thinker_era

A first pass in attempts to fix crashes when ACS causes map changes.
Frustratingly still got a crash, but I think this is definitely the right foundation to work with.

src/acs/environment.cpp

@@ -330,7 +330,16 @@ ACSVM::Word Environment::callSpecImpl
 	);
 
 	activator_t *activator = static_cast<activator_t *>(Z_Calloc(sizeof(activator_t), PU_LEVEL, nullptr));
-	auto __ = srb2::finally([activator]() { Z_Free(activator); });
+	auto __ = srb2::finally(
+		[info, activator]()
+		{
+			if (info->thread_era == thinker_era)
+			{
+				P_SetTarget(&activator->mo, NULL);
+				Z_Free(activator);
+			}
+		}
+	);
 
 	// This needs manually set, as ACS just uses indicies in the
 	// compiled string table and not actual strings, and SRB2 has

src/acs/thread.hpp

@@ -67,6 +67,7 @@ enum acs_tagType_e
 class ThreadInfo : public ACSVM::ThreadInfo
 {
 public:
+	UINT32 thread_era;			// If equal to thinker_era, mobj pointers are safe.
 	mobj_t *mo;					// Object that activated this thread.
 	line_t *line;				// Linedef that activated this thread.
 	UINT8 side;					// Front / back side of said linedef.
@@ -75,6 +76,7 @@ public:
 	bool fromLineSpecial;		// Called from P_ProcessLineSpecial.
 
 	ThreadInfo() :
+		thread_era { thinker_era },
 		mo{ nullptr },
 		line{ nullptr },
 		side{ 0 },
@@ -85,6 +87,7 @@ public:
 	}
 
 	ThreadInfo(const ThreadInfo &info) :
+		thread_era { thinker_era },
 		mo{ nullptr },
 		line{ info.line },
 		side{ info.side },
@@ -96,6 +99,7 @@ public:
 	}
 
 	ThreadInfo(const activator_t *activator) :
+		thread_era { thinker_era },
 		mo{ nullptr },
 		line{ activator->line },
 		side{ activator->side },
@@ -108,11 +112,15 @@ public:
 
 	~ThreadInfo()
 	{
-		P_SetTarget(&mo, nullptr);
+		if (thread_era == thinker_era)
+		{
+			P_SetTarget(&mo, nullptr);
+		}
 	}
 
 	ThreadInfo &operator = (const ThreadInfo &info)
 	{
+		thread_era = thinker_era;
 		P_SetTarget(&mo, info.mo);
 		line = info.line;
 		side = info.side;

src/p_local.h

@@ -83,6 +83,7 @@ extern thinker_t thlist[];
 extern mobj_t *mobjcache;
 
 void P_InitThinkers(void);
+void P_InvalidateThinkersWithoutInit(void);
 void P_AddThinker(const thinklistnum_t n, thinker_t *thinker);
 void P_RemoveThinker(thinker_t *thinker);
 void P_UnlinkThinker(thinker_t *thinker);

src/p_tick.c

@@ -41,6 +41,8 @@
 
 tic_t leveltime;
 
+UINT32 thinker_era = 0;
+
 INT32 P_AltFlip(INT32 n, tic_t tics)
 {
 	return leveltime % (2 * tics) < tics ? n : -(n);
@@ -201,8 +203,20 @@ void P_InitThinkers(void)
 	boss3cap = NULL;
 	waypointcap = NULL;
 	kitemcap = NULL;
+	P_InvalidateThinkersWithoutInit();
 	for (i = 0; i < NUM_THINKERLISTS; i++)
 		thlist[i].prev = thlist[i].next = &thlist[i];
+	
+	iquehead = iquetail = 0;
+}
+
+//
+// P_InvalidateThinkersWithoutInit
+//
+
+void P_InvalidateThinkersWithoutInit(void)
+{
+	thinker_era++;
 }
 
 // Adds a new thinker at the end of the list.

src/p_tick.h

@@ -34,6 +34,8 @@ void P_DoTeamscrambling(void);
 void P_RemoveThinkerDelayed(thinker_t *thinker); //killed
 mobj_t *P_SetTarget(mobj_t **mo, mobj_t *target);   // killough 11/98
 
+extern UINT32 thinker_era;
+
 // Negate the value for tics
 INT32 P_AltFlip(INT32 value, tic_t tics);
 #define P_RandomFlip(value) P_AltFlip(value, 1)