file_path = dir.path().join("file.txt");
        fs::write(&file_path, b"Lorem ipsum")?;

        let event = rx
            .recv_timeout(Duration::from_secs(10))
            .expect("no events received")
            .expect("received an error");

        assert_eq!(event.paths, vec![file_path]);

        Ok(())
    }
}