timestamp.h
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#ifndef OSDEV_COMPONENTS_TIMESTAMP_H
#define OSDEV_COMPONENTS_TIMESTAMP_H
#include <limits>
#include <stdexcept>
#include <QString>
namespace osdev {
namespace components {
/**
* @brief Timestamp class that allows formation of a sequence of ordered events.
*/
class Timestamp
{
public:
/**
* @brief Creates an invalid timestamp. This is the oldest possible timestamp.
* @note A timestamp can only become valid by assigning a valid timestamp to it.
*/
Timestamp();
/**
* @brief Creates a timestamp based on miliseconds since the epoch.
* @param msecsSinceEpoch Number of miliseconds since the epoch. Value 0 leads to valid timestamp.
* @note Timestamp with value 0 is larger then the invalid timestamp.
*/
explicit Timestamp(unsigned long long msecsSinceEpoch);
// default constructable and movable.
Timestamp(const Timestamp&) = default;
Timestamp& operator=(const Timestamp&) = default;
Timestamp(Timestamp&&) = default;
Timestamp& operator=(Timestamp&&) = default;
/**
* @return true if this timestamp is valid, false otherwise.
*/
bool valid() const
{
return (m_seqNr > 0);
}
/**
* @return true if this timestamp is smaller (older) then rhs.
*/
bool operator<(const Timestamp& rhs) const;
/**
* @brief Prefix addition operator.
* Increases the Timestamp sequencenumber so that timestamps with the same number of msecs since the epoch can also be ordered.
* @note An invalid timestamp remains invalid.
* @return Reference to this timestamp.
* @throw std::out_of_range exception when seqnr is about to overflow.
*/
Timestamp& operator++();
/**
* @brief Postfix addition operator.
* Increases the Timestamp sequencenumber so that timestamps with the same number of msecs since the epoch can also be ordered.
* @note An invalid timestamp remains invalid.
* @return The timestamp as it was before increment.
* @throw std::out_of_range exception when seqnr is about to overflow.
*/
Timestamp operator++(int);
/**
* @return Stringified timestamp as msecsSinceEpoch:seqNr.
*/
QString toString() const;
private:
unsigned long long m_msecsSinceEpoch; ///< Number of miliseconds since the epoch.
unsigned long long m_seqNr; ///< Sequence number.
};
} /* End namespace components */
} /* End namespace osdev */
#endif /* OSDEV_COMPONENTS_TIMESTAMP_H */