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ref count fails

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Started by zerochen October 11, 2012 11:08 PM

6 comments, last by zerochen 11 years, 6 months ago

zerochen

542

Author

October 11, 2012 11:08 PM

hi,

i have following base structure
Script:



class A

{

};



class B

{

	  void init()

	  {

			 create("A");

	  };

};

pseudo c++:



asIScriptObject* create(string s)

{

	   int id = getClassId(s);

	   return reinterpret_cast<asIScriptObject*>(engine->CreateScriptObject(id));

}

so now to my problem.

i create class B and than i call the function init() from B that creates a new object from A
something like this:

pseudo call stack:



objB = create("B")

objB.callMethod("init")

that calls

objA = create("A")

after that the ref count of objB is 1 (as expected)
the ref count of objA is 2 (have to be 1)

have i an error in my logic?

i tracked this down to:
as_scriptobject.cpp line 122
that line doesnt dec the ref counter of objA but it does it for objB.

is that because to call a script function there has to be an active context?

is this a bug or have i call the release func myself?

thx for help
zerochen

WitchLord

4,835

October 12, 2012 12:57 AM

I don't see anything wrong with what you're doing. It might be a problem with the nested context functionality in AngelScript.

How have you registered the create() function with AngelScript?

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zerochen

542

Author

October 12, 2012 01:56 PM

with angelscript in c++ yes



CScriptHandle CScriptFunction::createObject(const std::string& name, const core::vector3df& pos)

r = script->getEngine()->RegisterGlobalFunction("ref@ CreateObject(const string& in, const vector3df& in)", asMETHODPR(CScriptFunction, createObject, (const std::string&, const core::vector3df&), CScriptHandle), this, asCALL_THISCALL); assert( r >= 0 );

i wrote a patch for angelscript that allows me to register a global script function as a method of a class.
maybe thats the problem but i use it for weeks without any problems. i think it is the nested context
here is the patch file.



Index: include/angelscript.h

===================================================================

--- include/angelscript.h (Revision 1359)

+++ include/angelscript.h (Arbeitskopie)

@@ -520,6 +520,7 @@

  virtual asIJITCompiler *GetJITCompiler() const = 0;



  // Global functions

+ virtual int	 RegisterGlobalFunction(const char* declaration, const asSFuncPtr &funcPointer, void* obj, asDWORD callConv) = 0;

  virtual int				RegisterGlobalFunction(const char *declaration, const asSFuncPtr &funcPointer, asDWORD callConv) = 0;

  virtual asUINT			 GetGlobalFunctionCount() const = 0;

#ifdef AS_DEPRECATED

Index: source/as_callfunc.cpp

===================================================================

--- source/as_callfunc.cpp (Revision 1359)

+++ source/as_callfunc.cpp (Arbeitskopie)

@@ -409,12 +409,8 @@



  if( callConv >= ICC_THISCALL )

  {

-  if( objectPointer )

+  if(!((obj = objectPointer) || (obj = descr->GetUserData())))

   {

-   obj = objectPointer;

-  }

-  else

-  {

	// The object pointer should be popped from the context stack

	popSize += AS_PTR_SIZE;



Index: source/as_scriptengine.cpp

===================================================================

--- source/as_scriptengine.cpp (Revision 1359)

+++ source/as_scriptengine.cpp (Arbeitskopie)

@@ -2458,6 +2458,83 @@

}



// interface

+int asCScriptEngine::RegisterGlobalFunction(const char* declaration, const asSFuncPtr &funcPointer, void* obj, asDWORD callConv)

+{

+ asSSystemFunctionInterface internal;

+

+ int r = DetectCallingConvention(true, funcPointer, callConv, &internal);

+ if( r < 0 )

+  return ConfigError(r, "RegisterGlobalFunction", declaration, 0);

+

+ if( callConv != asCALL_THISCALL)

+  return ConfigError(asNOT_SUPPORTED, "RegisterGlobalFunction", declaration, 0);

+

+ isPrepared = false;

+

+ // Put the system function in the list of system functions

+ asSSystemFunctionInterface *newInterface = asNEW(asSSystemFunctionInterface)(internal);

+

+ if( newInterface == 0 )

+  return ConfigError(asOUT_OF_MEMORY, "RegisterGlobalFunction", declaration, 0);

+

+ asCScriptFunction *func = asNEW(asCScriptFunction)(this, 0, asFUNC_SYSTEM);

+

+ if( func == 0 )

+ {

+  asDELETE(newInterface, asSSystemFunctionInterface);

+  return ConfigError(asOUT_OF_MEMORY, "RegisterGlobalFunction", declaration, 0);

+ }

+

+ func->sysFuncIntf = newInterface;

+ func->SetUserData(obj);

+

+ asCBuilder bld(this, 0);

+ r = bld.ParseFunctionDeclaration(0, declaration, func, true, &newInterface->paramAutoHandles, &newInterface->returnAutoHandle, defaultNamespace);

+ if( r < 0 )

+ {

+  // Set as dummy function before deleting

+  func->funcType = asFUNC_DUMMY;

+  asDELETE(func,asCScriptFunction);

+  return ConfigError(asINVALID_DECLARATION, "RegisterGlobalFunction", declaration, 0);

+ }

+

+ // TODO: namespace: What if the declaration defined an explicit namespace?

+ func->nameSpace = defaultNamespace;

+

+ // Check name conflicts

+ r = bld.CheckNameConflict(func->name.AddressOf(), 0, 0, defaultNamespace);

+ if( r < 0 )

+ {

+  asDELETE(func,asCScriptFunction);

+  return ConfigError(asNAME_TAKEN, "RegisterGlobalFunction", declaration, 0);

+ }

+

+ func->id = GetNextScriptFunctionId();

+ SetScriptFunction(func);

+

+ currentGroup->scriptFunctions.PushLast(func);

+ func->accessMask = defaultAccessMask;

+ registeredGlobalFuncs.PushLast(func);

+

+ // If parameter type from other groups are used, add references

+ if( func->returnType.GetObjectType() )

+ {

+  asCConfigGroup *group = FindConfigGroupForObjectType(func->returnType.GetObjectType());

+  currentGroup->RefConfigGroup(group);

+ }

+ for( asUINT n = 0; n < func->parameterTypes.GetLength(); n++ )

+ {

+  if( func->parameterTypes[n].GetObjectType() )

+  {

+   asCConfigGroup *group = FindConfigGroupForObjectType(func->parameterTypes[n].GetObjectType());

+   currentGroup->RefConfigGroup(group);

+  }

+ }

+

+ // Return the function id as success

+ return func->id;

+}

+

int asCScriptEngine::RegisterGlobalFunction(const char *declaration, const asSFuncPtr &funcPointer, asDWORD callConv)

{

  asSSystemFunctionInterface internal;

Index: source/as_scriptengine.h

===================================================================

--- source/as_scriptengine.h (Revision 1359)

+++ source/as_scriptengine.h (Arbeitskopie)

@@ -100,6 +100,7 @@

	 virtual asIJITCompiler *GetJITCompiler() const;



  // Global functions

+ virtual int	   RegisterGlobalFunction(const char* declaration, const asSFuncPtr &funcPointer, void* obj, asDWORD callConv);

  virtual int				RegisterGlobalFunction(const char *declaration, const asSFuncPtr &funcPointer, asDWORD callConv);

  virtual asUINT			 GetGlobalFunctionCount() const;

#ifdef AS_DEPRECATED

i just copied the RegisterGlobalFunction, added the void* obj pointer to the function and set it after

func->sysFuncIntf = newInterface;
+ func->SetUserData(obj);

ah i use the lastest angelscript svn version of couse

WitchLord

4,835

October 12, 2012 05:36 PM

Your modification to the engine to allow registration of a class method as a global function doesn't appear to be the cause of the problem.

I see you're using the CScriptHandle add-on to return the newly created object. That might have something to do with the problem.

Do you mind showing how the CScriptFunction::createObject method is implemented? At least the part from the call to asIScriptEngine::CreateScriptObject to the return of the CScriptHandle? There might be something there that is causing the problem.

In meantime I'll try to reproduce the problem with what you've already shown.

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WitchLord

4,835

October 12, 2012 07:13 PM

I implemented the CreateObject function like this:



static CScriptHandle CreateObject(const string &s)

{

  asIScriptContext *ctx = asGetActiveContext();

  asIScriptEngine *engine = ctx->GetEngine();

  asIScriptModule *mod = engine->GetModule("test");

  asIObjectType *type = mod->GetObjectTypeByName(s.c_str());





  // The object will start with ref count == 1

  asIScriptObject *obj = reinterpret_cast<asIScriptObject*>(engine->CreateScriptObject(type->GetTypeId()));



  // Put the object in the generic handle container for return

  CScriptHandle ref(obj, type);





  // The CScriptHandle increased the ref count when it

  // stored the handle internally so we need to release one

  obj->Release();



  return ref;

}

I don't get any wrong reference counts when the function is implemented like this.

Do you release() the ref count after putting the object into the CScriptHandle?

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AngelScript - free scripting library - BMFont - free bitmap font generator - Tower - free puzzle game

zerochen

542

Author

October 12, 2012 07:15 PM



// this function is called from angelscript

CScriptHandle CScriptFunction::createObject(const std::string& name, const core::vector3df& pos)

{

int id = builder.GetModule()->GetTypeIdByDecl(name.c_str());

if(id == asINVALID_TYPE)

{

   //error msg

  return CScriptHandle();

}



asIScriptObject* s = reinterpret_cast<asIScriptObject*>(engine->CreateScriptObject(id));

//here the ref count is sometimes 2



if(!scriptObj)

  return CScriptHandle();



// set pos

// add it to an objArray



return CScriptHandle(scriptObj, scriptObj->GetObjectType());

}

// The CScriptHandle increased the ref count when it
// stored the handle internally so we need to release one[/quote]

yes but if the CScriptHandle will be destroyed the ref counter will dec

but the problem is direct after the engine createObject function so i think it is a angelscript problem

i will write a little example that reproduce the problem but now i have no time sry

WitchLord

4,835

October 12, 2012 11:50 PM

The ref count after CreateScriptObject() can be 2 if the object requires garbage collections. What happens then is that the object notifies the garbage collector of its existence, which will increment the ref counter.

Anyway, in your implementation of CScriptFunction::createObject() you need to release the reference after creating the CScriptHandle that will be returned.

AngelCode.com - game development and more - Reference DB - game developer references
AngelScript - free scripting library - BMFont - free bitmap font generator - Tower - free puzzle game

zerochen

542

Author

October 18, 2012 09:15 AM

ok thx that solved the problem. i thought it was because the createScriptObject func returns sometimes an obj with ref count 2

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