Setup daemon tracking.

Track original path before resolution for later git copying and
messaging.

src/cli.rs

@@ -10,7 +10,7 @@ use std::io::Write;
 pub fn write_config(mut pending: PathConfig) -> config::Result<()> {
     println!(
         "Generating config at {}...\n",
-        Success.paint(pending.0.display().to_string())
+        Success.paint(pending.0.unresolved().display().to_string())
     );
 
     print!(
@@ -45,9 +45,9 @@ pub fn write_config(mut pending: PathConfig) -> config::Result<()> {
 pub fn list_packages(config: PathConfig) {
     println!(
         "Listing packages in {}...\n",
-        Success.paint(config.0.display().to_string())
+        Success.paint(config.0.unresolved().display().to_string())
     );
-    // TODO(jrpotter): Alphabetize the output list.
+    // Alphabetical ordered ensured by B-tree implementation.
     for (k, _) in config.1.packages {
         println!("• {}", k);
     }

src/config.rs

@@ -1,7 +1,6 @@
-use super::path;
-use super::path::{NormalPathBuf, Normalize};
+use super::path::ResPathBuf;
 use serde_derive::{Deserialize, Serialize};
-use std::collections::HashMap;
+use std::collections::BTreeMap;
 use std::io::Write;
 use std::path::PathBuf;
 use std::{error, fmt, fs, io};
@@ -61,7 +60,7 @@ pub struct Package {
 #[derive(Debug, Deserialize, Serialize)]
 pub struct Config {
     pub remote: Remote,
-    pub packages: HashMap<String, Package>,
+    pub packages: BTreeMap<String, Package>,
 }
 
 impl Config {
@@ -71,10 +70,10 @@ impl Config {
 }
 
 #[derive(Debug)]
-pub struct PathConfig(pub NormalPathBuf, pub Config);
+pub struct PathConfig(pub ResPathBuf, pub Config);
 
 impl PathConfig {
-    pub fn new(path: &NormalPathBuf, config: Option<Config>) -> Self {
+    pub fn new(path: &ResPathBuf, config: Option<Config>) -> Self {
         PathConfig(
             path.clone(),
             config.unwrap_or(Config {
@@ -82,7 +81,7 @@ impl PathConfig {
                     owner: "example-user".to_owned(),
                     name: "home-config".to_owned(),
                 },
-                packages: HashMap::new(),
+                packages: BTreeMap::new(),
             }),
         )
     }
@@ -111,7 +110,7 @@ pub fn default_paths() -> Vec<PathBuf> {
     DEFAULT_PATHS.iter().map(|s| PathBuf::from(s)).collect()
 }
 
-pub fn load(candidates: &Vec<NormalPathBuf>) -> Result<PathConfig> {
+pub fn load(candidates: &Vec<ResPathBuf>) -> Result<PathConfig> {
     // When trying our paths, the only acceptable error is a `NotFound` file.
     // Anything else should be surfaced to the end user.
     for candidate in candidates {
@@ -126,3 +125,9 @@ pub fn load(candidates: &Vec<NormalPathBuf>) -> Result<PathConfig> {
     }
     Err(Error::MissingConfig)
 }
+
+pub fn reload(config: &PathConfig) -> Result<PathConfig> {
+    // TODO(jrpotter): Let's add a proper logging solution.
+    println!("Configuration reloaded.");
+    load(&vec![config.0.clone()])
+}

src/daemon.rs

@@ -1,99 +1,210 @@
 use super::config;
 use super::config::PathConfig;
 use super::path;
-use super::path::{NormalPathBuf, Normalize};
-use notify::{RecommendedWatcher, Watcher};
+use super::path::ResPathBuf;
+use notify::{DebouncedEvent, RecommendedWatcher, RecursiveMode, Watcher};
 use std::collections::HashSet;
+use std::error::Error;
 use std::path::PathBuf;
 use std::sync::mpsc::channel;
+use std::sync::mpsc::{Receiver, Sender, TryRecvError};
+use std::thread;
 use std::time::Duration;
 
 // TODO(jrpotter): Add logging.
 // TODO(jrpotter): Add pid file to only allow one daemon at a time.
 
+// Used for both polling and debouncing file system events.
+const WATCH_FREQUENCY: Duration = Duration::from_secs(5);
+
 // ========================================
-// State
+// Polling
 // ========================================
 
-struct WatchState {
-    // Paths that we were not able to watch properly but could potentially do so
-    // in the future. These include paths that did not exist at the time of
-    // canonicalization or did not have environment variables defined that may
-    // be defined later on.
-    pending: HashSet<PathBuf>,
-    // Paths that we are currently watching.
-    watching: HashSet<NormalPathBuf>,
-    // Paths that are not valid and will never become valid. These may include
-    // paths that include prefixes or refer to directories that could never be
-    // reached (e.g. parent of root).
-    invalid: HashSet<PathBuf>,
+enum PollEvent {
+    Pending(PathBuf),
+    Clear,
 }
 
-impl WatchState {
-    pub fn new(config: &PathConfig) -> notify::Result<Self> {
-        let mut pending: HashSet<PathBuf> = HashSet::new();
-        let mut watching: HashSet<NormalPathBuf> = HashSet::new();
-        watching.insert(config.0.clone());
-        // We try and resolve our configuration again here. We want to
-        // specifically track any new configs that may pop up with higher
-        // priority.
-        for path in config::default_paths() {
-            match path::normalize(&path)? {
-                // TODO(jrpotter): Check if the path can be canonicalized.
-                Normalize::Done(p) => watching.insert(p),
-                Normalize::Pending => pending.insert(path),
-            };
+fn resolve_pending(tx: &Sender<DebouncedEvent>, pending: &HashSet<PathBuf>) -> Vec<PathBuf> {
+    let mut to_remove = vec![];
+    for path in pending {
+        match path::resolve(&path) {
+            Ok(Some(resolved)) => {
+                to_remove.push(path.clone());
+                tx.send(DebouncedEvent::Create(resolved.into()))
+                    .expect("File watcher channel closed.");
+            }
+            Ok(None) => (),
+            Err(e) => {
+                to_remove.push(path.clone());
+                eprintln!(
+                    "Encountered unexpected error {} when processing path {}",
+                    e,
+                    path.display()
+                )
+            }
         }
+    }
+    to_remove
+}
+
+fn poll_pending(tx: Sender<DebouncedEvent>, rx: Receiver<PollEvent>) {
+    let mut pending = HashSet::new();
+    loop {
+        match rx.try_recv() {
+            Ok(PollEvent::Pending(path)) => {
+                pending.insert(path);
+            }
+            Ok(PollEvent::Clear) => pending.clear(),
+            Err(TryRecvError::Empty) => {
+                resolve_pending(&tx, &pending).iter().for_each(|r| {
+                    pending.remove(r);
+                });
+                thread::sleep(WATCH_FREQUENCY);
+            }
+            Err(TryRecvError::Disconnected) => panic!("Polling channel closed."),
+        }
+    }
+}
+
+// ========================================
+// File Watcher
+// ========================================
+
+struct WatchState<'a> {
+    poll_tx: Sender<PollEvent>,
+    watcher: &'a mut RecommendedWatcher,
+    watching: HashSet<ResPathBuf>,
+}
+
+impl<'a> WatchState<'a> {
+    pub fn new(
+        poll_tx: Sender<PollEvent>,
+        watcher: &'a mut RecommendedWatcher,
+    ) -> notify::Result<Self> {
         Ok(WatchState {
-            pending,
-            watching,
-            invalid: HashSet::new(),
+            poll_tx,
+            watcher,
+            watching: HashSet::new(),
         })
     }
+
+    fn send_poll(&self, event: PollEvent) {
+        self.poll_tx.send(event).expect("Polling channel closed.");
+    }
+
+    fn watch(&mut self, path: ResPathBuf) {
+        match self.watcher.watch(&path, RecursiveMode::NonRecursive) {
+            Ok(()) => {
+                self.watching.insert(path);
+            }
+            Err(e) => {
+                eprintln!(
+                    "Encountered unexpected error {} when watching path {}",
+                    e,
+                    path.unresolved().display()
+                );
+            }
+        }
+    }
+
+    /// Reads in the new path config, updating all watched and pending files
+    /// according to the packages in the specified config.
+    pub fn update(&mut self, config: &PathConfig) {
+        self.send_poll(PollEvent::Clear);
+        for path in &self.watching {
+            match self.watcher.unwatch(&path) {
+                Ok(()) => (),
+                Err(e) => {
+                    eprintln!(
+                        "Encountered unexpected error {} when unwatching path {}",
+                        e,
+                        path.unresolved().display()
+                    );
+                }
+            }
+        }
+        self.watching.clear();
+        for (_, package) in &config.1.packages {
+            for path in &package.configs {
+                match path::resolve(&path) {
+                    Ok(None) => self.send_poll(PollEvent::Pending(path.clone())),
+                    Ok(Some(n)) => self.watch(n),
+                    Err(_) => (),
+                }
+            }
+        }
+    }
 }
 
 // ========================================
 // Daemon
 // ========================================
 
-fn reload_config(config: &PathConfig) -> notify::Result<WatchState> {
-    let state = WatchState::new(config)?;
-    Ok(state)
-}
-
-pub fn launch(config: PathConfig) -> notify::Result<()> {
-    let (tx, rx) = channel();
-    // Create a "debounced" watcher. Events will not trigger until after the
-    // specified duration has passed with no additional changes.
-    let mut watcher: RecommendedWatcher = Watcher::new(tx, Duration::from_secs(2))?;
-    // for (_, package) in &config.1.packages {
-    //     for path in &package.configs {
-    //         match normalize_path(&path) {
-    //             // `notify-rs` is not able to handle files that do not exist and
-    //             // are then created. This is handled internally by the library
-    //             // via the `fs::canonicalize` which fails on missing paths. So
-    //             // track which paths end up missing and apply polling on them.
-    //             Ok(normalized) => match watcher.watch(&normalized, RecursiveMode::NonRecursive) {
-    //                 Ok(_) => {
-    //                     tracked_paths.insert(normalized);
-    //                 }
-    //                 Err(notify::Error::PathNotFound) => {
-    //                     missing_paths.insert(normalized);
-    //                 }
-    //                 Err(e) => return Err(e),
-    //             },
-    //             // TODO(jrpotter): Retry even in cases where environment
-    //             // variables are not defined.
-    //             Err(e) => eprintln!("{}", e),
-    //         };
-    //     }
-    // }
-    // This is a simple loop, but you may want to use more complex logic here,
-    // for example to handle I/O.
+pub fn launch(mut config: PathConfig) -> Result<(), Box<dyn Error>> {
+    let (poll_tx, poll_rx) = channel();
+    let (watch_tx, watch_rx) = channel();
+    let watch_tx1 = watch_tx.clone();
+    // `notify-rs` internally uses `fs::canonicalize` on each path we try to
+    // watch, but this fails if no file exists at the given path. In these
+    // cases, we rely on a basic polling strategy to check if the files ever
+    // come into existence.
+    thread::spawn(move || poll_pending(watch_tx, poll_rx));
+    // Track our original config file separately from the other files that may
+    // be defined in the config. We want to make sure we're always alerted on
+    // changes to it for hot reloading purposes, and not worry that our wrapper
+    // will ever clear it from its watch state.
+    let mut watcher: RecommendedWatcher = Watcher::new(watch_tx1, WATCH_FREQUENCY)?;
+    watcher.watch(&config.0, RecursiveMode::NonRecursive)?;
+    let mut state = WatchState::new(poll_tx, &mut watcher)?;
+    state.update(&config);
     loop {
-        match rx.recv() {
-            Ok(event) => println!("{:?}", event),
-            Err(e) => println!("watch error: {:?}", e),
+        // Received paths should always be the fully resolved ones so safe to
+        // compare against our current config path.
+        match watch_rx.recv() {
+            Ok(DebouncedEvent::NoticeWrite(_)) => {
+                // Intentionally ignore in favor of stronger signals.
+            }
+            Ok(DebouncedEvent::NoticeRemove(_)) => {
+                // Intentionally ignore in favor of stronger signals.
+            }
+            Ok(DebouncedEvent::Create(p)) => {
+                if config.0 == p {
+                    config = config::reload(&config)?;
+                    state.update(&config);
+                }
+                println!("Create {}", p.display());
+            }
+            Ok(DebouncedEvent::Write(p)) => {
+                if config.0 == p {
+                    config = config::reload(&config)?;
+                    state.update(&config);
+                }
+                println!("Write {}", p.display());
+            }
+            // Do not try reloading our primary config in any of the following
+            // cases since it may lead to undesired behavior. If our config has
+            // e.g. been removed, let's just keep using what we have in memory
+            // in the chance it may be added back.
+            Ok(DebouncedEvent::Chmod(p)) => {
+                println!("Chmod {}", p.display());
+            }
+            Ok(DebouncedEvent::Remove(p)) => {
+                println!("Remove {}", p.display());
+            }
+            Ok(DebouncedEvent::Rename(src, dst)) => {
+                println!("Rename {} {}", src.display(), dst.display())
+            }
+            Ok(DebouncedEvent::Rescan) => {
+                println!("Rescanning");
+            }
+            Ok(DebouncedEvent::Error(e, _maybe_path)) => {
+                println!("Error {}", e);
+            }
+            Err(e) => {
+                println!("watch error: {:?}", e);
+            }
         }
     }
 }

src/lib.rs

@@ -4,7 +4,7 @@ pub mod daemon;
 pub mod path;
 
 use config::PathConfig;
-use path::NormalPathBuf;
+use path::ResPathBuf;
 use std::error::Error;
 use std::io;
 
@@ -18,7 +18,7 @@ pub fn run_daemon(config: PathConfig) -> Result<(), Box<dyn Error>> {
     Ok(())
 }
 
-pub fn run_init(candidates: Vec<NormalPathBuf>) -> Result<(), config::Error> {
+pub fn run_init(candidates: Vec<ResPathBuf>) -> Result<(), config::Error> {
     debug_assert!(!candidates.is_empty(), "Empty candidates found in `init`.");
     if candidates.is_empty() {
         return Err(config::Error::FileError(io::Error::new(

src/main.rs

@@ -1,5 +1,5 @@
 use clap::{App, AppSettings, Arg};
-use homesync::path::{NormalPathBuf, Normalize};
+use homesync::path::ResPathBuf;
 use std::error::Error;
 use std::io;
 use std::path::PathBuf;
@@ -54,18 +54,18 @@ fn dispatch(matches: clap::ArgMatches) -> Result<(), Box<dyn Error>> {
     }
 }
 
-fn find_candidates(matches: &clap::ArgMatches) -> Result<Vec<NormalPathBuf>, Box<dyn Error>> {
+fn find_candidates(matches: &clap::ArgMatches) -> Result<Vec<ResPathBuf>, io::Error> {
     let candidates = match matches.value_of("config") {
         Some(config_match) => vec![PathBuf::from(config_match)],
         None => homesync::config::default_paths(),
     };
-    let mut normals = vec![];
+    let mut resolved = vec![];
     for candidate in candidates {
-        if let Ok(Normalize::Done(n)) = homesync::path::normalize(&candidate) {
-            normals.push(n);
+        if let Ok(Some(r)) = homesync::path::resolve(&candidate) {
+            resolved.push(r);
         }
     }
-    if normals.is_empty() {
+    if resolved.is_empty() {
         if let Some(config_match) = matches.value_of("config") {
             Err(io::Error::new(
                 io::ErrorKind::NotFound,
@@ -79,6 +79,6 @@ fn find_candidates(matches: &clap::ArgMatches) -> Result<Vec<NormalPathBuf>, Box
             ))?
         }
     } else {
-        Ok(normals)
+        Ok(resolved)
     }
 }

src/path.rs

@@ -9,45 +9,67 @@ use std::path::{Component, Path, PathBuf};
 // Path
 // ========================================
 
-#[derive(Clone, Debug, Eq, PartialEq)]
-pub struct NormalPathBuf(PathBuf);
+#[derive(Clone, Debug)]
+pub struct ResPathBuf {
+    inner: PathBuf,
+    unresolved: PathBuf,
+}
 
-impl NormalPathBuf {
+impl ResPathBuf {
     pub fn display(&self) -> std::path::Display {
-        self.0.display()
+        self.inner.display()
+    }
+
+    pub fn unresolved(&self) -> &PathBuf {
+        return &self.unresolved;
     }
 }
 
-impl AsRef<Path> for NormalPathBuf {
+impl PartialEq<ResPathBuf> for ResPathBuf {
+    fn eq(&self, other: &Self) -> bool {
+        self.inner == other.inner
+    }
+}
+
+impl PartialEq<PathBuf> for ResPathBuf {
+    fn eq(&self, other: &PathBuf) -> bool {
+        self.inner == *other
+    }
+}
+
+impl Eq for ResPathBuf {}
+
+impl From<ResPathBuf> for PathBuf {
+    fn from(path: ResPathBuf) -> PathBuf {
+        path.inner
+    }
+}
+
+impl AsRef<Path> for ResPathBuf {
     fn as_ref(&self) -> &Path {
-        &self.0
+        &self.inner
     }
 }
 
-impl AsRef<PathBuf> for NormalPathBuf {
+impl AsRef<PathBuf> for ResPathBuf {
     fn as_ref(&self) -> &PathBuf {
-        &self.0
+        &self.inner
     }
 }
 
-impl Hash for NormalPathBuf {
+impl Hash for ResPathBuf {
     fn hash<H: Hasher>(&self, h: &mut H) {
-        for component in self.0.components() {
+        for component in self.inner.components() {
             component.hash(h);
         }
     }
 }
 
-pub enum Normalize {
-    Done(NormalPathBuf), // An instance of a fully resolved path.
-    Pending,             // An instance of a path that cannot yet be normalized.
-}
-
-// Find environment variables found within the argument and expand them if
-// possible.
-//
-// Returns `None` in the case an environment variable present within the
-// argument is not defined.
+/// Find environment variables found within the argument and expand them if
+/// possible.
+///
+/// Returns `None` in the case an environment variable present within the
+/// argument is not defined.
 fn expand_env(s: &OsStr) -> Option<OsString> {
     let re = Regex::new(r"\$(?P<env>[[:alnum:]]+)").unwrap();
     let lossy = s.to_string_lossy();
@@ -59,17 +81,14 @@ fn expand_env(s: &OsStr) -> Option<OsString> {
     Some(path.into())
 }
 
-// Normalizes the provided path, returning a new instance.
-//
-// There currently does not exist a method that yields some canonical path for
-// files that do not exist (at least in the parts of the standard library I've
-// looked in). We create a consistent view of every path so as to avoid watching
-// the same path multiple times, which would duplicate messages on changes.
-//
-// Note this does not actually prevent the issue fully. We could have two paths
-// that refer to the same real path - normalization would not catch this.
-pub fn normalize(path: &Path) -> io::Result<Normalize> {
-    let mut pb = env::current_dir()?;
+/// Attempt to resolve the provided path, returning a fully resolved path
+/// instance.
+///
+/// If the provided file does not exist but could potentially exist in the
+/// future (e.g. for paths with environment variables defined), this will
+/// return a `None` instead of an error.
+pub fn resolve(path: &Path) -> io::Result<Option<ResPathBuf>> {
+    let mut expanded = env::current_dir()?;
     for comp in path.components() {
         match comp {
             Component::Prefix(_) => {
@@ -79,12 +98,12 @@ pub fn normalize(path: &Path) -> io::Result<Normalize> {
                 ))
             }
             Component::RootDir => {
-                pb.clear();
-                pb.push(Component::RootDir)
+                expanded.clear();
+                expanded.push(Component::RootDir)
             }
             Component::CurDir => (), // Make no changes.
             Component::ParentDir => {
-                if !pb.pop() {
+                if !expanded.pop() {
                     return Err(io::Error::new(
                         io::ErrorKind::InvalidInput,
                         "Cannot take parent of root.",
@@ -92,12 +111,19 @@ pub fn normalize(path: &Path) -> io::Result<Normalize> {
                 }
             }
             Component::Normal(c) => match expand_env(c) {
-                Some(c) => pb.push(Component::Normal(&c)),
+                Some(c) => expanded.push(Component::Normal(&c)),
                 // The environment variable isn't defined yet but might be in
                 // the future.
-                None => return Ok(Normalize::Pending),
+                None => return Ok(None),
             },
         }
     }
-    Ok(Normalize::Done(NormalPathBuf(pb)))
+    match expanded.canonicalize() {
+        Ok(resolved) => Ok(Some(ResPathBuf {
+            inner: resolved,
+            unresolved: path.to_path_buf(),
+        })),
+        Err(e) if e.kind() == io::ErrorKind::NotFound => Ok(None),
+        Err(e) => Err(e),
+    }
 }