Bug 1233881 - Support dynamically setting log levels at runtime via prefs. r=froydnj

Adds support for changing log levels at runtime via 'logging.*' preferences.
2015-12-22 15:09:41 -08:00
parent d27a213d1c
commit f0d76384f7
6 changed files with 161 additions and 5 deletions
--- a/xpcom/base/LogModulePrefWatcher.cpp
+++ b/xpcom/base/LogModulePrefWatcher.cpp
@@ -0,0 +1,90 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "LogModulePrefWatcher.h"
+
+#include "mozilla/Logging.h"
+#include "mozilla/Preferences.h"
+#include "nsString.h"
+
+static const char kLoggingPrefPrefix[] = "logging.";
+
+namespace mozilla {
+
+NS_IMPL_ISUPPORTS(LogModulePrefWatcher, nsIObserver)
+
+/**
+ * Loads the log level from the given pref and updates the corresponding
+ * LogModule.
+ */
+void
+LoadPrefValue(const char* aName)
+{
+  LogLevel logLevel = LogLevel::Disabled;
+
+  int32_t prefLevel = 0;
+  nsAutoCString prefStr;
+
+  if (Preferences::GetInt(aName, &prefLevel) == NS_OK) {
+    logLevel = ToLogLevel(prefLevel);
+  } else if (Preferences::GetCString(aName, &prefStr) == NS_OK) {
+    if (prefStr.LowerCaseEqualsLiteral("error")) {
+      logLevel = LogLevel::Error;
+    } else if (prefStr.LowerCaseEqualsLiteral("warning")) {
+      logLevel = LogLevel::Warning;
+    } else if (prefStr.LowerCaseEqualsLiteral("info")) {
+      logLevel = LogLevel::Info;
+    } else if (prefStr.LowerCaseEqualsLiteral("debug")) {
+      logLevel = LogLevel::Debug;
+    } else if (prefStr.LowerCaseEqualsLiteral("verbose")) {
+      logLevel = LogLevel::Verbose;
+    }
+  }
+
+  const char* moduleName = aName + strlen(kLoggingPrefPrefix);
+  LogModule::Get(moduleName)->SetLevel(logLevel);
+}
+
+void
+LoadExistingPrefs()
+{
+  uint32_t count;
+  char** names;
+  nsresult rv = Preferences::GetRootBranch()->
+      GetChildList(kLoggingPrefPrefix, &count, &names);
+  if (NS_SUCCEEDED(rv) && count) {
+    for (size_t i = 0; i < count; i++) {
+      LoadPrefValue(names[i]);
+    }
+    NS_FREE_XPCOM_ALLOCATED_POINTER_ARRAY(count, names);
+  }
+}
+
+LogModulePrefWatcher::LogModulePrefWatcher()
+{
+}
+
+void
+LogModulePrefWatcher::RegisterPrefWatcher()
+{
+  RefPtr<LogModulePrefWatcher> prefWatcher = new LogModulePrefWatcher();
+  Preferences::AddStrongObserver(prefWatcher, kLoggingPrefPrefix);
+  LoadExistingPrefs();
+}
+
+NS_IMETHODIMP
+LogModulePrefWatcher::Observe(nsISupports* aSubject, const char* aTopic,
+                              const char16_t* aData)
+{
+  if (strcmp(NS_PREFBRANCH_PREFCHANGE_TOPIC_ID, aTopic) == 0) {
+    NS_LossyConvertUTF16toASCII prefName(aData);
+    LoadPrefValue(prefName.get());
+  }
+
+  return NS_OK;
+}
+
+} // namespace mozilla