base/time/time_win_unittest.cc

   1 // Copyright (c) 2012 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/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       // Since using _beginthreadex() (as opposed to _beginthread),
 103       // an explicit CloseHandle() is supposed to be called.
 104       CloseHandle(threads[index]);
 105     }
 106
 107     CloseHandle(g_rollover_test_start);
 108
 109     // Teardown
 110     MockTimeTicks::UninstallTicker();
 111   }
 112 }
 113
 114 TEST(TimeTicks, SubMillisecondTimers) {
 115   // HighResNow doesn't work on some systems.  Since the product still works
 116   // even if it doesn't work, it makes this entire test questionable.
 117   if (!TimeTicks::IsHighResClockWorking())
 118     return;
 119
 120   const int kRetries = 1000;
 121   bool saw_submillisecond_timer = false;
 122
 123   // Run kRetries attempts to see a sub-millisecond timer.
 124   for (int index = 0; index < kRetries; index++) {
 125     TimeTicks last_time = TimeTicks::HighResNow();
 126     TimeDelta delta;
 127     // Spin until the clock has detected a change.
 128     do {
 129       delta = TimeTicks::HighResNow() - last_time;
 130     } while (delta.InMicroseconds() == 0);
 131     if (delta.InMicroseconds() < 1000) {
 132       saw_submillisecond_timer = true;
 133       break;
 134     }
 135   }
 136   EXPECT_TRUE(saw_submillisecond_timer);
 137 }
 138
 139 TEST(TimeTicks, TimeGetTimeCaps) {
 140   // Test some basic assumptions that we expect about how timeGetDevCaps works.
 141
 142   TIMECAPS caps;
 143   MMRESULT status = timeGetDevCaps(&caps, sizeof(caps));
 144   EXPECT_EQ(TIMERR_NOERROR, status);
 145   if (status != TIMERR_NOERROR) {
 146     printf("Could not get timeGetDevCaps\n");
 147     return;
 148   }
 149
 150   EXPECT_GE(static_cast<int>(caps.wPeriodMin), 1);
 151   EXPECT_GT(static_cast<int>(caps.wPeriodMax), 1);
 152   EXPECT_GE(static_cast<int>(caps.wPeriodMin), 1);
 153   EXPECT_GT(static_cast<int>(caps.wPeriodMax), 1);
 154   printf("timeGetTime range is %d to %dms\n", caps.wPeriodMin,
 155     caps.wPeriodMax);
 156 }
 157
 158 TEST(TimeTicks, QueryPerformanceFrequency) {
 159   // Test some basic assumptions that we expect about QPC.
 160
 161   LARGE_INTEGER frequency;
 162   BOOL rv = QueryPerformanceFrequency(&frequency);
 163   EXPECT_EQ(TRUE, rv);
 164   EXPECT_GT(frequency.QuadPart, 1000000);  // Expect at least 1MHz
 165   printf("QueryPerformanceFrequency is %5.2fMHz\n",
 166     frequency.QuadPart / 1000000.0);
 167 }
 168
 169 TEST(TimeTicks, TimerPerformance) {
 170   // Verify that various timer mechanisms can always complete quickly.
 171   // Note:  This is a somewhat arbitrary test.
 172   const int kLoops = 10000;
 173
 174   typedef TimeTicks (*TestFunc)();
 175   struct TestCase {
 176     TestFunc func;
 177     const char *description;
 178   };
 179   // Cheating a bit here:  assumes sizeof(TimeTicks) == sizeof(Time)
 180   // in order to create a single test case list.
 181   COMPILE_ASSERT(sizeof(TimeTicks) == sizeof(Time),
 182                  test_only_works_with_same_sizes);
 183   TestCase cases[] = {
 184     { reinterpret_cast<TestFunc>(Time::Now), "Time::Now" },
 185     { TimeTicks::Now, "TimeTicks::Now" },
 186     { TimeTicks::HighResNow, "TimeTicks::HighResNow" },
 187     { NULL, "" }
 188   };
 189
 190   int test_case = 0;
 191   while (cases[test_case].func) {
 192     TimeTicks start = TimeTicks::HighResNow();
 193     for (int index = 0; index < kLoops; index++)
 194       cases[test_case].func();
 195     TimeTicks stop = TimeTicks::HighResNow();
 196     // Turning off the check for acceptible delays.  Without this check,
 197     // the test really doesn't do much other than measure.  But the
 198     // measurements are still useful for testing timers on various platforms.
 199     // The reason to remove the check is because the tests run on many
 200     // buildbots, some of which are VMs.  These machines can run horribly
 201     // slow, and there is really no value for checking against a max timer.
 202     //const int kMaxTime = 35;  // Maximum acceptible milliseconds for test.
 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 // http://crbug.com/396384
 211 TEST(TimeTicks, DISABLED_Drift) {
 212   // If QPC is disabled, this isn't measuring anything.
 213   if (!TimeTicks::IsHighResClockWorking())
 214     return;
 215
 216   const int kIterations = 100;
 217   int64 total_drift = 0;
 218
 219   for (int i = 0; i < kIterations; ++i) {
 220     int64 drift_microseconds = TimeTicks::GetQPCDriftMicroseconds();
 221
 222     // Make sure the drift never exceeds our limit.
 223     EXPECT_LT(drift_microseconds, 50000);
 224
 225     // Sleep for a few milliseconds (note that it means 1000 microseconds).
 226     // If we check the drift too frequently, it's going to increase
 227     // monotonically, making our measurement less realistic.
 228     base::PlatformThread::Sleep(
 229         base::TimeDelta::FromMilliseconds((i % 2 == 0) ? 1 : 2));
 230
 231     total_drift += drift_microseconds;
 232   }
 233
 234   // Sanity check. We expect some time drift to occur, especially across
 235   // the number of iterations we do.
 236   EXPECT_LT(0, total_drift);
 237
 238   printf("average time drift in microseconds: %lld\n",
 239          total_drift / kIterations);
 240 }
 241
 242 int64 QPCValueToMicrosecondsSafely(LONGLONG qpc_value,
 243                                    int64 ticks_per_second) {
 244   int64 whole_seconds = qpc_value / ticks_per_second;
 245   int64 leftover_ticks = qpc_value % ticks_per_second;
 246   int64 microseconds = (whole_seconds * Time::kMicrosecondsPerSecond) +
 247                        ((leftover_ticks * Time::kMicrosecondsPerSecond) /
 248                         ticks_per_second);
 249   return microseconds;
 250 }
 251
 252 TEST(TimeTicks, FromQPCValue) {
 253   if (!TimeTicks::IsHighResClockWorking())
 254     return;
 255   LARGE_INTEGER frequency;
 256   QueryPerformanceFrequency(&frequency);
 257   int64 ticks_per_second = frequency.QuadPart;
 258   LONGLONG qpc_value = Time::kQPCOverflowThreshold;
 259   TimeTicks expected_value = TimeTicks::FromInternalValue(
 260     QPCValueToMicrosecondsSafely(qpc_value + 1, ticks_per_second));
 261   EXPECT_EQ(expected_value,
 262             TimeTicks::FromQPCValue(qpc_value + 1));
 263   expected_value = TimeTicks::FromInternalValue(
 264     QPCValueToMicrosecondsSafely(qpc_value, ticks_per_second));
 265   EXPECT_EQ(expected_value,
 266             TimeTicks::FromQPCValue(qpc_value));
 267   expected_value = TimeTicks::FromInternalValue(
 268     QPCValueToMicrosecondsSafely(qpc_value - 1, ticks_per_second));
 269   EXPECT_EQ(expected_value,
 270             TimeTicks::FromQPCValue(qpc_value - 1));
 271 }