1 files changed, 111 insertions, 0 deletions
diff --git a/site_scons/site_tools/protobuf_compiler.py b/site_scons/site_tools/protobuf_compiler.py
new file mode 100644
index 00000000000..46178e4cc23
--- /dev/null
+++ b/site_scons/site_tools/protobuf_compiler.py
@@ -0,0 +1,111 @@
+# Copyright 2022 MongoDB Inc.
+#
+# Permission is hereby granted, free of charge, to any person obtaining
+# a copy of this software and associated documentation files (the
+# "Software"), to deal in the Software without restriction, including
+# without limitation the rights to use, copy, modify, merge, publish,
+# distribute, sublicense, and/or sell copies of the Software, and to
+# permit persons to whom the Software is furnished to do so, subject to
+# the following conditions:
+#
+# The above copyright notice and this permission notice shall be included
+# in all copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY
+# KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE
+# WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+# LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+# OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+# WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+#
+"""Protobuf Compiler Scons Tool."""
+
+import os
+
+import SCons
+
+def protoc_emitter(target, source, env):
+
+    first_source = str(source[0])
+
+    if not first_source.endswith(".proto"):
+        raise ValueError("Bad protoc file name '%s', it must end with '.proto' " % (first_source))
+
+    base_file_name, _ = SCons.Util.splitext(str(target[0]))
+
+    message_source = env.File(base_file_name + ".grpc.pb.cc")
+    message_header = env.File(base_file_name + ".grpc.pb.h")
+    class_source = env.File(base_file_name + ".pb.cc")
+    class_header = env.File(base_file_name + ".pb.h")
+    new_targets = [message_source, message_header, class_source, class_header]
+
+    # So we can put these in generated source alias because ninja must generate all sources before
+    # it will compile anything because it doesn't know how to parse dependencies from generic
+    # generation inputs. We could teach it by telling it a script to call during the build that
+    # will output the dep file similar to how gcc will do for make with -MD. But we would need to
+    # teach it for all generated source before we could stop gen_all before compile. For now we can
+    # at least make compile_commands.json dependent on these so it still can be used for IDE work.
+    #env.Alias("generated-sources", new_targets)
+    env.Depends(env.File("#compile_commands.json"), new_targets)
+
+    return new_targets, source
+
+def protocActionGen(source, target, env, for_signature):
+    working_dir = os.path.dirname(target[0].srcnode().path)
+    cpp_out = os.path.dirname(target[0].path)
+    os.makedirs(cpp_out, exist_ok=True)
+    protoc_path = os.path.abspath(env.subst('$PROTOC'))
+    env['PROTOC_GENOUT_DIR'] = os.path.abspath(cpp_out)
+
+    # protoc doesn't play nice with scons variant dir. It will build in the --cpp_out dir,
+    # but it always uses the path of the source inside the cpp_out dir. This means you end
+    # up with really long paths, where most of its duplicated like:
+    # $BUILD_DIR_PATH/$SOURCE_DIR_PATH/$GENERATED_SOURCE_FILE
+    # The other option is to change to the source directory and pass the source directly.
+    return env.subst(f"cd {working_dir} && {protoc_path} $PROTOCFLAGS ${{SOURCE.file}}", target=target, source=source)
+
+def protoc_scanner(node, env, path):
+
+    # TODO Make this scanner understand how to parse .proto files to find .proto
+    # dependencies.
+    deps = []
+    protoc_flags = env.Flatten(env.subst_list("$PROTOCFLAGS"))
+    for flag in protoc_flags:
+        if '--plugin' in flag:
+            # this option should have an '=', so we can always take the last token to
+            # find the path
+            #https://developers.google.com/protocol-buffers/docs/reference/cpp/google.protobuf.compiler.plugin
+            deps.append(env.File(flag.split('=')[-1]))
+    deps.append(env.File("$PROTOC"))
+
+    return deps
+
+protoc_scanner = SCons.Scanner.Scanner(function=protoc_scanner, skeys=[".proto"])
+
+def generate(env):
+
+    ProtocAction = SCons.Action.CommandGeneratorAction(
+        protocActionGen,
+        {"cmdstr": "Generating Protocal Buffers from ${SOURCE}"}
+        if not env.get("VERBOSE", "").lower() in ['true', '1'] else {"cmdstr": ""},
+    )
+
+    ProtocBuilder = SCons.Builder.Builder(
+        action=ProtocAction,
+        emitter=protoc_emitter,
+        src_suffix=".proto",
+        suffix=".cc",
+        source_scanner=protoc_scanner,
+        single_source=1,
+    )
+
+    env.Append(SCANNERS=protoc_scanner)
+
+    env["BUILDERS"]["Protoc"] = ProtocBuilder
+    env["PROTOC"] = env.get('PROTOC', env.WhereIs('protoc'))
+    env["PROTOC_GENOUT_DIR"] = "."
+    env['PROTOCFLAGS'] = SCons.Util.CLVar('')
+
+def exists(env):
+    return True