Add experiments to skip waiting for updates of collection and table views

Schemas/configuration.json

@@ -19,10 +19,13 @@
                     "exp_unfair_lock",
                     "exp_infer_layer_defaults",
                     "exp_network_image_queue",
-                    "exp_dealloc_queue_v2",
                     "exp_collection_teardown",
                     "exp_framesetter_cache",
-                    "exp_skip_clear_data"
+                    "exp_skip_clear_data",
+                    "exp_did_enter_preload_skip_asm_layout",
+                    "exp_disable_a11y_cache",
+                    "exp_skip_a11y_wait",
+                    "exp_new_default_cell_layout_mode"
                 ]
     		}
 		}

Source/ASCollectionView.mm

@@ -317,6 +317,12 @@ - (instancetype)_initWithFrame:(CGRect)frame collectionViewLayout:(UICollectionV
 
   [self _configureCollectionViewLayout:layout];
 
+  if (ASActivateExperimentalFeature(ASExperimentalNewDefaultCellLayoutMode)) {
+    _cellLayoutMode = ASCellLayoutModeSyncForSmallContent;
+  } else {
+    _cellLayoutMode = ASCellLayoutModeNone;
+  }
+
   return self;
 }
 
@@ -1868,17 +1874,22 @@ - (BOOL)dataController:(ASDataController *)dataController shouldSynchronouslyPro
   if (ASCellLayoutModeIncludes(ASCellLayoutModeAlwaysAsync)) {
     return NO;
   }
-  // The heuristics below apply to the ASCellLayoutModeNone.
-  // If we have very few ASCellNodes (besides UIKit passthrough ones), match UIKit by blocking.
-  if (changeSet.countForAsyncLayout < 2) {
-    return YES;
-  }
-  CGSize contentSize = self.contentSize;
-  CGSize boundsSize = self.bounds.size;
-  if (contentSize.height <= boundsSize.height && contentSize.width <= boundsSize.width) {
-    return YES;
+  if (ASCellLayoutModeIncludes(ASCellLayoutModeSyncForSmallContent)) {
+    // Reload data is expensive, don't block main while doing so.
+    if (changeSet.includesReloadData) {
+      return NO;
+    }
+    // If we have very few ASCellNodes (besides UIKit passthrough ones), match UIKit by blocking.
+    if (changeSet.countForAsyncLayout < 2) {
+      return YES;
+    }
+    CGSize contentSize = self.contentSize;
+    CGSize boundsSize = self.bounds.size;
+    if (contentSize.height <= boundsSize.height && contentSize.width <= boundsSize.width) {
+      return YES;
+    }
   }
-  return NO;
+  return NO; // ASCellLayoutModeNone
 }
 
 - (BOOL)dataControllerShouldSerializeNodeCreation:(ASDataController *)dataController
@@ -2465,7 +2476,9 @@ - (void)setPrefetchingEnabled:(BOOL)prefetchingEnabled
 
 - (NSArray *)accessibilityElements
 {
-  [self waitUntilAllUpdatesAreCommitted];
+  if (!ASActivateExperimentalFeature(ASExperimentalSkipAccessibilityWait)) {
+    [self waitUntilAllUpdatesAreCommitted];
+  }
   return [super accessibilityElements];
 }
 

Source/ASCollectionViewProtocols.h

@@ -16,6 +16,11 @@ typedef NS_OPTIONS(NSUInteger, ASCellLayoutMode) {
    * each flag listed below is used.
    */
   ASCellLayoutModeNone = 0,
+  /**
+   * If ASCellLayoutModeSyncForSmallContent is enabled it will cause ASDataController to wait on the
+   * background queue if the amount of new content is small.
+   */
+  ASCellLayoutModeSyncForSmallContent = 1 << 1,
   /**
    * If ASCellLayoutModeAlwaysSync is enabled it will cause the ASDataController to wait on the
    * background queue, and this ensures that any new / changed cells are in the hierarchy by the
@@ -26,26 +31,26 @@ typedef NS_OPTIONS(NSUInteger, ASCellLayoutMode) {
    * default behavior is synchronous when there are 0 or 1 ASCellNodes in the data source, and
    * asynchronous when there are 2 or more.
   */
-  ASCellLayoutModeAlwaysSync = 1 << 1,                // Default OFF
-  ASCellLayoutModeAlwaysAsync = 1 << 2,               // Default OFF
-  ASCellLayoutModeForceIfNeeded = 1 << 3,             // Deprecated, default OFF.
-  ASCellLayoutModeAlwaysPassthroughDelegate = 1 << 4, // Deprecated, default ON.
+  ASCellLayoutModeAlwaysSync = 1 << 2,                // Default OFF
+  ASCellLayoutModeAlwaysAsync = 1 << 3,               // Default OFF
+  ASCellLayoutModeForceIfNeeded = 1 << 4,             // Deprecated, default OFF.
+  ASCellLayoutModeAlwaysPassthroughDelegate = 1 << 5, // Deprecated, default ON.
   /** Instead of using performBatchUpdates: prefer using reloadData for changes for collection view */
-  ASCellLayoutModeAlwaysReloadData = 1 << 5,          // Default OFF
+  ASCellLayoutModeAlwaysReloadData = 1 << 6,          // Default OFF
   /** If flag is enabled nodes are *not* gonna be range managed. */
-  ASCellLayoutModeDisableRangeController = 1 << 6,    // Default OFF
-  ASCellLayoutModeAlwaysLazy = 1 << 7,                // Deprecated, default OFF.
+  ASCellLayoutModeDisableRangeController = 1 << 7,    // Default OFF
+  ASCellLayoutModeAlwaysLazy = 1 << 8,                // Deprecated, default OFF.
   /**
    * Defines if the node creation should happen serialized and not in parallel within the
    * data controller
    */
-  ASCellLayoutModeSerializeNodeCreation = 1 << 8,     // Default OFF
+  ASCellLayoutModeSerializeNodeCreation = 1 << 9,     // Default OFF
   /**
    * When set, the performBatchUpdates: API (including animation) is used when handling Section
    * Reload operations. This is useful only when ASCellLayoutModeAlwaysReloadData is enabled and
    * cell height animations are desired.
    */
-  ASCellLayoutModeAlwaysBatchUpdateSectionReload = 1 << 9 // Default OFF
+  ASCellLayoutModeAlwaysBatchUpdateSectionReload = 1 << 10 // Default OFF
 };
 
 NS_ASSUME_NONNULL_BEGIN

Source/ASExperimentalFeatures.h

@@ -29,6 +29,8 @@ typedef NS_OPTIONS(NSUInteger, ASExperimentalFeatures) {
   ASExperimentalSkipClearData = 1 << 8,                     // exp_skip_clear_data
   ASExperimentalDidEnterPreloadSkipASMLayout = 1 << 9,      // exp_did_enter_preload_skip_asm_layout
   ASExperimentalDisableAccessibilityCache = 1 << 10,        // exp_disable_a11y_cache
+  ASExperimentalSkipAccessibilityWait = 1 << 11,            // exp_skip_a11y_wait
+  ASExperimentalNewDefaultCellLayoutMode = 1 << 12,         // exp_new_default_cell_layout_mode
   ASExperimentalFeatureAll = 0xFFFFFFFF
 };
 

Source/ASExperimentalFeatures.mm

@@ -22,7 +22,9 @@
                                       @"exp_framesetter_cache",
                                       @"exp_skip_clear_data",
                                       @"exp_did_enter_preload_skip_asm_layout",
-                                      @"exp_disable_a11y_cache"]));
+                                      @"exp_disable_a11y_cache",
+                                      @"exp_skip_a11y_wait",
+                                      @"exp_new_default_cell_layout_mode"]));
 
   if (flags == ASExperimentalFeatureAll) {
     return allNames;

Source/ASTableView.mm

@@ -1677,14 +1677,20 @@ - (BOOL)dataControllerShouldSerializeNodeCreation:(ASDataController *)dataContro
 
 - (BOOL)dataController:(ASDataController *)dataController shouldSynchronouslyProcessChangeSet:(_ASHierarchyChangeSet *)changeSet
 {
-  // For more details on this method, see the comment in the ASCollectionView implementation.
-  if (changeSet.countForAsyncLayout < 2) {
-    return YES;
-  }
-  CGSize contentSize = self.contentSize;
-  CGSize boundsSize = self.bounds.size;
-  if (contentSize.height <= boundsSize.height && contentSize.width <= boundsSize.width) {
-    return YES;
+  if (ASActivateExperimentalFeature(ASExperimentalNewDefaultCellLayoutMode)) {
+    // Reload data is expensive, don't block main while doing so.
+    if (changeSet.includesReloadData) {
+      return NO;
+    }
+    // For more details on this method, see the comment in the ASCollectionView implementation.
+    if (changeSet.countForAsyncLayout < 2) {
+      return YES;
+    }
+    CGSize contentSize = self.contentSize;
+    CGSize boundsSize = self.bounds.size;
+    if (contentSize.height <= boundsSize.height && contentSize.width <= boundsSize.width) {
+      return YES;
+    }
   }
   return NO;
 }
@@ -2004,7 +2010,9 @@ - (void)didMoveToSuperview
 
 - (NSArray *)accessibilityElements
 {
-  [self waitUntilAllUpdatesAreCommitted];
+  if (!ASActivateExperimentalFeature(ASExperimentalSkipAccessibilityWait)) {
+    [self waitUntilAllUpdatesAreCommitted];
+  }
   return [super accessibilityElements];
 }
 

Tests/ASCollectionViewTests.mm

@@ -163,7 +163,6 @@ - (instancetype)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibB
 @interface ASCollectionView (InternalTesting)
 
 - (NSArray<NSString *> *)dataController:(ASDataController *)dataController supplementaryNodeKindsInSections:(NSIndexSet *)sections;
-- (BOOL)dataController:(ASDataController *)dataController shouldSynchronouslyProcessChangeSet:(_ASHierarchyChangeSet *)changeSet;
 
 @end
 
@@ -1047,15 +1046,24 @@ - (void)_primitiveBatchFetchingFillTestAnimated:(BOOL)animated visible:(BOOL)vis
 
 - (void)testInitialRangeBounds
 {
-  [self testInitialRangeBoundsWithCellLayoutMode:ASCellLayoutModeNone];
+  [self testInitialRangeBoundsWithCellLayoutMode:ASCellLayoutModeNone
+           shouldWaitUntilAllUpdatesAreProcessed:YES];
+}
+
+- (void)testInitialRangeBoundsCellLayoutModeSyncForSmallContent
+{
+  [self testInitialRangeBoundsWithCellLayoutMode:ASCellLayoutModeSyncForSmallContent
+           shouldWaitUntilAllUpdatesAreProcessed:YES]; // Need to wait because the first initial data load is always async
 }
 
 - (void)testInitialRangeBoundsCellLayoutModeAlwaysAsync
 {
-  [self testInitialRangeBoundsWithCellLayoutMode:ASCellLayoutModeAlwaysAsync];
+  [self testInitialRangeBoundsWithCellLayoutMode:ASCellLayoutModeAlwaysAsync
+           shouldWaitUntilAllUpdatesAreProcessed:YES];
 }
 
 - (void)testInitialRangeBoundsWithCellLayoutMode:(ASCellLayoutMode)cellLayoutMode
+           shouldWaitUntilAllUpdatesAreProcessed:(BOOL)shouldWait
 {
   UIWindow *window = [[UIWindow alloc] initWithFrame:[UIScreen mainScreen].bounds];
   ASCollectionViewTestController *testController = [[ASCollectionViewTestController alloc] initWithNibName:nil bundle:nil];
@@ -1071,19 +1079,17 @@ - (void)testInitialRangeBoundsWithCellLayoutMode:(ASCellLayoutMode)cellLayoutMod
   // Trigger the initial reload to start 
   [window layoutIfNeeded];
 
-  // Test the APIs that monitor ASCollectionNode update handling if collection node should
-  // layout asynchronously
-  if (![cn.view dataController:nil shouldSynchronouslyProcessChangeSet:nil]) {
+  if (shouldWait) {
     XCTAssertTrue(cn.isProcessingUpdates, @"ASCollectionNode should still be processing updates after initial layoutIfNeeded call (reloadData)");
-
+    
     [cn onDidFinishProcessingUpdates:^{
       XCTAssertTrue(!cn.isProcessingUpdates, @"ASCollectionNode should no longer be processing updates inside -onDidFinishProcessingUpdates: block");
     }];
-
+    
     // Wait for ASDK reload to finish
     [cn waitUntilAllUpdatesAreProcessed];
   }
-
+  
   XCTAssertTrue(!cn.isProcessingUpdates, @"ASCollectionNode should no longer be processing updates after -wait call");
 
   // Force UIKit to read updated data & range controller to update and account for it

Tests/ASConfigurationTests.mm

@@ -28,7 +28,9 @@
   ASExperimentalFramesetterCache,
   ASExperimentalSkipClearData,
   ASExperimentalDidEnterPreloadSkipASMLayout,
-  ASExperimentalDisableAccessibilityCache
+  ASExperimentalDisableAccessibilityCache,
+  ASExperimentalSkipAccessibilityWait,
+  ASExperimentalNewDefaultCellLayoutMode
 };
 
 @interface ASConfigurationTests : ASTestCase <ASConfigurationDelegate>
@@ -51,7 +53,9 @@ + (NSArray *)names {
     @"exp_framesetter_cache",
     @"exp_skip_clear_data",
     @"exp_did_enter_preload_skip_asm_layout",
-    @"exp_disable_a11y_cache"
+    @"exp_disable_a11y_cache",
+    @"exp_skip_a11y_wait",
+    @"exp_new_default_cell_layout_mode"
   ];
 }