don't uvloop.install on import (#2303)

[etc/vim.git] / src / black / concurrency.py

diff --git a/src/black/concurrency.py b/src/black/concurrency.py
index 119a9a71fafc8828913e9d91ae65df3dfb2aab0d..69d79f534e82fc32267e61a1a10e319ca51585bd 100644 (file)
--- a/src/black/concurrency.py
+++ b/src/black/concurrency.py
@@ -6,6 +6,21 @@ from typing import Any, Iterable
 from black.output import err
 
 
+def maybe_install_uvloop() -> None:
+    """If our environment has uvloop installed we use it.
+
+    This is called only from command-line entry points to avoid
+    interfering with the parent process if Black is used as a library.
+
+    """
+    try:
+        import uvloop
+
+        uvloop.install()
+    except ImportError:
+        pass
+
+
 def cancel(tasks: Iterable["asyncio.Task[Any]"]) -> None:
     """asyncio signal handler that cancels all `tasks` and reports to stderr."""
     err("Aborted!")