Panda3D
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00001 // Filename: updateSeq.h 00002 // Created by: drose (30Sep99) 00003 // 00004 //////////////////////////////////////////////////////////////////// 00005 // 00006 // PANDA 3D SOFTWARE 00007 // Copyright (c) Carnegie Mellon University. All rights reserved. 00008 // 00009 // All use of this software is subject to the terms of the revised BSD 00010 // license. You should have received a copy of this license along 00011 // with this source code in a file named "LICENSE." 00012 // 00013 //////////////////////////////////////////////////////////////////// 00014 00015 #ifndef UPDATE_SEQ 00016 #define UPDATE_SEQ 00017 00018 #include "pandabase.h" 00019 #include "pmutex.h" 00020 #include "mutexHolder.h" 00021 #include "atomicAdjust.h" 00022 #include "numeric_types.h" 00023 00024 //////////////////////////////////////////////////////////////////// 00025 // Class : UpdateSeq 00026 // Description : This is a sequence number that increments 00027 // monotonically. It can be used to track cache 00028 // updates, or serve as a kind of timestamp for any 00029 // changing properties. 00030 // 00031 // A special class is used instead of simply an int, so 00032 // we can elegantly handle such things as wraparound and 00033 // special cases. There are two special cases. 00034 // Firstly, a sequence number is 'initial' when it is 00035 // first created. This sequence is older than any other 00036 // sequence number. Secondly, a sequence number may be 00037 // explicitly set to 'old'. This is older than any 00038 // other sequence number except 'initial'. Finally, we 00039 // have the explicit number 'fresh', which is newer 00040 // than any other sequence number. All other sequences 00041 // are numeric and are monotonically increasing. 00042 //////////////////////////////////////////////////////////////////// 00043 class EXPCL_PANDA_PUTIL UpdateSeq { 00044 PUBLISHED: 00045 INLINE UpdateSeq(); 00046 INLINE static UpdateSeq initial(); 00047 INLINE static UpdateSeq old(); 00048 INLINE static UpdateSeq fresh(); 00049 00050 INLINE UpdateSeq(const UpdateSeq ©); 00051 INLINE UpdateSeq &operator = (const UpdateSeq ©); 00052 00053 INLINE void clear(); 00054 00055 INLINE bool is_initial() const; 00056 INLINE bool is_old() const; 00057 INLINE bool is_fresh() const; 00058 INLINE bool is_special() const; 00059 00060 INLINE bool operator == (const UpdateSeq &other) const; 00061 INLINE bool operator != (const UpdateSeq &other) const; 00062 INLINE bool operator < (const UpdateSeq &other) const; 00063 INLINE bool operator <= (const UpdateSeq &other) const; 00064 INLINE bool operator > (const UpdateSeq &other) const; 00065 INLINE bool operator >= (const UpdateSeq &other) const; 00066 00067 INLINE UpdateSeq operator ++ (); 00068 INLINE UpdateSeq operator ++ (int); 00069 00070 INLINE void output(ostream &out) const; 00071 00072 private: 00073 INLINE static bool priv_is_special(AtomicAdjust::Integer seq); 00074 INLINE static bool priv_lt(AtomicAdjust::Integer a, AtomicAdjust::Integer b); 00075 INLINE static bool priv_le(AtomicAdjust::Integer a, AtomicAdjust::Integer b); 00076 00077 private: 00078 enum SpecialCases { 00079 SC_initial = 0, 00080 SC_old = 1, 00081 SC_fresh = ~(unsigned int)0, 00082 }; 00083 00084 AtomicAdjust::Integer _seq; 00085 }; 00086 00087 INLINE ostream &operator << (ostream &out, const UpdateSeq &value); 00088 00089 #include "updateSeq.I" 00090 00091 #endif