create IGListUpdateTransactionBuilder

Summary: Now, lets move pending changes to a separate object `IGListUpdateTransactionBuilder`, which can we discarded once the update actually starts.

Reviewed By: patters

Differential Revision: D23145774

fbshipit-source-id: e12de178de33497f476972a9ad89ebb4e8d413ab

Source/IGListKit/IGListExperimentalAdapterUpdater.m

@@ -35,10 +35,7 @@ typedef void (^IGListAdapterUpdaterCompletionBlock)(BOOL);
     IGAssertMainThread();
 
     if (self = [super init]) {
-        // the default is to use animations unless NO is passed
-        _queuedUpdateIsAnimated = YES;
-        _completionBlocks = [NSMutableArray new];
-        _itemUpdateBlocks = [NSMutableArray new];
+        _transactionBuilder = [IGListUpdateTransactionBuilder new];
         _allowsBackgroundReloading = YES;
         _allowsReloadingOnTooManyUpdates = YES;
     }
@@ -48,18 +45,16 @@ typedef void (^IGListAdapterUpdaterCompletionBlock)(BOOL);
 #pragma mark - Private API
 
 - (BOOL)hasChanges {
-    return self.hasQueuedReloadData
-    || self.itemUpdateBlocks.count > 0
-    || self.dataBlock != nil;
+    return [self.transactionBuilder hasChanges];
 }
 
 - (void)performReloadDataWithCollectionViewBlock:(IGListCollectionViewBlock)collectionViewBlock {
     IGAssertMainThread();
 
     id<IGListAdapterUpdaterDelegate> delegate = self.delegate;
-    void (^reloadUpdates)(void) = self.reloadUpdates;
-    NSArray *itemUpdateBlocks = [self.itemUpdateBlocks copy];
-    NSArray *completionBlocks = [self.completionBlocks copy];
+    void (^reloadUpdates)(void) = [self.transactionBuilder reloadBlock];
+    NSArray *itemUpdateBlocks = [self.transactionBuilder itemUpdateBlocks];
+    NSArray *completionBlocks = [self.transactionBuilder completionBlocks];
 
     [self cleanStateBeforeUpdates];
 
@@ -118,13 +113,13 @@ typedef void (^IGListAdapterUpdaterCompletionBlock)(BOOL);
 
     // create local variables so we can immediately clean our state but pass these items into the batch update block
     id<IGListAdapterUpdaterDelegate> delegate = self.delegate;
-    IGListTransitionDataBlock dataBlock = [self.dataBlock copy];
-    IGListTransitionDataApplyBlock applyDataBlock = [self.applyDataBlock copy];
-    NSArray *completionBlocks = [self.completionBlocks copy];
-    const BOOL animated = self.queuedUpdateIsAnimated;
+    IGListTransitionDataBlock dataBlock = [self.transactionBuilder dataBlock];
+    IGListTransitionDataApplyBlock applyDataBlock = [self.transactionBuilder applyDataBlock];
+    NSArray *completionBlocks = [self.transactionBuilder completionBlocks];
+    const BOOL animated = [self.transactionBuilder animated];
     const BOOL allowsReloadingOnTooManyUpdates = self.allowsReloadingOnTooManyUpdates;
     const IGListExperiment experiments = self.experiments;
-    NSArray *itemUpdateBlocks = [self.itemUpdateBlocks copy];
+    NSArray *itemUpdateBlocks = [self.transactionBuilder itemUpdateBlocks];
 
     // clean up all state so that new updates can be coalesced while the current update is in flight
     [self cleanStateBeforeUpdates];
@@ -319,23 +314,8 @@ willPerformBatchUpdatesWithCollectionView:collectionView
 }
 
 - (void)cleanStateBeforeUpdates {
-    self.queuedUpdateIsAnimated = YES;
+    _transactionBuilder = [IGListUpdateTransactionBuilder new];
 
-    // destroy to/from transition items
-    self.dataBlock = nil;
-
-    // destroy reloadData state
-    self.reloadUpdates = nil;
-    self.queuedReloadData = NO;
-
-    // remove indexpath/item changes
-    self.applyDataBlock = nil;
-
-    // removes all object completion blocks. done before updates to start collecting completion blocks for coalesced
-    // or re-entrant object updates
-    [self.completionBlocks removeAllObjects];
-
-    [self.itemUpdateBlocks removeAllObjects];
     self.inUpdateCompletionBlocks = [NSMutableArray new];
     self.inUpdateItemCollector = [IGListItemUpdatesCollector new];
 }
@@ -360,7 +340,7 @@ willPerformBatchUpdatesWithCollectionView:collectionView
             return;
         }
 
-        if (weakSelf.hasQueuedReloadData) {
+        if (weakSelf.transactionBuilder.hasReloadData) {
             [weakSelf performReloadDataWithCollectionViewBlock:collectionViewBlock];
         } else {
             [weakSelf performBatchUpdatesWithCollectionViewBlock:collectionViewBlock];
@@ -410,20 +390,11 @@ static NSUInteger IGListIdentifierHash(const void *item, NSUInteger (*size)(cons
     IGParameterAssert(dataBlock != nil);
     IGParameterAssert(applyDataBlock != nil);
 
-    // will call the dataBlock after the dispatch
-    self.dataBlock = dataBlock;
-
-    // always use the last update block, even though this should always do the exact same thing
-    self.applyDataBlock = applyDataBlock;
-
-    // disabled animations will always take priority
-    // reset to YES in -cleanupState
-    self.queuedUpdateIsAnimated = self.queuedUpdateIsAnimated && animated;
-
-    IGListUpdatingCompletion localCompletion = completion;
-    if (localCompletion) {
-        [self.completionBlocks addObject:localCompletion];
-    }
+    [self.transactionBuilder addSectionBatchUpdateAnimated:animated
+                                      collectionViewBlock:collectionViewBlock
+                                                dataBlock:dataBlock
+                                           applyDataBlock:applyDataBlock
+                                               completion:completion];
 
     [self _queueUpdateWithCollectionViewBlock:collectionViewBlock];
 }
@@ -445,15 +416,10 @@ static NSUInteger IGListIdentifierHash(const void *item, NSUInteger (*size)(cons
         }
         itemUpdates();
     } else {
-        if (completion != nil) {
-            [self.completionBlocks addObject:completion];
-        }
-
-        [self.itemUpdateBlocks addObject:itemUpdates];
-
-        // disabled animations will always take priority
-        // reset to YES in -cleanupState
-        self.queuedUpdateIsAnimated = self.queuedUpdateIsAnimated && animated;
+        [self.transactionBuilder addItemBatchUpdateAnimated:animated
+                                       collectionViewBlock:collectionViewBlock
+                                               itemUpdates:itemUpdates
+                                                completion:completion];
 
         [self _queueUpdateWithCollectionViewBlock:collectionViewBlock];
     }
@@ -554,13 +520,10 @@ static NSUInteger IGListIdentifierHash(const void *item, NSUInteger (*size)(cons
     IGParameterAssert(collectionViewBlock != nil);
     IGParameterAssert(reloadUpdateBlock != nil);
 
-    IGListUpdatingCompletion localCompletion = completion;
-    if (localCompletion) {
-        [self.completionBlocks addObject:localCompletion];
-    }
+    [self.transactionBuilder addReloadDataWithCollectionViewBlock:collectionViewBlock
+                                                     reloadBlock:reloadUpdateBlock
+                                                      completion:completion];
 
-    self.reloadUpdates = reloadUpdateBlock;
-    self.queuedReloadData = YES;
     [self _queueUpdateWithCollectionViewBlock:collectionViewBlock];
 }
 

Source/IGListKit/Internal/IGListExperimentalAdapterUpdaterInternal.h

@@ -14,26 +14,17 @@
 #import "IGListExperimentalAdapterUpdater.h"
 #import "IGListBatchUpdateState.h"
 #import "IGListItemUpdatesCollector.h"
+#import "IGListUpdateTransactionBuilder.h"
 
 NS_ASSUME_NONNULL_BEGIN
 
 @interface IGListExperimentalAdapterUpdater ()
 
-@property (nonatomic, copy, nullable) IGListTransitionDataBlock dataBlock;
-@property (nonatomic, strong) NSMutableArray<IGListUpdatingCompletion> *completionBlocks;
-
-@property (nonatomic, assign) BOOL queuedUpdateIsAnimated;
-
-@property (nonatomic, strong) NSMutableArray<IGListItemUpdateBlock> *itemUpdateBlocks;
+@property (nonatomic, strong, readonly) IGListUpdateTransactionBuilder *transactionBuilder;
 
 @property (nonatomic, strong) NSMutableArray<IGListUpdatingCompletion> *inUpdateCompletionBlocks;
 @property (nonatomic, strong) IGListItemUpdatesCollector *inUpdateItemCollector;
 
-@property (nonatomic, copy, nullable) IGListTransitionDataApplyBlock applyDataBlock;
-
-@property (nonatomic, copy, nullable) IGListReloadUpdateBlock reloadUpdates;
-@property (nonatomic, assign, getter=hasQueuedReloadData) BOOL queuedReloadData;
-
 @property (nonatomic, assign) IGListBatchUpdateState state;
 @property (nonatomic, strong, nullable) IGListBatchUpdateData *applyingUpdateData;
 

Source/IGListKit/Internal/IGListUpdateTransactionBuilder.h

@@ -0,0 +1,79 @@
+/*
+* Copyright (c) Facebook, Inc. and its affiliates.
+*
+* This source code is licensed under the MIT license found in the
+* LICENSE file in the root directory of this source tree.
+*/
+
+#import <Foundation/Foundation.h>
+
+#import <IGListDiffKit/IGListMacros.h>
+#import <IGListKit/IGListUpdatingDelegate.h>
+#import <IGListKit/IGListUpdatingDelegateExperimental.h>
+
+@protocol IGListAdapterUpdaterDelegate;
+@protocol IGListAdapterUpdating;
+
+NS_ASSUME_NONNULL_BEGIN
+
+/// Class to collect reload & update information before actually starting the transition.
+IGLK_SUBCLASSING_RESTRICTED
+@interface IGListUpdateTransactionBuilder : NSObject
+
+/**
+ Add a section-level update.
+
+ @param animated A flag indicating if the transition should be animated.
+ @param collectionViewBlock A block returning the collecion view to perform updates on.
+ @param dataBlock A block which returns the transition data
+ @param applyDataBlock A block that applies the data passed from the `dataBlock` block
+ @param completion A completion block to execute when the update is finished.
+*/
+- (void)addSectionBatchUpdateAnimated:(BOOL)animated
+                  collectionViewBlock:(IGListCollectionViewBlock)collectionViewBlock
+                            dataBlock:(IGListTransitionDataBlock)dataBlock
+                       applyDataBlock:(IGListTransitionDataApplyBlock)applyDataBlock
+                           completion:(nullable IGListUpdatingCompletion)completion;
+
+/**
+ Add a item-level update.
+
+ @param animated A flag indicating if the transition should be animated.
+ @param collectionViewBlock A block returning the collecion view to perform updates on.
+ @param itemUpdates A block containing all of the updates.
+ @param completion A completion block to execute when the update is finished.
+*/
+- (void)addItemBatchUpdateAnimated:(BOOL)animated
+               collectionViewBlock:(IGListCollectionViewBlock)collectionViewBlock
+                       itemUpdates:(IGListItemUpdateBlock)itemUpdates
+                        completion:(nullable IGListUpdatingCompletion)completion;
+
+/**
+Completely reload data in the collection.
+
+@param collectionViewBlock A block returning the collecion view to reload.
+@param reloadBlock A block that must be called when the adapter reloads the collection view.
+@param completion A completion block to execute when the reload is finished.
+*/
+- (void)addReloadDataWithCollectionViewBlock:(IGListCollectionViewBlock)collectionViewBlock
+                                 reloadBlock:(IGListReloadUpdateBlock)reloadBlock
+                                  completion:(nullable IGListUpdatingCompletion)completion;
+
+// Batch updates
+- (nullable IGListTransitionDataBlock)dataBlock;
+- (nullable IGListTransitionDataApplyBlock)applyDataBlock;
+- (NSMutableArray<IGListItemUpdateBlock> *)itemUpdateBlocks;
+- (BOOL)animated;
+
+// Reload
+- (BOOL)hasReloadData;
+- (nullable IGListReloadUpdateBlock)reloadBlock;
+
+// Both
+- (nullable IGListCollectionViewBlock)collectionViewBlock;
+- (NSMutableArray<IGListUpdatingCompletion> *)completionBlocks;
+- (BOOL)hasChanges;
+
+@end
+
+NS_ASSUME_NONNULL_END

Source/IGListKit/Internal/IGListUpdateTransactionBuilder.m

@@ -0,0 +1,95 @@
+/*
+* Copyright (c) Facebook, Inc. and its affiliates.
+*
+* This source code is licensed under the MIT license found in the
+* LICENSE file in the root directory of this source tree.
+*/
+
+#import "IGListUpdateTransactionBuilder.h"
+
+@interface IGListUpdateTransactionBuilder ()
+// Batch updates
+@property (nonatomic, copy, readwrite, nullable) IGListTransitionDataBlock dataBlock;
+@property (nonatomic, copy, readwrite, nullable) IGListTransitionDataApplyBlock applyDataBlock;
+@property (nonatomic, strong, readonly) NSMutableArray<IGListItemUpdateBlock> *itemUpdateBlocks;
+@property (nonatomic, assign, readwrite) BOOL animated;
+// Reload
+@property (nonatomic, assign, readwrite) BOOL hasReloadData;
+@property (nonatomic, copy, readwrite, nullable) IGListReloadUpdateBlock reloadBlock;
+// Both
+@property (nonatomic, copy, readwrite, nullable) IGListCollectionViewBlock collectionViewBlock;
+@property (nonatomic, strong, readonly) NSMutableArray<IGListUpdatingCompletion> *completionBlocks;
+@end
+
+@implementation IGListUpdateTransactionBuilder
+
+- (instancetype)init {
+    if (self = [super init]) {
+        _animated = YES;
+        _itemUpdateBlocks = [NSMutableArray new];
+        _completionBlocks = [NSMutableArray new];
+    }
+    return self;
+}
+
+#pragma mark - Add changes
+
+- (void)addSectionBatchUpdateAnimated:(BOOL)animated
+                  collectionViewBlock:(IGListCollectionViewBlock)collectionViewBlock
+                            dataBlock:(IGListTransitionDataBlock)dataBlock
+                       applyDataBlock:(IGListTransitionDataApplyBlock)applyDataBlock
+                           completion:(IGListUpdatingCompletion)completion {
+    // disabled animations will always take priority
+    // reset to YES in -cleanupState
+    self.animated = self.animated && animated;
+    self.collectionViewBlock = collectionViewBlock;
+
+    // will call the dataBlock after the dispatch
+    self.dataBlock = dataBlock;
+
+    // always use the last update block, even though this should always do the exact same thing
+    self.applyDataBlock = applyDataBlock;
+
+    IGListUpdatingCompletion localCompletion = completion;
+    if (localCompletion) {
+        [self.completionBlocks addObject:localCompletion];
+    }
+}
+
+- (void)addItemBatchUpdateAnimated:(BOOL)animated
+               collectionViewBlock:(IGListCollectionViewBlock)collectionViewBlock
+                       itemUpdates:(IGListItemUpdateBlock)itemUpdates
+                        completion:(nullable IGListUpdatingCompletion)completion {
+    // disabled animations will always take priority
+    // reset to YES in -cleanupState
+    self.animated = self.animated && animated;
+    self.collectionViewBlock = collectionViewBlock;
+
+    [self.itemUpdateBlocks addObject:itemUpdates];
+
+    IGListUpdatingCompletion localCompletion = completion;
+    if (localCompletion) {
+        [self.completionBlocks addObject:localCompletion];
+    }
+}
+
+- (void)addReloadDataWithCollectionViewBlock:(IGListCollectionViewBlock)collectionViewBlock
+                                 reloadBlock:(IGListReloadUpdateBlock)reloadBlock
+                                  completion:(nullable IGListUpdatingCompletion)completion {
+    self.hasReloadData = YES;
+    self.collectionViewBlock = collectionViewBlock;
+    self.reloadBlock = reloadBlock;
+
+    IGListUpdatingCompletion localCompletion = completion;
+    if (localCompletion) {
+        [self.completionBlocks addObject:localCompletion];
+    }
+}
+
+- (BOOL)hasChanges {
+    return self.hasReloadData
+    || self.itemUpdateBlocks.count > 0
+    || self.dataBlock != nil;
+}
+
+@end