LuaThreading

This module was created for fixing problem with multi threading in Lua. It supports creating dedicated lua state, and syncing main lua thread with another thread.

How to use

Include LuaThreading into your project

CreateProject(...)
    -- ...
    IncludeLuaShared() -- Do not forget to include LuaShared
    IncludeLuaThreading()
    -- ...

If you're using CMake:

target_include_libraries(<your_library> PRIVATE LuaThreading)
# P.S: Use my CMake fork of garrysmod_common

Initialize LuaThreading

#include <lua_threading.hpp>

GMOD_MODULE_OPEN() {
    LuaThreading::Initialize(LUA);

    // Register think somewhere here
    // ...

    return 0;
}

GMOD_MODULE_CLOSE() {
	LuaThreading::Deinitialize(LUA);

    // ...

	return 0;
}

Registering think function for thread syncing

LUA->GetField(GarrysMod::Lua::INDEX_GLOBAL, "timer");
LUA->GetField(-1, "Create");
LUA->PushString("my_super_think"); // identifier
LUA->PushNumber(0); // delay
LUA->PushNumber(0); // repetitions
LUA->PushCFunction(LuaThreading::Think);
LUA->Call(4, 0);
LUA->Pop();

// Or if you already have think function then just call think

LuaThreading::Think(LUA);

Acquiring lua state from anywhere

{
    // Getting lua state (and syncing threads if needed)
    LuaThreading::Lua LUA = LuaThreading::AcquireLua(); // Or LuaThreading::Lua();
    // Using Lua as Garrysmod::Lua::ILuaBase*
    LUA->GetField(GarrysMod::Lua::INDEX_GLOBAL, "print");
    LUA->PushString("Hello World");
    LUA->Call(1, 0);
} // Here main thread will be desynced, if it was synced
  // That means what LuaThreading::Lua will hold main thread until it destroyed


// Or we can force sync by passing boolean
LuaThreading::AcquireLua(true); // Will sync with main thread
LuaThreading::AcquireLua(false); // Won't sync

Reference

// lua_threading.hpp

namespace LuaThreading {
    // Global Thread ID to determine if we need to sync threads
    extern std::thread::id MainThreadID;

    class Lua {
    public:
        lua_State* state;

        Lua(); // Runs LuaThreading::NeedSync internally
        Lua(bool sync); // true if you need to sync with main thread

        ~Lua(); // Destructor will unlock main thread, if it was locked

        // Copying is prohibited
        Lua(const Lua& other) = delete;
        Lua& operator=(const Lua& other) = delete;

        // Move constructor is permitted, but not move statement
        Lua(Lua&& other) noexcept;
        Lua& operator=(Lua&& other) = delete;

        // You can use LuaThreading::Lua class as it was Garrysmod::Lua::ILuaBase*
        GarrysMod::Lua::ILuaBase* operator->() const;
    }

    // Returns true, if called in non main thread
    bool NeedSync();

    // Same as LuaThreading::Lua();
    Lua AcquireLua();
    Lua AcquireLua(bool sync);

    void Initialize(GarrysMod::Lua::ILuaBase* LUA);
    void Deinitialize(GarrysMod::Lua::ILuaBase* LUA);

    int Think(lua_State* L);
    int Think(GarrysMod::Lua::ILuaBase* LUA);
}

ToDo

• Create joinable std::thread with context, so we can avoid deadlocks if thread was joined