Bug 1795312 - Optimize serializing enums as JSON string keys for principals. r=farre

Depends on D166953

Differential Revision: https://phabricator.services.mozilla.com/D166954

caps/BasePrincipal.cpp

@@ -47,6 +47,13 @@
 
 namespace mozilla {
 
+const char* BasePrincipal::JSONEnumKeyStrings[4] = {
+    "0",
+    "1",
+    "2",
+    "3",
+};
+
 BasePrincipal::BasePrincipal(PrincipalKind aKind,
                              const nsACString& aOriginNoSuffix,
                              const OriginAttributes& aOriginAttributes)
@@ -398,8 +405,10 @@ nsresult BasePrincipal::ToJSON(nsACString& aJSON) {
 }
 
 nsresult BasePrincipal::ToJSON(Json::Value& aObject) {
-  std::string key = std::to_string(Kind());
-  nsresult rv = PopulateJSONObject((aObject[key] = Json::objectValue));
+  static_assert(eKindMax < ArrayLength(JSONEnumKeyStrings));
+  nsresult rv = PopulateJSONObject(
+      (aObject[Json::StaticString(JSONEnumKeyStrings[Kind()])] =
+           Json::objectValue));
   NS_ENSURE_SUCCESS(rv, rv);
 
   return NS_OK;
@@ -1588,4 +1597,11 @@ BasePrincipal::Deserializer::Write(nsIObjectOutputStream* aStream) {
   return NS_OK;
 }
 
+/* static */
+void BasePrincipal::SetJSONValue(Json::Value& aObject, const char* aKey,
+                                 const nsCString& aValue) {
+  aObject[Json::StaticString(aKey)] =
+      Json::Value(aValue.BeginReading(), aValue.EndReading());
+}
+
 }  // namespace mozilla

caps/BasePrincipal.h

@@ -342,6 +342,23 @@ class BasePrincipal : public nsJSPrincipals {
     RefPtr<BasePrincipal> mPrincipal;
   };
 
+ private:
+  static const char* JSONEnumKeyStrings[4];
+
+  static void SetJSONValue(Json::Value& aObject, const char* aKey,
+                           const nsCString& aValue);
+
+ protected:
+  template <size_t EnumValue>
+  static inline constexpr const char* JSONEnumKeyString() {
+    static_assert(EnumValue < ArrayLength(JSONEnumKeyStrings));
+    return JSONEnumKeyStrings[EnumValue];
+  }
+  template <size_t EnumValue>
+  static void SetJSONValue(Json::Value& aObject, const nsCString& aValue) {
+    SetJSONValue(aObject, JSONEnumKeyString<EnumValue>(), aValue);
+  }
+
  private:
   static already_AddRefed<BasePrincipal> CreateContentPrincipal(
       nsIURI* aURI, const OriginAttributes& aAttrs,

caps/ContentPrincipal.cpp

@@ -623,7 +623,7 @@ nsresult ContentPrincipal::PopulateJSONObject(Json::Value& aObject) {
   //        Key          ----------------------
   //                                |
   //                              Value
-  aObject[std::to_string(eURI)] = principalURI.get();
+  SetJSONValue<eURI>(aObject, principalURI);
 
   if (GetHasExplicitDomain()) {
     nsAutoCString domainStr;
@@ -632,13 +632,13 @@ nsresult ContentPrincipal::PopulateJSONObject(Json::Value& aObject) {
       rv = mDomain->GetSpec(domainStr);
       NS_ENSURE_SUCCESS(rv, rv);
     }
-    aObject[std::to_string(eDomain)] = domainStr.get();
+    SetJSONValue<eDomain>(aObject, domainStr);
   }
 
   nsAutoCString suffix;
   OriginAttributesRef().CreateSuffix(suffix);
   if (suffix.Length() > 0) {
-    aObject[std::to_string(eSuffix)] = suffix.get();
+    SetJSONValue<eSuffix>(aObject, suffix);
   }
 
   return NS_OK;

caps/ExpandedPrincipal.cpp

@@ -291,8 +291,9 @@ nsresult ExpandedPrincipal::GetSiteIdentifier(SiteIdentifier& aSite) {
 }
 
 nsresult ExpandedPrincipal::PopulateJSONObject(Json::Value& aObject) {
-  Json::Value& principalList = aObject[std::to_string(eSpecs)] =
-      Json::arrayValue;
+  Json::Value& principalList =
+      aObject[Json::StaticString(JSONEnumKeyString<eSpecs>())] =
+          Json::arrayValue;
   for (const auto& principal : mPrincipals) {
     Json::Value object = Json::objectValue;
     nsresult rv = BasePrincipal::Cast(principal)->ToJSON(object);
@@ -304,7 +305,7 @@ nsresult ExpandedPrincipal::PopulateJSONObject(Json::Value& aObject) {
   nsAutoCString suffix;
   OriginAttributesRef().CreateSuffix(suffix);
   if (suffix.Length() > 0) {
-    aObject[std::to_string(eSuffix)] = suffix.get();
+    SetJSONValue<eSuffix>(aObject, suffix);
   }
 
   return NS_OK;

caps/NullPrincipal.cpp

@@ -240,12 +240,12 @@ nsresult NullPrincipal::PopulateJSONObject(Json::Value& aObject) {
   nsAutoCString principalURI;
   nsresult rv = mURI->GetSpec(principalURI);
   NS_ENSURE_SUCCESS(rv, rv);
-  aObject[std::to_string(eSpec)] = principalURI.get();
+  SetJSONValue<eSpec>(aObject, principalURI);
 
   nsAutoCString suffix;
   OriginAttributesRef().CreateSuffix(suffix);
   if (suffix.Length() > 0) {
-    aObject[std::to_string(eSuffix)] = suffix.get();
+    SetJSONValue<eSuffix>(aObject, suffix);
   }
 
   return NS_OK;