D10200: rhg: Make `files` work on repo-relative paths when possible

[SimonSapin]

SimonSapin created this revision.
Herald added a reviewer: hg-reviewers.
Herald added a subscriber: mercurial-patches.

REVISION SUMMARY
  When the current directory is outside of the repository we need to turn
  everything into absolute filesystem paths in order to compute correct
  relative paths.
  
  This was previously done unconditionally, but is not necessary when
  the current directory is inside the repository.
  
  With this change `rhg files > /dev/null` at the root of a mozilla-central
  snapshot goes from ~150 ms to ~70 ms. My repository is located at a
  somewhat long path though (93 bytes). The effect may not be as pronounced
  at a shorter path.

REPOSITORY
  rHG Mercurial

BRANCH
  default

REVISION DETAIL
  https://phab.mercurial-scm.org/D10200

AFFECTED FILES
  rust/rhg/src/commands/files.rs

CHANGE DETAILS

diff --git a/rust/rhg/src/commands/files.rs b/rust/rhg/src/commands/files.rs
--- a/rust/rhg/src/commands/files.rs
+++ b/rust/rhg/src/commands/files.rs
@@ -45,17 +45,28 @@
     repo: &Repo,
     files: impl IntoIterator<Item = &'a HgPath>,
 ) -> Result<(), CommandError> {
-    let cwd = HgPathBuf::from(get_bytes_from_path(hg::utils::current_dir()?));
-    let working_directory =
-        HgPathBuf::from(get_bytes_from_path(repo.working_directory_path()));
-
     let mut stdout = ui.stdout_buffer();
+    let cwd = hg::utils::current_dir()?;
+    let working_directory = repo.working_directory_path();
 
-    for file in files {
-        let file = working_directory.join(file);
-        stdout.write_all(relativize_path(&file, &cwd).as_ref())?;
-        stdout.write_all(b"\n")?;
+    if let Ok(cwd_relative_to_repo) = cwd.strip_prefix(working_directory) {
+        // The current directory is inside the repo, so we can work with relative paths
+        let cwd = HgPathBuf::from(get_bytes_from_path(cwd_relative_to_repo));
+        for file in files {
+            stdout.write_all(relativize_path(&file, &cwd).as_ref())?;
+            stdout.write_all(b"\n")?;
+        }
+    } else {
+        let cwd = HgPathBuf::from(get_bytes_from_path(cwd));
+        let working_directory = HgPathBuf::from(get_bytes_from_path(working_directory));
+        for file in files {
+            // Absolute path in the filesystem
+            let file = working_directory.join(file);
+            stdout.write_all(relativize_path(&file, &cwd).as_ref())?;
+            stdout.write_all(b"\n")?;
+        }
     }
+
     stdout.flush()?;
     Ok(())
 }



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