Keep the previous dynamic pool in memory

Due to sm64 weirdness, I can't reliably free memory at certain points
The hacky solution is to keep the previous dynamic pool in memory,
essentially requiring two frees to actually clear all memory from it

data/dynos_mgr_models.cpp

@@ -21,18 +21,12 @@ struct ModelInfo {
     enum ModelPool modelPool;
 };
 
-struct ScheduledFreePool {
-    struct DynamicPool* pool;
-};
-
 static struct DynamicPool* sModelPools[MODEL_POOL_MAX] = { 0 };
 
 static std::map<void*, struct ModelInfo> sAssetMap[MODEL_POOL_MAX];
 static std::map<u32, std::vector<struct ModelInfo>> sIdMap;
 static std::map<u32, u32> sOverwriteMap;
 
-static std::vector<struct ScheduledFreePool> sPoolsToFree;
-
 static u32 find_empty_id() {
     u32 id = 256;
     while (true) {
@@ -168,12 +162,7 @@ void DynOS_Model_ClearPool(enum ModelPool aModelPool) {
     if (!sModelPools[aModelPool]) { return; }
 
     // schedule pool to be freed
-    sPoolsToFree.push_back({
-        .pool = sModelPools[aModelPool],
-    });
-
-    // clear pointer
-    sModelPools[aModelPool] = NULL;
+    dynamic_pool_free_pool(sModelPools[aModelPool]);
 
     // clear overwrite
     if (aModelPool == MODEL_POOL_LEVEL) {
@@ -202,12 +191,4 @@ void DynOS_Model_ClearPool(enum ModelPool aModelPool) {
 
 void DynOS_Model_Update() {
 
-    // only free a pool when we've scheduled at least 3
-    // this is required because the way that sm64 loads areas is actually insane
-    // if we free immediately, the camera graph node is incorrect on the star selection screen
-    if (sPoolsToFree.size() <= 2) { return; }
-
-    auto& it = sPoolsToFree[0];
-    dynamic_pool_free_pool(it.pool);
-    sPoolsToFree.erase(sPoolsToFree.begin());
 }

src/engine/level_script.c

@@ -366,7 +366,6 @@ static void level_reset_globals(void) {
     // free previous level pool
     if (gLevelPool != NULL) {
         dynamic_pool_free_pool(gLevelPool);
-        gLevelPool = NULL;
     }
 
     // reset envfx

src/game/envfx_snow.c

@@ -156,11 +156,8 @@ void envfx_update_snowflake_count(s32 mode, Vec3s marioPos) {
  * Deallocate the buffer storing snow particles and set the environment effect
  * to none.
  */
-void envfx_cleanup_snow(void *snowParticleArray) {
+void envfx_cleanup_snow(UNUSED void *snowParticleArray) {
     if (gEnvFxMode) {
-        if (snowParticleArray) {
-            dynamic_pool_free(gLevelPool, snowParticleArray);
-        }
         gEnvFxMode = ENVFX_MODE_NONE;
     }
 }

src/game/memory.c

@@ -16,6 +16,7 @@ struct DynamicPool* dynamic_pool_init(void) {
     struct DynamicPool* pool = calloc(1, sizeof(struct DynamicPool));
     pool->usedSpace = 0;
     pool->tail = NULL;
+    pool->nextFree = NULL;
     return pool;
 }
 
@@ -75,14 +76,19 @@ bool dynamic_pool_contains(struct DynamicPool *pool, void* ptr) {
 
 void dynamic_pool_free_pool(struct DynamicPool *pool) {
     if (!pool) { return; }
-    struct DynamicPoolNode* node = pool->tail;
+
+    struct DynamicPoolNode* node = pool->nextFree;
     while (node) {
         struct DynamicPoolNode* prev = node->prev;
         free(node->ptr);
         free(node);
         node = prev;
     }
-    free(pool);
+
+    // schedule current pool to be free'd on the next call
+    pool->nextFree = pool->tail;
+    pool->tail = NULL;
+    pool->usedSpace = 0;
 }
 
   //////////////////

src/game/memory.h

@@ -14,6 +14,7 @@
 struct DynamicPool
 {
     u32 usedSpace;
+    struct DynamicPoolNode* nextFree;
     struct DynamicPoolNode* tail;
 };
 

src/game/paintings.c

@@ -1526,8 +1526,14 @@ Gfx *display_painting_rippling(struct Painting *painting) {
     }
 
     // The mesh data is freed every frame.
-    dynamic_pool_free(gLevelPool, painting->ripples.paintingMesh);
-    dynamic_pool_free(gLevelPool, painting->ripples.paintingTriNorms);
+    if (painting->ripples.paintingMesh) {
+        dynamic_pool_free(gLevelPool, painting->ripples.paintingMesh);
+        painting->ripples.paintingMesh = NULL;
+    }
+    if (painting->ripples.paintingTriNorms) {
+        dynamic_pool_free(gLevelPool, painting->ripples.paintingTriNorms);
+        painting->ripples.paintingTriNorms = NULL;
+    }
     return dlist;
 }