base/time_win_unittest.cc

   1 // Copyright (c) 2010 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 <windows.h>
   6 #include <mmsystem.h>
   7 #include <process.h>
   8
   9 #include "base/threading/platform_thread.h"
  10 #include "base/time.h"
  11 #include "testing/gtest/include/gtest/gtest.h"
  12
  13 using base::Time;
  14 using base::TimeDelta;
  15 using base::TimeTicks;
  16
  17 namespace {
  18
  19 class MockTimeTicks : public TimeTicks {
  20  public:
  21   static DWORD Ticker() {
  22     return static_cast<int>(InterlockedIncrement(&ticker_));
  23   }
  24
  25   static void InstallTicker() {
  26     old_tick_function_ = SetMockTickFunction(&Ticker);
  27     ticker_ = -5;
  28   }
  29
  30   static void UninstallTicker() {
  31     SetMockTickFunction(old_tick_function_);
  32   }
  33
  34  private:
  35   static volatile LONG ticker_;
  36   static TickFunctionType old_tick_function_;
  37 };
  38
  39 volatile LONG MockTimeTicks::ticker_;
  40 MockTimeTicks::TickFunctionType MockTimeTicks::old_tick_function_;
  41
  42 HANDLE g_rollover_test_start;
  43
  44 unsigned __stdcall RolloverTestThreadMain(void* param) {
  45   int64 counter = reinterpret_cast<int64>(param);
  46   DWORD rv = WaitForSingleObject(g_rollover_test_start, INFINITE);
  47   EXPECT_EQ(rv, WAIT_OBJECT_0);
  48
  49   TimeTicks last = TimeTicks::Now();
  50   for (int index = 0; index < counter; index++) {
  51     TimeTicks now = TimeTicks::Now();
  52     int64 milliseconds = (now - last).InMilliseconds();
  53     // This is a tight loop; we could have looped faster than our
  54     // measurements, so the time might be 0 millis.
  55     EXPECT_GE(milliseconds, 0);
  56     EXPECT_LT(milliseconds, 250);
  57     last = now;
  58   }
  59   return 0;
  60 }
  61
  62 }  // namespace
  63
  64 TEST(TimeTicks, WinRollover) {
  65   // The internal counter rolls over at ~49days.  We'll use a mock
  66   // timer to test this case.
  67   // Basic test algorithm:
  68   //   1) Set clock to rollover - N
  69   //   2) Create N threads
  70   //   3) Start the threads
  71   //   4) Each thread loops through TimeTicks() N times
  72   //   5) Each thread verifies integrity of result.
  73
  74   const int kThreads = 8;
  75   // Use int64 so we can cast into a void* without a compiler warning.
  76   const int64 kChecks = 10;
  77
  78   // It takes a lot of iterations to reproduce the bug!
  79   // (See bug 1081395)
  80   for (int loop = 0; loop < 4096; loop++) {
  81     // Setup
  82     MockTimeTicks::InstallTicker();
  83     g_rollover_test_start = CreateEvent(0, TRUE, FALSE, 0);
  84     HANDLE threads[kThreads];
  85
  86     for (int index = 0; index < kThreads; index++) {
  87       void* argument = reinterpret_cast<void*>(kChecks);
  88       unsigned thread_id;
  89       threads[index] = reinterpret_cast<HANDLE>(
  90         _beginthreadex(NULL, 0, RolloverTestThreadMain, argument, 0,
  91           &thread_id));
  92       EXPECT_NE((HANDLE)NULL, threads[index]);
  93     }
  94
  95     // Start!
  96     SetEvent(g_rollover_test_start);
  97
  98     // Wait for threads to finish
  99     for (int index = 0; index < kThreads; index++) {
 100       DWORD rv = WaitForSingleObject(threads[index], INFINITE);
 101       EXPECT_EQ(rv, WAIT_OBJECT_0);
 102     }
 103
 104     CloseHandle(g_rollover_test_start);
 105
 106     // Teardown
 107     MockTimeTicks::UninstallTicker();
 108   }
 109 }
 110
 111 TEST(TimeTicks, SubMillisecondTimers) {
 112   // HighResNow doesn't work on some systems.  Since the product still works
 113   // even if it doesn't work, it makes this entire test questionable.
 114   if (!TimeTicks::IsHighResClockWorking())
 115     return;
 116
 117   const int kRetries = 1000;
 118   bool saw_submillisecond_timer = false;
 119
 120   // Run kRetries attempts to see a sub-millisecond timer.
 121   for (int index = 0; index < 1000; index++) {
 122     TimeTicks last_time = TimeTicks::HighResNow();
 123     TimeDelta delta;
 124     // Spin until the clock has detected a change.
 125     do {
 126       delta = TimeTicks::HighResNow() - last_time;
 127     } while (delta.InMicroseconds() == 0);
 128     if (delta.InMicroseconds() < 1000) {
 129       saw_submillisecond_timer = true;
 130       break;
 131     }
 132   }
 133   EXPECT_TRUE(saw_submillisecond_timer);
 134 }
 135
 136 TEST(TimeTicks, TimeGetTimeCaps) {
 137   // Test some basic assumptions that we expect about how timeGetDevCaps works.
 138
 139   TIMECAPS caps;
 140   MMRESULT status = timeGetDevCaps(&caps, sizeof(caps));
 141   EXPECT_EQ(TIMERR_NOERROR, status);
 142   if (status != TIMERR_NOERROR) {
 143     printf("Could not get timeGetDevCaps\n");
 144     return;
 145   }
 146
 147   EXPECT_GE(static_cast<int>(caps.wPeriodMin), 1);
 148   EXPECT_GT(static_cast<int>(caps.wPeriodMax), 1);
 149   EXPECT_GE(static_cast<int>(caps.wPeriodMin), 1);
 150   EXPECT_GT(static_cast<int>(caps.wPeriodMax), 1);
 151   printf("timeGetTime range is %d to %dms\n", caps.wPeriodMin,
 152     caps.wPeriodMax);
 153 }
 154
 155 TEST(TimeTicks, QueryPerformanceFrequency) {
 156   // Test some basic assumptions that we expect about QPC.
 157
 158   LARGE_INTEGER frequency;
 159   BOOL rv = QueryPerformanceFrequency(&frequency);
 160   EXPECT_EQ(TRUE, rv);
 161   EXPECT_GT(frequency.QuadPart, 1000000);  // Expect at least 1MHz
 162   printf("QueryPerformanceFrequency is %5.2fMHz\n",
 163     frequency.QuadPart / 1000000.0);
 164 }
 165
 166 TEST(TimeTicks, TimerPerformance) {
 167   // Verify that various timer mechanisms can always complete quickly.
 168   // Note:  This is a somewhat arbitrary test.
 169   const int kLoops = 10000;
 170   // Due to the fact that these run on bbots, which are horribly slow,
 171   // we can't really make any guarantees about minimum runtime.
 172   // Really, we want these to finish in ~10ms, and that is generous.
 173   const int kMaxTime = 35;  // Maximum acceptible milliseconds for test.
 174
 175   typedef TimeTicks (*TestFunc)();
 176   struct TestCase {
 177     TestFunc func;
 178     char *description;
 179   };
 180   // Cheating a bit here:  assumes sizeof(TimeTicks) == sizeof(Time)
 181   // in order to create a single test case list.
 182   COMPILE_ASSERT(sizeof(TimeTicks) == sizeof(Time),
 183                  test_only_works_with_same_sizes);
 184   TestCase cases[] = {
 185     { reinterpret_cast<TestFunc>(Time::Now), "Time::Now" },
 186     { TimeTicks::Now, "TimeTicks::Now" },
 187     { TimeTicks::HighResNow, "TimeTicks::HighResNow" },
 188     { NULL, "" }
 189   };
 190
 191   int test_case = 0;
 192   while (cases[test_case].func) {
 193     TimeTicks start = TimeTicks::HighResNow();
 194     for (int index = 0; index < kLoops; index++)
 195       cases[test_case].func();
 196     TimeTicks stop = TimeTicks::HighResNow();
 197     // Turning off the check for acceptible delays.  Without this check,
 198     // the test really doesn't do much other than measure.  But the
 199     // measurements are still useful for testing timers on various platforms.
 200     // The reason to remove the check is because the tests run on many
 201     // buildbots, some of which are VMs.  These machines can run horribly
 202     // slow, and there is really no value for checking against a max timer.
 203     //EXPECT_LT((stop - start).InMilliseconds(), kMaxTime);
 204     printf("%s: %1.2fus per call\n", cases[test_case].description,
 205       (stop - start).InMillisecondsF() * 1000 / kLoops);
 206     test_case++;
 207   }
 208 }
 209
 210 TEST(TimeTicks, Drift) {
 211   const int kIterations = 100;
 212   int64 total_drift = 0;
 213
 214   for (int i = 0; i < kIterations; ++i) {
 215     int64 drift_microseconds = TimeTicks::GetQPCDriftMicroseconds();
 216
 217     // Make sure the drift never exceeds our limit.
 218     EXPECT_LT(drift_microseconds, 50000);
 219
 220     // Sleep for a few milliseconds (note that it means 1000 microseconds).
 221     // If we check the drift too frequently, it's going to increase
 222     // monotonically, making our measurement less realistic.
 223     base::PlatformThread::Sleep((i % 2 == 0) ? 1 : 2);
 224
 225     total_drift += drift_microseconds;
 226   }
 227
 228   // Sanity check. We expect some time drift to occur, especially across
 229   // the number of iterations we do. However, if the QPC is disabled, this
 230   // is not measuring anything (drift is zero in that case).
 231   EXPECT_LT(0, total_drift);
 232
 233   printf("average time drift in microseconds: %lld\n",
 234          total_drift / kIterations);
 235 }