source/game/accessguard.h

   1 #ifndef MSP_GAME_ACCESSGUARD_H_
   2 #define MSP_GAME_ACCESSGUARD_H_
   3
   4 #include <cstdint>
   5 #include <stdexcept>
   6 #include <string>
   7 #include <vector>
   8 #include <msp/core/noncopyable.h>
   9 #include <msp/debug/demangle.h>
  10 #include "mspgame_api.h"
  11
  12 namespace Msp::Game {
  13
  14 class MSPGAME_API invalid_access: public std::logic_error
  15 {
  16 public:
  17         invalid_access(const std::string &w): logic_error(w) { }
  18 };
  19
  20
  21 class MSPGAME_API AccessGuard
  22 {
  23 public:
  24         struct Create { static std::string describe() { return "create"; } };
  25         struct Destroy { static std::string describe() { return "destroy"; } };
  26         template<typename T> struct Read { static std::string describe(); };
  27         template<typename T> struct Write { static std::string describe(); };
  28
  29         template<typename T = void>
  30         struct BlockForScope: NonCopyable
  31         {
  32                 BlockForScope() { get_instance().block<T>(); }
  33                 ~BlockForScope() { get_instance().unblock<T>(); }
  34         };
  35
  36 private:
  37         const uint8_t UNBLOCKED = 0;
  38         const uint8_t BLOCKED = 1;
  39
  40         std::uint8_t default_flag = UNBLOCKED;
  41         std::vector<std::uint8_t> flags;
  42
  43         static thread_local AccessGuard *instance;
  44
  45 public:
  46         AccessGuard();
  47         AccessGuard(AccessGuard &&);
  48         AccessGuard &operator=(AccessGuard &&);
  49         ~AccessGuard();
  50
  51         static AccessGuard &get_instance();
  52
  53         void block_all();
  54         void unblock_all();
  55
  56 private:
  57         static unsigned get_next_index();
  58
  59         template<typename T>
  60         static unsigned get_index();
  61
  62         template<typename T>
  63         std::uint8_t &get();
  64
  65 public:
  66         template<typename T>
  67         void block() { get<T>() = BLOCKED; }
  68
  69         template<typename T>
  70         void unblock() { get<T>() = UNBLOCKED; }
  71
  72         template<typename T>
  73         void check();
  74 };
  75
  76
  77 template<typename T>
  78 inline unsigned AccessGuard::get_index()
  79 {
  80         static unsigned index = get_next_index();
  81         return index;
  82 }
  83
  84 template<typename T>
  85 inline std::uint8_t &AccessGuard::get()
  86 {
  87         unsigned index = get_index<T>();
  88         if(flags.size()<=index)
  89                 flags.resize(index+1, default_flag);
  90         return flags[index];
  91 }
  92
  93 template<>
  94 inline void AccessGuard::block<void>()
  95 { block_all(); }
  96
  97 template<>
  98 inline void AccessGuard::unblock<void>()
  99 { unblock_all(); }
 100
 101 template<typename T>
 102 inline void AccessGuard::check()
 103 {
 104         unsigned index = get_index<T>();
 105         if((index<flags.size() ? flags[index] : default_flag) != UNBLOCKED)
 106                 throw invalid_access(T::describe());
 107 }
 108
 109
 110 template<typename T>
 111 inline std::string AccessGuard::Read<T>::describe()
 112 {
 113         return "read "+Debug::demangle(typeid(T).name());
 114 }
 115
 116 template<typename T>
 117 inline std::string AccessGuard::Write<T>::describe()
 118 {
 119         return "write "+Debug::demangle(typeid(T).name());
 120 }
 121
 122 } // namespace Msp::Game
 123
 124 #endif