import FIREFOX_52_6_0esr_RELEASE from mozilla-esr52 hg repo

mozglue/misc/TimeStamp_windows.cpp

@@ -0,0 +1,576 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+// Implement TimeStamp::Now() with QueryPerformanceCounter() controlled with
+// values of GetTickCount().
+
+#include "mozilla/MathAlgorithms.h"
+#include "mozilla/TimeStamp.h"
+
+#include <stdio.h>
+#include <intrin.h>
+#include <windows.h>
+
+// To enable logging define to your favorite logging API
+#define LOG(x)
+
+class AutoCriticalSection
+{
+public:
+  AutoCriticalSection(LPCRITICAL_SECTION aSection)
+    : mSection(aSection)
+  {
+    ::EnterCriticalSection(mSection);
+  }
+  ~AutoCriticalSection()
+  {
+    ::LeaveCriticalSection(mSection);
+  }
+private:
+  LPCRITICAL_SECTION mSection;
+};
+
+// Estimate of the smallest duration of time we can measure.
+static volatile ULONGLONG sResolution;
+static volatile ULONGLONG sResolutionSigDigs;
+static const double   kNsPerSecd  = 1000000000.0;
+static const LONGLONG kNsPerMillisec = 1000000;
+
+// ----------------------------------------------------------------------------
+// Global constants
+// ----------------------------------------------------------------------------
+
+// Tolerance to failures settings.
+//
+// What is the interval we want to have failure free.
+// in [ms]
+static const uint32_t kFailureFreeInterval = 5000;
+// How many failures we are willing to tolerate in the interval.
+static const uint32_t kMaxFailuresPerInterval = 4;
+// What is the threshold to treat fluctuations as actual failures.
+// in [ms]
+static const uint32_t kFailureThreshold = 50;
+
+// If we are not able to get the value of GTC time increment, use this value
+// which is the most usual increment.
+static const DWORD kDefaultTimeIncrement = 156001;
+
+// ----------------------------------------------------------------------------
+// Global variables, not changing at runtime
+// ----------------------------------------------------------------------------
+
+/**
+ * The [mt] unit:
+ *
+ * Many values are kept in ticks of the Performance Coutner x 1000,
+ * further just referred as [mt], meaning milli-ticks.
+ *
+ * This is needed to preserve maximum precision of the performance frequency
+ * representation.  GetTickCount values in milliseconds are multiplied with
+ * frequency per second.  Therefor we need to multiply QPC value by 1000 to
+ * have the same units to allow simple arithmentic with both QPC and GTC.
+ */
+
+#define ms2mt(x) ((x) * sFrequencyPerSec)
+#define mt2ms(x) ((x) / sFrequencyPerSec)
+#define mt2ms_f(x) (double(x) / sFrequencyPerSec)
+
+// Result of QueryPerformanceFrequency
+static LONGLONG sFrequencyPerSec = 0;
+
+// How much we are tolerant to GTC occasional loose of resoltion.
+// This number says how many multiples of the minimal GTC resolution
+// detected on the system are acceptable.  This number is empirical.
+static const LONGLONG kGTCTickLeapTolerance = 4;
+
+// Base tolerance (more: "inability of detection" range) threshold is calculated
+// dynamically, and kept in sGTCResulutionThreshold.
+//
+// Schematically, QPC worked "100%" correctly if ((GTC_now - GTC_epoch) -
+// (QPC_now - QPC_epoch)) was in  [-sGTCResulutionThreshold, sGTCResulutionThreshold]
+// interval every time we'd compared two time stamps.
+// If not, then we check the overflow behind this basic threshold
+// is in kFailureThreshold.  If not, we condider it as a QPC failure.  If too many
+// failures in short time are detected, QPC is considered faulty and disabled.
+//
+// Kept in [mt]
+static LONGLONG sGTCResulutionThreshold;
+
+// If QPC is found faulty for two stamps in this interval, we engage
+// the fault detection algorithm.  For duration larger then this limit
+// we bypass using durations calculated from QPC when jitter is detected,
+// but don't touch the sUseQPC flag.
+//
+// Value is in [ms].
+static const uint32_t kHardFailureLimit = 2000;
+// Conversion to [mt]
+static LONGLONG sHardFailureLimit;
+
+// Conversion of kFailureFreeInterval and kFailureThreshold to [mt]
+static LONGLONG sFailureFreeInterval;
+static LONGLONG sFailureThreshold;
+
+// ----------------------------------------------------------------------------
+// Systemm status flags
+// ----------------------------------------------------------------------------
+
+// Flag for stable TSC that indicates platform where QPC is stable.
+static bool sHasStableTSC = false;
+
+// ----------------------------------------------------------------------------
+// Global state variables, changing at runtime
+// ----------------------------------------------------------------------------
+
+// Initially true, set to false when QPC is found unstable and never
+// returns back to true since that time.
+static bool volatile sUseQPC = true;
+
+// ----------------------------------------------------------------------------
+// Global lock
+// ----------------------------------------------------------------------------
+
+// Thread spin count before entering the full wait state for sTimeStampLock.
+// Inspired by Rob Arnold's work on PRMJ_Now().
+static const DWORD kLockSpinCount = 4096;
+
+// Common mutex (thanks the relative complexity of the logic, this is better
+// then using CMPXCHG8B.)
+// It is protecting the globals bellow.
+static CRITICAL_SECTION sTimeStampLock;
+
+// ----------------------------------------------------------------------------
+// Global lock protected variables
+// ----------------------------------------------------------------------------
+
+// Timestamp in future until QPC must behave correctly.
+// Set to now + kFailureFreeInterval on first QPC failure detection.
+// Set to now + E * kFailureFreeInterval on following errors,
+//   where E is number of errors detected during last kFailureFreeInterval
+//   milliseconds, calculated simply as:
+//   E = (sFaultIntoleranceCheckpoint - now) / kFailureFreeInterval + 1.
+// When E > kMaxFailuresPerInterval -> disable QPC.
+//
+// Kept in [mt]
+static ULONGLONG sFaultIntoleranceCheckpoint = 0;
+
+// Used only when GetTickCount64 is not available on the platform.
+// Last result of GetTickCount call.
+//
+// Kept in [ms]
+static DWORD sLastGTCResult = 0;
+
+// Higher part of the 64-bit value of MozGetTickCount64,
+// incremented atomically.
+static DWORD sLastGTCRollover = 0;
+
+namespace mozilla {
+
+typedef ULONGLONG (WINAPI* GetTickCount64_t)();
+static GetTickCount64_t sGetTickCount64 = nullptr;
+
+// Function protecting GetTickCount result from rolling over,
+// result is in [ms]
+static ULONGLONG WINAPI
+MozGetTickCount64()
+{
+  DWORD GTC = ::GetTickCount();
+
+  // Cheaper then CMPXCHG8B
+  AutoCriticalSection lock(&sTimeStampLock);
+
+  // Pull the rollover counter forward only if new value of GTC goes way
+  // down under the last saved result
+  if ((sLastGTCResult > GTC) && ((sLastGTCResult - GTC) > (1UL << 30))) {
+    ++sLastGTCRollover;
+  }
+
+  sLastGTCResult = GTC;
+  return ULONGLONG(sLastGTCRollover) << 32 | sLastGTCResult;
+}
+
+// Result is in [mt]
+static inline ULONGLONG
+PerformanceCounter()
+{
+  LARGE_INTEGER pc;
+  ::QueryPerformanceCounter(&pc);
+  return pc.QuadPart * 1000ULL;
+}
+
+static void
+InitThresholds()
+{
+  DWORD timeAdjustment = 0, timeIncrement = 0;
+  BOOL timeAdjustmentDisabled;
+  GetSystemTimeAdjustment(&timeAdjustment,
+                          &timeIncrement,
+                          &timeAdjustmentDisabled);
+
+  LOG(("TimeStamp: timeIncrement=%d [100ns]", timeIncrement));
+
+  if (!timeIncrement) {
+    timeIncrement = kDefaultTimeIncrement;
+  }
+
+  // Ceiling to a millisecond
+  // Example values: 156001, 210000
+  DWORD timeIncrementCeil = timeIncrement;
+  // Don't want to round up if already rounded, values will be: 156000, 209999
+  timeIncrementCeil -= 1;
+  // Convert to ms, values will be: 15, 20
+  timeIncrementCeil /= 10000;
+  // Round up, values will be: 16, 21
+  timeIncrementCeil += 1;
+  // Convert back to 100ns, values will be: 160000, 210000
+  timeIncrementCeil *= 10000;
+
+  // How many milli-ticks has the interval rounded up
+  LONGLONG ticksPerGetTickCountResolutionCeiling =
+    (int64_t(timeIncrementCeil) * sFrequencyPerSec) / 10000LL;
+
+  // GTC may jump by 32 (2*16) ms in two steps, therefor use the ceiling value.
+  sGTCResulutionThreshold =
+    LONGLONG(kGTCTickLeapTolerance * ticksPerGetTickCountResolutionCeiling);
+
+  sHardFailureLimit = ms2mt(kHardFailureLimit);
+  sFailureFreeInterval = ms2mt(kFailureFreeInterval);
+  sFailureThreshold = ms2mt(kFailureThreshold);
+}
+
+static void
+InitResolution()
+{
+  // 10 total trials is arbitrary: what we're trying to avoid by
+  // looping is getting unlucky and being interrupted by a context
+  // switch or signal, or being bitten by paging/cache effects
+
+  ULONGLONG minres = ~0ULL;
+  int loops = 10;
+  do {
+    ULONGLONG start = PerformanceCounter();
+    ULONGLONG end = PerformanceCounter();
+
+    ULONGLONG candidate = (end - start);
+    if (candidate < minres) {
+      minres = candidate;
+    }
+  } while (--loops && minres);
+
+  if (0 == minres) {
+    minres = 1;
+  }
+
+  // Converting minres that is in [mt] to nanosecods, multiplicating
+  // the argument to preserve resolution.
+  ULONGLONG result = mt2ms(minres * kNsPerMillisec);
+  if (0 == result) {
+    result = 1;
+  }
+
+  sResolution = result;
+
+  // find the number of significant digits in mResolution, for the
+  // sake of ToSecondsSigDigits()
+  ULONGLONG sigDigs;
+  for (sigDigs = 1;
+       !(sigDigs == result || 10 * sigDigs > result);
+       sigDigs *= 10);
+
+  sResolutionSigDigs = sigDigs;
+}
+
+// ----------------------------------------------------------------------------
+// TimeStampValue implementation
+// ----------------------------------------------------------------------------
+MFBT_API
+TimeStampValue::TimeStampValue(ULONGLONG aGTC, ULONGLONG aQPC, bool aHasQPC)
+  : mGTC(aGTC)
+  , mQPC(aQPC)
+  , mHasQPC(aHasQPC)
+  , mIsNull(false)
+{
+}
+
+MFBT_API TimeStampValue&
+TimeStampValue::operator+=(const int64_t aOther)
+{
+  mGTC += aOther;
+  mQPC += aOther;
+  return *this;
+}
+
+MFBT_API TimeStampValue&
+TimeStampValue::operator-=(const int64_t aOther)
+{
+  mGTC -= aOther;
+  mQPC -= aOther;
+  return *this;
+}
+
+// If the duration is less then two seconds, perform check of QPC stability
+// by comparing both GTC and QPC calculated durations of this and aOther.
+MFBT_API uint64_t
+TimeStampValue::CheckQPC(const TimeStampValue& aOther) const
+{
+  uint64_t deltaGTC = mGTC - aOther.mGTC;
+
+  if (!mHasQPC || !aOther.mHasQPC) { // Both not holding QPC
+    return deltaGTC;
+  }
+
+  uint64_t deltaQPC = mQPC - aOther.mQPC;
+
+  if (sHasStableTSC) { // For stable TSC there is no need to check
+    return deltaQPC;
+  }
+
+  // Check QPC is sane before using it.
+  int64_t diff = DeprecatedAbs(int64_t(deltaQPC) - int64_t(deltaGTC));
+  if (diff <= sGTCResulutionThreshold) {
+    return deltaQPC;
+  }
+
+  // Treat absolutely for calibration purposes
+  int64_t duration = DeprecatedAbs(int64_t(deltaGTC));
+  int64_t overflow = diff - sGTCResulutionThreshold;
+
+  LOG(("TimeStamp: QPC check after %llums with overflow %1.4fms",
+       mt2ms(duration), mt2ms_f(overflow)));
+
+  if (overflow <= sFailureThreshold) {  // We are in the limit, let go.
+    return deltaQPC;
+  }
+
+  // QPC deviates, don't use it, since now this method may only return deltaGTC.
+
+  if (!sUseQPC) { // QPC already disabled, no need to run the fault tolerance algorithm.
+    return deltaGTC;
+  }
+
+  LOG(("TimeStamp: QPC jittered over failure threshold"));
+
+  if (duration < sHardFailureLimit) {
+    // Interval between the two time stamps is very short, consider
+    // QPC as unstable and record a failure.
+    uint64_t now = ms2mt(sGetTickCount64());
+
+    AutoCriticalSection lock(&sTimeStampLock);
+
+    if (sFaultIntoleranceCheckpoint && sFaultIntoleranceCheckpoint > now) {
+      // There's already been an error in the last fault intollerant interval.
+      // Time since now to the checkpoint actually holds information on how many
+      // failures there were in the failure free interval we have defined.
+      uint64_t failureCount =
+        (sFaultIntoleranceCheckpoint - now + sFailureFreeInterval - 1) /
+        sFailureFreeInterval;
+      if (failureCount > kMaxFailuresPerInterval) {
+        sUseQPC = false;
+        LOG(("TimeStamp: QPC disabled"));
+      } else {
+        // Move the fault intolerance checkpoint more to the future, prolong it
+        // to reflect the number of detected failures.
+        ++failureCount;
+        sFaultIntoleranceCheckpoint = now + failureCount * sFailureFreeInterval;
+        LOG(("TimeStamp: recording %dth QPC failure", failureCount));
+      }
+    } else {
+      // Setup fault intolerance checkpoint in the future for first detected error.
+      sFaultIntoleranceCheckpoint = now + sFailureFreeInterval;
+      LOG(("TimeStamp: recording 1st QPC failure"));
+    }
+  }
+
+  return deltaGTC;
+}
+
+MFBT_API uint64_t
+TimeStampValue::operator-(const TimeStampValue& aOther) const
+{
+  if (mIsNull && aOther.mIsNull) {
+    return uint64_t(0);
+  }
+
+  return CheckQPC(aOther);
+}
+
+// ----------------------------------------------------------------------------
+// TimeDuration and TimeStamp implementation
+// ----------------------------------------------------------------------------
+
+MFBT_API double
+BaseTimeDurationPlatformUtils::ToSeconds(int64_t aTicks)
+{
+  // Converting before arithmetic avoids blocked store forward
+  return double(aTicks) / (double(sFrequencyPerSec) * 1000.0);
+}
+
+MFBT_API double
+BaseTimeDurationPlatformUtils::ToSecondsSigDigits(int64_t aTicks)
+{
+  // don't report a value < mResolution ...
+  LONGLONG resolution = sResolution;
+  LONGLONG resolutionSigDigs = sResolutionSigDigs;
+  LONGLONG valueSigDigs = resolution * (aTicks / resolution);
+  // and chop off insignificant digits
+  valueSigDigs = resolutionSigDigs * (valueSigDigs / resolutionSigDigs);
+  return double(valueSigDigs) / kNsPerSecd;
+}
+
+MFBT_API int64_t
+BaseTimeDurationPlatformUtils::TicksFromMilliseconds(double aMilliseconds)
+{
+  double result = ms2mt(aMilliseconds);
+  if (result > INT64_MAX) {
+    return INT64_MAX;
+  } else if (result < INT64_MIN) {
+    return INT64_MIN;
+  }
+
+  return result;
+}
+
+MFBT_API int64_t
+BaseTimeDurationPlatformUtils::ResolutionInTicks()
+{
+  return static_cast<int64_t>(sResolution);
+}
+
+static bool
+HasStableTSC()
+{
+  union
+  {
+    int regs[4];
+    struct
+    {
+      int nIds;
+      char cpuString[12];
+    };
+  } cpuInfo;
+
+  __cpuid(cpuInfo.regs, 0);
+  // Only allow Intel CPUs for now
+  // The order of the registers is reg[1], reg[3], reg[2].  We just adjust the
+  // string so that we can compare in one go.
+  if (_strnicmp(cpuInfo.cpuString, "GenuntelineI",
+                sizeof(cpuInfo.cpuString))) {
+    return false;
+  }
+
+  int regs[4];
+
+  // detect if the Advanced Power Management feature is supported
+  __cpuid(regs, 0x80000000);
+  if (regs[0] < 0x80000007) {
+    return false;
+  }
+
+  __cpuid(regs, 0x80000007);
+  // if bit 8 is set than TSC will run at a constant rate
+  // in all ACPI P-state, C-states and T-states
+  return regs[3] & (1 << 8);
+}
+
+static bool gInitialized = false;
+
+MFBT_API void
+TimeStamp::Startup()
+{
+  if (gInitialized) {
+    return;
+  }
+
+  gInitialized = true;
+
+  // Decide which implementation to use for the high-performance timer.
+
+  HMODULE kernelDLL = GetModuleHandleW(L"kernel32.dll");
+  sGetTickCount64 = reinterpret_cast<GetTickCount64_t>(
+    GetProcAddress(kernelDLL, "GetTickCount64"));
+  if (!sGetTickCount64) {
+    // If the platform does not support the GetTickCount64 (Windows XP doesn't),
+    // then use our fallback implementation based on GetTickCount.
+    sGetTickCount64 = MozGetTickCount64;
+  }
+
+  InitializeCriticalSectionAndSpinCount(&sTimeStampLock, kLockSpinCount);
+
+  sHasStableTSC = HasStableTSC();
+  LOG(("TimeStamp: HasStableTSC=%d", sHasStableTSC));
+
+  LARGE_INTEGER freq;
+  sUseQPC = ::QueryPerformanceFrequency(&freq);
+  if (!sUseQPC) {
+    // No Performance Counter.  Fall back to use GetTickCount.
+    InitResolution();
+
+    LOG(("TimeStamp: using GetTickCount"));
+    return;
+  }
+
+  sFrequencyPerSec = freq.QuadPart;
+  LOG(("TimeStamp: QPC frequency=%llu", sFrequencyPerSec));
+
+  InitThresholds();
+  InitResolution();
+
+  return;
+}
+
+MFBT_API void
+TimeStamp::Shutdown()
+{
+  DeleteCriticalSection(&sTimeStampLock);
+}
+
+MFBT_API TimeStamp
+TimeStamp::Now(bool aHighResolution)
+{
+  // sUseQPC is volatile
+  bool useQPC = (aHighResolution && sUseQPC);
+
+  // Both values are in [mt] units.
+  ULONGLONG QPC = useQPC ? PerformanceCounter() : uint64_t(0);
+  ULONGLONG GTC = ms2mt(sGetTickCount64());
+  return TimeStamp(TimeStampValue(GTC, QPC, useQPC));
+}
+
+// Computes and returns the process uptime in microseconds.
+// Returns 0 if an error was encountered.
+
+MFBT_API uint64_t
+TimeStamp::ComputeProcessUptime()
+{
+  SYSTEMTIME nowSys;
+  GetSystemTime(&nowSys);
+
+  FILETIME now;
+  bool success = SystemTimeToFileTime(&nowSys, &now);
+
+  if (!success) {
+    return 0;
+  }
+
+  FILETIME start, foo, bar, baz;
+  success = GetProcessTimes(GetCurrentProcess(), &start, &foo, &bar, &baz);
+
+  if (!success) {
+    return 0;
+  }
+
+  ULARGE_INTEGER startUsec = {{
+     start.dwLowDateTime,
+     start.dwHighDateTime
+  }};
+  ULARGE_INTEGER nowUsec = {{
+    now.dwLowDateTime,
+    now.dwHighDateTime
+  }};
+
+  return (nowUsec.QuadPart - startUsec.QuadPart) / 10ULL;
+}
+
+} // namespace mozilla