93 lines
2.9 KiB
C
93 lines
2.9 KiB
C
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/**
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* PANDA 3D SOFTWARE
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* Copyright (c) Carnegie Mellon University. All rights reserved.
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*
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* All use of this software is subject to the terms of the revised BSD
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* license. You should have received a copy of this license along
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* with this source code in a file named "LICENSE."
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*
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* @file updateSeq.h
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* @author drose
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* @date 1999-09-30
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*/
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#ifndef UPDATE_SEQ
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#define UPDATE_SEQ
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#include "pandabase.h"
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#include "pmutex.h"
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#include "mutexHolder.h"
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#include "atomicAdjust.h"
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#include "numeric_types.h"
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/**
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* This is a sequence number that increments monotonically. It can be used to
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* track cache updates, or serve as a kind of timestamp for any changing
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* properties.
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*
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* A special class is used instead of simply an int, so we can elegantly
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* handle such things as wraparound and special cases. There are two special
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* cases. Firstly, a sequence number is 'initial' when it is first created.
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* This sequence is older than any other sequence number. Secondly, a
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* sequence number may be explicitly set to 'old'. This is older than any
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* other sequence number except 'initial'. Finally, we have the explicit
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* number 'fresh', which is newer than any other sequence number. All other
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* sequences are numeric and are monotonically increasing.
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*/
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class EXPCL_PANDA_PUTIL UpdateSeq {
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private:
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constexpr UpdateSeq(unsigned int seq);
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PUBLISHED:
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constexpr UpdateSeq();
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constexpr static UpdateSeq initial() { return UpdateSeq(SC_initial); }
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constexpr static UpdateSeq old() { return UpdateSeq(SC_old); }
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constexpr static UpdateSeq fresh() { return UpdateSeq(SC_fresh); }
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INLINE UpdateSeq(const UpdateSeq ©);
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constexpr UpdateSeq(const UpdateSeq &&from) noexcept;
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INLINE UpdateSeq &operator = (const UpdateSeq ©);
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INLINE void clear();
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INLINE bool is_initial() const;
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INLINE bool is_old() const;
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INLINE bool is_fresh() const;
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INLINE bool is_special() const;
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INLINE bool operator == (const UpdateSeq &other) const;
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INLINE bool operator != (const UpdateSeq &other) const;
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INLINE bool operator < (const UpdateSeq &other) const;
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INLINE bool operator <= (const UpdateSeq &other) const;
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INLINE bool operator > (const UpdateSeq &other) const;
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INLINE bool operator >= (const UpdateSeq &other) const;
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INLINE UpdateSeq operator ++ ();
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INLINE UpdateSeq operator ++ (int);
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INLINE AtomicAdjust::Integer get_seq() const;
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MAKE_PROPERTY(seq, get_seq);
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INLINE void output(std::ostream &out) const;
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private:
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INLINE static bool priv_is_special(AtomicAdjust::Integer seq);
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INLINE static bool priv_lt(AtomicAdjust::Integer a, AtomicAdjust::Integer b);
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INLINE static bool priv_le(AtomicAdjust::Integer a, AtomicAdjust::Integer b);
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private:
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enum SpecialCases : unsigned int {
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SC_initial = 0,
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SC_old = 1,
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SC_fresh = ~(unsigned int)0,
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};
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AtomicAdjust::Integer _seq;
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};
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INLINE std::ostream &operator << (std::ostream &out, const UpdateSeq &value);
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#include "updateSeq.I"
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#endif
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