cc/base/histograms.cc

   1 // Copyright 2015 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 "cc/base/histograms.h"
   6
   7 #include <algorithm>
   8 #include <cmath>
   9 #include <cstring>
  10 #include <limits>
  11
  12 #include "base/lazy_instance.h"
  13 #include "base/logging.h"
  14 #include "base/numerics/safe_conversions.h"
  15 #include "base/synchronization/lock.h"
  16
  17 namespace cc {
  18
  19 // Global data tracking the client name that was set.
  20 // Both of these variables are protected by the lock.
  21 static base::LazyInstance<base::Lock>::Leaky g_client_name_lock =
  22     LAZY_INSTANCE_INITIALIZER;
  23 static const char* g_client_name = nullptr;
  24 static bool g_multiple_client_names_set = false;
  25
  26 void SetClientNameForMetrics(const char* client_name) {
  27   base::AutoLock auto_lock(g_client_name_lock.Get());
  28
  29   // Only warn once.
  30   if (g_multiple_client_names_set)
  31     return;
  32
  33   // If a different name is set, return nullptr from now on and log a warning.
  34   const char* old_client_name = g_client_name;
  35   if (old_client_name && strcmp(old_client_name, client_name)) {
  36     g_client_name = nullptr;
  37     g_multiple_client_names_set = true;
  38     LOG(WARNING) << "Started multiple compositor clients (" << old_client_name
  39                  << ", " << client_name
  40                  << ") in one process. Some metrics will be disabled.";
  41     return;
  42   }
  43
  44   // If the client name is being set for the first time, store it.
  45   if (!old_client_name)
  46     g_client_name = client_name;
  47 }
  48
  49 const char* GetClientNameForMetrics() {
  50   base::AutoLock auto_lock(g_client_name_lock.Get());
  51   return g_client_name;
  52 }
  53
  54 // Minimum elapsed time of 1us to limit weighting of fast calls.
  55 static const int64 kMinimumTimeMicroseconds = 1;
  56
  57 ScopedUMAHistogramAreaTimerBase::ScopedUMAHistogramAreaTimerBase() : area_(0) {
  58 }
  59
  60 ScopedUMAHistogramAreaTimerBase::~ScopedUMAHistogramAreaTimerBase() {
  61 }
  62
  63 bool ScopedUMAHistogramAreaTimerBase::GetHistogramValues(
  64     Sample* time_microseconds,
  65     Sample* pixels_per_ms) const {
  66   return GetHistogramValues(
  67       timer_.Elapsed(), area_.ValueOrDefault(std::numeric_limits<int>::max()),
  68       time_microseconds, pixels_per_ms);
  69 }
  70
  71 // static
  72 bool ScopedUMAHistogramAreaTimerBase::GetHistogramValues(
  73     base::TimeDelta elapsed,
  74     int area,
  75     Sample* time_microseconds,
  76     Sample* pixels_per_ms) {
  77   elapsed = std::max(
  78       elapsed, base::TimeDelta::FromMicroseconds(kMinimumTimeMicroseconds));
  79   double area_per_time = area / elapsed.InMillisecondsF();
  80   // It is not clear how NaN can get here, but we've gotten crashes from
  81   // saturated_cast. http://crbug.com/486214
  82   if (std::isnan(area_per_time))
  83     return false;
  84   *time_microseconds = base::saturated_cast<Sample>(elapsed.InMicroseconds());
  85   *pixels_per_ms = base::saturated_cast<Sample>(area_per_time);
  86   return true;
  87 }
  88
  89 }  // namespace cc