[image_decode_bench] Use //base CommandLine to process arguments

 - use //base CommandLine to process the command line arguments
 - add support for benching multiple input image files
 - include the input file file name in the output
 - add program usage and help arguments -h --help
 - retain the -i iterations option for now
 - remove an old TODO

Bug: 601198
Change-Id: Ib4e942dcc89ef9ff7eda6271f0cb3d0f93c5cca1
Reviewed-on: https://chromium-review.googlesource.com/c/1454104Reviewed-by: Leon Scroggins <scroggo@chromium.org>
Commit-Queue: Noel Gordon <noel@chromium.org>
Cr-Commit-Position: refs/heads/master@{#630123}

third_party/blink/renderer/platform/testing/image_decode_bench.cc

@@ -4,13 +4,7 @@
 
 // Provides a minimal wrapping of the Blink image decoders. Used to perform
 // a non-threaded, memory-to-memory image decode using micro second accuracy
-// clocks to measure image decode time. Basic usage:
-//
-//   % ninja -C out/Release image_decode_bench &&
-//      ./out/Release/image_decode_bench file [iterations]
-//
-// TODO(noel): Consider adding md5 checksum support to WTF. Use it to compute
-// the decoded image frame md5 and output that value.
+// clocks to measure image decode time.
 //
 // TODO(noel): Consider integrating this tool in Chrome telemetry for realz,
 // using the image corpora used to assess Blink image decode performance. See
@@ -82,55 +76,75 @@ void DecodeImageData(SharedBuffer* data, ImageMeta* image) {
   image->frames = frame_count;
 }
 
+const char* program = nullptr;
+
+base::CommandLine* CommandLineInitialize(int argc, char* argv[]) {
+  program = argv[0];
+  CHECK(base::CommandLine::Init(argc, argv));
+  return base::CommandLine::ForCurrentProcess();
+}
+
+void ShowUsageAndExit() {
+  fprintf(stderr, "Usage: %s [-i=iterations] file [file...]\n", program);
+  exit(1);
+}
+
+bool CommandLineHelp(const base::CommandLine* command_line) {
+  return command_line->HasSwitch("help") || command_line->HasSwitch("h");
+}
+
+unsigned CommandLineIterations(const base::CommandLine* command_line) {
+  if (!command_line->HasSwitch("i"))
+    return 1;
+  int iterations = atoi(command_line->GetSwitchValueASCII("i").c_str());
+  if (iterations >= 1)
+    return unsigned(iterations);
+  ShowUsageAndExit();
+  return 0;
+}
+
 }  // namespace
 
 int ImageDecodeBenchMain(int argc, char* argv[]) {
-  base::CommandLine::Init(argc, argv);
-  const char* program = argv[0];
+  base::CommandLine* command_line = CommandLineInitialize(argc, argv);
 
-  if (argc < 2) {
-    fprintf(stderr, "Usage: %s file [iterations]\n", program);
-    exit(1);
-  }
+  if (CommandLineHelp(command_line) || !command_line->GetArgs().size())
+    ShowUsageAndExit();
 
-  // Control bench decode iterations.
-
-  size_t decode_iterations = 1;
-  if (argc >= 3) {
-    char* end = nullptr;
-    decode_iterations = strtol(argv[2], &end, 10);
-    if (*end != '\0' || !decode_iterations) {
-      fprintf(stderr,
-              "Second argument should be number of iterations. "
-              "The default is 1. You supplied %s\n",
-              argv[2]);
-      exit(1);
-    }
-  }
+  const unsigned iterations = CommandLineIterations(command_line);
+
+  // Setup Blink platform.
 
   std::unique_ptr<Platform> platform = std::make_unique<Platform>();
   Platform::CreateMainThreadAndInitialize(platform.get());
 
-  // Read entire file content into |data| (a contiguous block of memory) then
-  // decode it to verify the image and record its ImageMeta data.
+  // Bench each image file.
 
-  ImageMeta image = {argv[1], 0, 0, 0, 0};
-  scoped_refptr<SharedBuffer> data = ReadFile(argv[1]);
-  DecodeImageData(data.get(), &image);
+  for (const auto& file : command_line->GetArgs()) {
+    const char* name = file.c_str();
 
-  // Image decode bench for decode_iterations.
+    // Read entire file content into |data| (a contiguous block of memory) then
+    // decode it to verify the image and record its ImageMeta data.
 
-  double total_time = 0.0;
-  for (size_t i = 0; i < decode_iterations; ++i) {
-    image.time = 0.0;
+    ImageMeta image = {name, 0, 0, 0, 0};
+    scoped_refptr<SharedBuffer> data = ReadFile(name);
     DecodeImageData(data.get(), &image);
-    total_time += image.time;
-  }
 
-  // Results to stdout.
+    // Image decode bench for iterations.
+
+    double total_time = 0.0;
+    for (unsigned i = 0; i < iterations; ++i) {
+      image.time = 0.0;
+      DecodeImageData(data.get(), &image);
+      total_time += image.time;
+    }
+
+    // Results to stdout.
+
+    double average_time = total_time / iterations;
+    printf("%f %f %s\n", total_time, average_time, name);
+  }
 
-  double average_time = total_time / decode_iterations;
-  printf("%f %f\n", total_time, average_time);
   return 0;
 }