ch02-sysinfo/sysinfo.h

#ifndef SYSINFO_H
#define SYSINFO_H

/**
 * @brief The SysInfo 接口
 */
class SysInfo {
 public:
  static SysInfo& instance();
  virtual ~SysInfo();

  // Allows the derived class to perform any initialization process depending on
  // the OS platform
  virtual void init() = 0;
  virtual double cpuLoadAverage() = 0;
  virtual double memoryUsed() = 0;

 protected:
  explicit SysInfo();

 private:
  SysInfo(const SysInfo& rhs);
  SysInfo& operator=(const SysInfo& rhs);
};

#endif  // SYSINFO_H