Fix #8060: Increase performance of closing tabs (#8061)

Sources/Brave/Frontend/Browser/BrowserViewController/BrowserViewController+TabManagerDelegate.swift

@@ -377,7 +377,7 @@ extension BrowserViewController: TabManagerDelegate {
           let alert = UIAlertController(title: nil, message: Strings.closeAllTabsPrompt, preferredStyle: .actionSheet)
           let cancelAction = UIAlertAction(title: Strings.CancelString, style: .cancel)
           let closedTabsTitle = String(format: Strings.closeAllTabsTitle, tabManager.tabsForCurrentMode.count)
-          let closeAllAction = UIAlertAction(title: closedTabsTitle, style: .destructive) { _ in
+          let closeAllAction = UIAlertAction(title: closedTabsTitle, style: .destructive) { [unowned self] _ in
             if !privateBrowsingManager.isPrivateBrowsing {
               // Add the tab information to recently closed before removing
               tabManager.addAllTabsToRecentlyClosed()

Sources/Brave/Frontend/Browser/Helpers/ScreenshotHelper.swift

@@ -39,15 +39,15 @@ class ScreenshotHelper {
       // This is for a bug in certain iOS 13 versions, snapshots cannot be taken correctly without this boolean being set
       configuration.afterScreenUpdates = false
 
-      webView.takeSnapshot(with: configuration) { image, error in
+      webView.takeSnapshot(with: configuration) { [weak tab] image, error in
         if let image = image {
-          tab.setScreenshot(image)
+          tab?.setScreenshot(image)
         } else if let error = error {
           Logger.module.error("\(error.localizedDescription)")
-          tab.setScreenshot(nil)
+          tab?.setScreenshot(nil)
         } else {
           Logger.module.error("Cannot snapshot Tab Screenshot - No error description")
-          tab.setScreenshot(nil)
+          tab?.setScreenshot(nil)
         }
       }
     }

Sources/Brave/Frontend/Browser/Tab.swift

@@ -281,7 +281,7 @@ class Tab: NSObject {
   var onPageReadyStateChanged: ((ReadyState.State) -> Void)?
 
   // If this tab has been opened from another, its parent will point to the tab from which it was opened
-  var parent: Tab?
+  weak var parent: Tab?
 
   fileprivate var contentScriptManager = TabContentScriptManager()
   private var userScripts = Set<UserScriptManager.ScriptType>()
@@ -420,6 +420,7 @@ class Tab: NSObject {
     }
 
     // Remove the tab history from saved tabs
+    // To remove history from WebKit, we simply update the session data AFTER calling "clear" above
     SessionTab.update(tabId: id, interactionState: webView.sessionData ?? Data(), title: title, url: webView.url ?? TabManager.ntpInteralURL)
   }
 

Sources/Brave/Frontend/Browser/TabManager.swift

@@ -319,7 +319,9 @@ class TabManager: NSObject {
       _selectedIndex = -1
     }
 
-    preserveScreenshots()
+    if let previousTab = previous {
+      preserveScreenshot(for: previousTab)
+    }
 
     if let t = selectedTab, t.webView == nil {
       selectedTab?.createWebview()
@@ -564,14 +566,14 @@ class TabManager: NSObject {
       tab.webStateDebounceTimer = Timer.scheduledTimer(withTimeInterval: 1.0, repeats: false) { [weak self, weak tab] _ in
         guard let self = self, let tab = tab else { return }
         tab.webStateDebounceTimer?.invalidate()
-        
+
         if state == .complete || state == .loaded || state == .pushstate || state == .popstate || state == .replacestate {
-          
+
           if Preferences.Privacy.privateBrowsingOnly.value || (tab.isPrivate && !Preferences.Privacy.persistentPrivateBrowsing.value) {
             return
           }
-          
-          self.preserveScreenshots()
+
+          self.preserveScreenshot(for: tab)
           self.saveTab(tab)
         }
       }
@@ -907,16 +909,12 @@ class TabManager: NSObject {
     }
   }
 
-  private func preserveScreenshots() {
+  private func preserveScreenshot(for tab: Tab) {
     assert(Thread.isMainThread)
     if isRestoring { return }
-
-    Task { @MainActor in
-      for tab in allTabs {
-        guard let screenshot = tab.screenshot else { continue }
-        SessionTab.updateScreenshot(tabId: tab.id, screenshot: screenshot)
-      }
-    }
+
+    guard let screenshot = tab.screenshot else { return }
+    SessionTab.updateScreenshot(tabId: tab.id, screenshot: screenshot)
   }
 
   @MainActor fileprivate var restoreTabsInternal: Tab? {
@@ -1186,7 +1184,7 @@ extension TabManager: WKNavigationDelegate {
           return
         }
 
-        preserveScreenshots()
+        preserveScreenshot(for: tab)
         saveTab(tab)
       }
     }