xref: /third_party/gn/src/util/ticks.cc (revision 6d528ed9) 
1// Copyright 2018 The Chromium Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5#include "ticks.h"
6
7#include "base/logging.h"
8#include "build_config.h"
9
10#if defined(OS_WIN)
11#include <windows.h>
12#elif defined(OS_MACOSX)
13#include <mach/mach_time.h>
14#elif defined(OS_POSIX)
15#include <time.h>
16#else
17#error Port.
18#endif
19
20namespace {
21
22bool g_initialized;
23
24#if defined(OS_WIN)
25LARGE_INTEGER g_frequency;
26LARGE_INTEGER g_start;
27#elif defined(OS_MACOSX)
28mach_timebase_info_data_t g_timebase;
29uint64_t g_start;
30#elif defined(OS_POSIX)
31uint64_t g_start;
32#else
33#error Port.
34#endif
35
36#if !defined(OS_MACOSX)
37constexpr uint64_t kNano = 1'000'000'000;
38#endif
39
40void Init() {
41  DCHECK(!g_initialized);
42
43#if defined(OS_WIN)
44  QueryPerformanceFrequency(&g_frequency);
45  QueryPerformanceCounter(&g_start);
46#elif defined(OS_MACOSX)
47  mach_timebase_info(&g_timebase);
48  g_start = (mach_absolute_time() * g_timebase.numer) / g_timebase.denom;
49#elif defined(OS_POSIX)
50  struct timespec ts;
51  clock_gettime(CLOCK_MONOTONIC, &ts);
52  g_start = static_cast<uint64_t>(ts.tv_sec) * kNano +
53            static_cast<uint64_t>(ts.tv_nsec);
54#else
55#error Port.
56#endif
57
58  g_initialized = true;
59}
60
61}  // namespace
62
63Ticks TicksNow() {
64  static bool initialized = []() {
65    Init();
66    return true;
67  }();
68  DCHECK(initialized);
69
70  Ticks now;
71
72#if defined(OS_WIN)
73  LARGE_INTEGER t;
74  QueryPerformanceCounter(&t);
75  now = ((t.QuadPart - g_start.QuadPart) * kNano) / g_frequency.QuadPart;
76#elif defined(OS_MACOSX)
77  now =
78      ((mach_absolute_time() * g_timebase.numer) / g_timebase.denom) - g_start;
79#elif defined(OS_POSIX)
80  struct timespec ts;
81  clock_gettime(CLOCK_MONOTONIC, &ts);
82  now = (static_cast<uint64_t>(ts.tv_sec) * kNano +
83         static_cast<uint64_t>(ts.tv_nsec)) -
84        g_start;
85#else
86#error Port.
87#endif
88
89  return now;
90}
91
92TickDelta TicksDelta(Ticks new_ticks, Ticks old_ticks) {
93  DCHECK(new_ticks >= old_ticks);
94  return TickDelta(new_ticks - old_ticks);
95}
96