Bug 1876589 - Avoid getting and processing preferences for each logging call to ConsoleInstance. r=emilio

This moves handling of the preferences and log value setting into ConsoleInstance, which is where the preferences
are received. It also makes ConsoleInstance add a listener on the preferences service so that updates are triggered.

The functionality is already covered by dom/console/tests/test_jsm.xhtml

Differential Revision: https://phabricator.services.mozilla.com/D199657

browser/base/content/test/performance/browser_preferences_usage.js

@@ -190,16 +190,6 @@ add_task(async function navigate_around() {
     },
   };
 
-  if (Services.prefs.getBoolPref("browser.translations.enable")) {
-    // The translations pref logs the translation decision on each DOMContentLoaded,
-    // and only shows the log by the preferences set in the console.createInstance.
-    // See Bug 1835693. This means that it is invoked on each page load.
-    knownProblematicPrefs["browser.translations.logLevel"] = {
-      min: 50,
-      max: 150,
-    };
-  }
-
   if (SpecialPowers.useRemoteSubframes) {
     // We access this when considering starting a new content process.
     // Because there is no complete list of content process types,

dom/console/Console.cpp

@@ -885,7 +885,7 @@ Console::Console(JSContext* aCx, nsIGlobalObject* aGlobal,
       mInnerID(aInnerWindowID),
       mDumpToStdout(false),
       mChromeInstance(false),
-      mMaxLogLevel(ConsoleLogLevel::All),
+      mCurrentLogLevel(WebIDLLogLevelToInteger(ConsoleLogLevel::All)),
       mStatus(eUnknown),
       mCreationTimeStamp(TimeStamp::Now()) {
   // Let's enable the dumping to stdout by default for chrome.
@@ -2832,43 +2832,8 @@ void Console::ExecuteDumpFunction(const nsAString& aMessage) {
   fflush(stdout);
 }
 
-ConsoleLogLevel PrefToValue(const nsAString& aPref,
-                            const ConsoleLogLevel aLevel) {
-  if (!NS_IsMainThread()) {
-    NS_WARNING("Console.maxLogLevelPref is not supported on workers!");
-    return ConsoleLogLevel::All;
-  }
-  if (aPref.IsEmpty()) {
-    return aLevel;
-  }
-
-  NS_ConvertUTF16toUTF8 pref(aPref);
-  nsAutoCString value;
-  nsresult rv = Preferences::GetCString(pref.get(), value);
-  if (NS_WARN_IF(NS_FAILED(rv))) {
-    return aLevel;
-  }
-
-  int index = FindEnumStringIndexImpl(value.get(), value.Length(),
-                                      ConsoleLogLevelValues::strings);
-  if (NS_WARN_IF(index < 0)) {
-    nsString message;
-    message.AssignLiteral("Invalid Console.maxLogLevelPref value: ");
-    message.Append(NS_ConvertUTF8toUTF16(value));
-
-    nsContentUtils::LogSimpleConsoleError(message, "chrome"_ns, false,
-                                          true /* from chrome context*/);
-    return aLevel;
-  }
-
-  MOZ_ASSERT(index < (int)ConsoleLogLevelValues::Count);
-  return static_cast<ConsoleLogLevel>(index);
-}
-
 bool Console::ShouldProceed(MethodName aName) const {
-  ConsoleLogLevel maxLogLevel = PrefToValue(mMaxLogLevelPref, mMaxLogLevel);
-  return WebIDLLogLevelToInteger(maxLogLevel) <=
-         InternalLogLevelToInteger(aName);
+  return mCurrentLogLevel <= InternalLogLevelToInteger(aName);
 }
 
 uint32_t Console::WebIDLLogLevelToInteger(ConsoleLogLevel aLevel) const {

dom/console/Console.h

@@ -425,8 +425,7 @@ class Console final : public nsIObserver, public nsSupportsWeakReference {
   bool mDumpToStdout;
   nsString mPrefix;
   bool mChromeInstance;
-  ConsoleLogLevel mMaxLogLevel;
-  nsString mMaxLogLevelPref;
+  uint32_t mCurrentLogLevel;
 
   enum { eUnknown, eInitialized, eShuttingDown } mStatus;
 

dom/console/ConsoleInstance.cpp

@@ -44,7 +44,8 @@ ConsoleUtils::Level WebIDLevelToConsoleUtilsLevel(ConsoleLevel aLevel) {
 
 ConsoleInstance::ConsoleInstance(JSContext* aCx,
                                  const ConsoleInstanceOptions& aOptions)
-    : mConsole(new Console(aCx, nullptr, 0, 0)) {
+    : mMaxLogLevel(ConsoleLogLevel::All),
+      mConsole(new Console(aCx, nullptr, 0, 0)) {
   mConsole->mConsoleID = aOptions.mConsoleID;
   mConsole->mPassedInnerID = aOptions.mInnerID;
 
@@ -58,27 +59,81 @@ ConsoleInstance::ConsoleInstance(JSContext* aCx,
   mConsole->mChromeInstance = true;
 
   if (aOptions.mMaxLogLevel.WasPassed()) {
-    mConsole->mMaxLogLevel = aOptions.mMaxLogLevel.Value();
+    mMaxLogLevel = aOptions.mMaxLogLevel.Value();
   }
 
   if (!aOptions.mMaxLogLevelPref.IsEmpty()) {
-    mConsole->mMaxLogLevelPref = aOptions.mMaxLogLevelPref;
-    NS_ConvertUTF16toUTF8 pref(aOptions.mMaxLogLevelPref);
-    nsAutoCString value;
-    nsresult rv = Preferences::GetCString(pref.get(), value);
-    if (NS_WARN_IF(NS_FAILED(rv))) {
-      nsString message;
-      message.AssignLiteral(
-          "Console.maxLogLevelPref used with a non-existing pref: ");
-      message.Append(aOptions.mMaxLogLevelPref);
-
-      nsContentUtils::LogSimpleConsoleError(message, "chrome"_ns, false,
-                                            true /* from chrome context*/);
+    if (!NS_IsMainThread()) {
+      NS_WARNING("Console.maxLogLevelPref is not supported on workers!");
+      // Set the log level based on what we have.
+      SetLogLevel();
+      return;
     }
+
+    CopyUTF16toUTF8(aOptions.mMaxLogLevelPref, mMaxLogLevelPref);
+
+    Preferences::RegisterCallback(MaxLogLevelPrefChangedCallback,
+                                  mMaxLogLevelPref, this);
   }
+  SetLogLevel();
 }
 
-ConsoleInstance::~ConsoleInstance() = default;
+ConsoleInstance::~ConsoleInstance() {
+  AssertIsOnMainThread();
+  if (!mMaxLogLevelPref.IsEmpty()) {
+    Preferences::UnregisterCallback(MaxLogLevelPrefChangedCallback,
+                                    mMaxLogLevelPref, this);
+  }
+};
+
+ConsoleLogLevel PrefToValue(const nsACString& aPref,
+                            const ConsoleLogLevel aLevel) {
+  if (aPref.IsEmpty()) {
+    return aLevel;
+  }
+
+  nsAutoCString value;
+  nsresult rv = Preferences::GetCString(PromiseFlatCString(aPref).get(), value);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    nsString message;
+    message.AssignLiteral(
+        "Console.maxLogLevelPref used with a non-existing pref: ");
+    message.Append(NS_ConvertUTF8toUTF16(aPref));
+
+    nsContentUtils::LogSimpleConsoleError(message, "chrome"_ns, false,
+                                          true /* from chrome context*/);
+    return aLevel;
+  }
+
+  int index = FindEnumStringIndexImpl(value.get(), value.Length(),
+                                      ConsoleLogLevelValues::strings);
+  if (NS_WARN_IF(index < 0)) {
+    nsString message;
+    message.AssignLiteral("Invalid Console.maxLogLevelPref value: ");
+    message.Append(NS_ConvertUTF8toUTF16(value));
+
+    nsContentUtils::LogSimpleConsoleError(message, "chrome"_ns, false,
+                                          true /* from chrome context*/);
+    return aLevel;
+  }
+
+  MOZ_ASSERT(index < (int)ConsoleLogLevelValues::Count);
+  return static_cast<ConsoleLogLevel>(index);
+}
+
+void ConsoleInstance::SetLogLevel() {
+  mConsole->mCurrentLogLevel = mConsole->WebIDLLogLevelToInteger(
+      PrefToValue(mMaxLogLevelPref, mMaxLogLevel));
+}
+
+// static
+void ConsoleInstance::MaxLogLevelPrefChangedCallback(
+    const char* /* aPrefName */, void* aSelf) {
+  AssertIsOnMainThread();
+  if (RefPtr console = static_cast<ConsoleInstance*>(aSelf)) {
+    console->SetLogLevel();
+  }
+}
 
 JSObject* ConsoleInstance::WrapObject(JSContext* aCx,
                                       JS::Handle<JSObject*> aGivenProto) {

dom/console/ConsoleInstance.h

@@ -106,6 +106,12 @@ class ConsoleInstance final : public nsISupports, public nsWrapperCache {
  private:
   ~ConsoleInstance();
 
+  void SetLogLevel();
+  static void MaxLogLevelPrefChangedCallback(const char* /* aPrefName */,
+                                             void* /* aClosure */);
+
+  ConsoleLogLevel mMaxLogLevel;
+  nsCString mMaxLogLevelPref;
   RefPtr<Console> mConsole;
 };
 

dom/console/tests/test_jsm.xhtml

@@ -83,6 +83,9 @@ async function test() {
   await SpecialPowers.pushPrefEnv({set: [["pref.test.console", "log"]]})
   ConsoleTest.go(dumpFunction);
 
+  // ConsoleTest.go() has already tested the console without this preference.
+  // This test checks that the addition of the preference is tracked and
+  // correctly applied.
   await SpecialPowers.pushPrefEnv({
     set: [["pref.test.console.notset", "Log"]],
   });