class UpdateSeq

This is a sequence number that increments monotonically. It can be used to track cache updates, or serve as a kind of timestamp for any changing properties.

A special class is used instead of simply an int, so we can elegantly handle such things as wraparound and special cases. There are two special cases. Firstly, a sequence number is ‘initial’ when it is first created. This sequence is older than any other sequence number. Secondly, a sequence number may be explicitly set to ‘old’. This is older than any other sequence number except ‘initial’. Finally, we have the explicit number ‘fresh’, which is newer than any other sequence number. All other sequences are numeric and are monotonically increasing.

Inheritance diagram

constexpr UpdateSeq(void)
UpdateSeq(UpdateSeq const &copy)

Creates an UpdateSeq in the given state.

Creates an UpdateSeq in the ‘initial’ state.

void clear(void)

Resets the UpdateSeq to the ‘initial’ state.

static constexpr UpdateSeq fresh(void)
AtomicAdjust::Integer get_seq(void) const

Returns the internal integer value associated with the UpdateSeq. Useful for debugging only.

static constexpr UpdateSeq initial(void)
bool is_fresh(void) const

Returns true if the UpdateSeq is in the ‘fresh’ state.

bool is_initial(void) const

Returns true if the UpdateSeq is in the ‘initial’ state.

bool is_old(void) const

Returns true if the UpdateSeq is in the ‘old’ state.

bool is_special(void) const

Returns true if the UpdateSeq is in any special states, i.e. ‘initial’, ‘old’, or ‘fresh’.

static constexpr UpdateSeq old(void)
void output(std::ostream &out) const