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Added cLuaState::cCallback for representing (resettable) Lua callbacks.

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This commit is contained in:
Mattes D 2016-03-02 11:34:39 +01:00
parent 1462e4f70e
commit 1f75d45222
2 changed files with 231 additions and 7 deletions
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149
src/Bindings/LuaState.cpp
View File

@ -20,6 +20,10 @@ extern "C"
#include "../Entities/Entity.h"
#include "../BlockEntities/BlockEntity.h"
// fwd: "SQLite/lsqlite3.c"
extern "C"
{
@ -39,6 +43,10 @@ extern "C"
const cLuaState::cRet cLuaState::Return = {};
/** Each Lua state stores a pointer to its creating cLuaState in Lua globals, under this name.
This way any cLuaState can reference the main cLuaState's TrackedCallbacks, mutex etc. */
static const char * g_CanonLuaStateGlobalName = "_CuberiteInternal_CanonLuaState";
@ -113,6 +121,72 @@ cLuaStateTracker & cLuaStateTracker::Get(void)
////////////////////////////////////////////////////////////////////////////////
// cLuaState::cCallback:
bool cLuaState::cCallback::RefStack(cLuaState & a_LuaState, int a_StackPos)
{
// Check if the stack contains a function:
if (!lua_isfunction(a_LuaState, a_StackPos))
{
return false;
}
// Clear any previous callback:
Clear();
// Add self to LuaState's callback-tracking:
a_LuaState.TrackCallback(*this);
// Store the new callback:
cCSLock Lock(m_CS);
m_Ref.RefStack(a_LuaState, a_StackPos);
return true;
}
void cLuaState::cCallback::Clear(void)
{
// Free the callback reference:
lua_State * luaState = nullptr;
{
cCSLock Lock(m_CS);
if (!m_Ref.IsValid())
{
return;
}
luaState = m_Ref.GetLuaState();
m_Ref.UnRef();
}
// Remove from LuaState's callback-tracking:
cLuaState(luaState).UntrackCallback(*this);
}
void cLuaState::cCallback::Invalidate(void)
{
cCSLock Lock(m_CS);
if (!m_Ref.IsValid())
{
LOGD("%s: Invalidating an already invalid callback at %p, this should not happen",
__FUNCTION__, reinterpret_cast<void *>(this)
);
return;
}
m_Ref.UnRef();
}
////////////////////////////////////////////////////////////////////////////////
// cLuaState:
@ -170,6 +244,10 @@ void cLuaState::Create(void)
luaL_openlibs(m_LuaState);
m_IsOwned = true;
cLuaStateTracker::Add(*this);
// Add the CanonLuaState value into the Lua state, so that we can get it from anywhere:
lua_pushlightuserdata(m_LuaState, reinterpret_cast<void *>(this));
lua_setglobal(m_LuaState, g_CanonLuaStateGlobalName);
}
@ -206,6 +284,16 @@ void cLuaState::Close(void)
Detach();
return;
}
// Invalidate all callbacks:
{
cCSLock Lock(m_CSTrackedCallbacks);
for (auto & c: m_TrackedCallbacks)
{
c->Invalidate();
}
}
cLuaStateTracker::Del(*this);
lua_close(m_LuaState);
m_LuaState = nullptr;
@ -871,6 +959,15 @@ bool cLuaState::GetStackValue(int a_StackPos, cRef & a_Ref)
bool cLuaState::GetStackValue(int a_StackPos, cCallback & a_Callback)
{
return a_Callback.RefStack(*this, a_StackPos);
}
bool cLuaState::GetStackValue(int a_StackPos, double & a_ReturnedVal)
{
if (lua_isnumber(m_LuaState, a_StackPos))
@ -1701,6 +1798,52 @@ int cLuaState::BreakIntoDebugger(lua_State * a_LuaState)
void cLuaState::TrackCallback(cCallback & a_Callback)
{
// Get the CanonLuaState global from Lua:
auto cb = WalkToNamedGlobal(g_CanonLuaStateGlobalName);
if (!cb.IsValid())
{
LOGWARNING("%s: Lua state %p has invalid CanonLuaState!", __FUNCTION__, reinterpret_cast<void *>(m_LuaState));
return;
}
auto & canonState = *reinterpret_cast<cLuaState *>(lua_touserdata(m_LuaState, -1));
// Add the callback:
cCSLock Lock(canonState.m_CSTrackedCallbacks);
canonState.m_TrackedCallbacks.push_back(&a_Callback);
}
void cLuaState::UntrackCallback(cCallback & a_Callback)
{
// Get the CanonLuaState global from Lua:
auto cb = WalkToNamedGlobal(g_CanonLuaStateGlobalName);
if (!cb.IsValid())
{
LOGWARNING("%s: Lua state %p has invalid CanonLuaState!", __FUNCTION__, reinterpret_cast<void *>(m_LuaState));
return;
}
auto & canonState = *reinterpret_cast<cLuaState *>(lua_touserdata(m_LuaState, -1));
// Remove the callback:
cCSLock Lock(canonState.m_CSTrackedCallbacks);
auto & trackedCallbacks = canonState.m_TrackedCallbacks;
trackedCallbacks.erase(std::remove_if(trackedCallbacks.begin(), trackedCallbacks.end(),
[&a_Callback](cCallback * a_StoredCallback)
{
return (a_StoredCallback == &a_Callback);
}
));
}
////////////////////////////////////////////////////////////////////////////////
// cLuaState::cRef:
@ -1756,7 +1899,7 @@ void cLuaState::cRef::RefStack(cLuaState & a_LuaState, int a_StackPos)
{
UnRef();
}
m_LuaState = &a_LuaState;
m_LuaState = a_LuaState;
lua_pushvalue(a_LuaState, a_StackPos); // Push a copy of the value at a_StackPos onto the stack
m_Ref = luaL_ref(a_LuaState, LUA_REGISTRYINDEX);
}
@ -1767,11 +1910,9 @@ void cLuaState::cRef::RefStack(cLuaState & a_LuaState, int a_StackPos)
void cLuaState::cRef::UnRef(void)
{
ASSERT(m_LuaState->IsValid()); // The reference should be destroyed before destroying the LuaState
if (IsValid())
{
luaL_unref(*m_LuaState, LUA_REGISTRYINDEX, m_Ref);
luaL_unref(m_LuaState, LUA_REGISTRYINDEX, m_Ref);
}
m_LuaState = nullptr;
m_Ref = LUA_REFNIL;

89
src/Bindings/LuaState.h
View File

@ -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);
} ;