xLua: try to dispose a LuaEnv with C# callback!

该错误主要是在调用LuaEnv.Dispose()时引起,一般用于游戏重启时将整个lua虚拟机重置.
报错的主要原因有:

在同一个方法中释放了delegate的引用,但又立即调用了LuaEnv.Dispose().
没有在C#侧释放标记有[CSharpCallLua]的delegate(赋值为null).

详细说明可以在xLua自带的FAQ(xLua/Doc/faq.md)中找到.

对于第1个问题, 可以将LuaEnv.Dispose()的释放代码单独放到另一个方法中, 参考 https://github.com/Tencent/xLua/issues/634
对于第2个问题:
xlua提供了一个lua方法(该方法位于XLua/Resources/xlua/util.lua.txt中): print_func_ref_by_csharp()来打印所有通过delegate注入到C#中的lua方法. 通过得到的信息可以依次检查lua往C#中的哪些地方注入了方法,这样就在C#中去把那些delegate类型的变量赋值为null进行释放了.

但依然难免出现疏忽的情况,且当大量使用C#调用lua这种逻辑时,排查问题会更麻烦,所以如果想在报错时确切的知道到底是lua的哪个调用处没有释放,就需要对xLua源码进行额外的处理(v2.1.13测试没问题).

报错的地方是在LuaEnv.cs的Dispose(bool dispose)方法中抛出的, 如下图:

image.png

该处又是调用了translator.AllDelegateBridgeReleased()来得到的检查结果, translator是ObjectTranslator.cs

在生成的各种wrap文件中,对于delegate的获取处理有如下类似代码:

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ObjectTranslator translator = ObjectTranslatorPool.Instance.Find(L);
XXClass gen_to_be_invoked = (XXClass)translator.FastGetCSObj(L, 1);
gen_to_be_invoked.DelegateHandler = translator.GetDelegate<XXClass.DelegateType>(L, 2);

translator依然是ObjectTranslator,其GetDelegate()定义如下图:

image.png

对于delegate类型的lua传入肯定是个function,所以一定会执行到红圈处的代码,即CreateDelegateBridge().
修改逻辑如下:

在CreateDelegateBridge()时获取delegate的包装对象WeakReference; 同时获取lua处的调用堆栈信息,即通过lua的debug.getinfo()来得到lua传入function到C#时的文件和代码行号. 将这2个信息保存起来.
在ReleaseLuaBase()中移除保存的信息,该方法被LuaEnv.Tick()调用.
在AllDelegateBridgeReleased()中,当检查到某个delegate没有释放时,就打印其WeakReference(在第1步中)关联保存的lua信息,即可精确得到具体是哪里没有释放.

具体修改代码如下:

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Dictionary<int, WeakReference> delegate_bridges = new Dictionary<int, WeakReference>();

#if UNITY_EDITOR
// 保存weakReference的hash
private List<int> bridgeLuaRefs = new List<int>();
// 保存对应的lua stack info
private List<string> bridgeLuaRefs2 = new List<string>();
// 开关
public bool debugDelegateBridgeRelease = false;
#endif

public object CreateDelegateBridge(RealStatePtr L, Type delegateType, int idx)
{
WeakReference weakRef = null;
#if UNITY_EDITOR
object obj;
if (this.debugDelegateBridgeRelease)
{
string luaStack = this._GetLuaStack(L);
obj = this._CreateDelegateBridge(L, delegateType, idx, out weakRef);
if (weakRef != null)
{
bridgeLuaRefs.Add(weakRef.GetHashCode());
bridgeLuaRefs2.Add(luaStack);
}
}
else
{
obj = this._CreateDelegateBridge(L, delegateType, idx, out weakRef);
}
return obj;
#else
return this._CreateDelegateBridge(L, delegateType, idx, out weakRef);
#endif
}

#if UNITY_EDITOR
private string _GetLuaStack(RealStatePtr L)
{
var oldTop = LuaAPI.lua_gettop(L);

// @see https://www.lua.org/pil/25.2.html
int debug = LuaAPI.xlua_getglobal(L, "debug");
LuaAPI.xlua_pushasciistring(L, "getinfo");
LuaAPI.xlua_pgettable(L, -2); // 获取getinfo function
LuaAPI.xlua_pushinteger(L, 2); // 传入getinfo()第1个参数
LuaAPI.xlua_pushasciistring(L, "Sl"); // 传入getinfo()第2个参数
var strIndex = LuaAPI.lua_pcall(L, 2, 1, 0); // 此时在栈上的结果是一个table
// @see https://www.lua.org/pil/25.1.html
LuaAPI.lua_pushstring(L, "source"); // 要获取一个table某个key下的值, 要先传入key的值='source'
LuaAPI.xlua_pgettable(L, -2); // 获取table[key]返回的值,此时是一个string
var luasource = LuaAPI.lua_tostring(L, -1);
LuaAPI.lua_pop(L, 1); // 弹出结果

LuaAPI.lua_pushstring(L, "currentline");
LuaAPI.xlua_pgettable(L, -2);
var currentline = LuaAPI.lua_tostring(L, -1);
LuaAPI.lua_pop(L, 1);
LuaAPI.lua_settop(L, oldTop);

string luaStack = luasource + ":" + currentline;
return luaStack;
}
#endif

private object _CreateDelegateBridge(RealStatePtr L, Type delegateType, int idx, out WeakReference weakRef)
{

LuaAPI.lua_pushvalue(L, idx);
LuaAPI.lua_rawget(L, LuaIndexes.LUA_REGISTRYINDEX);
if (!LuaAPI.lua_isnil(L, -1))
{
int referenced = LuaAPI.xlua_tointeger(L, -1);
LuaAPI.lua_pop(L, 1);

weakRef = delegate_bridges[referenced];
if (weakRef.IsAlive)
{
if (delegateType == null)
{
return weakRef.Target;
}
DelegateBridgeBase exist_bridge = weakRef.Target as DelegateBridgeBase;
Delegate exist_delegate;
if (exist_bridge.TryGetDelegate(delegateType, out exist_delegate))
{
return exist_delegate;
}
else
{
exist_delegate = getDelegate(exist_bridge, delegateType);
exist_bridge.AddDelegate(delegateType, exist_delegate);
return exist_delegate;
}
}
}
else
{
LuaAPI.lua_pop(L, 1);
}

LuaAPI.lua_pushvalue(L, idx);
int reference = LuaAPI.luaL_ref(L);
LuaAPI.lua_pushvalue(L, idx);
LuaAPI.lua_pushnumber(L, reference);
LuaAPI.lua_rawset(L, LuaIndexes.LUA_REGISTRYINDEX);
DelegateBridgeBase bridge;
try
{
#if (UNITY_EDITOR || XLUA_GENERAL) && !NET_STANDARD_2_0
if (!DelegateBridge.Gen_Flag)
{
bridge = Activator.CreateInstance(delegate_birdge_type, new object[] { reference, luaEnv }) as DelegateBridgeBase;
}
else
#endif
{
bridge = new DelegateBridge(reference, luaEnv);
}
}
catch (Exception e)
{
LuaAPI.lua_pushvalue(L, idx);
LuaAPI.lua_pushnil(L);
LuaAPI.lua_rawset(L, LuaIndexes.LUA_REGISTRYINDEX);
LuaAPI.lua_pushnil(L);
LuaAPI.xlua_rawseti(L, LuaIndexes.LUA_REGISTRYINDEX, reference);
throw e;
}
if (delegateType == null)
{
weakRef = new WeakReference(bridge);
delegate_bridges[reference] = weakRef;
return bridge;
}
try
{
var ret = getDelegate(bridge, delegateType);
bridge.AddDelegate(delegateType, ret);
weakRef = new WeakReference(bridge);
delegate_bridges[reference] = weakRef;
return ret;
}
catch (Exception e)
{
bridge.Dispose();
throw e;
}
}

public bool AllDelegateBridgeReleased()
{
var _bridgeLuaRefs = this.bridgeLuaRefs;
var _bridgeLuaRefs2 = this.bridgeLuaRefs2;
this.bridgeLuaRefs = new List<int>();
this.bridgeLuaRefs2 = new List<string>();
foreach (var kv in delegate_bridges)
{
if (kv.Value.IsAlive)
{
#if UNITY_EDITOR
if (this.debugDelegateBridgeRelease)
{
var hash = kv.Value.GetHashCode();
for (int i = 0; i < _bridgeLuaRefs.Count; i++)
{
if (_bridgeLuaRefs[i] == hash)
{
UnityEngine.Debug.Log("未释放lua引用: " + _bridgeLuaRefs2.Count + " : " + _bridgeLuaRefs2[i]);
break;
}
}
}
#endif
return false;
}
}
return true;
}

public void ReleaseLuaBase(RealStatePtr L, int reference, bool is_delegate)
{
if (is_delegate)
{
LuaAPI.xlua_rawgeti(L, LuaIndexes.LUA_REGISTRYINDEX, reference);
if (LuaAPI.lua_isnil(L, -1))
{
LuaAPI.lua_pop(L, 1);
}
else
{
LuaAPI.lua_pushvalue(L, -1);
LuaAPI.lua_rawget(L, LuaIndexes.LUA_REGISTRYINDEX);
if (LuaAPI.lua_type(L, -1) == LuaTypes.LUA_TNUMBER && LuaAPI.xlua_tointeger(L, -1) == reference) //
{
//UnityEngine.Debug.LogWarning("release delegate ref = " + luaReference);
LuaAPI.lua_pop(L, 1);// pop LUA_REGISTRYINDEX[func]
LuaAPI.lua_pushnil(L);
LuaAPI.lua_rawset(L, LuaIndexes.LUA_REGISTRYINDEX); // LUA_REGISTRYINDEX[func] = nil
}
else //another Delegate ref the function before the GC tick
{
LuaAPI.lua_pop(L, 2); // pop LUA_REGISTRYINDEX[func] & func
}
}

LuaAPI.lua_unref(L, reference);

WeakReference weakRef = null;
delegate_bridges.TryGetValue(reference, out weakRef);
delegate_bridges.Remove(reference);

#if UNITY_EDITOR
if (this.debugDelegateBridgeRelease && weakRef != null)
{
var hash = weakRef.GetHashCode();
for (int i = 0; i < this.bridgeLuaRefs.Count; i++)
{
if (bridgeLuaRefs[i] == hash)
{
bridgeLuaRefs.RemoveAt(i);
bridgeLuaRefs2.RemoveAt(i);
break;
}
}
}
#endif
}
else
{
LuaAPI.lua_unref(L, reference);
}
}

在使用new LuaEnv()的地方设置luaEnv.translator.debugDelegateBridgeRelease = true.

转载请注明出处: https://www.jianshu.com/p/58d20d46560a