Appy _spawn_patch.py to grpcio_tools

tools/distrib/python/grpcio_tools/MANIFEST.in

@@ -1,4 +1,5 @@
 include _parallel_compile_patch.py
+include _spawn_patch.py
 include grpc_version.py
 include protoc_deps.py
 include protoc_lib_deps.py

tools/distrib/python/grpcio_tools/_spawn_patch.py

@@ -0,0 +1,64 @@
+# Copyright 2016 gRPC authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+"""Patches the spawn() command for windows compilers.
+
+Windows has an 8191 character command line limit, but some compilers
+support an @command_file directive where command_file is a file
+containing the full command line.
+"""
+
+from distutils import ccompiler
+import os
+import os.path
+import shutil
+import sys
+import tempfile
+
+MAX_COMMAND_LENGTH = 8191
+
+_classic_spawn = ccompiler.CCompiler.spawn
+
+
+def _commandfile_spawn(self, command, **kwargs):
+    command_length = sum([len(arg) for arg in command])
+    if os.name == "nt" and command_length > MAX_COMMAND_LENGTH:
+        # Even if this command doesn't support the @command_file, it will
+        # fail as is so we try blindly
+        print("Command line length exceeded, using command file")
+        print(" ".join(command))
+        temporary_directory = tempfile.mkdtemp()
+        command_filename = os.path.abspath(
+            os.path.join(temporary_directory, "command")
+        )
+        with open(command_filename, "w") as command_file:
+            escaped_args = [
+                '"' + arg.replace("\\", "\\\\") + '"' for arg in command[1:]
+            ]
+            # add each arg on a separate line to avoid hitting the
+            # "line in command file contains 131071 or more characters" error
+            # (can happen for extra long link commands)
+            command_file.write(" \n".join(escaped_args))
+        modified_command = command[:1] + ["@{}".format(command_filename)]
+        try:
+            _classic_spawn(self, modified_command, **kwargs)
+        finally:
+            shutil.rmtree(temporary_directory)
+    else:
+        _classic_spawn(self, command, **kwargs)
+
+
+def monkeypatch_spawn():
+    """Monkeypatching is dumb, but it's either that or we become maintainers of
+    something much, much bigger."""
+    ccompiler.CCompiler.spawn = _commandfile_spawn

tools/distrib/python/grpcio_tools/setup.py

@@ -37,6 +37,7 @@ os.chdir(os.path.dirname(os.path.abspath(__file__)))
 sys.path.insert(0, os.path.abspath("."))
 
 import _parallel_compile_patch
+import _spawn_patch
 import protoc_lib_deps
 
 import grpc_version
@@ -48,6 +49,7 @@ else:
     _EXT_INIT_SYMBOL = "PyInit__protoc_compiler"
 
 _parallel_compile_patch.monkeypatch_compile_maybe()
+_spawn_patch.monkeypatch_spawn()
 
 CLASSIFIERS = [
     "Development Status :: 5 - Production/Stable",