Run database fetches async, in the timeline, when appropriate — for instance, when All Unread is selected and new articles come in.

Frameworks/Account/Account.swift

@@ -36,6 +36,16 @@ public enum AccountType: Int {
 	// TODO: more
 }
 
+public enum FetchType {
+	case starred
+	case unread
+	case today
+	case unreadForFolder(Folder)
+	case feed(Feed)
+	case articleIDs(Set<String>)
+	case search(String)
+}
+
 public final class Account: DisplayNameProvider, UnreadCountProvider, Container, Hashable {
 
     public struct UserInfoKey {
@@ -471,85 +481,44 @@ public final class Account: DisplayNameProvider, UnreadCountProvider, Container,
 		}
 	}
 
-	public func fetchArticles(forArticleIDs articleIDs: Set<String>) -> Set<Article> {
+	public func fetchArticles(_ fetchType: FetchType) -> Set<Article> {
-		return database.fetchArticles(forArticleIDs: articleIDs)
+		switch fetchType {
-	}
+		case .starred:
-	
+			return fetchStarredArticles()
-	public func fetchArticles(for feed: Feed) -> Set<Article> {
+		case .unread:
-
+			return fetchUnreadArticles()
-		let articles = database.fetchArticles(for: feed.feedID)
+		case .today:
-		validateUnreadCount(feed, articles)
+			return fetchTodayArticles()
-		return articles
+		case .unreadForFolder(let folder):
-	}
+			return fetchArticles(folder: folder)
-
+		case .feed(let feed):
-	public func fetchUnreadArticles(for feed: Feed) -> Set<Article> {
+			return fetchArticles(feed: feed)
-
+		case .articleIDs(let articleIDs):
-		let articles = database.fetchUnreadArticles(for: Set([feed.feedID]))
+			return fetchArticles(articleIDs: articleIDs)
-		validateUnreadCount(feed, articles)
+		case .search(let searchString):
-		return articles
+			return fetchArticlesMatching(searchString)
-	}
-
-	public func fetchUnreadArticles() -> Set<Article> {
-
-		return fetchUnreadArticles(forContainer: self)
-	}
-
-	public func fetchArticles(folder: Folder) -> Set<Article> {
-
-		return fetchUnreadArticles(forContainer: folder)
-	}
-
-	public func fetchUnreadArticles(forContainer container: Container) -> Set<Article> {
-
-		let feeds = container.flattenedFeeds()
-		let articles = database.fetchUnreadArticles(for: feeds.feedIDs())
-
-		// Validate unread counts. This was the site of a performance slowdown:
-		// it was calling going through the entire list of articles once per feed:
-		// feeds.forEach { validateUnreadCount($0, articles) }
-		// Now we loop through articles exactly once. This makes a huge difference.
-
-		var unreadCountStorage = [String: Int]() // [FeedID: Int]
-		articles.forEach { (article) in
-			precondition(!article.status.read)
-			unreadCountStorage[article.feedID, default: 0] += 1
 		}
-		feeds.forEach { (feed) in
+	}
-			let unreadCount = unreadCountStorage[feed.feedID, default: 0]
+
-			feed.unreadCount = unreadCount
+	public func fetchArticlesAsync(_ fetchType: FetchType, _ callback: @escaping ArticleSetBlock) {
+		switch fetchType {
+		case .starred:
+			fetchStarredArticlesAsync(callback)
+		case .unread:
+			fetchUnreadArticlesAsync(callback)
+		case .today:
+			fetchTodayArticlesAsync(callback)
+		case .unreadForFolder(let folder):
+			fetchArticlesAsync(folder: folder, callback)
+		case .feed(let feed):
+			fetchArticlesAsync(feed: feed, callback)
+		case .articleIDs(let articleIDs):
+			fetchArticlesAsync(articleIDs: articleIDs, callback)
+		case .search(let searchString):
+			fetchArticlesMatchingAsync(searchString, callback)
 		}
-
-		return articles
 	}
 
-	public func fetchTodayArticles() -> Set<Article> {
-
-		return database.fetchTodayArticles(for: flattenedFeeds().feedIDs())
-	}
-
-	public func fetchStarredArticles() -> Set<Article> {
-
-		return database.fetchStarredArticles(for: flattenedFeeds().feedIDs())
-	}
-
-	public func fetchArticlesMatching(_ searchString: String) -> Set<Article> {
-		return database.fetchArticlesMatching(searchString, for: flattenedFeeds().feedIDs())
-	}
-
-	private func validateUnreadCount(_ feed: Feed, _ articles: Set<Article>) {
-
-		// articles must contain all the unread articles for the feed.
-		// The unread number should match the feed’s unread count.
-
-		let feedUnreadCount = articles.reduce(0) { (result, article) -> Int in
-			if article.feed == feed && !article.status.read {
-				return result + 1
-			}
-			return result
-		}
-
-		feed.unreadCount = feedUnreadCount
-	}
 
 	public func fetchUnreadCountForToday(_ callback: @escaping (Int) -> Void) {
 
@@ -816,6 +785,133 @@ extension Account: FeedMetadataDelegate {
 	}
 }
 
+// MARK: - Fetching (Private)
+
+private extension Account {
+
+	func fetchStarredArticles() -> Set<Article> {
+		return database.fetchStarredArticles(flattenedFeeds().feedIDs())
+	}
+
+	func fetchStarredArticlesAsync(_ callback: @escaping ArticleSetBlock) {
+		database.fetchedStarredArticlesAsync(flattenedFeeds().feedIDs(), callback)
+	}
+
+	func fetchUnreadArticles() -> Set<Article> {
+		return fetchUnreadArticles(forContainer: self)
+	}
+
+	func fetchUnreadArticlesAsync(_ callback: @escaping ArticleSetBlock) {
+		fetchUnreadArticlesAsync(forContainer: self, callback)
+	}
+
+	func fetchTodayArticles() -> Set<Article> {
+		return database.fetchTodayArticles(flattenedFeeds().feedIDs())
+	}
+
+	func fetchTodayArticlesAsync(_ callback: @escaping ArticleSetBlock) {
+		database.fetchTodayArticlesAsync(flattenedFeeds().feedIDs(), callback)
+	}
+
+	func fetchArticles(folder: Folder) -> Set<Article> {
+		return fetchUnreadArticles(forContainer: folder)
+	}
+
+	func fetchArticlesAsync(folder: Folder, _ callback: @escaping ArticleSetBlock) {
+		fetchUnreadArticlesAsync(forContainer: folder, callback)
+	}
+
+	func fetchArticles(feed: Feed) -> Set<Article> {
+		let articles = database.fetchArticles(feed.feedID)
+		validateUnreadCount(feed, articles)
+		return articles
+	}
+
+	func fetchArticlesAsync(feed: Feed, _ callback: @escaping ArticleSetBlock) {
+		database.fetchArticlesAsync(feed.feedID) { [weak self] (articles) in
+			self?.validateUnreadCount(feed, articles)
+			callback(articles)
+		}
+	}
+
+	func fetchArticlesMatching(_ searchString: String) -> Set<Article> {
+		return database.fetchArticlesMatching(searchString, flattenedFeeds().feedIDs())
+	}
+
+	func fetchArticlesMatchingAsync(_ searchString: String, _ callback: @escaping ArticleSetBlock) {
+		database.fetchArticlesMatchingAsync(searchString, flattenedFeeds().feedIDs(), callback)
+	}
+
+	func fetchArticles(articleIDs: Set<String>) -> Set<Article> {
+		return database.fetchArticles(articleIDs: articleIDs)
+	}
+
+	func fetchArticlesAsync(articleIDs: Set<String>, _ callback: @escaping ArticleSetBlock) {
+		return database.fetchArticlesAsync(articleIDs: articleIDs, callback)
+	}
+
+	func fetchUnreadArticles(feed: Feed) -> Set<Article> {
+		let articles = database.fetchUnreadArticles(Set([feed.feedID]))
+		validateUnreadCount(feed, articles)
+		return articles
+	}
+
+	func fetchUnreadArticlesAsync(for feed: Feed, callback: @escaping (Set<Article>) -> Void) {
+		//		database.fetchUnreadArticlesAsync(for: Set([feed.feedID])) { [weak self] (articles) in
+		//			self?.validateUnreadCount(feed, articles)
+		//			callback(articles)
+		//		}
+	}
+
+
+	func fetchUnreadArticles(forContainer container: Container) -> Set<Article> {
+		let feeds = container.flattenedFeeds()
+		let articles = database.fetchUnreadArticles(feeds.feedIDs())
+		validateUnreadCountsAfterFetchingUnreadArticles(feeds, articles)
+		return articles
+	}
+
+	func fetchUnreadArticlesAsync(forContainer container: Container, _ callback: @escaping ArticleSetBlock) {
+		let feeds = container.flattenedFeeds()
+		database.fetchUnreadArticlesAsync(feeds.feedIDs()) { [weak self] (articles) in
+			self?.validateUnreadCountsAfterFetchingUnreadArticles(feeds, articles)
+			callback(articles)
+		}
+	}
+
+	func validateUnreadCountsAfterFetchingUnreadArticles(_ feeds: Set<Feed>, _ articles: Set<Article>) {
+		// Validate unread counts. This was the site of a performance slowdown:
+		// it was calling going through the entire list of articles once per feed:
+		// feeds.forEach { validateUnreadCount($0, articles) }
+		// Now we loop through articles exactly once. This makes a huge difference.
+
+		var unreadCountStorage = [String: Int]() // [FeedID: Int]
+		articles.forEach { (article) in
+			precondition(!article.status.read)
+			unreadCountStorage[article.feedID, default: 0] += 1
+		}
+		feeds.forEach { (feed) in
+			let unreadCount = unreadCountStorage[feed.feedID, default: 0]
+			feed.unreadCount = unreadCount
+		}
+	}
+
+	func validateUnreadCount(_ feed: Feed, _ articles: Set<Article>) {
+
+		// articles must contain all the unread articles for the feed.
+		// The unread number should match the feed’s unread count.
+
+		let feedUnreadCount = articles.reduce(0) { (result, article) -> Int in
+			if article.feed == feed && !article.status.read {
+				return result + 1
+			}
+			return result
+		}
+
+		feed.unreadCount = feedUnreadCount
+	}
+}
+
 // MARK: - Disk (Private)
 
 private extension Account {

Frameworks/Account/AccountManager.swift

@@ -202,7 +202,39 @@ public final class AccountManager: UnreadCountProvider {
 
 		unreadCount = calculateUnreadCount(activeAccounts)
 	}
-	
+
+	// MARK: - Fetching Articles
+
+	// These fetch articles from active accounts and return a merged Set<Article>.
+
+	public func fetchArticles(_ fetchType: FetchType) ->  Set<Article> {
+		precondition(Thread.isMainThread)
+
+		var articles = Set<Article>()
+		for account in activeAccounts {
+			articles.formUnion(account.fetchArticles(fetchType))
+		}
+		return articles
+	}
+
+	public func fetchArticlesAsync(_ fetchType: FetchType, _ callback: @escaping ArticleSetBlock) {
+		precondition(Thread.isMainThread)
+		
+		var allFetchedArticles = Set<Article>()
+		let numberOfAccounts = activeAccounts.count
+		var accountsReporting = 0
+
+		for account in activeAccounts {
+			account.fetchArticlesAsync(fetchType) { (articles) in
+				allFetchedArticles.formUnion(articles)
+				accountsReporting += 1
+				if accountsReporting == numberOfAccounts {
+					callback(allFetchedArticles)
+				}
+			}
+		}
+	}
+
 	// MARK: Notifications
 	
 	@objc dynamic func unreadCountDidChange(_ notification: Notification) {

Frameworks/Account/ArticleFetcher.swift

@@ -12,44 +12,59 @@ import Articles
 public protocol ArticleFetcher {
 
 	func fetchArticles() -> Set<Article>
+	func fetchArticlesAsync(_ callback: @escaping ArticleSetBlock)
 	func fetchUnreadArticles() -> Set<Article>
+	func fetchUnreadArticlesAsync(_ callback: @escaping ArticleSetBlock)
 }
 
 extension Feed: ArticleFetcher {
 
 	public func fetchArticles() -> Set<Article> {
+		return account?.fetchArticles(.feed(self)) ?? Set<Article>()
+	}
 
+	public func fetchArticlesAsync(_ callback: @escaping ArticleSetBlock) {
 		guard let account = account else {
 			assertionFailure("Expected feed.account, but got nil.")
-			return Set<Article>()
+			callback(Set<Article>())
+			return
 		}
-		return account.fetchArticles(for: self)
+		account.fetchArticlesAsync(.feed(self), callback)
 	}
 
 	public func fetchUnreadArticles() -> Set<Article> {
+		preconditionFailure("feed.fetchUnreadArticles is unused.")
+	}
 
-		guard let account = account else {
+	public func fetchUnreadArticlesAsync(_ callback: @escaping ArticleSetBlock) {
-			assertionFailure("Expected feed.account, but got nil.")
+		preconditionFailure("feed.fetchUnreadArticlesAsync is unused.")
-			return Set<Article>()
-		}
-		return account.fetchUnreadArticles(for: self)
 	}
 }
 
 extension Folder: ArticleFetcher {
 
 	public func fetchArticles() -> Set<Article> {
-
 		return fetchUnreadArticles()
 	}
 
-	public func fetchUnreadArticles() -> Set<Article> {
+	public func fetchArticlesAsync(_ callback: @escaping ArticleSetBlock) {
+		fetchUnreadArticlesAsync(callback)
+	}
 
+	public func fetchUnreadArticles() -> Set<Article> {
 		guard let account = account else {
 			assertionFailure("Expected folder.account, but got nil.")
 			return Set<Article>()
 		}
+		return account.fetchArticles(.unreadForFolder(self))
+	}
 
-		return account.fetchArticles(folder: self)
+	public func fetchUnreadArticlesAsync(_ callback: @escaping ArticleSetBlock) {
+		guard let account = account else {
+			assertionFailure("Expected folder.account, but got nil.")
+			callback(Set<Article>())
+			return
+		}
+		account.fetchArticlesAsync(.unreadForFolder(self), callback)
 	}
 }

Frameworks/Account/Feedbin/FeedbinAccountDelegate.swift

@@ -1131,7 +1131,7 @@ private extension FeedbinAccountDelegate {
 		
 		// Mark articles as unread
 		let deltaUnreadArticleIDs = feedbinUnreadArticleIDs.subtracting(currentUnreadArticleIDs)
-		let markUnreadArticles = account.fetchArticles(forArticleIDs: deltaUnreadArticleIDs)
+		let markUnreadArticles = account.fetchArticles(.articleIDs(deltaUnreadArticleIDs))
 		DispatchQueue.main.async {
 			_ = account.update(markUnreadArticles, statusKey: .read, flag: false)
 		}
@@ -1147,7 +1147,7 @@ private extension FeedbinAccountDelegate {
 		
 		// Mark articles as read
 		let deltaReadArticleIDs = currentUnreadArticleIDs.subtracting(feedbinUnreadArticleIDs)
-		let markReadArticles = account.fetchArticles(forArticleIDs: deltaReadArticleIDs)
+		let markReadArticles = account.fetchArticles(.articleIDs(deltaReadArticleIDs))
 		DispatchQueue.main.async {
 			_ = account.update(markReadArticles, statusKey: .read, flag: true)
 		}
@@ -1174,7 +1174,7 @@ private extension FeedbinAccountDelegate {
 		
 		// Mark articles as starred
 		let deltaStarredArticleIDs = feedbinStarredArticleIDs.subtracting(currentStarredArticleIDs)
-		let markStarredArticles = account.fetchArticles(forArticleIDs: deltaStarredArticleIDs)
+		let markStarredArticles = account.fetchArticles(.articleIDs(deltaStarredArticleIDs))
 		DispatchQueue.main.async {
 			_ = account.update(markStarredArticles, statusKey: .starred, flag: true)
 		}
@@ -1190,7 +1190,7 @@ private extension FeedbinAccountDelegate {
 		
 		// Mark articles as unstarred
 		let deltaUnstarredArticleIDs = currentStarredArticleIDs.subtracting(feedbinStarredArticleIDs)
-		let markUnstarredArticles = account.fetchArticles(forArticleIDs: deltaUnstarredArticleIDs)
+		let markUnstarredArticles = account.fetchArticles(.articleIDs(deltaUnstarredArticleIDs))
 		DispatchQueue.main.async {
 			_ = account.update(markUnstarredArticles, statusKey: .starred, flag: false)
 		}

Frameworks/Articles/Article.swift

@@ -8,6 +8,8 @@
 
 import Foundation
 
+public typealias ArticleSetBlock = (Set<Article>) -> Void
+
 public struct Article: Hashable {
 
 	public let articleID: String // Unique database ID (possibly sync service ID)

Frameworks/ArticlesDatabase/ArticlesDatabase.swift

@@ -12,10 +12,12 @@ import RSDatabase
 import RSParser
 import Articles
 
-// This file and UnreadCountDictionary are the entirety of the public API for Database.framework.
+// This file is the entirety of the public API for ArticlesDatabase.framework.
 // Everything else is implementation.
 
-public typealias ArticleResultBlock = (Set<Article>) -> Void
+// Main thread only.
+
+public typealias UnreadCountDictionary = [String: Int] // feedID: unreadCount
 public typealias UnreadCountCompletionBlock = (UnreadCountDictionary) -> Void
 public typealias UpdateArticlesWithFeedCompletionBlock = (Set<Article>?, Set<Article>?) -> Void //newArticles, updatedArticles
 
@@ -46,38 +48,60 @@ public final class ArticlesDatabase {
 
 	// MARK: - Fetching Articles
 
-	public func fetchArticles(for feedID: String) -> Set<Article> {
+	public func fetchArticles(_ feedID: String) -> Set<Article> {
 		return articlesTable.fetchArticles(feedID)
 	}
 	
-	public func fetchArticles(forArticleIDs articleIDs: Set<String>) -> Set<Article> {
+	public func fetchArticles(articleIDs: Set<String>) -> Set<Article> {
-		return articlesTable.fetchArticles(forArticleIDs: articleIDs)
+		return articlesTable.fetchArticles(articleIDs: articleIDs)
 	}
 
-	public func fetchArticlesAsync(for feedID: String, _ resultBlock: @escaping ArticleResultBlock) {
+	public func fetchUnreadArticles(_ feedIDs: Set<String>) -> Set<Article> {
-		articlesTable.fetchArticlesAsync(feedID, withLimits: true, resultBlock)
+		return articlesTable.fetchUnreadArticles(feedIDs)
 	}
 
-	public func fetchUnreadArticles(for feedIDs: Set<String>) -> Set<Article> {
+	public func fetchTodayArticles(_ feedIDs: Set<String>) -> Set<Article> {
-		return articlesTable.fetchUnreadArticles(for: feedIDs)
+		return articlesTable.fetchTodayArticles(feedIDs)
 	}
 
-	public func fetchTodayArticles(for feedIDs: Set<String>) -> Set<Article> {
+	public func fetchStarredArticles(_ feedIDs: Set<String>) -> Set<Article> {
-		return articlesTable.fetchTodayArticles(for: feedIDs)
+		return articlesTable.fetchStarredArticles(feedIDs)
 	}
 
-	public func fetchStarredArticles(for feedIDs: Set<String>) -> Set<Article> {
+	public func fetchArticlesMatching(_ searchString: String, _ feedIDs: Set<String>) -> Set<Article> {
-		return articlesTable.fetchStarredArticles(for: feedIDs)
+		return articlesTable.fetchArticlesMatching(searchString, feedIDs)
 	}
 
-	public func fetchArticlesMatching(_ searchString: String, for feedIDs: Set<String>) -> Set<Article> {
+	// MARK: - Fetching Articles Async
-		return articlesTable.fetchArticlesMatching(searchString, for: feedIDs)
+
+	public func fetchArticlesAsync(_ feedID: String, _ callback: @escaping ArticleSetBlock) {
+		articlesTable.fetchArticlesAsync(feedID, callback)
+	}
+
+	public func fetchArticlesAsync(articleIDs: Set<String>, _ callback: @escaping  ArticleSetBlock) {
+		articlesTable.fetchArticlesAsync(articleIDs: articleIDs, callback)
+	}
+
+	public func fetchUnreadArticlesAsync(_ feedIDs: Set<String>, _ callback: @escaping ArticleSetBlock) {
+		articlesTable.fetchUnreadArticlesAsync(feedIDs, callback)
+	}
+
+	public func fetchTodayArticlesAsync(_ feedIDs: Set<String>, _ callback: @escaping ArticleSetBlock) {
+		articlesTable.fetchTodayArticlesAsync(feedIDs, callback)
+	}
+
+	public func fetchedStarredArticlesAsync(_ feedIDs: Set<String>, _ callback: @escaping ArticleSetBlock) {
+		articlesTable.fetchStarredArticlesAsync(feedIDs, callback)
+	}
+
+	public func fetchArticlesMatchingAsync(_ searchString: String, _ feedIDs: Set<String>, _ callback: @escaping ArticleSetBlock) {
+		articlesTable.fetchArticlesMatchingAsync(searchString, feedIDs, callback)
 	}
 
 	// MARK: - Unread Counts
 	
-	public func fetchUnreadCounts(for feedIDs: Set<String>, _ completion: @escaping UnreadCountCompletionBlock) {
+	public func fetchUnreadCounts(for feedIDs: Set<String>, _ callback: @escaping UnreadCountCompletionBlock) {
-		articlesTable.fetchUnreadCounts(feedIDs, completion)
+		articlesTable.fetchUnreadCounts(feedIDs, callback)
 	}
 
 	public func fetchUnreadCount(for feedIDs: Set<String>, since: Date, callback: @escaping (Int) -> Void) {
@@ -88,8 +112,8 @@ public final class ArticlesDatabase {
 		articlesTable.fetchStarredAndUnreadCount(feedIDs, callback)
 	}
 
-	public func fetchAllNonZeroUnreadCounts(_ completion: @escaping UnreadCountCompletionBlock) {
+	public func fetchAllNonZeroUnreadCounts(_ callback: @escaping UnreadCountCompletionBlock) {
-		articlesTable.fetchAllUnreadCounts(completion)
+		articlesTable.fetchAllUnreadCounts(callback)
 	}
 
 	// MARK: - Saving and Updating Articles

Frameworks/ArticlesDatabase/ArticlesDatabase.xcodeproj/project.pbxproj

@@ -23,7 +23,6 @@
 		8455807A1F0AF67D003CCFA1 /* ArticleStatus+Database.swift in Sources */ = {isa = PBXBuildFile; fileRef = 845580791F0AF67D003CCFA1 /* ArticleStatus+Database.swift */; };
 		8455807C1F0C0DBD003CCFA1 /* Attachment+Database.swift in Sources */ = {isa = PBXBuildFile; fileRef = 8455807B1F0C0DBD003CCFA1 /* Attachment+Database.swift */; };
 		8477ACBC2221E76F00DF7F37 /* SearchTable.swift in Sources */ = {isa = PBXBuildFile; fileRef = 8477ACBB2221E76F00DF7F37 /* SearchTable.swift */; };
-		848AD2961F58A91E004FB0EC /* UnreadCountDictionary.swift in Sources */ = {isa = PBXBuildFile; fileRef = 848AD2951F58A91E004FB0EC /* UnreadCountDictionary.swift */; };
 		848E3EB920FBCFD20004B7ED /* RSCore.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = 848E3EB820FBCFD20004B7ED /* RSCore.framework */; };
 		848E3EBD20FBCFDE0004B7ED /* RSDatabase.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = 848E3EBC20FBCFDE0004B7ED /* RSDatabase.framework */; };
 		84E156EA1F0AB80500F8CC05 /* ArticlesDatabase.swift in Sources */ = {isa = PBXBuildFile; fileRef = 84E156E91F0AB80500F8CC05 /* ArticlesDatabase.swift */; };
@@ -131,7 +130,6 @@
 		8455807B1F0C0DBD003CCFA1 /* Attachment+Database.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; name = "Attachment+Database.swift"; path = "Extensions/Attachment+Database.swift"; sourceTree = "<group>"; };
 		8461461E1F0ABC7300870CB3 /* RSParser.xcodeproj */ = {isa = PBXFileReference; lastKnownFileType = "wrapper.pb-project"; name = RSParser.xcodeproj; path = ../RSParser/RSParser.xcodeproj; sourceTree = "<group>"; };
 		8477ACBB2221E76F00DF7F37 /* SearchTable.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = SearchTable.swift; sourceTree = "<group>"; };
-		848AD2951F58A91E004FB0EC /* UnreadCountDictionary.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = UnreadCountDictionary.swift; sourceTree = "<group>"; };
 		848E3EB820FBCFD20004B7ED /* RSCore.framework */ = {isa = PBXFileReference; explicitFileType = wrapper.framework; path = RSCore.framework; sourceTree = BUILT_PRODUCTS_DIR; };
 		848E3EBA20FBCFD80004B7ED /* RSParser.framework */ = {isa = PBXFileReference; explicitFileType = wrapper.framework; path = RSParser.framework; sourceTree = BUILT_PRODUCTS_DIR; };
 		848E3EBC20FBCFDE0004B7ED /* RSDatabase.framework */ = {isa = PBXFileReference; explicitFileType = wrapper.framework; path = RSDatabase.framework; sourceTree = BUILT_PRODUCTS_DIR; };
@@ -178,7 +176,6 @@
 			isa = PBXGroup;
 			children = (
 				84E156E91F0AB80500F8CC05 /* ArticlesDatabase.swift */,
-				848AD2951F58A91E004FB0EC /* UnreadCountDictionary.swift */,
 				845580661F0AEBCD003CCFA1 /* Constants.swift */,
 				84E156EB1F0AB80E00F8CC05 /* ArticlesTable.swift */,
 				8477ACBB2221E76F00DF7F37 /* SearchTable.swift */,
@@ -356,13 +353,13 @@
 				TargetAttributes = {
 					844BEE361F0AB3AA004AB7CD = {
 						CreatedOnToolsVersion = 8.3.2;
-						DevelopmentTeam = SHJK2V3AJG;
+						DevelopmentTeam = 9C84TZ7Q6Z;
 						LastSwiftMigration = 0830;
 						ProvisioningStyle = Automatic;
 					};
 					844BEE3F1F0AB3AB004AB7CD = {
 						CreatedOnToolsVersion = 8.3.2;
-						DevelopmentTeam = SHJK2V3AJG;
+						DevelopmentTeam = 9C84TZ7Q6Z;
 						ProvisioningStyle = Automatic;
 					};
 				};
@@ -501,7 +498,6 @@
 			files = (
 				845580671F0AEBCD003CCFA1 /* Constants.swift in Sources */,
 				843CB9961F34174100EE6581 /* Author+Database.swift in Sources */,
-				848AD2961F58A91E004FB0EC /* UnreadCountDictionary.swift in Sources */,
 				845580761F0AF670003CCFA1 /* Article+Database.swift in Sources */,
 				8455807A1F0AF67D003CCFA1 /* ArticleStatus+Database.swift in Sources */,
 				8455807C1F0C0DBD003CCFA1 /* Attachment+Database.swift in Sources */,

Frameworks/ArticlesDatabase/ArticlesTable.swift

@@ -29,6 +29,8 @@ final class ArticlesTable: DatabaseTable {
 	private var articleCutoffDate = NSDate.rs_dateWithNumberOfDays(inThePast: 3 * 31)!
 	private var maximumArticleCutoffDate = NSDate.rs_dateWithNumberOfDays(inThePast: 4 * 31)!
 
+	private typealias ArticlesFetchMethod = (FMDatabase) -> Set<Article>
+
 	init(name: String, accountID: String, queue: RSDatabaseQueue) {
 
 		self.name = name
@@ -43,52 +45,109 @@ final class ArticlesTable: DatabaseTable {
 		self.attachmentsLookupTable = DatabaseLookupTable(name: DatabaseTableName.attachmentsLookup, objectIDKey: DatabaseKey.articleID, relatedObjectIDKey: DatabaseKey.attachmentID, relatedTable: attachmentsTable, relationshipName: RelationshipName.attachments)
 	}
 
-	// MARK: Fetching
+	// MARK: - Fetch Articles for Feed
 	
 	func fetchArticles(_ feedID: String) -> Set<Article> {
-		
+		return fetchArticles{ self.fetchArticlesForFeedID(feedID, withLimits: true, $0) }
-		var articles = Set<Article>()
+	}
 
-		queue.fetchSync { (database) in
+	func fetchArticlesAsync(_ feedID: String, _ callback: @escaping ArticleSetBlock) {
-			articles = self.fetchArticlesForFeedID(feedID, withLimits: true, database: database)
+		fetchArticlesAsync({ self.fetchArticlesForFeedID(feedID, withLimits: true, $0) }, callback)
+	}
+
+	private func fetchArticlesForFeedID(_ feedID: String, withLimits: Bool, _ database: FMDatabase) -> Set<Article> {
+		return fetchArticlesWithWhereClause(database, whereClause: "articles.feedID = ?", parameters: [feedID as AnyObject], withLimits: withLimits)
+	}
+
+	// MARK: - Fetch Articles by articleID
+
+	func fetchArticles(articleIDs: Set<String>) -> Set<Article> {
+		return fetchArticles{ self.fetchArticles(articleIDs: articleIDs, $0) }
+	}
+
+	func fetchArticlesAsync(articleIDs: Set<String>, _ callback: @escaping ArticleSetBlock) {
+		return fetchArticlesAsync({ self.fetchArticles(articleIDs: articleIDs, $0) }, callback)
+	}
+
+	private func fetchArticles(articleIDs: Set<String>, _ database: FMDatabase) -> Set<Article> {
+		if articleIDs.isEmpty {
+			return Set<Article>()
+		}
+		let parameters = articleIDs.map { $0 as AnyObject }
+		let placeholders = NSString.rs_SQLValueList(withPlaceholders: UInt(articleIDs.count))!
+		let whereClause = "articleID in \(placeholders)"
+		return fetchArticlesWithWhereClause(database, whereClause: whereClause, parameters: parameters, withLimits: false)
+	}
+
+	// MARK: - Fetch Unread Articles
+
+	func fetchUnreadArticles(_ feedIDs: Set<String>) -> Set<Article> {
+		return fetchArticles{ self.fetchUnreadArticles(feedIDs, $0) }
+	}
+
+	func fetchUnreadArticlesAsync(_ feedIDs: Set<String>, _ callback: @escaping ArticleSetBlock) {
+		fetchArticlesAsync({ self.fetchUnreadArticles(feedIDs, $0) }, callback)
+	}
+
+	private func fetchUnreadArticles(_ feedIDs: Set<String>, _ database: FMDatabase) -> Set<Article> {
+		// select * from articles natural join statuses where feedID in ('http://ranchero.com/xml/rss.xml') and read=0
+		if feedIDs.isEmpty {
+			return Set<Article>()
+		}
+		let parameters = feedIDs.map { $0 as AnyObject }
+		let placeholders = NSString.rs_SQLValueList(withPlaceholders: UInt(feedIDs.count))!
+		let whereClause = "feedID in \(placeholders) and read=0"
+		return fetchArticlesWithWhereClause(database, whereClause: whereClause, parameters: parameters, withLimits: true)
+	}
+
+	// MARK: - Fetch Today Articles
+
+	func fetchTodayArticles(_ feedIDs: Set<String>) -> Set<Article> {
+		return fetchArticles{ self.fetchTodayArticles(feedIDs, $0) }
+	}
+
+	func fetchTodayArticlesAsync(_ feedIDs: Set<String>, _ callback: @escaping ArticleSetBlock) {
+		fetchArticlesAsync({ self.fetchTodayArticles(feedIDs, $0) }, callback)
+	}
+
+	private func fetchTodayArticles(_ feedIDs: Set<String>, _ database: FMDatabase) -> Set<Article> {
+		// select * from articles natural join statuses where feedID in ('http://ranchero.com/xml/rss.xml') and (datePublished > ? || (datePublished is null and dateArrived > ?)
+		//
+		// datePublished may be nil, so we fall back to dateArrived.
+		if feedIDs.isEmpty {
+			return Set<Article>()
+		}
+		let startOfToday = NSCalendar.startOfToday()
+		let parameters = feedIDs.map { $0 as AnyObject } + [startOfToday as AnyObject, startOfToday as AnyObject]
+		let placeholders = NSString.rs_SQLValueList(withPlaceholders: UInt(feedIDs.count))!
+		let whereClause = "feedID in \(placeholders) and (datePublished > ? or (datePublished is null and dateArrived > ?)) and userDeleted = 0"
+		return fetchArticlesWithWhereClause(database, whereClause: whereClause, parameters: parameters, withLimits: false)
+	}
+
+	// MARK: - Fetch Starred Articles
+
+	func fetchStarredArticles(_ feedIDs: Set<String>) -> Set<Article> {
+		return fetchArticles{ self.fetchStarredArticles(feedIDs, $0) }
+	}
+
+	func fetchStarredArticlesAsync(_ feedIDs: Set<String>, _ callback: @escaping ArticleSetBlock) {
+		fetchArticlesAsync({ self.fetchStarredArticles(feedIDs, $0) }, callback)
+	}
+
+	private func fetchStarredArticles(_ feedIDs: Set<String>, _ database: FMDatabase) -> Set<Article> {
+		// select * from articles natural join statuses where feedID in ('http://ranchero.com/xml/rss.xml') and starred = 1 and userDeleted = 0;
+		if feedIDs.isEmpty {
+			return Set<Article>()
+		}
+		let parameters = feedIDs.map { $0 as AnyObject }
+		let placeholders = NSString.rs_SQLValueList(withPlaceholders: UInt(feedIDs.count))!
+		let whereClause = "feedID in \(placeholders) and starred = 1 and userDeleted = 0"
+		return fetchArticlesWithWhereClause(database, whereClause: whereClause, parameters: parameters, withLimits: false)
 		}
 
-		return articles
+	// MARK: - Fetch Search Articles
-	}
 
-	public func fetchArticles(forArticleIDs articleIDs: Set<String>) -> Set<Article> {
+	func fetchArticlesMatching(_ searchString: String, _ feedIDs: Set<String>) -> Set<Article> {
-		
-		return fetchArticlesForIDs(articleIDs)
-	}
-	
-	func fetchArticlesAsync(_ feedID: String, withLimits: Bool, _ resultBlock: @escaping ArticleResultBlock) {
-
-		queue.fetch { (database) in
-
-			let articles = self.fetchArticlesForFeedID(feedID, withLimits: withLimits, database: database)
-
-			DispatchQueue.main.async {
-				resultBlock(articles)
-			}
-		}
-	}
-	
-	func fetchUnreadArticles(for feedIDs: Set<String>) -> Set<Article> {
-
-		return fetchUnreadArticles(feedIDs)
-	}
-
-	public func fetchTodayArticles(for feedIDs: Set<String>) -> Set<Article> {
-
-		return fetchTodayArticles(feedIDs)
-	}
-
-	public func fetchStarredArticles(for feedIDs: Set<String>) -> Set<Article> {
-
-		return fetchStarredArticles(feedIDs)
-	}
-
-	func fetchArticlesMatching(_ searchString: String, for feedIDs: Set<String>) -> Set<Article> {
 		var articles: Set<Article> = Set<Article>()
 		queue.fetchSync { (database) in
 			articles = self.fetchArticlesMatching(searchString, database)
@@ -97,6 +156,32 @@ final class ArticlesTable: DatabaseTable {
 		return articles
 	}
 
+	func fetchArticlesMatchingAsync(_ searchString: String, _ feedIDs: Set<String>, _ callback: @escaping ArticleSetBlock) {
+		fetchArticlesAsync({ self.fetchArticlesMatching(searchString, feedIDs, $0) }, callback)
+	}
+
+	private func fetchArticlesMatching(_ searchString: String, _ feedIDs: Set<String>, _ database: FMDatabase) -> Set<Article> {
+		let sql = "select rowid from search where search match ?;"
+		let sqlSearchString = sqliteSearchString(with: searchString)
+		let searchStringParameters = [sqlSearchString]
+		guard let resultSet = database.executeQuery(sql, withArgumentsIn: searchStringParameters) else {
+			return Set<Article>()
+		}
+		let searchRowIDs = resultSet.mapToSet { $0.longLongInt(forColumnIndex: 0) }
+		if searchRowIDs.isEmpty {
+			return Set<Article>()
+		}
+
+		let placeholders = NSString.rs_SQLValueList(withPlaceholders: UInt(searchRowIDs.count))!
+		let whereClause = "searchRowID in \(placeholders)"
+		let parameters: [AnyObject] = Array(searchRowIDs) as [AnyObject]
+		let articles = fetchArticlesWithWhereClause(database, whereClause: whereClause, parameters: parameters, withLimits: true)
+		// TODO: include the feedIDs in the SQL rather than filtering here.
+		return articles.filter{ feedIDs.contains($0.feedID) }
+	}
+
+	// MARK: - Fetch Articles for Indexer
+
 	func fetchArticleSearchInfos(_ articleIDs: Set<String>, in database: FMDatabase) -> Set<ArticleSearchInfo>? {
 		let parameters = articleIDs.map { $0 as AnyObject }
 		let placeholders = NSString.rs_SQLValueList(withPlaceholders: UInt(articleIDs.count))!
@@ -159,7 +244,7 @@ final class ArticlesTable: DatabaseTable {
 				return
 			}
 
-			let fetchedArticles = self.fetchArticlesForFeedID(feedID, withLimits: false, database: database) //4
+			let fetchedArticles = self.fetchArticlesForFeedID(feedID, withLimits: false, database) //4
 			let fetchedArticlesDictionary = fetchedArticles.dictionary()
 			
 			let newArticles = self.findAndSaveNewArticles(incomingArticles, fetchedArticlesDictionary, database) //5
@@ -346,6 +431,23 @@ private extension ArticlesTable {
 
 	// MARK: Fetching
 
+	private func fetchArticles(_ fetchMethod: @escaping ArticlesFetchMethod) -> Set<Article> {
+		var articles = Set<Article>()
+		queue.fetchSync { (database) in
+			articles = fetchMethod(database)
+		}
+		return articles
+	}
+
+	private func fetchArticlesAsync(_ fetchMethod: @escaping ArticlesFetchMethod, _ callback: @escaping ArticleSetBlock) {
+		queue.fetch { (database) in
+			let articles = fetchMethod(database)
+			DispatchQueue.main.async {
+				callback(articles)
+			}
+		}
+	}
+
 	func articlesWithResultSet(_ resultSet: FMResultSet, _ database: FMDatabase) -> Set<Article> {
 
 		// 1. Create DatabaseArticles without related objects.
@@ -453,97 +555,6 @@ private extension ArticlesTable {
 		return numberWithSQLAndParameters(sql, [feedID, articleCutoffDate], in: database)
 	}
 	
-	func fetchArticlesForFeedID(_ feedID: String, withLimits: Bool, database: FMDatabase) -> Set<Article> {
-
-		return fetchArticlesWithWhereClause(database, whereClause: "articles.feedID = ?", parameters: [feedID as AnyObject], withLimits: withLimits)
-	}
-
-	func fetchArticlesForIDs(_ articleIDs: Set<String>) -> Set<Article> {
-
-		if articleIDs.isEmpty {
-			return Set<Article>()
-		}
-		
-		var articles = Set<Article>()
-		
-		queue.fetchSync { (database) in
-			
-			let parameters = articleIDs.map { $0 as AnyObject }
-			let placeholders = NSString.rs_SQLValueList(withPlaceholders: UInt(articleIDs.count))!
-			let whereClause = "articleID in \(placeholders)"
-			articles = self.fetchArticlesWithWhereClause(database, whereClause: whereClause, parameters: parameters, withLimits: false)
-		}
-		
-		return articles
-	}
-	
-	func fetchUnreadArticles(_ feedIDs: Set<String>) -> Set<Article> {
-
-		if feedIDs.isEmpty {
-			return Set<Article>()
-		}
-
-		var articles = Set<Article>()
-
-		queue.fetchSync { (database) in
-
-			// select * from articles natural join statuses where feedID in ('http://ranchero.com/xml/rss.xml') and read=0
-
-			let parameters = feedIDs.map { $0 as AnyObject }
-			let placeholders = NSString.rs_SQLValueList(withPlaceholders: UInt(feedIDs.count))!
-			let whereClause = "feedID in \(placeholders) and read=0"
-			articles = self.fetchArticlesWithWhereClause(database, whereClause: whereClause, parameters: parameters, withLimits: true)
-		}
-
-		return articles
-	}
-
-	func fetchTodayArticles(_ feedIDs: Set<String>) -> Set<Article> {
-
-		if feedIDs.isEmpty {
-			return Set<Article>()
-		}
-
-		var articles = Set<Article>()
-
-		queue.fetchSync { (database) in
-
-			// select * from articles natural join statuses where feedID in ('http://ranchero.com/xml/rss.xml') and (datePublished > ? || (datePublished is null and dateArrived > ?)
-			//
-			// datePublished may be nil, so we fall back to dateArrived.
-
-			let startOfToday = NSCalendar.startOfToday()
-			let parameters = feedIDs.map { $0 as AnyObject } + [startOfToday as AnyObject, startOfToday as AnyObject]
-			let placeholders = NSString.rs_SQLValueList(withPlaceholders: UInt(feedIDs.count))!
-			let whereClause = "feedID in \(placeholders) and (datePublished > ? or (datePublished is null and dateArrived > ?)) and userDeleted = 0"
-//			let whereClause = "feedID in \(placeholders) and datePublished > ? and userDeleted = 0"
-			articles = self.fetchArticlesWithWhereClause(database, whereClause: whereClause, parameters: parameters, withLimits: false)
-		}
-
-		return articles
-	}
-
-	func fetchStarredArticles(_ feedIDs: Set<String>) -> Set<Article> {
-
-		if feedIDs.isEmpty {
-			return Set<Article>()
-		}
-
-		var articles = Set<Article>()
-
-		queue.fetchSync { (database) in
-
-			// select * from articles natural join statuses where feedID in ('http://ranchero.com/xml/rss.xml') and starred = 1 and userDeleted = 0;
-
-			let parameters = feedIDs.map { $0 as AnyObject }
-			let placeholders = NSString.rs_SQLValueList(withPlaceholders: UInt(feedIDs.count))!
-			let whereClause = "feedID in \(placeholders) and starred = 1 and userDeleted = 0"
-			articles = self.fetchArticlesWithWhereClause(database, whereClause: whereClause, parameters: parameters, withLimits: false)
-		}
-
-		return articles
-	}
-
 	func fetchArticlesMatching(_ searchString: String, _ database: FMDatabase) -> Set<Article> {
 		let sql = "select rowid from search where search match ?;"
 		let sqlSearchString = sqliteSearchString(with: searchString)

Frameworks/ArticlesDatabase/UnreadCountDictionary.swift

@@ -1,28 +0,0 @@
-//
-//  UnreadCountDictionary.swift
-//  Database
-//
-//  Created by Brent Simmons on 8/31/17.
-//  Copyright © 2017 Ranchero Software. All rights reserved.
-//
-
-import Foundation
-import Articles
-
-public struct UnreadCountDictionary {
-	
-	private var dictionary = [String: Int]()
-
-	public var isEmpty: Bool {
-		return dictionary.count < 1
-	}
-	
-	public subscript(_ feedID: String) -> Int? {
-		get {
-			return dictionary[feedID]
-		}
-		set {
-			dictionary[feedID] = newValue
-		}
-	}
-}

Mac/MainWindow/Timeline/FetchRequestOperation.swift

@@ -0,0 +1,72 @@
+//
+//  FetchRequestOperation.swift
+//  NetNewsWire
+//
+//  Created by Brent Simmons on 6/20/19.
+//  Copyright © 2019 Ranchero Software. All rights reserved.
+//
+
+import Foundation
+import RSCore
+import Account
+import Articles
+
+// Main thread only.
+// Runs an asynchronous fetch.
+
+typealias FetchRequestOperationResultBlock = (Set<Article>, FetchRequestOperation) -> Void
+
+class FetchRequestOperation {
+
+	let id: Int
+	let resultBlock: FetchRequestOperationResultBlock
+	var isCanceled = false
+	var isFinished = false
+	private let representedObjects: [Any]
+
+	init(id: Int, representedObjects: [Any], resultBlock: @escaping FetchRequestOperationResultBlock) {
+		precondition(Thread.isMainThread)
+		self.id = id
+		self.representedObjects = representedObjects
+		self.resultBlock = resultBlock
+	}
+
+	func run(_ completion: @escaping (FetchRequestOperation) -> Void) {
+		precondition(Thread.isMainThread)
+		precondition(!isFinished)
+
+		if isCanceled {
+			completion(self)
+			return
+		}
+
+		let articleFetchers = representedObjects.compactMap{ $0 as? ArticleFetcher }
+		if articleFetchers.isEmpty {
+			isFinished = true
+			resultBlock(Set<Article>(), self)
+			completion(self)
+			return
+		}
+
+		let numberOfFetchers = articleFetchers.count
+		var fetchersReturned = 0
+		var fetchedArticles = Set<Article>()
+		for articleFetcher in articleFetchers {
+			articleFetcher.fetchArticlesAsync { (articles) in
+				precondition(Thread.isMainThread)
+				if self.isCanceled {
+					completion(self)
+					return
+				}
+				fetchedArticles.formUnion(articles)
+				fetchersReturned += 1
+				if fetchersReturned == numberOfFetchers {
+					self.isFinished = true
+					self.resultBlock(fetchedArticles, self)
+					completion(self)
+				}
+			}
+		}
+	}
+}
+

Mac/MainWindow/Timeline/FetchRequestQueue.swift

@@ -0,0 +1,54 @@
+//
+//  FetchRequestQueue.swift
+//  NetNewsWire
+//
+//  Created by Brent Simmons on 6/20/19.
+//  Copyright © 2019 Ranchero Software. All rights reserved.
+//
+
+import Foundation
+
+// Main thread only.
+
+class FetchRequestQueue {
+
+	private var pendingRequests = [FetchRequestOperation]()
+	private var currentRequest: FetchRequestOperation? = nil
+
+	func cancelAllRequests() {
+		precondition(Thread.isMainThread)
+		pendingRequests.forEach { $0.isCanceled = true }
+		currentRequest?.isCanceled = true
+		pendingRequests = [FetchRequestOperation]()
+	}
+
+	func add(_ fetchRequestOperation: FetchRequestOperation) {
+		precondition(Thread.isMainThread)
+		pendingRequests.append(fetchRequestOperation)
+		runNextRequestIfNeeded()
+	}
+}
+
+private extension FetchRequestQueue {
+
+	func runNextRequestIfNeeded() {
+		precondition(Thread.isMainThread)
+		removeCanceledAndFinishedRequests()
+		guard currentRequest == nil, let requestToRun = pendingRequests.first else {
+			return
+		}
+
+		currentRequest = requestToRun
+		pendingRequests.removeFirst()
+		requestToRun.run { (fetchRequestOperation) in
+			precondition(fetchRequestOperation === self.currentRequest)
+			precondition(fetchRequestOperation === requestToRun)
+			self.currentRequest = nil
+			self.runNextRequestIfNeeded()
+		}
+	}
+
+	func removeCanceledAndFinishedRequests() {
+		pendingRequests = pendingRequests.filter{ !$0.isCanceled && !$0.isFinished }
+	}
+}

Mac/MainWindow/Timeline/TimelineContainerViewController.swift

@@ -33,8 +33,10 @@ final class TimelineContainerViewController: NSViewController {
 	private lazy var regularTimelineViewController = {
 		return TimelineViewController(delegate: self)
 	}()
-	private lazy var searchTimelineViewController = {
+	private lazy var searchTimelineViewController: TimelineViewController = {
-		return TimelineViewController(delegate: self)
+		let viewController = TimelineViewController(delegate: self)
+		viewController.showsSearchResults = true
+		return viewController
 	}()
 
     override func viewDidLoad() {

Mac/MainWindow/Timeline/TimelineViewController.swift

@@ -40,9 +40,14 @@ final class TimelineViewController: NSViewController, UndoableCommandRunner {
 				}
 
 				selectionDidChange(nil)
-				fetchArticles()
+				if showsSearchResults {
-				if articles.count > 0 {
+					fetchAndReplaceArticlesAsync()
-					tableView.scrollRowToVisible(0)
+				}
+				else {
+					fetchAndReplaceArticlesSync()
+					if articles.count > 0 {
+						tableView.scrollRowToVisible(0)
+					}
 				}
 			}
 		}
@@ -50,7 +55,8 @@ final class TimelineViewController: NSViewController, UndoableCommandRunner {
 
 	private weak var delegate: TimelineDelegate?
 	var sharingServiceDelegate: NSSharingServiceDelegate?
-	
+
+	var showsSearchResults = false
 	var selectedArticles: [Article] {
 		return Array(articles.articlesForIndexes(tableView.selectedRowIndexes))
 	}
@@ -79,6 +85,8 @@ final class TimelineViewController: NSViewController, UndoableCommandRunner {
 	}
 
 	var undoableCommands = [UndoableCommand]()
+	private var fetchSerialNumber = 0
+	private let fetchRequestQueue = FetchRequestQueue()
 	private var articleRowMap = [String: Int]() // articleID: rowIndex
 	private var cellAppearance: TimelineCellAppearance!
 	private var cellAppearanceWithAvatar: TimelineCellAppearance!
@@ -100,7 +108,7 @@ final class TimelineViewController: NSViewController, UndoableCommandRunner {
 	}
 
 	private var didRegisterForNotifications = false
-	static let fetchAndMergeArticlesQueue = CoalescingQueue(name: "Fetch and Merge Articles", interval: 2.0, maxInterval: 5.0)
+	static let fetchAndMergeArticlesQueue = CoalescingQueue(name: "Fetch and Merge Articles", interval: 0.5, maxInterval: 2.0)
 
 	private var sortDirection = AppDefaults.timelineSortDirection {
 		didSet {
@@ -502,13 +510,13 @@ final class TimelineViewController: NSViewController, UndoableCommandRunner {
 
 	@objc func accountStateDidChange(_ note: Notification) {
 		if representedObjectsContainsAnyPseudoFeed() {
-			fetchArticles()
+			fetchAndReplaceArticlesAsync()
 		}
 	}
 	
 	@objc func accountsDidChange(_ note: Notification) {
 		if representedObjectsContainsAnyPseudoFeed() {
-			fetchArticles()
+			fetchAndReplaceArticlesAsync()
 		}
 	}
 
@@ -521,7 +529,7 @@ final class TimelineViewController: NSViewController, UndoableCommandRunner {
 	@objc func calendarDayChanged(_ note: Notification) {
 		if representedObjectsContainsTodayFeed() {
 			DispatchQueue.main.async { [weak self] in
-				self?.fetchArticles()
+				self?.fetchAndReplaceArticlesAsync()
 			}
 		}
 	}
@@ -606,24 +614,25 @@ final class TimelineViewController: NSViewController, UndoableCommandRunner {
 	}
 
 	@objc func fetchAndMergeArticles() {
-
 		guard let representedObjects = representedObjects else {
 			return
 		}
 
-		performBlockAndRestoreSelection {
+		fetchUnsortedArticlesAsync(for: representedObjects) { [weak self] (unsortedArticles) in
-
-			var unsortedArticles = fetchUnsortedArticles(for: representedObjects)
-
 			// Merge articles by articleID. For any unique articleID in current articles, add to unsortedArticles.
+			guard let strongSelf = self else {
+				return
+			}
 			let unsortedArticleIDs = unsortedArticles.articleIDs()
-			for article in articles {
+			var updatedArticles = unsortedArticles
+			for article in strongSelf.articles {
 				if !unsortedArticleIDs.contains(article.articleID) {
-					unsortedArticles.insert(article)
+					updatedArticles.insert(article)
 				}
 			}
-
+			strongSelf.performBlockAndRestoreSelection {
-			updateArticles(with: unsortedArticles)
+				strongSelf.replaceArticles(with: updatedArticles)
+			}
 		}
 	}
 }
@@ -842,7 +851,6 @@ private extension TimelineViewController {
 	}
 
 	func emptyTheTimeline() {
-
 		if !articles.isEmpty {
 			articles = [Article]()
 		}
@@ -852,7 +860,7 @@ private extension TimelineViewController {
 
 		performBlockAndRestoreSelection {
 			let unsortedArticles = Set(articles)
-			updateArticles(with: unsortedArticles)
+			replaceArticles(with: unsortedArticles)
 		}
 	}
 
@@ -919,18 +927,39 @@ private extension TimelineViewController {
 
 	// MARK: Fetching Articles
 
-	func fetchArticles() {
+	func fetchAndReplaceArticlesSync() {
-
+		// To be called when the user has made a change of selection in the sidebar.
+		// It blocks the main thread, so that there’s no async delay,
+		// so that the entire display refreshes at once.
+		// It’s a better user experience this way.
+		cancelPendingAsyncFetches()
 		guard let representedObjects = representedObjects else {
 			emptyTheTimeline()
 			return
 		}
-
+		let fetchedArticles = fetchUnsortedArticlesSync(for: representedObjects)
-		let fetchedArticles = fetchUnsortedArticles(for: representedObjects)
+		replaceArticles(with: fetchedArticles)
-		updateArticles(with: fetchedArticles)
 	}
 
-	func updateArticles(with unsortedArticles: Set<Article>) {
+	func fetchAndReplaceArticlesAsync() {
+		// To be called when we need to do an entire fetch, but an async delay is okay.
+		// Example: we have the Today feed selected, and the calendar day just changed.
+		cancelPendingAsyncFetches()
+		guard let representedObjects = representedObjects else {
+			emptyTheTimeline()
+			return
+		}
+		fetchUnsortedArticlesAsync(for: representedObjects) { [weak self] (articles) in
+			self?.replaceArticles(with: articles)
+		}
+	}
+
+	func cancelPendingAsyncFetches() {
+		fetchSerialNumber += 1
+		fetchRequestQueue.cancelAllRequests()
+	}
+
+	func replaceArticles(with unsortedArticles: Set<Article>) {
 
 		let sortedArticles = Array(unsortedArticles).sortedByDate(sortDirection)
 		if articles != sortedArticles {
@@ -938,20 +967,35 @@ private extension TimelineViewController {
 		}
 	}
 
-	func fetchUnsortedArticles(for representedObjects: [Any]) -> Set<Article> {
+	func fetchUnsortedArticlesSync(for representedObjects: [Any]) -> Set<Article> {
-
+		cancelPendingAsyncFetches()
-		var fetchedArticles = Set<Article>()
+		let articleFetchers = representedObjects.compactMap{ $0 as? ArticleFetcher }
-
+		if articleFetchers.isEmpty {
-		for object in representedObjects {
+			return Set<Article>()
-
-			if let articleFetcher = object as? ArticleFetcher {
-				fetchedArticles.formUnion(articleFetcher.fetchArticles())
-			}
 		}
 
+		var fetchedArticles = Set<Article>()
+		for articleFetcher in articleFetchers {
+			fetchedArticles.formUnion(articleFetcher.fetchArticles())
+		}
 		return fetchedArticles
 	}
 
+	func fetchUnsortedArticlesAsync(for representedObjects: [Any], callback: @escaping ArticleSetBlock) {
+		// The callback will *not* be called if the fetch is no longer relevant — that is,
+		// if it’s been superseded by a newer fetch, or the timeline was emptied, etc., it won’t get called.
+		precondition(Thread.isMainThread)
+		cancelPendingAsyncFetches()
+		let fetchOperation = FetchRequestOperation(id: fetchSerialNumber, representedObjects: representedObjects) { [weak self] (articles, operation) in
+			precondition(Thread.isMainThread)
+			guard !operation.isCanceled, let strongSelf = self, operation.id == strongSelf.fetchSerialNumber else {
+				return
+			}
+			callback(articles)
+		}
+		fetchRequestQueue.add(fetchOperation)
+	}
+
 	func selectArticles(_ articleIDs: [String]) {
 
 		let indexesToSelect = indexesForArticleIDs(Set(articleIDs))

NetNewsWire.xcodeproj/project.pbxproj

@@ -267,8 +267,14 @@
 		84C9FC9D2262A1A900D921D6 /* Assets.xcassets in Resources */ = {isa = PBXBuildFile; fileRef = 84C9FC9B2262A1A900D921D6 /* Assets.xcassets */; };
 		84C9FCA12262A1B300D921D6 /* Main.storyboard in Resources */ = {isa = PBXBuildFile; fileRef = 84C9FC9F2262A1B300D921D6 /* Main.storyboard */; };
 		84C9FCA42262A1B800D921D6 /* LaunchScreen.storyboard in Resources */ = {isa = PBXBuildFile; fileRef = 84C9FCA22262A1B800D921D6 /* LaunchScreen.storyboard */; };
+		84CAFCA422BC8C08007694F0 /* FetchRequestQueue.swift in Sources */ = {isa = PBXBuildFile; fileRef = 84CAFCA322BC8C08007694F0 /* FetchRequestQueue.swift */; };
+		84CAFCA522BC8C08007694F0 /* FetchRequestQueue.swift in Sources */ = {isa = PBXBuildFile; fileRef = 84CAFCA322BC8C08007694F0 /* FetchRequestQueue.swift */; };
+		84CAFCAF22BC8C35007694F0 /* FetchRequestOperation.swift in Sources */ = {isa = PBXBuildFile; fileRef = 84CAFCAE22BC8C35007694F0 /* FetchRequestOperation.swift */; };
+		84CAFCB022BC8C35007694F0 /* FetchRequestOperation.swift in Sources */ = {isa = PBXBuildFile; fileRef = 84CAFCAE22BC8C35007694F0 /* FetchRequestOperation.swift */; };
 		84CC88181FE59CBF00644329 /* SmartFeedsController.swift in Sources */ = {isa = PBXBuildFile; fileRef = 84CC88171FE59CBF00644329 /* SmartFeedsController.swift */; };
 		84D52E951FE588BB00D14F5B /* DetailStatusBarView.swift in Sources */ = {isa = PBXBuildFile; fileRef = 84D52E941FE588BB00D14F5B /* DetailStatusBarView.swift */; };
+		84DEE56522C32CA4005FC42C /* SmartFeedDelegate.swift in Sources */ = {isa = PBXBuildFile; fileRef = 84DEE56422C32CA4005FC42C /* SmartFeedDelegate.swift */; };
+		84DEE56622C32CA4005FC42C /* SmartFeedDelegate.swift in Sources */ = {isa = PBXBuildFile; fileRef = 84DEE56422C32CA4005FC42C /* SmartFeedDelegate.swift */; };
 		84E185B3203B74E500F69BFA /* SingleLineTextFieldSizer.swift in Sources */ = {isa = PBXBuildFile; fileRef = 84E185B2203B74E500F69BFA /* SingleLineTextFieldSizer.swift */; };
 		84E185C3203BB12600F69BFA /* MultilineTextFieldSizer.swift in Sources */ = {isa = PBXBuildFile; fileRef = 84E185C2203BB12600F69BFA /* MultilineTextFieldSizer.swift */; };
 		84E46C7D1F75EF7B005ECFB3 /* AppDefaults.swift in Sources */ = {isa = PBXBuildFile; fileRef = 84E46C7C1F75EF7B005ECFB3 /* AppDefaults.swift */; };
@@ -871,9 +877,12 @@
 		84C9FC9C2262A1A900D921D6 /* Info.plist */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = text.plist.xml; path = Info.plist; sourceTree = "<group>"; };
 		84C9FCA02262A1B300D921D6 /* Base */ = {isa = PBXFileReference; lastKnownFileType = file.storyboard; name = Base; path = Base.lproj/Main.storyboard; sourceTree = "<group>"; };
 		84C9FCA32262A1B800D921D6 /* Base */ = {isa = PBXFileReference; lastKnownFileType = file.storyboard; name = Base; path = Base.lproj/LaunchScreen.storyboard; sourceTree = "<group>"; };
+		84CAFCA322BC8C08007694F0 /* FetchRequestQueue.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = FetchRequestQueue.swift; sourceTree = "<group>"; };
+		84CAFCAE22BC8C35007694F0 /* FetchRequestOperation.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = FetchRequestOperation.swift; sourceTree = "<group>"; };
 		84CBDDAE1FD3674C005A61AA /* Technotes */ = {isa = PBXFileReference; lastKnownFileType = folder; path = Technotes; sourceTree = "<group>"; };
 		84CC88171FE59CBF00644329 /* SmartFeedsController.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = SmartFeedsController.swift; sourceTree = "<group>"; };
 		84D52E941FE588BB00D14F5B /* DetailStatusBarView.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = DetailStatusBarView.swift; sourceTree = "<group>"; };
+		84DEE56422C32CA4005FC42C /* SmartFeedDelegate.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = SmartFeedDelegate.swift; sourceTree = "<group>"; };
 		84E185B2203B74E500F69BFA /* SingleLineTextFieldSizer.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = SingleLineTextFieldSizer.swift; sourceTree = "<group>"; };
 		84E185C2203BB12600F69BFA /* MultilineTextFieldSizer.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = MultilineTextFieldSizer.swift; sourceTree = "<group>"; };
 		84E46C7C1F75EF7B005ECFB3 /* AppDefaults.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = AppDefaults.swift; sourceTree = "<group>"; };
@@ -1388,6 +1397,8 @@
 				84E8E0DA202EC49300562D8F /* TimelineViewController+ContextualMenus.swift */,
 				849A97691ED9EBC8007D329B /* TimelineTableRowView.swift */,
 				849A976A1ED9EBC8007D329B /* TimelineTableView.swift */,
+				84CAFCA322BC8C08007694F0 /* FetchRequestQueue.swift */,
+				84CAFCAE22BC8C35007694F0 /* FetchRequestOperation.swift */,
 				844B5B6C1FEA282400C7C76A /* Keyboard */,
 				84E95D231FB1087500552D99 /* ArticlePasteboardWriter.swift */,
 				849A976F1ED9EC04007D329B /* Cell */,
@@ -1724,6 +1735,7 @@
 				84F2D5351FC22FCB00998D64 /* PseudoFeed.swift */,
 				84F2D5391FC2308B00998D64 /* UnreadFeed.swift */,
 				845EE7C01FC2488C00854A1F /* SmartFeed.swift */,
+				84DEE56422C32CA4005FC42C /* SmartFeedDelegate.swift */,
 				84F2D5361FC22FCB00998D64 /* TodayFeedDelegate.swift */,
 				845EE7B01FC2366500854A1F /* StarredFeedDelegate.swift */,
 				8477ACBD22238E9500DF7F37 /* SearchFeedDelegate.swift */,
@@ -1942,12 +1954,12 @@
 				ORGANIZATIONNAME = "Ranchero Software";
 				TargetAttributes = {
 					6581C73220CED60000F4AD34 = {
-						DevelopmentTeam = SHJK2V3AJG;
+						DevelopmentTeam = M8L2WTLA8W;
 						ProvisioningStyle = Manual;
 					};
 					840D617B2029031C009BC708 = {
 						CreatedOnToolsVersion = 9.3;
-						DevelopmentTeam = SHJK2V3AJG;
+						DevelopmentTeam = M8L2WTLA8W;
 						ProvisioningStyle = Automatic;
 						SystemCapabilities = {
 							com.apple.BackgroundModes = {
@@ -1963,7 +1975,7 @@
 					};
 					849C645F1ED37A5D003D8FC0 = {
 						CreatedOnToolsVersion = 8.2.1;
-						DevelopmentTeam = SHJK2V3AJG;
+						DevelopmentTeam = M8L2WTLA8W;
 						ProvisioningStyle = Manual;
 						SystemCapabilities = {
 							com.apple.HardenedRuntime = {
@@ -1973,7 +1985,7 @@
 					};
 					849C64701ED37A5D003D8FC0 = {
 						CreatedOnToolsVersion = 8.2.1;
-						DevelopmentTeam = SHJK2V3AJG;
+						DevelopmentTeam = 9C84TZ7Q6Z;
 						ProvisioningStyle = Automatic;
 						TestTargetID = 849C645F1ED37A5D003D8FC0;
 					};
@@ -2335,6 +2347,7 @@
 				51C452852265093600C03939 /* AddFeedFolderPickerData.swift in Sources */,
 				51C4526B226508F600C03939 /* MasterFeedViewController.swift in Sources */,
 				5126EE97226CB48A00C22AFC /* NavigationStateController.swift in Sources */,
+				84CAFCB022BC8C35007694F0 /* FetchRequestOperation.swift in Sources */,
 				51EF0F77227716200050506E /* FaviconGenerator.swift in Sources */,
 				51C4525A226508D600C03939 /* UIStoryboard-Extensions.swift in Sources */,
 				5183CCEF227125970010922C /* SettingsViewController.swift in Sources */,
@@ -2368,6 +2381,7 @@
 				515436882291D75D005E1CDF /* AddLocalAccountViewController.swift in Sources */,
 				51C452AF2265108300C03939 /* ArticleArray.swift in Sources */,
 				51C4528E2265099C00C03939 /* SmartFeedsController.swift in Sources */,
+				84CAFCA522BC8C08007694F0 /* FetchRequestQueue.swift in Sources */,
 				51C4529C22650A1000C03939 /* SingleFaviconDownloader.swift in Sources */,
 				51E595A6228CC36500FCC42B /* ArticleStatusSyncTimer.swift in Sources */,
 				51C45290226509C100C03939 /* PseudoFeed.swift in Sources */,
@@ -2382,6 +2396,7 @@
 				5183CCE9226F68D90010922C /* AccountRefreshTimer.swift in Sources */,
 				51C452882265093600C03939 /* AddFeedViewController.swift in Sources */,
 				51C4529B22650A1000C03939 /* FaviconDownloader.swift in Sources */,
+				84DEE56622C32CA4005FC42C /* SmartFeedDelegate.swift in Sources */,
 				5183CCE3226F314C0010922C /* ProgressTableViewController.swift in Sources */,
 				512E09012268907400BDCFDD /* MasterFeedTableViewSectionHeader.swift in Sources */,
 				51C45268226508F600C03939 /* MasterFeedUnreadCountView.swift in Sources */,
@@ -2483,6 +2498,7 @@
 				849A97831ED9EC63007D329B /* SidebarStatusBarView.swift in Sources */,
 				84F2D5381FC22FCC00998D64 /* TodayFeedDelegate.swift in Sources */,
 				841ABA5E20145E9200980E11 /* FolderInspectorViewController.swift in Sources */,
+				84DEE56522C32CA4005FC42C /* SmartFeedDelegate.swift in Sources */,
 				845213231FCA5B11003B6E93 /* ImageDownloader.swift in Sources */,
 				51EF0F922279CA620050506E /* AccountsAddTableCellView.swift in Sources */,
 				849A97431ED9EAA9007D329B /* AddFolderWindowController.swift in Sources */,
@@ -2493,6 +2509,7 @@
 				849A97801ED9EC42007D329B /* DetailViewController.swift in Sources */,
 				84C9FC6722629B9000D921D6 /* AppDelegate.swift in Sources */,
 				84C9FC7A22629E1200D921D6 /* AccountsTableViewBackgroundView.swift in Sources */,
+				84CAFCAF22BC8C35007694F0 /* FetchRequestOperation.swift in Sources */,
 				8426119E1FCB6ED40086A189 /* HTMLMetadataDownloader.swift in Sources */,
 				849A976E1ED9EBC8007D329B /* TimelineViewController.swift in Sources */,
 				5154368B229404D1005E1CDF /* FaviconGenerator.swift in Sources */,
@@ -2514,6 +2531,7 @@
 				D5E4CC64202C1AC1009B4FFC /* MainWindowController+Scriptability.swift in Sources */,
 				84C9FC7922629E1200D921D6 /* PreferencesWindowController.swift in Sources */,
 				84411E711FE5FBFA004B527F /* SmallIconProvider.swift in Sources */,
+				84CAFCA422BC8C08007694F0 /* FetchRequestQueue.swift in Sources */,
 				844B5B591FE9FE4F00C7C76A /* SidebarKeyboardDelegate.swift in Sources */,
 				84C9FC7C22629E1200D921D6 /* AccountsPreferencesViewController.swift in Sources */,
 				51EC114C2149FE3300B296E3 /* FolderTreeMenu.swift in Sources */,

Shared/SmartFeeds/SearchFeedDelegate.swift

@@ -18,9 +18,11 @@ struct SearchFeedDelegate: SmartFeedDelegate {
 
 	let nameForDisplayPrefix = NSLocalizedString("Search: ", comment: "Search smart feed title prefix")
 	let searchString: String
+	let fetchType: FetchType
 
 	init(searchString: String) {
 		self.searchString = searchString
+		self.fetchType = .search(searchString)
 	}
 
 	func fetchUnreadCount(for: Account, callback: @escaping (Int) -> Void) {
@@ -28,19 +30,3 @@ struct SearchFeedDelegate: SmartFeedDelegate {
 	}
 }
 
-// MARK: - ArticleFetcher
-
-extension SearchFeedDelegate: ArticleFetcher {
-
-	func fetchArticles() -> Set<Article> {
-		var articles = Set<Article>()
-		for account in AccountManager.shared.activeAccounts {
-			articles.formUnion(account.fetchArticlesMatching(searchString))
-		}
-		return articles
-	}
-
-	func fetchUnreadArticles() -> Set<Article> {
-		return fetchArticles().unreadArticles()
-	}
-}

Shared/SmartFeeds/SmartFeed.swift

@@ -11,10 +11,6 @@ import RSCore
 import Articles
 import Account
 
-protocol SmartFeedDelegate: DisplayNameProvider, ArticleFetcher {
-	func fetchUnreadCount(for: Account, callback: @escaping (Int) -> Void)
-}
-
 final class SmartFeed: PseudoFeed {
 
 	var nameForDisplay: String {
@@ -61,9 +57,17 @@ extension SmartFeed: ArticleFetcher {
 		return delegate.fetchArticles()
 	}
 
+	func fetchArticlesAsync(_ callback: @escaping ArticleSetBlock) {
+		delegate.fetchArticlesAsync(callback)
+	}
+
 	func fetchUnreadArticles() -> Set<Article> {
 		return delegate.fetchUnreadArticles()
 	}
+
+	func fetchUnreadArticlesAsync(_ callback: @escaping ArticleSetBlock) {
+		delegate.fetchUnreadArticlesAsync(callback)
+	}
 }
 
 private extension SmartFeed {

Shared/SmartFeeds/SmartFeedDelegate.swift

@@ -0,0 +1,38 @@
+//
+//  SmartFeedDelegate.swift
+//  NetNewsWire
+//
+//  Created by Brent Simmons on 6/25/19.
+//  Copyright © 2019 Ranchero Software. All rights reserved.
+//
+
+import Foundation
+import Account
+import Articles
+import RSCore
+
+protocol SmartFeedDelegate: DisplayNameProvider, ArticleFetcher {
+
+	var fetchType: FetchType { get }
+
+	func fetchUnreadCount(for: Account, callback: @escaping (Int) -> Void)
+}
+
+extension SmartFeedDelegate {
+
+	func fetchArticles() -> Set<Article> {
+		return AccountManager.shared.fetchArticles(fetchType)
+	}
+
+	func fetchArticlesAsync(_ callback: @escaping ArticleSetBlock) {
+		AccountManager.shared.fetchArticlesAsync(fetchType, callback)
+	}
+
+	func fetchUnreadArticles() -> Set<Article> {
+		return fetchArticles().unreadArticles()
+	}
+
+	func fetchUnreadArticlesAsync(_ callback: @escaping ArticleSetBlock) {
+		fetchArticlesAsync{ callback($0.unreadArticles()) }
+	}
+}

Shared/SmartFeeds/StarredFeedDelegate.swift

@@ -10,30 +10,14 @@ import Foundation
 import Articles
 import Account
 
+// Main thread only.
 
 struct StarredFeedDelegate: SmartFeedDelegate {
 
 	let nameForDisplay = NSLocalizedString("Starred", comment: "Starred pseudo-feed title")
+	let fetchType: FetchType = .starred
 
 	func fetchUnreadCount(for account: Account, callback: @escaping (Int) -> Void) {
-
 		account.fetchUnreadCountForStarredArticles(callback)
 	}
-
-	// MARK: ArticleFetcher
-
-	func fetchArticles() -> Set<Article> {
-
-		var articles = Set<Article>()
-		for account in AccountManager.shared.activeAccounts {
-			articles.formUnion(account.fetchStarredArticles())
-		}
-		return articles
-	}
-
-	func fetchUnreadArticles() -> Set<Article> {
-
-		return fetchArticles().unreadArticles()
-	}
-
 }

Shared/SmartFeeds/TodayFeedDelegate.swift

@@ -13,26 +13,10 @@ import Account
 struct TodayFeedDelegate: SmartFeedDelegate {
 
 	let nameForDisplay = NSLocalizedString("Today", comment: "Today pseudo-feed title")
+	let fetchType = FetchType.today
 
 	func fetchUnreadCount(for account: Account, callback: @escaping (Int) -> Void) {
-
 		account.fetchUnreadCountForToday(callback)
 	}
-
-	// MARK: ArticleFetcher
-
-	func fetchArticles() -> Set<Article> {
-
-		var articles = Set<Article>()
-		for account in AccountManager.shared.activeAccounts {
-			articles.formUnion(account.fetchTodayArticles())
-		}
-		return articles
-	}
-
-	func fetchUnreadArticles() -> Set<Article> {
-
-		return fetchArticles().unreadArticles()
-	}
 }
 

Shared/SmartFeeds/UnreadFeed.swift

@@ -19,7 +19,8 @@ import Articles
 final class UnreadFeed: PseudoFeed {
 
 	let nameForDisplay = NSLocalizedString("All Unread", comment: "All Unread pseudo-feed title")
-
+	let fetchType = FetchType.unread
+	
 	var unreadCount = 0 {
 		didSet {
 			if unreadCount != oldValue {
@@ -50,16 +51,18 @@ final class UnreadFeed: PseudoFeed {
 extension UnreadFeed: ArticleFetcher {
 
 	func fetchArticles() -> Set<Article> {
-
 		return fetchUnreadArticles()
 	}
 
-	func fetchUnreadArticles() -> Set<Article> {
+	func fetchArticlesAsync(_ callback: @escaping ArticleSetBlock) {
+		fetchUnreadArticlesAsync(callback)
+	}
 
-		var articles = Set<Article>()
+	func fetchUnreadArticles() -> Set<Article> {
-		for account in AccountManager.shared.activeAccounts {
+		return AccountManager.shared.fetchArticles(fetchType)
-			articles.formUnion(account.fetchUnreadArticles())
+	}
-		}
+
-		return articles
+	func fetchUnreadArticlesAsync(_ callback: @escaping ArticleSetBlock) {
+		AccountManager.shared.fetchArticlesAsync(fetchType, callback)
 	}
 }