Make it run in parallel

Author: jepler

tools/black_bindings.py

@@ -1,4 +1,6 @@
 #!/usr/bin/python3
+from concurrent.futures import ThreadPoolExecutor
+import os
 import re
 import subprocess
 import sys
@@ -25,7 +27,7 @@ def transform(s):
     return "\n".join("//| " + line if line else "//|" for line in result) + "\n"
 
 
-for fn in sys.argv[1:]:
+def process_one_file(fn):
     with open(fn, "r", encoding="utf-8") as f:
         content = f.read()
 
@@ -40,3 +42,11 @@ def transform(s):
 
     with open(fn, "w", encoding="utf-8") as f:
         f.write("".join(newcontent))
+
+
+if __name__ == "__main__":
+    # Use a thread pool because most processing is inside black!
+    executor = ThreadPoolExecutor(max_workers=os.cpu_count())
+    for fn in sys.argv[1:]:
+        executor.submit(process_one_file, fn)
+    executor.shutdown()