third-party/benchmark/src/thread_timer.h

   1 #ifndef BENCHMARK_THREAD_TIMER_H
   2 #define BENCHMARK_THREAD_TIMER_H
   3
   4 #include "check.h"
   5 #include "timers.h"
   6
   7 namespace benchmark {
   8 namespace internal {
   9
  10 class ThreadTimer {
  11   explicit ThreadTimer(bool measure_process_cpu_time_)
  12       : measure_process_cpu_time(measure_process_cpu_time_) {}
  13
  14  public:
  15   static ThreadTimer Create() {
  16     return ThreadTimer(/*measure_process_cpu_time_=*/false);
  17   }
  18   static ThreadTimer CreateProcessCpuTime() {
  19     return ThreadTimer(/*measure_process_cpu_time_=*/true);
  20   }
  21
  22   // Called by each thread
  23   void StartTimer() {
  24     running_ = true;
  25     start_real_time_ = ChronoClockNow();
  26     start_cpu_time_ = ReadCpuTimerOfChoice();
  27   }
  28
  29   // Called by each thread
  30   void StopTimer() {
  31     BM_CHECK(running_);
  32     running_ = false;
  33     real_time_used_ += ChronoClockNow() - start_real_time_;
  34     // Floating point error can result in the subtraction producing a negative
  35     // time. Guard against that.
  36     cpu_time_used_ +=
  37         std::max<double>(ReadCpuTimerOfChoice() - start_cpu_time_, 0);
  38   }
  39
  40   // Called by each thread
  41   void SetIterationTime(double seconds) { manual_time_used_ += seconds; }
  42
  43   bool running() const { return running_; }
  44
  45   // REQUIRES: timer is not running
  46   double real_time_used() const {
  47     BM_CHECK(!running_);
  48     return real_time_used_;
  49   }
  50
  51   // REQUIRES: timer is not running
  52   double cpu_time_used() const {
  53     BM_CHECK(!running_);
  54     return cpu_time_used_;
  55   }
  56
  57   // REQUIRES: timer is not running
  58   double manual_time_used() const {
  59     BM_CHECK(!running_);
  60     return manual_time_used_;
  61   }
  62
  63  private:
  64   double ReadCpuTimerOfChoice() const {
  65     if (measure_process_cpu_time) return ProcessCPUUsage();
  66     return ThreadCPUUsage();
  67   }
  68
  69   // should the thread, or the process, time be measured?
  70   const bool measure_process_cpu_time;
  71
  72   bool running_ = false;        // Is the timer running
  73   double start_real_time_ = 0;  // If running_
  74   double start_cpu_time_ = 0;   // If running_
  75
  76   // Accumulated time so far (does not contain current slice if running_)
  77   double real_time_used_ = 0;
  78   double cpu_time_used_ = 0;
  79   // Manually set iteration time. User sets this with SetIterationTime(seconds).
  80   double manual_time_used_ = 0;
  81 };
  82
  83 }  // namespace internal
  84 }  // namespace benchmark
  85
  86 #endif  // BENCHMARK_THREAD_TIMER_H