lower diffing priority if the collection-view is not visible

Summary: Lower QOS to give on-screen work priority. Differential Revision: D60691856 fbshipit-source-id: 52b10e05cb999214ca6c6a8fe1cb3ce2dd847eb1
Instagram · Aug 6, 2024 · f429ec5 · f429ec5
1 parent 59365a1
commit f429ec5
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Showing 4 changed files with 22 additions and 4 deletions.
diff --git a/Source/IGListDiffKit/IGListExperiments.h b/Source/IGListDiffKit/IGListExperiments.h
@@ -33,6 +33,8 @@ typedef struct IGListAdaptiveDiffingExperimentConfig {
     BOOL higherQOSEnabled;
     /// If both item counts are under this number, we'll run the diffing on the main thread.
     NSInteger maxItemCountToRunOnMain;
+    /// Lower QOS if view is not visible according to `IGListViewVisibilityTracker`
+    BOOL lowerPriorityWhenViewNotVisible;
 } IGListAdaptiveDiffingExperimentConfig;
 
 /**

diff --git a/Source/IGListKit/Internal/IGListBatchUpdateTransaction.m b/Source/IGListKit/Internal/IGListBatchUpdateTransaction.m
@@ -112,6 +112,7 @@ - (void)_diff {
 
     __weak __typeof__(self) weakSelf = self;
     IGListPerformDiffWithData(data,
+                              self.collectionView,
                               self.config.allowsBackgroundDiffing,
                               self.config.adaptiveDiffingExperimentConfig,
                               ^(IGListIndexSetResult * _Nonnull result, BOOL onBackground) {

diff --git a/Source/IGListKit/Internal/IGListPerformDiff.h b/Source/IGListKit/Internal/IGListPerformDiff.h
@@ -29,12 +29,14 @@ typedef void (^IGListDiffExecutorCompletion)(IGListIndexSetResult *result, BOOL
  Perform diffing, which can happen sync or async depending on the params given.
 
  @param data Contains the objects before and after the update
+ @param view  View on which we will perform the update. Used to check visibility.
  @param allowsBackgroundDiffing Allows the diffing to be performed off the main thread
  @param adaptiveConfig Details of how the adaptive diffing should work
  @param completion Returns the diffing results. Can be called async or sync, but will be called on main thread.
  */
-NS_SWIFT_NAME(ListPerformDiff(data:allowsBackgroundDiffing:adaptiveConfig:completion:))
+NS_SWIFT_NAME(ListPerformDiff(data:view:allowsBackgroundDiffing:adaptiveConfig:completion:))
 FOUNDATION_EXTERN void IGListPerformDiffWithData(IGListTransitionData *_Nullable data,
+                                                 UIView *_Nullable view,
                                                  BOOL allowsBackgroundDiffing,
                                                  IGListAdaptiveDiffingExperimentConfig adaptiveConfig,
                                                  IGListDiffExecutorCompletion completion);

diff --git a/Source/IGListKit/Internal/IGListPerformDiff.m b/Source/IGListKit/Internal/IGListPerformDiff.m
@@ -14,6 +14,7 @@
 #endif
 
 #import "IGListTransitionData.h"
+#import "IGListViewVisibilityTracker.h"
 
 #pragma mark - Regular (not adaptive)
 
@@ -35,11 +36,21 @@ static void _regularPerformDiffWithData(IGListTransitionData *_Nullable data,
 
 #pragma mark - Adaptive
 
-static dispatch_queue_t _queueForData(IGListTransitionData *data, BOOL allowsBackground, IGListAdaptiveDiffingExperimentConfig adaptiveConfig) {
+static dispatch_queue_t _queueForData(IGListTransitionData *data, 
+                                      UIView *view,
+                                      BOOL allowsBackground,
+                                      IGListAdaptiveDiffingExperimentConfig adaptiveConfig) {
     if (!allowsBackground) {
         return dispatch_get_main_queue();
     }
 
+    if (adaptiveConfig.lowerPriorityWhenViewNotVisible) {
+        IGListViewVisibilityTracker *const tracker = IGListViewVisibilityTrackerAttachedOnView(view);
+        if (tracker && tracker.state == IGListViewVisibilityStateNotVisible) {
+            return dispatch_get_global_queue(QOS_CLASS_DEFAULT, 0);
+        }
+    }
+
     // If we don't have a lot of items, the dispatching back and forth can add unnecessary delay.
     if (data.fromObjects.count < adaptiveConfig.maxItemCountToRunOnMain
         && data.toObjects.count < adaptiveConfig.maxItemCountToRunOnMain) {
@@ -51,10 +62,11 @@ static dispatch_queue_t _queueForData(IGListTransitionData *data, BOOL allowsBac
 }
 
 static void _adaptivePerformDiffWithData(IGListTransitionData *_Nullable data,
+                                         UIView *view,
                                          BOOL allowsBackground,
                                          IGListAdaptiveDiffingExperimentConfig adaptiveConfig,
                                          IGListDiffExecutorCompletion completion) {
-    const dispatch_queue_t queue = _queueForData(data, allowsBackground, adaptiveConfig);
+    const dispatch_queue_t queue = _queueForData(data, view, allowsBackground, adaptiveConfig);
 
     if (queue == dispatch_get_main_queue() && [NSThread isMainThread]) {
         IGListIndexSetResult *const result = IGListDiff(data.fromObjects, data.toObjects, IGListDiffEquality);
@@ -72,6 +84,7 @@ static void _adaptivePerformDiffWithData(IGListTransitionData *_Nullable data,
 #pragma mark - Public
 
 void IGListPerformDiffWithData(IGListTransitionData *_Nullable data,
+                               UIView *view,
                                BOOL allowsBackground,
                                IGListAdaptiveDiffingExperimentConfig adaptiveConfig,
                                IGListDiffExecutorCompletion completion) {
@@ -80,7 +93,7 @@ void IGListPerformDiffWithData(IGListTransitionData *_Nullable data,
     }
 
     if (adaptiveConfig.enabled) {
-        _adaptivePerformDiffWithData(data, allowsBackground, adaptiveConfig, completion);
+        _adaptivePerformDiffWithData(data, view, allowsBackground, adaptiveConfig, completion);
     } else {
         // Just to be safe, lets keep the original code path intact while adaptive diffing is still an experiment.
         _regularPerformDiffWithData(data, allowsBackground, completion);