From 0e5674ffeabb4f911a9486da8ff3ba3a33d1d98c Mon Sep 17 00:00:00 2001
From: Ruslan Kuprieiev <kupruser@gmail.com>
Date: Sun, 8 Jan 2023 03:21:37 +0200
Subject: [PATCH] ls: compute relparts once for every dir

Cuts down `dvc ls . data/mnist/dataset --recursive` for me from ~25 to ~12
seconds.

`relparts` is an expensive operation as it calls `relpath` that calls `abspath`,
so we want to avoid calling it as much as possible.
---
 dvc/repo/ls.py | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/dvc/repo/ls.py b/dvc/repo/ls.py
index 1b989095f..598fa4e44 100644
--- a/dvc/repo/ls.py
+++ b/dvc/repo/ls.py
@@ -70,11 +70,12 @@ def _ls(
         if not recursive:
             files.update(dirs)
 
+        parts = fs.path.relparts(root, fs_path)
+        if parts == (".",):
+            parts = ()
+
         for name, entry in files.items():
-            entry_fs_path = fs.path.join(root, name)
-            relparts = fs.path.relparts(entry_fs_path, fs_path)
-            name = os.path.join(*relparts)
-            infos[name] = entry
+            infos[os.path.join(*parts, name)] = entry
 
         if not recursive:
             break