primer: Hypothesis now requires Python>=3.8 (GH-2602)

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

diff --git a/src/black/concurrency.py b/src/black/concurrency.py
index 119a9a71fafc8828913e9d91ae65df3dfb2aab0d..24f67b62f0617f79ab21fa9b036645338a4feb8e 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!")
@@ -27,9 +42,12 @@ def shutdown(loop: asyncio.AbstractEventLoop) -> None:
 
         for task in to_cancel:
             task.cancel()
-        loop.run_until_complete(
-            asyncio.gather(*to_cancel, loop=loop, return_exceptions=True)
-        )
+        if sys.version_info >= (3, 7):
+            loop.run_until_complete(asyncio.gather(*to_cancel, return_exceptions=True))
+        else:
+            loop.run_until_complete(
+                asyncio.gather(*to_cancel, loop=loop, return_exceptions=True)
+            )
     finally:
         # `concurrent.futures.Future` objects cannot be cancelled once they
         # are already running. There might be some when the `shutdown()` happened.