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WIP - Scroll performance fixes for when there are many read posts already #66

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WIP - Scroll performance fixes for when there are many read posts already #66

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32688ad
Scroll performance fixes for when there are many read posts already
mikedg1 Nov 18, 2024
ef6b503
Clean up
mikedg1 Nov 18, 2024
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70 changes: 41 additions & 29 deletions OpenArtemis/Views/Subreddits/SubredditFeedView.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -24,6 +24,8 @@ struct SubredditFeedView: View {
let appTheme: AppThemeSettings
let textSizePreference: TextSizePreference

@State var readPostIDs: Set<String> = [] // Post IDs that are maked read, this is kept to improve scrolling performance rather than checking the CoreData for each new item

@State private var forceCompactMode: Bool = false

@State private var posts: [Post] = []
Expand Down Expand Up @@ -61,9 +63,7 @@ struct SubredditFeedView: View {
ThemedList(appTheme: appTheme, textSizePreference: textSizePreference, stripStyling: true) {
if !posts.isEmpty && searchTerm.isEmpty {
ForEach(posts, id: \.id) { post in
var isRead: Bool {
readPosts.contains(where: { $0.readPostId == post.id })
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This seemed to be the bottleneck.

}
let isRead = readPostIDs.contains(post.id)
let justRead = readThisSession.contains(post.id)

var isSaved: Bool {
Expand All @@ -72,10 +72,11 @@ struct SubredditFeedView: View {

if !hideReadPosts || (!isRead || isSaved || (isRead && justRead)) {
PostFeedItemView(post: post, isRead: isRead, forceCompactMode: forceCompactMode, isSaved: isSaved, appTheme: appTheme, textSizePreference: textSizePreference, useLargeThumbnail: useLargeThumbnailForMediaPreview) {
handlePostTap(post, isRead: isRead)
handlePostTap(post)
}
.if(markReadOnScroll, transform: { postFeedItem in
postFeedItem.onScrolledOffTopOfScreen {
readPostIDs.insert(post.id)
PostUtils.shared.markRead(context: managedObjectContext, postId: post.id)
readThisSession.insert(post.id)
}
Expand Down Expand Up @@ -141,18 +142,13 @@ struct SubredditFeedView: View {
}

// MARK: - Private Methods

private func handlePostAppearance(_ postId: String) {
if !posts.isEmpty && posts.count > Int(Double(posts.count) * 0.85) {
if postId == posts[Int(Double(posts.count) * 0.85)].id {
scrapeSubreddit(lastPostAfter: lastPostAfter, sort: sortOption)
}
}
}

private func handlePostTap(_ post: Post, isRead: Bool) {
private func handlePostTap(_ post: Post) {
let isRead = readPostIDs.contains(post.id)

coordinator.path.append(PostResponse(post: post))
if !isRead {
readPostIDs.insert(post.id)

PostUtils.shared.markRead(context: managedObjectContext, postId: post.id)
if (!hideReadPostsImmediately) {
readThisSession.insert(post.id)
Expand Down Expand Up @@ -183,45 +179,61 @@ struct SubredditFeedView: View {
}
}

private func deferredTurnOffLoading() {
defer {
isLoading = false
}
}

private func scrapeSubreddit(lastPostAfter: String? = nil, sort: SortOption? = nil, searchTerm: String = "", preventListIdRefresh: Bool = false) {
self.isLoading = true
if !preventListIdRefresh { self.listIdentifier = MiscUtils.randomString(length: 4) }

if searchTerm.isEmpty {
RedditScraper.scrapeSubreddit(subreddit: subredditName, lastPostAfter: lastPostAfter, sort: sort,
trackingParamRemover: trackingParamRemover, over18: over18) { result in
defer {
isLoading = false
}

switch result {
case .success(let newPosts):
if newPosts.isEmpty && self.retryCount < 3 { // if a load fails, auto retry up to 3 times
self.retryCount += 1
self.scrapeSubreddit(lastPostAfter: lastPostAfter, sort: sort, searchTerm: searchTerm, preventListIdRefresh: preventListIdRefresh)

deferredTurnOffLoading()
} else {
self.retryCount = 0
for post in newPosts {
if !postIDs.contains(post.id) {
posts.append(post)
postIDs.insert(post.id)
DispatchQueue.global(qos: .background).async {
self.retryCount = 0

var newReadIds: Set<String> = []
newPosts.forEach { post in
let isRead = readPosts.contains(where: { $0.readPostId == post.id })
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We do the "slow" check on load, off the main thread.

if isRead {
newReadIds.insert(post.id)
}
}

if let newLastPost = newPosts.last {
self.lastPostAfter = newLastPost.id
}

DispatchQueue.main.async {
posts += newPosts
readPostIDs.formUnion(newReadIds)

deferredTurnOffLoading()
}
}

if let newLastPost = newPosts.last {
self.lastPostAfter = newLastPost.id
}
}
case .failure(let error):
deferredTurnOffLoading()

print("Error: \(error.localizedDescription)")
}
}
} else {
RedditScraper.search(query: searchTerm, searchType: "", sortBy: selectedSearchSortOption, topSortBy: selectedSearchTopOption,
trackingParamRemover: trackingParamRemover, over18: over18) { result in
defer {
isLoading = false
}
deferredTurnOffLoading()

switch result {
case .success(let newMedia):
Expand Down