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-rw-r--r--src/Bindings/LuaState.h89
1 files changed, 86 insertions, 3 deletions
diff --git a/src/Bindings/LuaState.h b/src/Bindings/LuaState.h
index b795a80d4..bce08f0fe 100644
--- a/src/Bindings/LuaState.h
+++ b/src/Bindings/LuaState.h
@@ -80,8 +80,11 @@ public:
/** Allows to use this class wherever an int (i. e. ref) is to be used */
explicit operator int(void) const { return m_Ref; }
+ /** Returns the Lua state associated with the value. */
+ lua_State * GetLuaState(void) { return m_LuaState; }
+
protected:
- cLuaState * m_LuaState;
+ lua_State * m_LuaState;
int m_Ref;
// Remove the copy-constructor:
@@ -112,6 +115,69 @@ public:
} ;
+ /** Represents a callback to Lua that C++ code can call.
+ Is thread-safe and unload-safe.
+ When the Lua state is unloaded, the callback returns an error instead of calling into non-existent code.
+ To receive the callback instance from the Lua side, use RefStack() or (better) cLuaState::GetStackValue().
+ Note that instances of this class are tracked in the canon LuaState instance, so that they can be invalidated
+ when the LuaState is unloaded; due to multithreading issues they can only be tracked by-ptr, which has
+ an unfortunate effect of disabling the copy and move constructors. */
+ class cCallback
+ {
+ public:
+ /** Creates an unbound callback instance. */
+ cCallback(void) = default;
+
+ ~cCallback()
+ {
+ Clear();
+ }
+
+ /** Calls the Lua callback, if still available.
+ Returns true if callback has been called.
+ Returns false if the Lua state isn't valid anymore. */
+ template <typename... Args>
+ bool Call(Args &&... args)
+ {
+ cCSLock Lock(m_CS);
+ if (!m_Ref.IsValid())
+ {
+ return false;
+ }
+ cLuaState(m_Ref.GetLuaState()).Call(m_Ref, std::forward<Args>(args)...);
+ return true;
+ }
+
+ /** Set the contained callback to the function in the specified Lua state's stack position.
+ If a callback has been previously contained, it is freed first. */
+ bool RefStack(cLuaState & a_LuaState, int a_StackPos);
+
+ /** Frees the contained callback, if any. */
+ void Clear(void);
+
+ protected:
+ friend class cLuaState;
+
+ /** The mutex protecting m_Ref against multithreaded access */
+ cCriticalSection m_CS;
+
+ /** Reference to the Lua callback */
+ cRef m_Ref;
+
+
+ /** Invalidates the callback, without untracking it from the cLuaState.
+ Called only from cLuaState when closing the Lua state. */
+ void Invalidate(void);
+
+ /** This class cannot be copied, because it is tracked in the LuaState by-ptr. */
+ cCallback(const cCallback &) = delete;
+
+ /** This class cannot be moved, because it is tracked in the LuaState by-ptr. */
+ cCallback(cCallback &&) = delete;
+ };
+ typedef SharedPtr<cCallback> cCallbackPtr;
+
+
/** A dummy class that's used only to delimit function args from return values for cLuaState::Call() */
class cRet
{
@@ -268,6 +334,7 @@ public:
bool GetStackValue(int a_StackPos, bool & a_Value);
bool GetStackValue(int a_StackPos, cPluginManager::CommandResult & a_Result);
bool GetStackValue(int a_StackPos, cRef & a_Ref);
+ bool GetStackValue(int a_StackPos, cCallback & a_Ref);
bool GetStackValue(int a_StackPos, double & a_Value);
bool GetStackValue(int a_StackPos, eBlockFace & a_Value);
bool GetStackValue(int a_StackPos, eWeather & a_Value);
@@ -453,8 +520,7 @@ protected:
bool m_IsOwned;
/** The subsystem name is used for reporting errors to the console, it is either "plugin %s" or "LuaScript"
- whatever is given to the constructor
- */
+ whatever is given to the constructor. */
AString m_SubsystemName;
/** Name of the currently pushed function (for the Push / Call chain) */
@@ -463,6 +529,15 @@ protected:
/** Number of arguments currently pushed (for the Push / Call chain) */
int m_NumCurrentFunctionArgs;
+ /** The tracked callbacks.
+ This object will invalidate all of these when it is about to be closed.
+ Protected against multithreaded access by m_CSTrackedCallbacks. */
+ std::vector<cCallback *> m_TrackedCallbacks;
+
+ /** Protects m_TrackedTallbacks against multithreaded access. */
+ cCriticalSection m_CSTrackedCallbacks;
+
+
/** Variadic template terminator: If there's nothing more to push / pop, just call the function.
Note that there are no return values either, because those are prefixed by a cRet value, so the arg list is never empty. */
bool PushCallPop(void)
@@ -545,6 +620,14 @@ protected:
/** Tries to break into the MobDebug debugger, if it is installed. */
static int BreakIntoDebugger(lua_State * a_LuaState);
+
+ /** Adds the specified callback to tracking.
+ The callback will be invalidated when this Lua state is about to be closed. */
+ void TrackCallback(cCallback & a_Callback);
+
+ /** Removes the specified callback from tracking.
+ The callback will no longer be invalidated when this Lua state is about to be closed. */
+ void UntrackCallback(cCallback & a_Callback);
} ;