Add file fingerprint to copy/remove only required files.

Updates the persistent volume using a fingerprint of all files in the
project, skipping any cache directories by default. If the file modified
date has changed, or the file has been added, copy it to the volume and
update it. If the file has been removed, then remove it from the host.
To avoid a massive command-line argument, we copy a file containing each
changed file on a line to the container, and then remove each file
by running a script on the container.

Author: Alexhuszagh

src/docker/remote.rs

@@ -1,7 +1,8 @@
-use std::io::Read;
+use std::collections::BTreeMap;
+use std::io::{self, BufRead, Read, Write};
 use std::path::{Path, PathBuf};
 use std::process::ExitStatus;
-use std::{env, fs};
+use std::{env, fs, time};
 
 use super::engine::Engine;
 use super::shared::*;
@@ -394,6 +395,205 @@ pub fn copy_volume_container_rust(
     Ok(())
 }
 
+type FingerprintMap = BTreeMap<String, time::SystemTime>;
+
+fn parse_project_fingerprint(path: &Path) -> Result<FingerprintMap> {
+    let epoch = time::SystemTime::UNIX_EPOCH;
+    let file = fs::OpenOptions::new().read(true).open(path)?;
+    let reader = io::BufReader::new(file);
+    let mut result = BTreeMap::new();
+    for line in reader.lines() {
+        let line = line?;
+        let (timestamp, relpath) = line
+            .split_once('\t')
+            .ok_or_else(|| eyre::eyre!("unable to parse fingerprint line '{line}'"))?;
+        let modified = epoch + time::Duration::from_millis(timestamp.parse::<u64>()?);
+        result.insert(relpath.to_string(), modified);
+    }
+
+    Ok(result)
+}
+
+fn write_project_fingerprint(path: &Path, fingerprint: &FingerprintMap) -> Result<()> {
+    let epoch = time::SystemTime::UNIX_EPOCH;
+    let mut file = fs::OpenOptions::new().write(true).create(true).open(path)?;
+    for (relpath, modified) in fingerprint {
+        let timestamp = modified.duration_since(epoch)?.as_millis() as u64;
+        writeln!(file, "{timestamp}\t{relpath}")?;
+    }
+
+    Ok(())
+}
+
+fn read_dir_fingerprint(
+    home: &Path,
+    path: &Path,
+    map: &mut FingerprintMap,
+    copy_cache: bool,
+) -> Result<()> {
+    let epoch = time::SystemTime::UNIX_EPOCH;
+    for entry in fs::read_dir(path)? {
+        let file = entry?;
+        let file_type = file.file_type()?;
+        // only parse known files types: 0 or 1 of these tests can pass.
+        if file_type.is_dir() {
+            if copy_cache || !is_cachedir(&file) {
+                read_dir_fingerprint(home, &path.join(file.file_name()), map, copy_cache)?;
+            }
+        } else if file_type.is_file() || file_type.is_symlink() {
+            // we're mounting to the same location, so this should fine
+            // we need to round the modified date to millis.
+            let modified = file.metadata()?.modified()?;
+            let millis = modified.duration_since(epoch)?.as_millis() as u64;
+            let rounded = epoch + time::Duration::from_millis(millis);
+            let relpath = file.path().strip_prefix(home)?.as_posix()?;
+            map.insert(relpath, rounded);
+        }
+    }
+
+    Ok(())
+}
+
+fn get_project_fingerprint(home: &Path, copy_cache: bool) -> Result<FingerprintMap> {
+    let mut result = BTreeMap::new();
+    read_dir_fingerprint(home, home, &mut result, copy_cache)?;
+    Ok(result)
+}
+
+fn get_fingerprint_difference<'a, 'b>(
+    previous: &'a FingerprintMap,
+    current: &'b FingerprintMap,
+) -> (Vec<&'b str>, Vec<&'a str>) {
+    // this can be added or updated
+    let changed: Vec<&str> = current
+        .iter()
+        .filter(|(ref k, ref v1)| {
+            previous
+                .get(&k.to_string())
+                .map(|ref v2| v1 != v2)
+                .unwrap_or(true)
+        })
+        .map(|(k, _)| k.as_str())
+        .collect();
+    let removed: Vec<&str> = previous
+        .iter()
+        .filter(|(ref k, _)| !current.contains_key(&k.to_string()))
+        .map(|(k, _)| k.as_str())
+        .collect();
+    (changed, removed)
+}
+
+// copy files for a docker volume, for remote host support
+// provides a list of files relative to src.
+fn copy_volume_file_list(
+    engine: &Engine,
+    container: &str,
+    src: &Path,
+    dst: &Path,
+    files: &[&str],
+    verbose: bool,
+) -> Result<ExitStatus> {
+    // SAFETY: safe, single-threaded execution.
+    let tempdir = unsafe { temp::TempDir::new()? };
+    let temppath = tempdir.path();
+    for file in files {
+        let src_path = src.join(file);
+        let dst_path = temppath.join(file);
+        fs::create_dir_all(dst_path.parent().expect("must have parent"))?;
+        fs::copy(&src_path, &dst_path)?;
+    }
+    copy_volume_files(engine, container, temppath, dst, verbose)
+}
+
+// removed files from a docker volume, for remote host support
+// provides a list of files relative to src.
+fn remove_volume_file_list(
+    engine: &Engine,
+    container: &str,
+    dst: &Path,
+    files: &[&str],
+    verbose: bool,
+) -> Result<ExitStatus> {
+    const PATH: &str = "/tmp/remove_list";
+    let mut script = vec![];
+    if verbose {
+        script.push("set -x".to_string());
+    }
+    script.push(format!(
+        "cat \"{PATH}\" | while read line; do
+    rm -f \"${{line}}\"
+done
+
+rm \"{PATH}\"
+"
+    ));
+
+    // SAFETY: safe, single-threaded execution.
+    let mut tempfile = unsafe { temp::TempFile::new()? };
+    for file in files {
+        writeln!(tempfile.file(), "{}", dst.join(file).as_posix()?)?;
+    }
+
+    // need to avoid having hundreds of files on the command, so
+    // just provide a single file name.
+    subcommand(engine, "cp")
+        .arg(tempfile.path())
+        .arg(format!("{container}:{PATH}"))
+        .run_and_get_status(verbose, true)?;
+
+    subcommand(engine, "exec")
+        .arg(container)
+        .args(&["sh", "-c", &script.join("\n")])
+        .run_and_get_status(verbose, true)
+        .map_err(Into::into)
+}
+
+fn copy_volume_container_project(
+    engine: &Engine,
+    container: &str,
+    src: &Path,
+    dst: &Path,
+    volume: &VolumeId,
+    copy_cache: bool,
+    verbose: bool,
+) -> Result<()> {
+    let copy_all = || {
+        if copy_cache {
+            copy_volume_files(engine, container, src, dst, verbose)
+        } else {
+            copy_volume_files_nocache(engine, container, src, dst, verbose)
+        }
+    };
+    match volume {
+        VolumeId::Keep(_) => {
+            let parent = temp::dir()?;
+            fs::create_dir_all(&parent)?;
+            let fingerprint = parent.join(container);
+            let current = get_project_fingerprint(src, copy_cache)?;
+            if fingerprint.exists() {
+                let previous = parse_project_fingerprint(&fingerprint)?;
+                let (changed, removed) = get_fingerprint_difference(&previous, &current);
+                write_project_fingerprint(&fingerprint, &current)?;
+
+                if !changed.is_empty() {
+                    copy_volume_file_list(engine, container, src, dst, &changed, verbose)?;
+                }
+                if !removed.is_empty() {
+                    remove_volume_file_list(engine, container, dst, &removed, verbose)?;
+                }
+            } else {
+                write_project_fingerprint(&fingerprint, &current)?;
+                copy_all()?;
+            }
+        }
+        VolumeId::Discard(_) => {
+            copy_all()?;
+        }
+    }
+
+    Ok(())
+}
+
 fn run_and_get_status(engine: &Engine, args: &[&str], verbose: bool) -> Result<ExitStatus> {
     command(engine)
         .args(args)
@@ -645,7 +845,15 @@ pub(crate) fn run(
     } else {
         mount_prefix_path.join("project")
     };
-    copy(&dirs.host_root, &mount_root)?;
+    copy_volume_container_project(
+        engine,
+        &container,
+        &dirs.host_root,
+        &mount_root,
+        &volume,
+        copy_cache,
+        verbose,
+    )?;
 
     let mut copied = vec![
         (&dirs.xargo, mount_prefix_path.join("xargo")),
@@ -692,7 +900,7 @@ pub(crate) fn run(
     let mut final_args = vec![];
     let mut iter = args.iter().cloned();
     let mut has_target_dir = false;
-    let target_dir_string = target_dir.to_utf8()?.to_string();
+    let target_dir_string = target_dir.as_posix()?;
     while let Some(arg) = iter.next() {
         if arg == "--target-dir" {
             has_target_dir = true;

src/temp.rs

@@ -34,12 +34,12 @@ pub(crate) unsafe fn clean() {
 
 /// # Safety
 /// Safe as long as we have single-threaded execution.
-unsafe fn push_tempfile() -> Result<&'static Path> {
+unsafe fn push_tempfile() -> Result<&'static mut tempfile::NamedTempFile> {
     let parent = dir()?;
     fs::create_dir_all(&parent).ok();
     let file = tempfile::NamedTempFile::new_in(&parent)?;
     FILES.push(file);
-    Ok(FILES.last().unwrap().path())
+    Ok(FILES.last_mut().unwrap())
 }
 
 /// # Safety
@@ -50,20 +50,24 @@ unsafe fn pop_tempfile() -> Option<tempfile::NamedTempFile> {
 
 #[derive(Debug)]
 pub struct TempFile {
-    path: &'static Path,
+    file: &'static mut tempfile::NamedTempFile,
 }
 
 impl TempFile {
     /// # Safety
     /// Safe as long as we have single-threaded execution.
     pub unsafe fn new() -> Result<Self> {
         Ok(Self {
-            path: push_tempfile()?,
+            file: push_tempfile()?,
         })
     }
 
-    pub fn path(&self) -> &'static Path {
-        self.path
+    pub fn file(&mut self) -> &mut tempfile::NamedTempFile {
+        self.file
+    }
+
+    pub fn path(&self) -> &Path {
+        self.file.path()
     }
 }