Fix memory leak caused by circular prop list chains.

The shapes library has such pointer chains. The leaks were getting pretty heavy because they included pointers to C4AulFuncs, which kept a lot of parts of the script engine and string tables in memory.

src/C4Globals.cpp

@@ -33,6 +33,7 @@
 C4Set<C4PropList *> C4PropList::PropLists;
 #endif
 C4Set<C4PropListNumbered *> C4PropListNumbered::PropLists;
+C4Set<C4PropListScript *> C4PropListScript::PropLists;
 std::vector<C4PropListNumbered *> C4PropListNumbered::ShelvedPropLists;
 int32_t C4PropListNumbered::EnumerationIndex = 0;
 C4StringTable  Strings;

src/game/C4Game.cpp

@@ -603,6 +603,9 @@ void C4Game::Clear()
 
 	C4PropListNumbered::ClearShelve(); // may be nonempty if there was a fatal error during section load
 	ScriptEngine.Clear();
+	// delete any remaining prop lists from circular chains
+	C4PropListNumbered::ClearNumberedPropLists(); 
+	C4PropListScript::ClearScriptPropLists();
 	MainSysLangStringTable.Clear();
 	ScenarioLangStringTable.Clear();
 	CloseScenario();

src/mape/cpp-handles/stub-handle.cpp

@@ -38,6 +38,7 @@
 C4Set<C4PropList *> C4PropList::PropLists;
 #endif
 C4Set<C4PropListNumbered *> C4PropListNumbered::PropLists;
+C4Set<C4PropListScript *> C4PropListScript::PropLists;
 std::vector<C4PropListNumbered *> C4PropListNumbered::ShelvedPropLists;
 int32_t C4PropListNumbered::EnumerationIndex = 0;
 C4StringTable Strings;

src/script/C4PropList.cpp

@@ -134,6 +134,20 @@ void C4PropListNumbered::ClearShelve()
 	ShelvedPropLists.clear();
 }
 
+void C4PropListNumbered::ClearNumberedPropLists()
+{
+	// empty all proplists to ensure safe deletion of proplists with circular references
+	// note that this the call to Clear() might delete some prop lists. So it is assumed that
+	// PropLists does not shrink its table as the number of values goes down
+	C4PropListNumbered *const* p_next = PropLists.First(), *const* p;
+	while ((p = p_next))
+	{
+		p_next = PropLists.Next(p);
+		// check *p since it might have been deleted by clearing the previous prop list
+		if (*p) (*p)->Clear();
+	}
+}
+
 C4PropListNumbered::C4PropListNumbered(C4PropList * prototype): C4PropList(prototype), Number(-1)
 {
 }
@@ -190,6 +204,28 @@ C4PropListNumbered::~C4PropListNumbered()
 		Log("removing numbered proplist without number");
 }
 
+void C4PropListScript::ClearScriptPropLists()
+{
+	// empty all proplists to ensure safe deletion of proplists with circular references
+	// note that this the call to Clear() might delete some prop lists. So it is assumed that
+	// PropLists does not shrink its table as the number of values goes down
+	// However, some values may be skipped due to table consolidation. Just fix it by iterating over the table until it's empty.
+	C4PropListScript *const* p_next, *const* p;
+	while ((p_next = PropLists.First()))
+	{
+		while ((p = p_next))
+		{
+			p_next = PropLists.Next(p);
+			// check *p since it might have been deleted by clearing the previous prop list
+			if (*p)
+			{
+				C4Value ref(C4VPropList(*p)); // keep a reference because prop list might delete itself within clearing method otherwise
+				(*p)->Clear();
+			}
+		}
+	}
+}
+
 void C4PropListStatic::RefCompileFunc(StdCompiler *pComp, C4ValueNumbers * numbers) const
 {
 	assert(!pComp->isCompiler());
@@ -609,7 +645,7 @@ C4PropertyName C4PropList::GetPropertyP(C4PropertyName n) const
 	return P_LAST;
 }
 
-int32_t C4PropList::GetPropertyInt(C4PropertyName n) const
+int32_t C4PropList::GetPropertyInt(C4PropertyName n, int32_t default_val) const
 {
 	C4String * k = &Strings.P[n];
 	if (Properties.Has(k))
@@ -618,9 +654,9 @@ int32_t C4PropList::GetPropertyInt(C4PropertyName n) const
 	}
 	if (GetPrototype())
 	{
-		return GetPrototype()->GetPropertyInt(n);
+		return GetPrototype()->GetPropertyInt(n, default_val);
 	}
-	return 0;
+	return default_val;
 }
 
 C4PropList *C4PropList::GetPropertyPropList(C4PropertyName n) const
@@ -800,3 +836,11 @@ unsigned int C4Set<C4PropList *>::Hash<C4PropList *>(C4PropList * const & e)
 {
 	return C4Set<C4PropListNumbered *>::Hash(static_cast<int>(reinterpret_cast<intptr_t>(e)));
 }
+
+template<> template<>
+unsigned int C4Set<C4PropListScript *>::Hash<C4PropListScript *>(C4PropListScript * const & e)
+{
+	// since script prop lists are only put in the set for reference keeping, just hash by pointer
+	// but use only some of the more significant bits because 
+	return reinterpret_cast<unsigned int>(e) / 63;
+}

src/script/C4PropList.h

@@ -113,7 +113,7 @@ public:
 	C4Value Call(C4String * k, C4AulParSet *pPars=0, bool fPassErrors=false);
 	C4Value Call(const char * k, C4AulParSet *pPars=0, bool fPassErrors=false);
 	C4PropertyName GetPropertyP(C4PropertyName k) const;
-	int32_t GetPropertyInt(C4PropertyName k) const;
+	int32_t GetPropertyInt(C4PropertyName k, int32_t default_val = 0) const;
 	C4PropList *GetPropertyPropList(C4PropertyName k) const;
 	bool HasProperty(C4String * k) const { return Properties.Has(k); }
 	// not allowed on frozen proplists
@@ -216,6 +216,7 @@ public:
 	static void ShelveNumberedPropLists(); // unnumber all proplists and put them on the shelve. To be used on remaining objects before a savegame load.
 	static void UnshelveNumberedPropLists(); // re-insert shelved proplists into main list
 	static void ClearShelve();
+	static void ClearNumberedPropLists(); // empty all properties in numbered prop lists. Used on game clear to ensure prop lists with circular references get cleared.
 protected:
 	C4PropListNumbered(C4PropList * prototype = 0);
 	void AcquireNumber(); // acquire a number and add to internal list
@@ -232,8 +233,14 @@ protected:
 class C4PropListScript: public C4PropList
 {
 public:
-	C4PropListScript(C4PropList * prototype = 0): C4PropList(prototype) { }
+	C4PropListScript(C4PropList * prototype = 0) : C4PropList(prototype) { PropLists.Add(this);  }
+	virtual ~C4PropListScript() { PropLists.Remove(this); }
 	bool Delete() { return true; }
+
+	static void ClearScriptPropLists(); // empty all properties in script-created prop lists. Used on game clear to ensure prop lists with circular references get cleared.
+
+protected:
+	static C4Set<C4PropListScript *> PropLists;
 };
 
 // PropLists declared in the game data

src/script/C4ScriptStandalone.cpp

@@ -34,6 +34,7 @@
 C4Set<C4PropList *> C4PropList::PropLists;
 #endif
 C4Set<C4PropListNumbered *> C4PropListNumbered::PropLists;
+C4Set<C4PropListScript *> C4PropListScript::PropLists;
 std::vector<C4PropListNumbered *> C4PropListNumbered::ShelvedPropLists;
 int32_t C4PropListNumbered::EnumerationIndex = 0;
 C4StringTable Strings;