C++ ThreadProfile::GetStack方法代码示例

void TableTicker::Tick(TickSample* sample)
{
  // Marker(s) come before the sample
  ProfileStack* stack = mPrimaryThreadProfile.GetStack();
  for (int i = 0; stack->getMarker(i) != NULL; i++) {
    mPrimaryThreadProfile.addTag(ProfileEntry('m', stack->getMarker(i)));
  }
  stack->mQueueClearMarker = true;

  bool recordSample = true;
  if (mJankOnly) {
    // if we are on a different event we can discard any temporary samples
    // we've kept around
    if (sLastSampledEventGeneration != sCurrentEventGeneration) {
      // XXX: we also probably want to add an entry to the profile to help
      // distinguish which samples are part of the same event. That, or record
      // the event generation in each sample
      mPrimaryThreadProfile.erase();
    }
    sLastSampledEventGeneration = sCurrentEventGeneration;

    recordSample = false;
    // only record the events when we have a we haven't seen a tracer event for 100ms
    if (!sLastTracerEvent.IsNull()) {
      TimeDuration delta = sample->timestamp - sLastTracerEvent;
      if (delta.ToMilliseconds() > 100.0) {
          recordSample = true;
      }
    }
  }

#if defined(USE_BACKTRACE) || defined(USE_NS_STACKWALK) || defined(USE_LIBUNWIND)
  if (mUseStackWalk) {
    doBacktrace(mPrimaryThreadProfile, sample);
  } else {
    doSampleStackTrace(stack, mPrimaryThreadProfile, sample);
  }
#else
  doSampleStackTrace(stack, mPrimaryThreadProfile, sample);
#endif

  if (recordSample)
    mPrimaryThreadProfile.flush();

  if (!sLastTracerEvent.IsNull() && sample) {
    TimeDuration delta = sample->timestamp - sLastTracerEvent;
    mPrimaryThreadProfile.addTag(ProfileEntry('r', delta.ToMilliseconds()));
  }

  if (sample) {
    TimeDuration delta = sample->timestamp - mStartTime;
    mPrimaryThreadProfile.addTag(ProfileEntry('t', delta.ToMilliseconds()));
  }

  if (sLastFrameNumber != sFrameNumber) {
    mPrimaryThreadProfile.addTag(ProfileEntry('f', sFrameNumber));
    sLastFrameNumber = sFrameNumber;
  }
}

void TableTicker::doBacktrace(ThreadProfile &aProfile, TickSample* aSample)
{
#ifndef XP_MACOSX
  uintptr_t thread = GetThreadHandle(platform_data());
  MOZ_ASSERT(thread);
#endif
  void* pc_array[1000];
  void* sp_array[1000];
  PCArray array = {
    pc_array,
    sp_array,
    mozilla::ArrayLength(pc_array),
    0
  };

  // Start with the current function.
  StackWalkCallback(aSample->pc, aSample->sp, &array);

#ifdef XP_MACOSX
  pthread_t pt = GetProfiledThread(platform_data());
  void *stackEnd = reinterpret_cast<void*>(-1);
  if (pt)
    stackEnd = static_cast<char*>(pthread_get_stackaddr_np(pt));
  nsresult rv = FramePointerStackWalk(StackWalkCallback, 0, &array, reinterpret_cast<void**>(aSample->fp), stackEnd);
#else
  nsresult rv = NS_StackWalk(StackWalkCallback, 0, &array, thread);
#endif
  if (NS_SUCCEEDED(rv)) {
    aProfile.addTag(ProfileEntry('s', "(root)"));

    ProfileStack* stack = aProfile.GetStack();
    int pseudoStackPos = 0;

    /* We have two stacks, the native C stack we extracted from unwinding,
     * and the pseudostack we managed during execution. We want to consolidate
     * the two in order. We do so by merging using the approximate stack address
     * when each entry was push. When pushing JS entry we may not now the stack
     * address in which case we have a NULL stack address in which case we assume
     * that it follows immediatly the previous element.
     *
     *  C Stack | Address    --  Pseudo Stack | Address
     *  main()  | 0x100          run_js()     | 0x40
     *  start() | 0x80           jsCanvas()   | NULL
     *  timer() | 0x50           drawLine()   | NULL
     *  azure() | 0x10
     *
     * Merged: main(), start(), timer(), run_js(), jsCanvas(), drawLine(), azure()
     */
    // i is the index in C stack starting at main and decreasing
    // pseudoStackPos is the position in the Pseudo stack starting
    // at the first frame (run_js in the example) and increasing.
    for (size_t i = array.count; i > 0; --i) {
      while (pseudoStackPos < stack->stackSize()) {
        volatile StackEntry& entry = stack->mStack[pseudoStackPos];

        if (entry.stackAddress() < array.sp_array[i-1] && entry.stackAddress())
          break;

        addProfileEntry(entry, aProfile, stack, array.array[0]);
        pseudoStackPos++;
      }

      aProfile.addTag(ProfileEntry('l', (void*)array.array[i-1]));
    }
  }
}