refactor: move iterating over files to Path extension trait

src/server/backups.rs

@@ -1,3 +1,4 @@
+use crate::server::path::PathExt;
 use chrono::{Local, Utc};
 use flate2::write::GzEncoder;
 use flate2::Compression;
@@ -14,52 +15,6 @@ extern "C" {
     fn getegid() -> u32;
 }
 
-/// List all files in `src_dir` and all child directories.
-fn files(src_dir: PathBuf) -> io::Result<HashSet<PathBuf>> {
-    let mut dirs = vec![src_dir.clone()];
-    let mut files: HashSet<PathBuf> = HashSet::new();
-
-    while let Some(dir) = dirs.pop() {
-        for res in dir.read_dir()? {
-            let entry = res?;
-
-            if entry.file_name() == "cache" {
-                continue;
-            }
-
-            if entry.file_type()?.is_dir() {
-                dirs.push(entry.path());
-            } else {
-                files.insert(entry.path().strip_prefix(&src_dir).unwrap().to_path_buf());
-            }
-        }
-    }
-
-    Ok(files)
-}
-
-/// Check whether a file has been modified since the given timestamp.
-///
-/// Note that this function will *only* return true if it can determine with certainty that the
-/// file has not been modified. If any errors occur while obtaining the required metadata (e.g. if
-/// the file system does not support this metadata), this function will return false.
-fn not_modified_since<T: AsRef<Path>>(time: chrono::DateTime<Utc>, path: T) -> bool {
-    let path = path.as_ref();
-
-    if let Ok(metadata) = path.metadata() {
-        let last_modified = metadata.modified();
-
-        if let Ok(last_modified) = last_modified {
-            let t: chrono::DateTime<Utc> = last_modified.into();
-            let t = t.with_timezone(&Local);
-
-            return t < time;
-        }
-    }
-
-    false
-}
-
 #[derive(Debug, PartialEq, Serialize, Deserialize)]
 pub enum BackupType {
     Full,
@@ -162,11 +117,7 @@ impl Backup {
 
     /// Returns a pointer to this backup's previous backup by cloning the Arc pointer.
     pub fn previous(&self) -> Option<Arc<Self>> {
-        if let Some(previous) = &self.previous {
-            Some(Arc::clone(&previous))
-        } else {
-            None
-        }
+        self.previous.as_ref().map(Arc::clone)
     }
 
     /// Calculate the full state of the backup by applying all its ancestors' delta's in order,
@@ -193,7 +144,7 @@ impl Backup {
             None
         } else if let Some(previous) = &self.previous {
             if n == 1 {
-                Some(Arc::clone(&previous))
+                Some(Arc::clone(previous))
             } else {
                 previous.ancestor(n - 1)
             }
@@ -232,26 +183,27 @@ impl Backup {
         let enc = GzEncoder::new(tar_gz, Compression::default());
         let mut ar = tar::Builder::new(enc);
 
-        let mut added: HashMap<PathBuf, HashSet<PathBuf>> = HashMap::new();
+        let mut delta = BackupDelta::new();
 
         for (dir_in_tar, src_dir) in dirs {
-            let files = files(src_dir.clone())?;
+            let mut added_files: HashSet<PathBuf> = HashSet::new();
 
-            for path in &files {
-                ar.append_path_with_name(src_dir.join(path), dir_in_tar.join(path))?;
+            for entry in src_dir.read_dir_recursive()?.ignored("cache").files() {
+                let path = entry?.path();
+                let stripped = path.strip_prefix(&src_dir).unwrap();
+
+                ar.append_path_with_name(&path, dir_in_tar.join(stripped))?;
+                added_files.insert(stripped.to_path_buf());
             }
 
-            added.insert(dir_in_tar, files);
+            delta.added.insert(dir_in_tar, added_files);
         }
 
         Ok(Backup {
             previous: None,
             type_: BackupType::Full,
             start_time,
-            delta: BackupDelta {
-                added,
-                removed: HashMap::new(),
-            },
+            delta,
         })
     }
 
@@ -274,17 +226,19 @@ impl Backup {
         let mut delta = BackupDelta::new();
 
         for (dir_in_tar, src_dir) in dirs {
-            let files = files(src_dir.clone())?;
-            let added_files = files
-                .iter()
-                // This explicit negation is because we wish to also include files for which we
-                // couldn't determine the last modified time
-                .filter(|p| !not_modified_since(previous.start_time, src_dir.join(p)))
-                .cloned()
-                .collect::<HashSet<PathBuf>>();
+            let mut all_files: HashSet<PathBuf> = HashSet::new();
+            let mut added_files: HashSet<PathBuf> = HashSet::new();
 
-            for path in added_files.iter() {
-                ar.append_path_with_name(src_dir.join(path), dir_in_tar.join(path))?;
+            for entry in src_dir.read_dir_recursive()?.ignored("cache").files() {
+                let path = entry?.path();
+                let stripped = path.strip_prefix(&src_dir).unwrap();
+
+                if !path.not_modified_since(previous.start_time) {
+                    ar.append_path_with_name(&path, dir_in_tar.join(stripped))?;
+                    added_files.insert(stripped.to_path_buf());
+                }
+
+                all_files.insert(stripped.to_path_buf());
             }
 
             delta.added.insert(dir_in_tar.clone(), added_files);
@@ -292,7 +246,7 @@ impl Backup {
             if let Some(previous_files) = previous_state.get(&dir_in_tar) {
                 delta.removed.insert(
                     dir_in_tar,
-                    previous_files.difference(&files).cloned().collect(),
+                    previous_files.difference(&all_files).cloned().collect(),
                 );
             }
         }

src/server/path.rs

@@ -1,19 +1,147 @@
-use chrono::Utc;
+use chrono::{Local, Utc};
 use std::collections::HashSet;
-use std::path::PathBuf;
+use std::ffi::OsString;
+use std::fs::DirEntry;
+use std::path::{Path, PathBuf};
 use std::{fs, io};
 
-struct ReadDirRecursive {
-    ignored_dirs: HashSet<PathBuf>,
-    read_dir: Option<fs::ReadDir>,
-    stack: Vec<fs::ReadDir>,
+pub struct ReadDirRecursive {
+    ignored: HashSet<OsString>,
+    read_dir: fs::ReadDir,
+    dir_stack: Vec<PathBuf>,
+    files_only: bool,
 }
 
 impl ReadDirRecursive {
-    // pub fn new()
+    /// Start the iterator for a new directory
+    pub fn start<P: AsRef<Path>>(path: P) -> io::Result<Self> {
+        let path = path.as_ref();
+        let read_dir = path.read_dir()?;
+
+        Ok(ReadDirRecursive {
+            ignored: HashSet::new(),
+            read_dir,
+            dir_stack: Vec::new(),
+            files_only: false,
+        })
     }
 
-trait PathExt {
-    fn modified_since(timestamp: chrono::DateTime<Utc>) -> bool;
-    fn read_dir_recusive() -> ReadDirRecursive;
+    pub fn ignored<S: Into<OsString>>(mut self, s: S) -> Self {
+        self.ignored.insert(s.into());
+
+        self
+    }
+
+    pub fn files(mut self) -> Self {
+        self.files_only = true;
+
+        self
+    }
+
+    /// Tries to populate the `read_dir` field with a new `ReadDir` instance to consume.
+    fn next_read_dir(&mut self) -> io::Result<bool> {
+        if let Some(path) = self.dir_stack.pop() {
+            self.read_dir = path.read_dir()?;
+
+            Ok(true)
+        } else {
+            Ok(false)
+        }
+    }
+
+    /// Convenience method to add a new directory to the stack.
+    fn push_entry(&mut self, entry: &io::Result<DirEntry>) {
+        if let Ok(entry) = entry {
+            if entry.path().is_dir() {
+                self.dir_stack.push(entry.path());
+            }
+        }
+    }
+
+    /// Determine whether an entry should be returned by the iterator.
+    fn should_return(&self, entry: &io::Result<DirEntry>) -> bool {
+        if let Ok(entry) = entry {
+            let mut res = !self.ignored.contains(&entry.file_name());
+
+            // Please just let me combine these already
+            if self.files_only {
+                if let Ok(file_type) = entry.file_type() {
+                    res = res && file_type.is_file();
+                }
+                // We  couldn't determine if it's a file, so we don't return it
+                else {
+                    res = false;
+                }
+            }
+
+            res
+        } else {
+            true
+        }
+    }
+}
+
+impl Iterator for ReadDirRecursive {
+    type Item = io::Result<DirEntry>;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        loop {
+            // First, we try to consume the current directory's items
+            while let Some(entry) = self.read_dir.next() {
+                self.push_entry(&entry);
+
+                if self.should_return(&entry) {
+                    return Some(entry);
+                }
+            }
+
+            // If we get an error while setting up a new directory, we return this, otherwise we
+            // keep trying to consume the directories
+            match self.next_read_dir() {
+                Ok(true) => (),
+                // There's no more directories to traverse, so the iterator is done
+                Ok(false) => return None,
+                Err(e) => return Some(Err(e)),
+            }
+        }
+    }
+}
+
+pub trait PathExt {
+    /// Confirm whether the file has not been modified since the given timestamp.
+    ///
+    /// This function will only return true if it can determine with certainty that the file hasn't
+    /// been modified.
+    ///
+    /// # Args
+    ///
+    /// * `timestamp` - Timestamp to compare modified time with
+    ///
+    /// # Returns
+    ///
+    /// True if the file has not been modified for sure, false otherwise.
+    fn not_modified_since(&self, timestamp: chrono::DateTime<Utc>) -> bool;
+
+    /// An extension of the `read_dir` command that runs through the entire underlying directory
+    /// structure using breadth-first search
+    fn read_dir_recursive(&self) -> io::Result<ReadDirRecursive>;
+}
+
+impl PathExt for Path {
+    fn not_modified_since(&self, timestamp: chrono::DateTime<Utc>) -> bool {
+        if let Ok(metadata) = self.metadata() {
+            if let Ok(last_modified) = metadata.modified() {
+                let t: chrono::DateTime<Utc> = last_modified.into();
+                let t = t.with_timezone(&Local);
+
+                return t < timestamp;
+            }
+        }
+
+        false
+    }
+
+    fn read_dir_recursive(&self) -> io::Result<ReadDirRecursive> {
+        ReadDirRecursive::start(self)
+    }
 }