92 lines
3.1 KiB
C++
92 lines
3.1 KiB
C++
// Filename: updateSeq.h
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// Created by: drose (30Sep99)
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//
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////////////////////////////////////////////////////////////////////
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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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////////////////////////////////////////////////////////////////////
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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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// Class : UpdateSeq
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// Description : This is a sequence number that increments
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// monotonically. It can be used to track cache
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// updates, or serve as a kind of timestamp for any
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// changing properties.
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//
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// A special class is used instead of simply an int, so
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// we can elegantly handle such things as wraparound and
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// special cases. There are two special cases.
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// Firstly, a sequence number is 'initial' when it is
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// first created. This sequence is older than any other
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// sequence number. Secondly, a sequence number may be
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// explicitly set to 'old'. This is older than any
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// other sequence number except 'initial'. Finally, we
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// have the explicit number 'fresh', which is newer
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// than any other sequence number. All other sequences
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// are numeric and are monotonically increasing.
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////////////////////////////////////////////////////////////////////
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class EXPCL_PANDA_PUTIL UpdateSeq {
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PUBLISHED:
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INLINE UpdateSeq();
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INLINE static UpdateSeq initial();
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INLINE static UpdateSeq old();
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INLINE static UpdateSeq fresh();
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INLINE UpdateSeq(const UpdateSeq ©);
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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 void output(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 {
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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 ostream &operator << (ostream &out, const UpdateSeq &value);
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#include "updateSeq.I"
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#endif
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