Kernel: allow unregistering BKE callback functions

Introduce `BKE_callback_remove()`, which undoes the effect of
`BKE_callback_add()`. It also respects `funcstore->alloc` by freeing the
removed `funcstore` when needed.

This allows for shorter-lived objects in memory to unregister their
callbacks at the end of their lifespan.

`BKE_callback_global_finalize()` has been adjusted so that the
responsibility "remove a callback" is given to one function only.

Reviewed by: campbellbarton

Differential Revision: https://developer.blender.org/D12625

2 files changed, 11 insertions, 4 deletions

diff --git a/source/blender/blenkernel/BKE_callbacks.h b/source/blender/blenkernel/BKE_callbacks.h
index ef2a0ed34a0..7c518f33c89 100644
--- a/source/blender/blenkernel/BKE_callbacks.h
+++ b/source/blender/blenkernel/BKE_callbacks.h
@@ -130,6 +130,7 @@ void BKE_callback_exec_id_depsgraph(struct Main *bmain,
                                     struct Depsgraph *depsgraph,
                                     eCbEvent evt);
 void BKE_callback_add(bCallbackFuncStore *funcstore, eCbEvent evt);
+void BKE_callback_remove(bCallbackFuncStore *funcstore, eCbEvent evt);
 
 void BKE_callback_global_init(void);
 void BKE_callback_global_finalize(void);
diff --git a/source/blender/blenkernel/intern/callbacks.c b/source/blender/blenkernel/intern/callbacks.c
index 11ee9492b44..87d5961b12e 100644
--- a/source/blender/blenkernel/intern/callbacks.c
+++ b/source/blender/blenkernel/intern/callbacks.c
@@ -80,6 +80,15 @@ void BKE_callback_add(bCallbackFuncStore *funcstore, eCbEvent evt)
   BLI_addtail(lb, funcstore);
 }
 
+void BKE_callback_remove(bCallbackFuncStore *funcstore, eCbEvent evt)
+{
+  ListBase *lb = &callback_slots[evt];
+  BLI_remlink(lb, funcstore);
+  if (funcstore->alloc) {
+    MEM_freeN(funcstore);
+  }
+}
+
 void BKE_callback_global_init(void)
 {
   /* do nothing */
@@ -95,10 +104,7 @@ void BKE_callback_global_finalize(void)
     bCallbackFuncStore *funcstore_next;
     for (funcstore = lb->first; funcstore; funcstore = funcstore_next) {
       funcstore_next = funcstore->next;
-      BLI_remlink(lb, funcstore);
-      if (funcstore->alloc) {
-        MEM_freeN(funcstore);
-      }
+      BKE_callback_remove(funcstore, evt);
     }
   }
 }