Allow passing a pointer to SDL_FreeEventMemory()

Also clarify in the documentation that you should not call SDL_FreeEventMemory(NULL) from your main thread.

include/SDL3/SDL_events.h

@@ -1428,14 +1428,20 @@ extern SDL_DECLSPEC void * SDLCALL SDL_AllocateEventMemory(size_t size);
  * Free temporary event memory allocated by SDL.
  *
  * This function frees temporary memory allocated for events and APIs that
- * return temporary strings. This memory is local to the thread that creates
+ * follow the SDL_GetStringRule. This memory is local to the thread that creates
  * it and is automatically freed for the main thread when pumping the event
- * loop. For other threads you may want to call this function periodically to
+ * loop. For other threads you may call this function periodically to
  * free any temporary memory created by that thread.
  *
+ * You can free a specific pointer, to provide more fine grained control over memory management, or you can pass NULL to free all pending temporary allocations. You should *NOT* pass NULL on your main event handling thread, as there may be temporary memory being used by events in-flight. For that thread SDL will call this internally when it's safe to do so.
+ *
  * Note that if you call SDL_AllocateEventMemory() on one thread and pass it
  * to another thread, e.g. via a user event, then you should be sure the other
- * thread has finished processing it before calling this function.
+ * thread has finished processing it before calling this function with NULL.
+ *
+ * All temporary memory is freed on the main thread in SDL_Quit() and for other threads when they call SDL_CleanupTLS(), which is automatically called at cleanup time for threads created using SDL_CreateThread().
+ *
+ * \param mem a pointer allocated with SDL_AllocateEventMemory(), or NULL to free all pending temporary allocations.
  *
  * \threadsafety It is safe to call this function from any thread.
  *
@@ -1443,7 +1449,7 @@ extern SDL_DECLSPEC void * SDLCALL SDL_AllocateEventMemory(size_t size);
  *
  * \sa SDL_AllocateEventMemory
  */
-extern SDL_DECLSPEC void SDLCALL SDL_FreeEventMemory(void);
+extern SDL_DECLSPEC void SDLCALL SDL_FreeEventMemory(const void *mem);
 
 /* Ends C function definitions when using C++ */
 #ifdef __cplusplus

include/SDL3/SDL_thread.h

@@ -520,6 +520,8 @@ extern SDL_DECLSPEC int SDLCALL SDL_SetTLS(SDL_TLSID *id, const void *value, SDL
 /**
  * Cleanup all TLS data for this thread.
  *
+ * If you are creating your threads outside of SDL and then calling SDL functions, you should call this function before your thread exits, to properly clean up SDL memory.
+ *
  * \threadsafety It is safe to call this function from any thread.
  *
  * \since This function is available since SDL 3.0.0.

src/dynapi/SDL_dynapi_procs.h

@@ -169,7 +169,7 @@ SDL_DYNAPI_PROC(int,SDL_FlushAudioStream,(SDL_AudioStream *a),(a),return)
 SDL_DYNAPI_PROC(void,SDL_FlushEvent,(Uint32 a),(a),)
 SDL_DYNAPI_PROC(void,SDL_FlushEvents,(Uint32 a, Uint32 b),(a,b),)
 SDL_DYNAPI_PROC(int,SDL_FlushRenderer,(SDL_Renderer *a),(a),return)
-SDL_DYNAPI_PROC(void,SDL_FreeEventMemory,(void),(),)
+SDL_DYNAPI_PROC(void,SDL_FreeEventMemory,(const void *a),(a),)
 SDL_DYNAPI_PROC(void,SDL_GDKSuspendComplete,(void),(),)
 SDL_DYNAPI_PROC(SDL_GLContext,SDL_GL_CreateContext,(SDL_Window *a),(a),return)
 SDL_DYNAPI_PROC(int,SDL_GL_DestroyContext,(SDL_GLContext a),(a),return)

src/events/SDL_events.c

@@ -110,12 +110,7 @@ static void SDL_CleanupEventMemory(void *data)
 {
     SDL_EventMemoryState *state = (SDL_EventMemoryState *)data;
 
-    while (state->head) {
-        SDL_EventMemory *entry = state->head;
-        state->head = entry->next;
-        SDL_free(entry->memory);
-        SDL_free(entry);
-    }
+    SDL_FreeEventMemory(NULL);
     SDL_free(state);
 }
 
@@ -217,9 +212,46 @@ static void SDL_FlushEventMemory(Uint32 eventID)
     }
 }
 
-void SDL_FreeEventMemory(void)
+void SDL_FreeEventMemory(const void *mem)
 {
-    SDL_FlushEventMemory(0);
+    SDL_EventMemoryState *state;
+
+    state = SDL_GetEventMemoryState(SDL_FALSE);
+    if (!state) {
+        return;
+    }
+
+    if (mem) {
+        SDL_EventMemory *prev = NULL, *entry;
+
+        for (entry = state->head; entry; prev = entry, entry = entry->next) {
+            if (mem == entry->memory) {
+                if (prev) {
+                    prev->next = entry->next;
+                }
+                if (entry == state->head) {
+                    state->head = entry->next;
+                }
+                if (entry == state->tail) {
+                    state->tail = prev;
+                }
+                SDL_free(entry->memory);
+                SDL_free(entry);
+                break;
+            }
+        }
+    } else {
+        if (state->head) {
+            while (state->head) {
+                SDL_EventMemory *entry = state->head;
+
+                state->head = entry->next;
+                SDL_free(entry->memory);
+                SDL_free(entry);
+            }
+            state->tail = NULL;
+        }
+    }
 }
 
 #ifndef SDL_JOYSTICK_DISABLED
@@ -741,7 +773,7 @@ void SDL_StopEventLoop(void)
     SDL_EventQ.free = NULL;
     SDL_AtomicSet(&SDL_sentinel_pending, 0);
 
-    SDL_FlushEventMemory(0);
+    SDL_FreeEventMemory(NULL);
 
     /* Clear disabled event state */
     for (i = 0; i < SDL_arraysize(SDL_disabled_events); ++i) {