Adds a generated file with the dawn git hash encoded at build time.

Bug: dawn:549
Change-Id: I5d6306f33b7ad2247ee75a0c5387a2bc6fac0497
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/83901
Reviewed-by: Austin Eng <enga@chromium.org>
Commit-Queue: Loko Kung <lokokung@google.com>

generator/dawn_generator.gni

@@ -39,6 +39,7 @@ import("generator_lib.gni")
 
 dawn_allowed_gen_output_dirs = [
   "src/dawn/",
+  "src/dawn/common/",
   "src/dawn/native/",
   "src/dawn/native/opengl/",
   "src/dawn/wire/client/",

generator/dawn_version_generator.py

@@ -0,0 +1,105 @@
+#!/usr/bin/env python3
+# Copyright 2022 The Dawn 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.
+
+import os, subprocess, sys
+
+from generator_lib import Generator, run_generator, FileRender
+
+
+def get_git():
+    return 'git.bat' if sys.platform == 'win32' else 'git'
+
+
+def get_gitHash(dawnDir):
+    result = subprocess.run([get_git(), 'rev-parse', 'HEAD'],
+                            stdout=subprocess.PIPE,
+                            cwd=dawnDir)
+    if result.returncode == 0:
+        return result.stdout.decode('utf-8').strip()
+    return ''
+
+
+def get_gitHead(dawnDir):
+    return [os.path.join(dawnDir, '.git', 'HEAD')]
+
+
+def unpackGitRef(packed, resolved):
+    with open(packed) as fin:
+        refs = fin.read().strip().split('\n')
+
+    # Strip comments
+    refs = [ref.split(' ') for ref in refs if ref.strip()[0] != '#']
+
+    # Parse results which are in the format [<gitHash>, <refFile>] from previous step.
+    refs = [gitHash for (gitHash, refFile) in refs if refFile == resolved]
+    if len(refs) == 1:
+        with open(resolved, 'w') as fout:
+            fout.write(refs[0] + '\n')
+        return True
+    return False
+
+
+def get_gitResolvedHead(dawnDir):
+    result = subprocess.run(
+        [get_git(), 'rev-parse', '--symbolic-full-name', 'HEAD'],
+        stdout=subprocess.PIPE,
+        cwd=dawnDir)
+    if result.returncode != 0:
+        raise Exception('Failed to execute git rev-parse to resolve git head.')
+
+    resolved = os.path.join(dawnDir, '.git',
+                            result.stdout.decode('utf-8').strip())
+
+    # Check a packed-refs file exists. If so, we need to potentially unpack and include it as a dep.
+    packed = os.path.join(dawnDir, '.git', 'packed-refs')
+    if os.path.exists(packed) and unpackGitRef(packed, resolved):
+        return [packed, resolved]
+
+    if not os.path.exists(resolved):
+        raise Exception('Unable to resolve git HEAD hash file:', path)
+    return [resolved]
+
+
+def compute_params(args):
+    return {
+        'get_gitHash': lambda: get_gitHash(os.path.abspath(args.dawn_dir)),
+    }
+
+
+class DawnVersionGenerator(Generator):
+    def get_description(self):
+        return 'Generates version dependent Dawn code. Currently regenerated dependent on git hash.'
+
+    def add_commandline_arguments(self, parser):
+        parser.add_argument('--dawn-dir',
+                            required=True,
+                            type=str,
+                            help='The Dawn root directory path to use')
+
+    def get_dependencies(self, args):
+        dawn_dir = os.path.abspath(args.dawn_dir)
+        return get_gitHead(dawn_dir) + get_gitResolvedHead(dawn_dir)
+
+    def get_file_renders(self, args):
+        params = compute_params(args)
+
+        return [
+            FileRender('dawn/common/Version.h',
+                       'src/dawn/common/Version_autogen.h', [params]),
+        ]
+
+
+if __name__ == '__main__':
+    sys.exit(run_generator(DawnVersionGenerator()))

generator/templates/dawn/common/Version.h

@@ -0,0 +1,24 @@
+// Copyright 2022 The Dawn 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.
+
+#ifndef COMMON_VERISON_AUTOGEN_H_
+#define COMMON_VERISON_AUTOGEN_H_
+
+namespace dawn {
+
+static constexpr char kGitHash[] = "{{get_gitHash()}}";
+
+} // namespace dawn
+
+#endif  // COMMON_VERISON_AUTOGEN_H_

src/dawn/common/BUILD.gn

@@ -15,6 +15,7 @@
 import("../../../scripts/dawn_overrides_with_defaults.gni")
 
 import("//build_overrides/build.gni")
+import("${dawn_root}/generator/dawn_generator.gni")
 import("${dawn_root}/scripts/dawn_features.gni")
 
 # Use Chromium's dcheck_always_on when available so that we respect it when
@@ -167,6 +168,15 @@ config("internal_config") {
 # Common dawn library
 ###############################################################################
 
+dawn_generator("dawn_version_gen") {
+  script = "${dawn_root}/generator/dawn_version_generator.py"
+  args = [
+    "--dawn-dir",
+    rebase_path("${dawn_root}", root_build_dir),
+  ]
+  outputs = [ "src/dawn/common/Version_autogen.h" ]
+}
+
 # This GN file is discovered by all Chromium builds, but common doesn't support
 # all of Chromium's OSes so we explicitly make the target visible only on
 # systems we know Dawn is able to compile on.
@@ -223,6 +233,8 @@ if (is_win || is_linux || is_chromeos || is_mac || is_fuchsia || is_android) {
       "xlib_with_undefs.h",
     ]
 
+    public_deps = [ ":dawn_version_gen" ]
+
     if (is_mac) {
       sources += [ "SystemUtils_mac.mm" ]
     }
@@ -241,7 +253,7 @@ if (is_win || is_linux || is_chromeos || is_mac || is_fuchsia || is_android) {
       ]
     }
     if (dawn_enable_vulkan) {
-      public_deps = [ "${dawn_root}/third_party/khronos:vulkan_headers" ]
+      public_deps += [ "${dawn_root}/third_party/khronos:vulkan_headers" ]
     }
     if (is_android) {
       libs = [ "log" ]

src/dawn/common/CMakeLists.txt

@@ -12,8 +12,17 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+DawnGenerator(
+    SCRIPT "${Dawn_SOURCE_DIR}/generator/dawn_version_generator.py"
+    PRINT_NAME "Dawn version based utilities"
+    ARGS "--dawn-dir"
+         "${Dawn_SOURCE_DIR}"
+    RESULT_VARIABLE "DAWN_VERSION_AUTOGEN_SOURCES"
+)
+
 add_library(dawn_common STATIC ${DAWN_DUMMY_FILE})
 target_sources(dawn_common PRIVATE
+    ${DAWN_VERSION_AUTOGEN_SOURCES}
     "Alloc.h"
     "Assert.cpp"
     "Assert.h"

src/dawn/tests/BUILD.gn

@@ -238,6 +238,7 @@ dawn_test("dawn_unittests") {
     "unittests/SystemUtilsTests.cpp",
     "unittests/ToBackendTests.cpp",
     "unittests/TypedIntegerTests.cpp",
+    "unittests/VersionTests.cpp",
     "unittests/native/CacheKeyTests.cpp",
     "unittests/native/CommandBufferEncodingTests.cpp",
     "unittests/native/CreatePipelineAsyncTaskTests.cpp",

src/dawn/tests/unittests/VersionTests.cpp

@@ -0,0 +1,29 @@
+// Copyright 2022 The Dawn 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.
+
+#include <gmock/gmock.h>
+#include <gtest/gtest.h>
+
+#include "dawn/common/Version_autogen.h"
+
+namespace dawn { namespace {
+
+    using ::testing::SizeIs;
+
+    TEST(VersionTests, GitCommitHashLength) {
+        // Git hashes should be 40 characters long.
+        EXPECT_THAT(std::string(kGitHash), SizeIs(40));
+    }
+
+}}  // namespace dawn::