Add a simple microbenchmark framework, packaging, and sample tests.

src/platform/microbenchmark/microbenchmark.cc

+// Copyright (c) 2009 The Chromium OS Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+// Some portions Copyright (c) 2009 The Chromium Authors.
+
+#include "microbenchmark/microbenchmark.h"
+
+namespace chromeos {
+// Commandline switch used to override the default number of runs for all
+// tests.
+const char *Microbenchmark::kRunsSwitch = "microbenchmark-runs";
+
+void Microbenchmark::Run(uint64 number_of_runs) {
+  runs_ = number_of_runs;
+  Setup(number_of_runs);
+
+  uint64 current_run = runs_;
+  struct timespec start_time;
+  struct timespec stop_time;
+  // First we time the scaffolding.
+  clock_gettime(CLOCK_REALTIME, &start_time);
+  while (current_run--) {
+    SingleTest(true);
+  }
+  clock_gettime(CLOCK_REALTIME, &stop_time);
+  scaffold_total_ns_ +=
+    ((stop_time.tv_sec - start_time.tv_sec) * 1000000000ULL) +
+    (stop_time.tv_nsec - start_time.tv_nsec);
+  scaffold_per_run_ns_ = scaffold_total_ns_ / runs_;
+  // Now the real deal.
+  current_run = runs_;
+  clock_gettime(CLOCK_REALTIME, &start_time);
+  while (current_run--) {
+    SingleTest(false);
+  }
+  clock_gettime(CLOCK_REALTIME, &stop_time);
+  total_ns_ += ((stop_time.tv_sec - start_time.tv_sec) * 1000000000ULL) +
+               (stop_time.tv_nsec - start_time.tv_nsec);
+  per_run_ns_ = total_ns_ / runs_;
+}
+
+void Microbenchmark::Print() const {
+  LOG(WARNING) << "All measurements in nanoseconds";
+  LOG(WARNING) << "Numbers may overflow and may not be statistically "
+               << "meaningful.";
+  std::cout << "MB:name,runs,total_ns,per_run_ns\nMB:"
+            << name() << "-scaffold,"
+            << runs() << ","
+            << scaffold_total_nanoseconds() << ","
+            << scaffold_per_run_nanoseconds() << "\nMB:"
+            << name() << ","
+            << runs() << ","
+            << total_nanoseconds() << ","
+            << per_run_nanoseconds() << "\nMB:"
+            << name() << "-adjusted,"
+            << runs() << ","
+            << total_nanoseconds() - scaffold_total_nanoseconds() << ""
+            << per_run_nanoseconds() - scaffold_per_run_nanoseconds()
+            << "\n";
+}
+
+// Hide away helper functions here.
+namespace microbenchmark_helper {
+// Empty setup function.
+void NoSetup(uint64) { }
+
+}  // namespace microbenchmark_helper
+}  // namespace chromeos
+