Only clear ASCollectionView's data during deallocation

This is a follow up on TextureGroup#1136. Our experiment results show that clearing data frequently is the cause of our TextureGroup#1 crash. @maicki and I believe that this is because if the collection view is being used, silently clearing its data without notifying the backing UICollectionView can put it out-of-sync and causes mayhem next time the collection view processes a batch update. If you look at the stack trace closely, you'll notice that the crash doesn't occur on the same run loop that clearData is called. This made it extremely tricky to investigate and identify the root cause. Another interesting question would be whether or not we want to clear the data during deallocation at all, since the data will be cleared out soon anyway.
nguyenhuy · Oct 1, 2018 · 93312f2 · 93312f2
1 parent 5e05793
commit 93312f2
Show file tree

Hide file tree

Showing 2 changed files with 5 additions and 4 deletions.
diff --git a/Source/ASCollectionView.mm b/Source/ASCollectionView.mm
@@ -577,7 +577,7 @@ - (void)_asyncDelegateOrDataSourceDidChange
 {
   ASDisplayNodeAssertMainThread();
 
-  if (_asyncDataSource == nil && _asyncDelegate == nil && !ASActivateExperimentalFeature(ASExperimentalSkipClearData)) {
+  if (_asyncDataSource == nil && _asyncDelegate == nil && _isDeallocating && ASActivateExperimentalFeature(ASExperimentalClearDataDuringDeallocation)) {
     [_dataController clearData];
   }
 }

diff --git a/Source/ASExperimentalFeatures.h b/Source/ASExperimentalFeatures.h
@@ -21,9 +21,10 @@ typedef NS_OPTIONS(NSUInteger, ASExperimentalFeatures) {
   ASExperimentalUnfairLock = 1 << 3,                        // exp_unfair_lock
   ASExperimentalLayerDefaults = 1 << 4,                     // exp_infer_layer_defaults
   ASExperimentalNetworkImageQueue = 1 << 5,                 // exp_network_image_queue
-  ASExperimentalCollectionTeardown = 1 << 6,                // exp_collection_teardown
-  ASExperimentalFramesetterCache = 1 << 7,                  // exp_framesetter_cache
-  ASExperimentalSkipClearData = 1 << 8,                     // exp_skip_clear_data
+  ASExperimentalDeallocQueue = 1 << 6,                      // exp_dealloc_queue_v2
+  ASExperimentalCollectionTeardown = 1 << 7,                // exp_collection_teardown
+  ASExperimentalFramesetterCache = 1 << 8,                  // exp_framesetter_cache
+  ASExperimentalClearDataDuringDeallocation = 1 << 9,       // exp_clear_data_during_deallocation
   ASExperimentalFeatureAll = 0xFFFFFFFF
 };