Avoid compiling rules every time the extension is loaded if the rules…

… haven't changed

https://bugs.webkit.org/show_bug.cgi?id=265473
rdar://118839289

Reviewed by Timothy Hatcher.

* Source/WebKit/UIProcess/Extensions/Cocoa/WebExtensionContextCocoa.mm:
(WebKit::WebExtensionContext::declarativeNetRequestRuleStore):
(WebKit::computeStringHashForContentBlockerRules): Compute the hash for these content blocker rules, making sure to
append the current version of the rule translator, so when it is updated, rules will be re-compiled.
(WebKit::WebExtensionContext::compileDeclarativeNetRequestRules): Before compiling the rule, perform a lookup and check
the hash.
* Source/WebKit/UIProcess/Extensions/Cocoa/_WKWebExtensionDeclarativeNetRequestRule.mm:
* Source/WebKit/UIProcess/Extensions/WebExtensionContext.h:

Canonical link: https://commits.webkit.org/271248@main

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

@@ -78,10 +78,14 @@
 static NSString * const backgroundContentEventListenersVersionKey = @"BackgroundContentEventListenersVersion";
 static NSString * const lastSeenBaseURLStateKey = @"LastSeenBaseURL";
 static NSString * const lastSeenVersionStateKey = @"LastSeenVersion";
+static NSString * const lastLoadedDNRHashStateKey = @"LastLoadedDNRHash";
 
 // Update this value when any changes are made to the WebExtensionEventListenerType enum.
 static constexpr NSInteger currentBackgroundContentListenerStateVersion = 2;
 
+// Update this value when any changes are made to the rule translation logic in _WKWebExtensionDeclarativeNetRequestRule.
+static constexpr NSInteger currentDeclarativeNetRequestRuleTranslatorVersion = 1;
+
 @interface _WKWebExtensionContextDelegate : NSObject <WKNavigationDelegate, WKUIDelegate> {
     WeakPtr<WebKit::WebExtensionContext> _webExtensionContext;
 }
@@ -2649,14 +2653,14 @@ static _WKWebExtensionContextError toAPI(WebExtensionContext::Error error)
 WKContentRuleListStore *WebExtensionContext::declarativeNetRequestRuleStore()
 {
     if (m_declarativeNetRequestRuleStore)
-        return m_declarativeNetRequestRuleStore;
+        return m_declarativeNetRequestRuleStore.get();
 
     String contentBlockerStorePath = m_extensionController->configuration().declarativeNetRequestStoreDirectory();
     if (contentBlockerStorePath.isEmpty())
         return nil;
 
     m_declarativeNetRequestRuleStore = [WKContentRuleListStore storeWithURL:[NSURL fileURLWithPath:contentBlockerStorePath]];
-    return m_declarativeNetRequestRuleStore;
+    return m_declarativeNetRequestRuleStore.get();
 }
 
 void WebExtensionContext::removeDeclarativeNetRequestRules()
@@ -2683,10 +2687,21 @@ static _WKWebExtensionContextError toAPI(WebExtensionContext::Error error)
     }];
 }
 
-void WebExtensionContext::compileDeclarativeNetRequestRules(NSArray *rulesData)
+static NSString *computeStringHashForContentBlockerRules(NSString *rules)
 {
-    // FIXME: rdar://118839289 - Avoid converting/compiling the rules data every time if the rules haven't changed.
+    SHA1 sha1;
+    sha1.addBytes(String(rules).span8());
+
+    SHA1::Digest digest;
+    sha1.computeHash(digest);
+
+    auto hashAsCString = SHA1::hexDigest(digest);
+    auto hashAsString = String::fromUTF8(hashAsCString);
+    return [hashAsString stringByAppendingString:[NSString stringWithFormat:@"-%zu", currentDeclarativeNetRequestRuleTranslatorVersion]];
+}
 
+void WebExtensionContext::compileDeclarativeNetRequestRules(NSArray *rulesData)
+{
     NSArray<NSString *> *jsonDeserializationErrorStrings;
     auto *allJSONObjects = [_WKWebExtensionDeclarativeNetRequestTranslator jsonObjectsFromData:rulesData errorStrings:&jsonDeserializationErrorStrings];
 
@@ -2697,15 +2712,33 @@ static _WKWebExtensionContextError toAPI(WebExtensionContext::Error error)
     if (!webKitRules)
         return;
 
-    [declarativeNetRequestRuleStore() compileContentRuleListForIdentifier:uniqueIdentifier() encodedContentRuleList:webKitRules completionHandler:^(WKContentRuleList *ruleList, NSError *error) {
-        if (error) {
-            RELEASE_LOG_ERROR(Extensions, "Error compiling declarativeNetRequest rules: %{public}@", privacyPreservingDescription(error));
-            return;
+    auto *previouslyLoadedHash = objectForKey<NSString>(m_state, lastLoadedDNRHashStateKey);
+    auto *hashOfWebKitRules = computeStringHashForContentBlockerRules(webKitRules);
+
+    [declarativeNetRequestRuleStore() lookUpContentRuleListForIdentifier:uniqueIdentifier() completionHandler:^(WKContentRuleList *foundRuleList, NSError *) {
+        if (foundRuleList) {
+            if ([previouslyLoadedHash isEqualToString:hashOfWebKitRules]) {
+                auto userContentControllers = hasAccessInPrivateBrowsing() ? extensionController()->allUserContentControllers() : extensionController()->allNonPrivateUserContentControllers();
+                for (auto& userContentController : userContentControllers)
+                    userContentController.addContentRuleList(*foundRuleList->_contentRuleList, m_baseURL);
+
+                return;
+            }
         }
 
-        auto userContentControllers = hasAccessInPrivateBrowsing() ? extensionController()->allUserContentControllers() : extensionController()->allNonPrivateUserContentControllers();
-        for (auto& userContentController : userContentControllers)
-            userContentController.addContentRuleList(*ruleList->_contentRuleList, m_baseURL);
+        [declarativeNetRequestRuleStore() compileContentRuleListForIdentifier:uniqueIdentifier() encodedContentRuleList:webKitRules completionHandler:^(WKContentRuleList *ruleList, NSError *error) {
+            if (error) {
+                RELEASE_LOG_ERROR(Extensions, "Error compiling declarativeNetRequest rules: %{public}@", privacyPreservingDescription(error));
+                return;
+            }
+
+            [m_state setObject:hashOfWebKitRules forKey:lastLoadedDNRHashStateKey];
+            writeStateToStorage();
+
+            auto userContentControllers = hasAccessInPrivateBrowsing() ? extensionController()->allUserContentControllers() : extensionController()->allNonPrivateUserContentControllers();
+            for (auto& userContentController : userContentControllers)
+                userContentController.addContentRuleList(*ruleList->_contentRuleList, m_baseURL);
+        }];
     }];
 }
 

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

@@ -36,6 +36,8 @@
 #import "WKContentRuleListInternal.h"
 #import "WebExtensionUtilities.h"
 
+// If any changes are made to the rule translation logic here, make sure to increment currentDeclarativeNetRequestRuleTranslatorVersion in WebExtensionContextCocoa.
+
 // Keys in the top level rule dictionary.
 static NSString * const declarativeNetRequestRuleIDKey = @"id";
 static NSString * const declarativeNetRequestRulePriorityKey = @"priority";

Source/WebKit/UIProcess/Extensions/WebExtensionContext.h

@@ -623,7 +623,7 @@ class WebExtensionContext : public API::ObjectImpl<API::Object::Type::WebExtensi
     CommandsVector m_commands;
     bool m_populatedCommands { false };
 
-    WKContentRuleListStore *m_declarativeNetRequestRuleStore;
+    RetainPtr<WKContentRuleListStore> m_declarativeNetRequestRuleStore;
 };
 
 template<typename T>