Added walk::walk_directory() impl

Fortune for enumerate-ordered's current commit: Future blessing − 末吉

src/walk.rs

@@ -16,6 +16,7 @@ use tokio::{
 use futures::future::{
     Future,
     OptionFuture,
+    BoxFuture,
 };
 
 #[derive(Debug, Clone, PartialEq, Eq, Hash, PartialOrd, Ord, Default)]
@@ -27,18 +28,19 @@ pub struct Config
     pub max_walkers: Option<NonZeroUsize>,
 }
 
-#[derive(Debug, Clone, PartialEq, Eq, Hash, PartialOrd, Ord)]
+#[derive(Debug, Clone)]
 struct UniqueState
 {
     // Decrease with each new depth until 0 is hit then do not proceed.
     recursion_depth: Option<usize>,
+    output_sender: mpsc::Sender<work::FileInfo>,
 }
 
 #[derive(Debug)]
 struct SharedState
 {
+    worker_config: Arc<work::Config>,
     config: Config,
-    output_sender: mpsc::Sender<work::FileInfo>,
     new_worker_semaphore: Option<Semaphore>,
 }
 
@@ -50,15 +52,79 @@ struct State {
     current: UniqueState,
 }
 
+impl State
+{
+    #[inline] 
+    pub fn create_file_info_generator(&self) -> impl Fn(PathBuf, std::fs::Metadata) -> work::FileInfo + '_
+    {
+	work::FileInfo::factory(Arc::clone(&self.shared.worker_config)) //XXX: ANOTHER unneeded Arc clone..
+    }
+    #[inline(always)] 
+    pub fn shared(&self) -> &SharedState
+    {
+	&self.shared
+    }
+    #[inline(always)] 
+    pub fn unique(&self) -> &UniqueState
+    {
+	&self.current
+    }
+    
+    #[inline(always)] 
+    pub fn unique_mut(&mut self) -> &mut UniqueState
+    {
+	&mut self.current
+    }
+
+    /// Create a `State` for a recursed child walk. 
+    #[inline] 
+    pub fn create_child(&self) -> Option<Self>
+    {
+	let recursion_depth = match self.current.recursion_depth.map(|depth| depth.saturating_sub(1)) {
+	    // Prevent child creation if recursion bound hits 0.
+	    Some(0) => return None,
+	    x => x,
+	};
+	Some(Self {
+	    shared: Arc::clone(&self.shared),
+	    current: UniqueState { recursion_depth, output_sender: self.current.output_sender.clone() },
+	})
+    }
+}
+
 /// Walk a single directory in the current task. Dispatch async results to `walk
-async fn walk_directory(state: &State, whence: impl AsRef<Path>) -> eyre::Result<usize>
+async fn walk_directory<F>(state: &State, mut push_child: F, whence: impl AsRef<Path>) -> eyre::Result<usize>
+    where F: FnMut(State, PathBuf)
 {
+    //use futures::future::FutureExt;
+    let mut read = tokio::fs::read_dir(whence).await.wrap_err("Failed to read-dir")?;
+    let sender = &state.current.output_sender;
+    let file_info = state.create_file_info_generator();
+    while let Some(fso) = read.next_entry().await.wrap_err("Failed to enumerate directory entry")?
+    {
+	let metadata = match fso.metadata().await {
+	    Ok(metadata) => metadata,
+	    Err(e) => {
+		error!("Failed to stat {:?}: {}", fso.file_name(), e);
+		continue;
+	    }
+	};
+	if metadata.is_file() {
+	    if let Err(_) = sender.send(file_info(fso.path(), metadata)).await {
+		warn!("Worker shut down, stopping iteration");
+		break;
+	    }
+	} else if metadata.is_dir() {
+	    let Some(state) = state.create_child() else { continue };
+	    push_child(state, fso.path());
+	} // Ignore symlinks.
+    }
     todo!("Walk to directory and output its files into `state`'s tx XXX: Does this function need to exist? We could just do this in walk_inner() directly: Explicit boxing doesn't need to be done as we're working with joinhandles and backing tasks")
 }
 
 /// This function is called recursively for each subdirectory in `whence` pertaining to the recursion rules.
 /// The function should await all its spawned children *after* finishing its own work on files, **and** dropping its semaphore `_permit`. Otherwise deadlock could occour easily.
-async fn walk_inner(state: State, whence: PathBuf) -> impl Future<Output = eyre::Result<usize>> + 'static
+async fn walk_inner(state: State, whence: PathBuf) -> impl Future<Output = eyre::Result<usize>> + Send + Sync + 'static
 {
     // Acquire permit *before* spawning.
     let _permit = {
@@ -85,6 +151,9 @@ async fn walk_inner(state: State, whence: PathBuf) -> impl Future<Output = eyre:
 	    // `JoinHandle<eyre::Result<size>>`s to recursion children
 	    // XXX: Maybe use mpsc for this instead: We send the JoinHandle's to a rx being looped on in a `join!` in the outer `async move {}` scope at the same time as this one. When the sender is dropped, the channel will close. We can join each child of the stream concurrently with `futures` (probably?) and bubble up panics when they are found.
 	    let mut children = Vec::new();
+	    let todo_res = walk_directory(&state, |state, whence| {
+		children.push(async move { walk_inner(state, whence).await }.boxed());
+	    }, &whence).await;
 	    
 	    todo!("counted += walk_directory(&state, &whence).await, etc...");
 	    Ok((counted, children))
@@ -100,17 +169,18 @@ async fn walk_inner(state: State, whence: PathBuf) -> impl Future<Output = eyre:
 }
 
 #[inline] 
-pub fn start_walk(cfg: Config, whence: impl AsRef<Path>, whereto: mpsc::Sender<work::FileInfo>) -> impl Future<Output = eyre::Result<usize>> + 'static
+pub fn start_walk(cfg: Config, worker: Arc<work::Config>, whence: impl AsRef<Path>, whereto: mpsc::Sender<work::FileInfo>) -> impl Future<Output = eyre::Result<usize>> + 'static
 {
     use futures::prelude::*;
     walk_inner(State {
 	current: UniqueState {
 	    recursion_depth: cfg.recursion_depth,
+	    output_sender: whereto,
 	},
 	shared: Arc::new(SharedState {
-	    output_sender: whereto,
 	    new_worker_semaphore: cfg.max_walkers.as_ref().map(|max| Semaphore::new(max.get())),
-	    config: cfg
+	    config: cfg,
+	    worker_config: worker,
 	}),
     }, whence.as_ref().to_owned())
 	.flatten()