- split up the OnDestroy method of interpolations.

It seems there can be rare conditions where an interpolation is 'lost' and later garbage collected. If that happens after the owning map is gone, all pointers in the interpolation object will be invalid and Destroy would crash while trying to unlink it. So anything that explicitly deletes an interpolation now has to manually unlink it from the map first so that OnDestroy can be kept clean of map references.

src/r_data/r_interpolate.cpp

@@ -62,7 +62,7 @@ public:
 
 	DSectorPlaneInterpolation() {}
 	DSectorPlaneInterpolation(sector_t *sector, bool plane, bool attach);
-	void OnDestroy() override;
+	void UnlinkFromMap() override;
 	void UpdateInterpolation();
 	void Restore();
 	void Interpolate(double smoothratio);
@@ -90,7 +90,7 @@ public:
 
 	DSectorScrollInterpolation() {}
 	DSectorScrollInterpolation(sector_t *sector, bool plane);
-	void OnDestroy() override;
+	void UnlinkFromMap() override;
 	void UpdateInterpolation();
 	void Restore();
 	void Interpolate(double smoothratio);
@@ -118,7 +118,7 @@ public:
 
 	DWallScrollInterpolation() {}
 	DWallScrollInterpolation(side_t *side, int part);
-	void OnDestroy() override;
+	void UnlinkFromMap() override;
 	void UpdateInterpolation();
 	void Restore();
 	void Interpolate(double smoothratio);
@@ -145,7 +145,7 @@ public:
 
 	DPolyobjInterpolation() {}
 	DPolyobjInterpolation(FPolyObj *poly);
-	void OnDestroy() override;
+	void UnlinkFromMap() override;
 	void UpdateInterpolation();
 	void Restore();
 	void Interpolate(double smoothratio);
@@ -302,10 +302,12 @@ void FInterpolator::ClearInterpolations()
 {
 	DInterpolation *probe = Head;
 	Head = nullptr;
+
 	while (probe != nullptr)
 	{
 		DInterpolation *next = probe->Next;
 		probe->Next = probe->Prev = nullptr;
+		probe->UnlinkFromMap();
 		probe->Destroy();
 		probe = next;
 	}
@@ -348,7 +350,11 @@ int DInterpolation::AddRef()
 int DInterpolation::DelRef(bool force)
 {
 	if (refcount > 0) --refcount;
-	if (force && refcount == 0) Destroy();
+	if (force && refcount == 0)
+	{
+		UnlinkFromMap();
+		Destroy();
+	}
 	return refcount;
 }
 
@@ -358,11 +364,10 @@ int DInterpolation::DelRef(bool force)
 //
 //==========================================================================
 
-void DInterpolation::OnDestroy()
+void DInterpolation::UnlinkFromMap()
 {
 	Level->interpolator.RemoveInterpolation(this);
 	refcount = 0;
-	Super::OnDestroy();
 }
 
 //==========================================================================
@@ -411,7 +416,7 @@ DSectorPlaneInterpolation::DSectorPlaneInterpolation(sector_t *_sector, bool _pl
 //
 //==========================================================================
 
-void DSectorPlaneInterpolation::OnDestroy()
+void DSectorPlaneInterpolation::UnlinkFromMap()
 {
 	if (sector != nullptr)
 	{
@@ -425,12 +430,11 @@ void DSectorPlaneInterpolation::OnDestroy()
 		}
 		sector = nullptr;
 	}
-	for(unsigned i=0; i<attached.Size(); i++)
+	for (unsigned i = 0; i < attached.Size(); i++)
 	{
 		attached[i]->DelRef();
 	}
 	attached.Reset();
-	Super::OnDestroy();
 }
 
 //==========================================================================
@@ -508,7 +512,7 @@ void DSectorPlaneInterpolation::Interpolate(double smoothratio)
 	{
 		pplane->setD(oldheight + (bakheight - oldheight) * smoothratio);
 		sector->SetPlaneTexZ(pos, oldtexz + (baktexz - oldtexz) * smoothratio, true);
-	P_RecalculateAttached3DFloors(sector);
+		P_RecalculateAttached3DFloors(sector);
 		sector->CheckPortalPlane(pos);
 	}
 }
@@ -572,7 +576,7 @@ DSectorScrollInterpolation::DSectorScrollInterpolation(sector_t *_sector, bool _
 //
 //==========================================================================
 
-void DSectorScrollInterpolation::OnDestroy()
+void DSectorScrollInterpolation::UnlinkFromMap()
 {
 	if (sector != nullptr)
 	{
@@ -586,7 +590,6 @@ void DSectorScrollInterpolation::OnDestroy()
 		}
 		sector = nullptr;
 	}
-	Super::OnDestroy();
 }
 
 //==========================================================================
@@ -626,6 +629,7 @@ void DSectorScrollInterpolation::Interpolate(double smoothratio)
 
 	if (refcount == 0 && oldx == bakx && oldy == baky)
 	{
+		UnlinkFromMap();
 		Destroy();
 	}
 	else
@@ -678,14 +682,13 @@ DWallScrollInterpolation::DWallScrollInterpolation(side_t *_side, int _part)
 //
 //==========================================================================
 
-void DWallScrollInterpolation::OnDestroy()
+void DWallScrollInterpolation::UnlinkFromMap()
 {
 	if (side != nullptr)
 	{
 		side->textures[part].interpolation = nullptr;
 		side = nullptr;
 	}
-	Super::OnDestroy();
 }
 
 //==========================================================================
@@ -725,6 +728,7 @@ void DWallScrollInterpolation::Interpolate(double smoothratio)
 
 	if (refcount == 0 && oldx == bakx && oldy == baky)
 	{
+		UnlinkFromMap();
 		Destroy();
 	}
 	else
@@ -777,13 +781,12 @@ DPolyobjInterpolation::DPolyobjInterpolation(FPolyObj *po)
 //
 //==========================================================================
 
-void DPolyobjInterpolation::OnDestroy()
+void DPolyobjInterpolation::UnlinkFromMap()
 {
 	if (poly != nullptr)
 	{
 		poly->interpolation = nullptr;
 	}
-	Super::OnDestroy();
 }
 
 //==========================================================================
@@ -844,6 +847,7 @@ void DPolyobjInterpolation::Interpolate(double smoothratio)
 	}
 	if (refcount == 0 && !changed)
 	{
+		UnlinkFromMap();
 		Destroy();
 	}
 	else

src/r_data/r_interpolate.h

@@ -30,7 +30,7 @@ public:
 	int AddRef();
 	int DelRef(bool force = false);
 
-	void OnDestroy() override;
+	virtual void UnlinkFromMap();
 	virtual void UpdateInterpolation() = 0;
 	virtual void Restore() = 0;
 	virtual void Interpolate(double smoothratio) = 0;