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#ifndef MOZC_BASE_CPU_STATS_H_
#define MOZC_BASE_CPU_STATS_H_

#include <cstdint>

#include "base/port.h"

namespace mozc {

class CPUStatsInterface {
 public:
  CPUStatsInterface() {}
  virtual ~CPUStatsInterface() {}

  // Returns the percentage of total CPU load since the last time
  // this method was called.
  // The return value must be in the range of [0.0 .. 1.0].
  virtual float GetSystemCPULoad() = 0;

  // Returns the percentage of current process's CPU load
  // since the last time this method was called.
  // If the process has multi-threads, the return value
  // may be larger than 1.0.
  // Use GetNumberOfProcessors to normalize the CPU load by
  // the number of processors.
  virtual float GetCurrentProcessCPULoad() = 0;

  // returns the number of processors.
  virtual size_t GetNumberOfProcessors() const = 0;
};

// default implementation
class CPUStats : public CPUStatsInterface {
 public:
  CPUStats();
  ~CPUStats() override;

  // return 0.0 if CPU load is unknown
  float GetSystemCPULoad() override;

  // return 0.0 if CPU load is unknown
  float GetCurrentProcessCPULoad() override;

  // return the number of processors
  size_t GetNumberOfProcessors() const override;

 private:
  uint64_t prev_system_total_times_;
  uint64_t prev_system_cpu_times_;
  uint64_t prev_current_process_total_times_;
  uint64_t prev_current_process_cpu_times_;
};

}  // namespace mozc

#endif  // MOZC_BASE_CPU_STATS_H_
