Debounce new tile loading, use actor mutex for thread-safety

openmobilemaps · Jan 24, 2024 · 50da5a7 · 50da5a7
1 parent 2074653
commit 50da5a7
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Showing 2 changed files with 34 additions and 5 deletions.
diff --git a/shared/public/Tiled2dMapSource.h b/shared/public/Tiled2dMapSource.h
@@ -164,8 +164,9 @@ class Tiled2dMapSource :
     void onVisibleTilesChanged(const std::vector<VisibleTilesLayer> &pyramid, int keepZoomLevelOffset = 0);
 
 private:
-    void performLoadingTask(Tiled2dMapTileInfo tile, size_t loaderIndex);
+    void onStableTriggerNewTileLoading(uint64_t updateId);
 
+    void performLoadingTask(Tiled2dMapTileInfo tile, size_t loaderIndex);
 
     void updateTileMasks();
 
@@ -181,11 +182,14 @@ class Tiled2dMapSource :
 
     std::unordered_map<size_t, std::map<Tiled2dMapTileInfo, ErrorInfo>> errorTiles;
     std::optional<long long> nextDelayTaskExecution;
+    std::vector<PrioritizedTiled2dMapTileInfo> pendingTilesToLoad;
 
     std::unordered_set<Tiled2dMapTileInfo> notFoundTiles;
 
     std::string layerName;
 
+    uint64_t currentNewTilesUpdateId = 0;
+    const static int64_t PENDING_NEW_TILE_DEBOUNCE_MS = 200;
 };
 
 #include "Tiled2dMapSourceImpl.h"
diff --git a/shared/public/Tiled2dMapSourceImpl.h b/shared/public/Tiled2dMapSourceImpl.h
@@ -361,17 +361,42 @@ void Tiled2dMapSource<T, L, R>::onVisibleTilesChanged(const std::vector<VisibleT
         }
     }
 
-    std::sort(toAdd.begin(), toAdd.end());
-
-    for (const auto &addedTile : toAdd) {
-        performLoadingTask(addedTile.tileInfo, 0);
+    if (auto strongScheduler = scheduler.lock()) {
+        std::lock_guard<std::recursive_mutex> lock(mailbox->receivingMutex);
+        std::weak_ptr<Tiled2dMapSource> weakSelfPtr = std::dynamic_pointer_cast<Tiled2dMapSource>(
+                shared_from_this());
+        std::sort(toAdd.begin(), toAdd.end());
+        if (toAdd != pendingTilesToLoad) {
+            long newId = ++currentNewTilesUpdateId;
+            pendingTilesToLoad = toAdd;
+            strongScheduler->addTask(std::make_shared<LambdaTask>(
+                    TaskConfig("DebounceNewTilesLoad_" + std::to_string(newId), PENDING_NEW_TILE_DEBOUNCE_MS, TaskPriority::NORMAL,
+                               ExecutionEnvironment::COMPUTATION),
+                    [weakSelfPtr, newId] {
+                        if (auto strongSelf = weakSelfPtr.lock()) {
+                            strongSelf->onStableTriggerNewTileLoading(newId);
+                        }
+                    }));
+        }
     }
+
     //if we removed tiles, we potentially need to update the tilemasks - also if no new tile is loaded
     updateTileMasks();
 
     notifyTilesUpdates();
 }
 
+template<class T, class L, class R>
+void Tiled2dMapSource<T, L, R>::onStableTriggerNewTileLoading(uint64_t updateId) {
+    for (const auto &tileToLoad : pendingTilesToLoad) {
+        std::lock_guard<std::recursive_mutex> lock(mailbox->receivingMutex);
+        if (updateId != currentNewTilesUpdateId) {
+            break;
+        }
+        performLoadingTask(tileToLoad.tileInfo, 0);
+    }
+}
+
 template<class T, class L, class R>
 void Tiled2dMapSource<T, L, R>::performLoadingTask(Tiled2dMapTileInfo tile, size_t loaderIndex) {
     if (currentlyLoading.count(tile) != 0) return;