historical/toontown-classic.git/panda/include/updateSeq.h
2024-01-16 11:20:27 -06:00

92 lines
2.9 KiB
C++

/**
* PANDA 3D SOFTWARE
* Copyright (c) Carnegie Mellon University. All rights reserved.
*
* All use of this software is subject to the terms of the revised BSD
* license. You should have received a copy of this license along
* with this source code in a file named "LICENSE."
*
* @file updateSeq.h
* @author drose
* @date 1999-09-30
*/
#ifndef UPDATE_SEQ
#define UPDATE_SEQ
#include "pandabase.h"
#include "pmutex.h"
#include "mutexHolder.h"
#include "atomicAdjust.h"
#include "numeric_types.h"
/**
* 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.
*/
class EXPCL_PANDA_PUTIL UpdateSeq {
private:
constexpr UpdateSeq(unsigned int seq);
PUBLISHED:
constexpr UpdateSeq();
constexpr static UpdateSeq initial() { return UpdateSeq(SC_initial); }
constexpr static UpdateSeq old() { return UpdateSeq(SC_old); }
constexpr static UpdateSeq fresh() { return UpdateSeq(SC_fresh); }
INLINE UpdateSeq(const UpdateSeq &copy);
constexpr UpdateSeq(const UpdateSeq &&from) noexcept;
INLINE UpdateSeq &operator = (const UpdateSeq &copy);
INLINE void clear();
INLINE bool is_initial() const;
INLINE bool is_old() const;
INLINE bool is_fresh() const;
INLINE bool is_special() const;
INLINE bool operator == (const UpdateSeq &other) const;
INLINE bool operator != (const UpdateSeq &other) const;
INLINE bool operator < (const UpdateSeq &other) const;
INLINE bool operator <= (const UpdateSeq &other) const;
INLINE bool operator > (const UpdateSeq &other) const;
INLINE bool operator >= (const UpdateSeq &other) const;
INLINE UpdateSeq operator ++ ();
INLINE UpdateSeq operator ++ (int);
INLINE AtomicAdjust::Integer get_seq() const;
MAKE_PROPERTY(seq, get_seq);
INLINE void output(std::ostream &out) const;
private:
INLINE static bool priv_is_special(AtomicAdjust::Integer seq);
INLINE static bool priv_lt(AtomicAdjust::Integer a, AtomicAdjust::Integer b);
INLINE static bool priv_le(AtomicAdjust::Integer a, AtomicAdjust::Integer b);
private:
enum SpecialCases : unsigned int {
SC_initial = 0,
SC_old = 1,
SC_fresh = ~(unsigned int)0,
};
AtomicAdjust::Integer _seq;
};
INLINE std::ostream &operator << (std::ostream &out, const UpdateSeq &value);
#include "updateSeq.I"
#endif