Faster gitignore

isort/settings.py

@@ -4,6 +4,7 @@
 """
 import configparser
 import fnmatch
+import glob
 import os
 import posixpath
 import re
@@ -214,6 +215,8 @@ class _Config:
     reverse_sort: bool = False
     star_first: bool = False
     import_dependencies = Dict[str, str]
+    git_folders: Set[Path] = field(default_factory=set)
+    git_ignore_files: Set[Path] = field(default_factory=set)
 
     def __post_init__(self):
         py_version = self.py_version
@@ -521,10 +524,26 @@ def is_skipped(self, file_path: Path) -> bool:
             if file_path.name == ".git":  # pragma: no cover
                 return True
 
-            result = subprocess.run(  # nosec # skipcq: PYL-W1510
-                ["git", "-C", str(file_path.parent), "check-ignore", "--quiet", os_path]
-            )
-            if result.returncode == 0:
+            for folder in self.git_folders:
+                if folder in file_path.parents:
+                    break
+            else:
+                topfolder_result = subprocess.run([
+                    "git", "-C", str(file_path.parent), "rev-parse", "--show-toplevel"
+                ], capture_output=True)
+                if topfolder_result.returncode == 0:
+                    git_folder = Path(
+                        topfolder_result.stdout.decode('utf-8').split("\n")[0]
+                    )
+                    files = glob.glob(str(git_folder)+"/**/*", recursive=True)
+                    files_result = subprocess.run(
+                        ["git", "-C", git_folder, "check-ignore", *files], capture_output=True
+                    ).stdout.decode('utf-8').split("\n")
+                    files_result = files_result[:-1] if files_result else files_result
+                    self.git_ignore_files.update({Path(f) for f in files_result})
+                    self.git_folders.add(git_folder)
+
+            if file_path in self.git_ignore_files:
                 return True
 
         normalized_path = os_path.replace("\\", "/")
@@ -543,8 +562,8 @@ def is_skipped(self, file_path: Path) -> bool:
                 return True
             position = os.path.split(position[0])
 
-        for glob in self.skip_globs:
-            if fnmatch.fnmatch(file_name, glob) or fnmatch.fnmatch("/" + file_name, glob):
+        for sglob in self.skip_globs:
+            if fnmatch.fnmatch(file_name, sglob) or fnmatch.fnmatch("/" + file_name, sglob):
                 return True
 
         if not (os.path.isfile(os_path) or os.path.isdir(os_path) or os.path.islink(os_path)):