1 files changed, 95 insertions, 0 deletions
diff --git a/gn/src/util/ticks.cc b/gn/src/util/ticks.cc
new file mode 100644
index 00000000000..121c7199120
--- /dev/null
+++ b/gn/src/util/ticks.cc
@@ -0,0 +1,95 @@
+// Copyright 2018 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "ticks.h"
+
+#include "base/logging.h"
+#include "build_config.h"
+
+#if defined(OS_WIN)
+#include <windows.h>
+#elif defined(OS_MACOSX)
+#include <mach/mach_time.h>
+#elif defined(OS_POSIX)
+#include <time.h>
+#else
+#error Port.
+#endif
+
+namespace {
+
+bool g_initialized;
+
+#if defined(OS_WIN)
+LARGE_INTEGER g_frequency;
+LARGE_INTEGER g_start;
+#elif defined(OS_MACOSX)
+mach_timebase_info_data_t g_timebase;
+uint64_t g_start;
+#elif defined(OS_POSIX)
+uint64_t g_start;
+#else
+#error Port.
+#endif
+
+#if !defined(OS_MACOSX)
+constexpr uint64_t kNano = 1'000'000'000;
+#endif
+
+void Init() {
+  DCHECK(!g_initialized);
+
+#if defined(OS_WIN)
+  QueryPerformanceFrequency(&g_frequency);
+  QueryPerformanceCounter(&g_start);
+#elif defined(OS_MACOSX)
+  mach_timebase_info(&g_timebase);
+  g_start = (mach_absolute_time() * g_timebase.numer) / g_timebase.denom;
+#elif defined(OS_POSIX)
+  struct timespec ts;
+  clock_gettime(CLOCK_MONOTONIC, &ts);
+  g_start = static_cast<uint64_t>(ts.tv_sec) * kNano +
+            static_cast<uint64_t>(ts.tv_nsec);
+#else
+#error Port.
+#endif
+
+  g_initialized = true;
+}
+
+}  // namespace
+
+Ticks TicksNow() {
+  static bool initialized = []() {
+    Init();
+    return true;
+  }();
+  DCHECK(initialized);
+
+  Ticks now;
+
+#if defined(OS_WIN)
+  LARGE_INTEGER t;
+  QueryPerformanceCounter(&t);
+  now = ((t.QuadPart - g_start.QuadPart) * kNano) / g_frequency.QuadPart;
+#elif defined(OS_MACOSX)
+  now =
+      ((mach_absolute_time() * g_timebase.numer) / g_timebase.denom) - g_start;
+#elif defined(OS_POSIX)
+  struct timespec ts;
+  clock_gettime(CLOCK_MONOTONIC, &ts);
+  now = (static_cast<uint64_t>(ts.tv_sec) * kNano +
+         static_cast<uint64_t>(ts.tv_nsec)) -
+        g_start;
+#else
+#error Port.
+#endif
+
+  return now;
+}
+
+TickDelta TicksDelta(Ticks new_ticks, Ticks old_ticks) {
+  DCHECK(new_ticks >= old_ticks);
+  return TickDelta(new_ticks - old_ticks);
+}