From a4bbf659442d1d97ea3709a01aa61e46ce169c1c Mon Sep 17 00:00:00 2001
From: Maurice Parker <mo@vincode.io>
Date: Tue, 25 Feb 2020 10:42:56 -0800
Subject: [PATCH] Coalesce unread count backing store rebuilds to prevent feeds
 list flickering while syncing and the feeds filter is engaged.  (Regression)

---
 iOS/SceneCoordinator.swift | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/iOS/SceneCoordinator.swift b/iOS/SceneCoordinator.swift
index 254e63ba9..5df9e65ab 100644
--- a/iOS/SceneCoordinator.swift
+++ b/iOS/SceneCoordinator.swift
@@ -61,6 +61,7 @@ class SceneCoordinator: NSObject, UndoableCommandRunner, UnreadCountProvider {
 	private var wasRootSplitViewControllerCollapsed = false
 	
 	private let fetchAndMergeArticlesQueue = CoalescingQueue(name: "Fetch and Merge Articles", interval: 0.5)
+	private let rebuildBackingStoresWithMergeQueue = CoalescingQueue(name: "Rebuild The Backing Stores by Merging", interval: 0.5)
 	private var fetchSerialNumber = 0
 	private let fetchRequestQueue = FetchRequestQueue()
 	
@@ -445,9 +446,7 @@ class SceneCoordinator: NSObject, UndoableCommandRunner, UnreadCountProvider {
 			return
 		}
 
-		addShadowTableToFilterExceptions()
-		rebuildBackingStores()
-		treeControllerDelegate.resetFilterExceptions()
+		rebuildBackingStoresWithMergeQueue.add(self, #selector(rebuildBackingStoresWithMerge))
 	}
 
 	@objc func statusesDidChange(_ note: Notification) {
@@ -569,6 +568,7 @@ class SceneCoordinator: NSObject, UndoableCommandRunner, UnreadCountProvider {
 	
 	func suspend() {
 		fetchAndMergeArticlesQueue.performCallsImmediately()
+		rebuildBackingStoresWithMergeQueue.performCallsImmediately()
 		fetchRequestQueue.cancelAllRequests()
 	}
 	
@@ -1362,6 +1362,12 @@ private extension SceneCoordinator {
 		}
 	}
 	
+	@objc func rebuildBackingStoresWithMerge() {
+		addShadowTableToFilterExceptions()
+		rebuildBackingStores()
+		treeControllerDelegate.resetFilterExceptions()
+	}
+	
 	func rebuildShadowTable() {
 		shadowTable = [[Node]]()