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cuberite-2a
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Fixed race conditions and forgotten clear in Lua ref tracking. (#3530) 

This fixes occasional crashes on plugin reload.
This commit is contained in:
Mattes D 2017-01-13 10:31:05 +01:00 committed by GitHub
parent f62711f97c
commit fb0fc07579
3 changed files with 23 additions and 13 deletions
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11
src/Bindings/LuaState.cpp
View File

@ -218,7 +218,7 @@ void cLuaState::cTrackedRef::Clear(void)
// Free the reference:
lua_State * luaState = nullptr;
{
auto cs = m_CS;
auto cs = m_CS.load();
if (cs != nullptr)
{
cCSLock Lock(*cs);
@ -246,7 +246,7 @@ void cLuaState::cTrackedRef::Clear(void)
bool cLuaState::cTrackedRef::IsValid(void)
{
auto cs = m_CS;
auto cs = m_CS.load();
if (cs == nullptr)
{
return false;
@ -261,7 +261,7 @@ bool cLuaState::cTrackedRef::IsValid(void)
bool cLuaState::cTrackedRef::IsSameLuaState(cLuaState & a_LuaState)
{
auto cs = m_CS;
auto cs = m_CS.load();
if (cs == nullptr)
{
return false;
@ -285,7 +285,7 @@ bool cLuaState::cTrackedRef::IsSameLuaState(cLuaState & a_LuaState)
void cLuaState::cTrackedRef::Invalidate(void)
{
auto cs = m_CS;
auto cs = m_CS.load();
if (cs == nullptr)
{
// Already invalid
@ -548,6 +548,7 @@ void cLuaState::Close(void)
{
r->Invalidate();
}
m_TrackedRefs.clear();
}
cCanonLuaStates::Remove(*this);
@ -2357,6 +2358,7 @@ void cLuaState::cRef::RefStack(cLuaState & a_LuaState, int a_StackPos)
{
UnRef();
}
ASSERT(cCanonLuaStates::GetCanonState(a_LuaState)->m_CS.IsLockedByCurrentThread());
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);
@ -2370,6 +2372,7 @@ void cLuaState::cRef::UnRef(void)
{
if (IsValid())
{
ASSERT(cCanonLuaStates::GetCanonState(m_LuaState)->m_CS.IsLockedByCurrentThread());
luaL_unref(m_LuaState, LUA_REGISTRYINDEX, m_Ref);
}
m_LuaState = nullptr;

24
src/Bindings/LuaState.h
View File

@ -35,6 +35,7 @@ extern "C"
#include "lua/src/lauxlib.h"
}
#include <atomic>
#include "../Vector3.h"
#include "../Defines.h"
#include "PluginManager.h"
@ -189,24 +190,29 @@ public:
}
/** Set the contained reference to the object at the specified Lua state's stack position.
If another reference has been previously contained, it is freed first. */
If another reference has been previously contained, it is Clear()-ed first. */
bool RefStack(cLuaState & a_LuaState, int a_StackPos);
/** Frees the contained reference, if any. */
/** Frees the contained reference, if any.
Untracks the reference from its canon Lua state. */
void Clear(void);
/** Returns true if the contained reference is valid. */
/** Returns true if the contained reference is valid.
(Note that depending on this value is not thread-safe, another thread may invalidate the ref in the meantime. It is meant for quick ASSERTs only). */
bool IsValid(void);
/** Returns true if the reference resides in the specified Lua state.
Internally, compares the reference's canon Lua state. */
Internally, compares the reference's canon Lua state.
(Note that depending on this value is not thread-safe, another thread may modify the ref in the meantime. It is meant for quick ASSERTs only). */
bool IsSameLuaState(cLuaState & a_LuaState);
protected:
friend class cLuaState;
/** The mutex protecting m_Ref against multithreaded access */
cCriticalSection * m_CS;
/** The mutex protecting m_Ref against multithreaded access.
Actually points to the canon Lua state's m_CriticalSection.
Is nullptr when ref is empty (not bound). */
std::atomic<cCriticalSection *> m_CS;
/** Reference to the Lua callback */
cRef m_Ref;
@ -254,7 +260,7 @@ public:
template <typename... Args>
bool Call(Args &&... args)
{
auto cs = m_CS;
auto cs = m_CS.load();
if (cs == nullptr)
{
return false;
@ -336,7 +342,7 @@ public:
template <typename... Args>
bool CallTableFn(const char * a_FnName, Args &&... args)
{
auto cs = m_CS;
auto cs = m_CS.load();
if (cs == nullptr)
{
return false;
@ -356,7 +362,7 @@ public:
template <typename... Args>
bool CallTableFnWithSelf(const char * a_FnName, Args &&... args)
{
auto cs = m_CS;
auto cs = m_CS.load();
if (cs == nullptr)
{
return false;

1
src/Generating/PrefabPiecePool.cpp
View File

@ -204,6 +204,7 @@ bool cPrefabPiecePool::LoadFromCubeset(const AString & a_Contents, const AString
// Load the file in the Lua interpreter:
cLuaState Lua(Printf("LoadablePiecePool %s", a_FileName.c_str()));
Lua.Create();
cLuaState::cLock lock(Lua);
if (!Lua.LoadString(a_Contents, a_FileName, a_LogWarnings))
{
// Reason for failure has already been logged in LoadFile()