Cherry-pick 247ec3b. rdar://123959934

    Create a faster cache of _WKWebExtensionTabs
    https://bugs.webkit.org/show_bug.cgi?id=270488
    rdar://123959934

    Reviewed by Timothy Hatcher.

    Instead of iterating over all of the tabs in m_tabMap and checking to see if their delegates match, create a new
    data structure that is a map table from the delegate to the identifier.

    This way, we can just do one O(1) lookup instead of an O(n) iteration.

    * Source/WebKit/UIProcess/Extensions/Cocoa/WebExtensionContextCocoa.mm:
    (WebKit::WebExtensionContext::WebExtensionContext):
    (WebKit::WebExtensionContext::getOrCreateTab const):
    (WebKit::WebExtensionContext::forgetTab const):
    * Source/WebKit/UIProcess/Extensions/WebExtensionContext.h:

    Canonical link: https://commits.webkit.org/275692@main

Source/WebKit/UIProcess/Extensions/Cocoa/WebExtensionContextCocoa.mm

@@ -178,6 +178,7 @@ - (void)webViewWebContentProcessDidTerminate:(WKWebView *)webView
     m_extension = extension.ptr();
     m_baseURL = URL { makeString("webkit-extension://", uniqueIdentifier(), '/') };
     m_delegate = [[_WKWebExtensionContextDelegate alloc] initWithWebExtensionContext:*this];
+    m_tabDelegateToIdentifierMap = [NSMapTable weakToStrongObjectsMapTable];
 }
 
 static _WKWebExtensionContextError toAPI(WebExtensionContext::Error error)
@@ -302,6 +303,7 @@ static _WKWebExtensionContextError toAPI(WebExtensionContext::Error error)
 
     m_tabMap.clear();
     m_extensionPageTabMap.clear();
+    [m_tabDelegateToIdentifierMap removeAllObjects];
 
     m_windowMap.clear();
     m_windowOrderVector.clear();
@@ -1485,13 +1487,18 @@ static _WKWebExtensionContextError toAPI(WebExtensionContext::Error error)
 {
     ASSERT(delegate);
 
-    for (Ref tab : m_tabMap.values()) {
-        if (tab->delegate() == delegate)
-            return tab;
+    if (NSNumber *tabIdentifier = [m_tabDelegateToIdentifierMap objectForKey:delegate]) {
+        if (auto tab = getTab(WebExtensionTabIdentifier(tabIdentifier.unsignedLongLongValue))) {
+            RELEASE_LOG_DEBUG(Extensions, "Using cached tab for identifier %{public}llu", tabIdentifier.unsignedLongLongValue);
+            return tab.releaseNonNull();
+        }
     }
 
     Ref tab = adoptRef(*new WebExtensionTab(*this, delegate));
-    m_tabMap.set(tab->identifier(), tab);
+
+    auto tabIdentifier = tab->identifier();
+    m_tabMap.set(tabIdentifier, tab);
+    [m_tabDelegateToIdentifierMap setObject:@(tabIdentifier.toUInt64()) forKey:delegate];
 
     RELEASE_LOG_DEBUG(Extensions, "Tab %{public}llu was created", tab->identifier().toUInt64());
 
@@ -1602,7 +1609,11 @@ static _WKWebExtensionContextError toAPI(WebExtensionContext::Error error)
 
 void WebExtensionContext::forgetTab(WebExtensionTabIdentifier identifier) const
 {
-    m_tabMap.remove(identifier);
+    RefPtr tab = m_tabMap.take(identifier);
+    if (!tab)
+        return;
+
+    [m_tabDelegateToIdentifierMap removeObjectForKey:tab->delegate()];
 }
 
 void WebExtensionContext::openNewTab(const WebExtensionTabParameters& parameters, CompletionHandler<void(RefPtr<WebExtensionTab>)>&& completionHandler)

Source/WebKit/UIProcess/Extensions/WebExtensionContext.h

@@ -81,7 +81,9 @@
 OBJC_CLASS NSArray;
 OBJC_CLASS NSDate;
 OBJC_CLASS NSDictionary;
+OBJC_CLASS NSMapTable;
 OBJC_CLASS NSMutableDictionary;
+OBJC_CLASS NSNumber;
 OBJC_CLASS NSString;
 OBJC_CLASS NSURL;
 OBJC_CLASS NSUUID;
@@ -875,6 +877,8 @@ class WebExtensionContext : public API::ObjectImpl<API::Object::Type::WebExtensi
     PageTabIdentifierMap m_extensionPageTabMap;
     PopupPageActionMap m_popupPageActionMap;
 
+    RetainPtr<NSMapTable> m_tabDelegateToIdentifierMap;
+
     CommandsVector m_commands;
     bool m_populatedCommands { false };