timestamp.h
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/* ****************************************************************************
* Copyright 2019 Open Systems Development BV *
* *
* Permission is hereby granted, free of charge, to any person obtaining a *
* copy of this software and associated documentation files (the "Software"), *
* to deal in the Software without restriction, including without limitation *
* the rights to use, copy, modify, merge, publish, distribute, sublicense, *
* and/or sell copies of the Software, and to permit persons to whom the *
* Software is furnished to do so, subject to the following conditions: *
* *
* The above copyright notice and this permission notice shall be included in *
* all copies or substantial portions of the Software. *
* *
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR *
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, *
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL *
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER *
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING *
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER *
* DEALINGS IN THE SOFTWARE. *
* ***************************************************************************/
#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 */