Blimp: change logger to use switch/case for types.

blimp/common/logging.cc

Index: blimp/common/logging.cc
diff --git a/blimp/common/logging.cc b/blimp/common/logging.cc
index 174c2b4554a1111de459d0fd429f0a662d1d9f7d..b7c861cc565ce93df481ffff04aab2922666428d 100644
--- a/blimp/common/logging.cc
+++ b/blimp/common/logging.cc
@@ -21,8 +21,7 @@
 namespace blimp {
 namespace {
 
-static base::LazyInstance<BlimpMessageLogger> g_logger =
-    LAZY_INSTANCE_INITIALIZER;
+typedef std::vector<std::pair<std::string, std::string>> LogFields;
 
 // The AddField() suite of functions are used to convert KV pairs with
 // arbitrarily typed values into string/string KV pairs for logging.
@@ -69,18 +68,18 @@ void AddField(const std::string& key, const T& value, LogFields* output) {
 // fields from BlimpMessages.
 
 // Logs fields from COMPOSITOR messages.
-class CompositorLogExtractor : public LogExtractor {
-  void ExtractFields(const BlimpMessage& message,
-                     LogFields* output) const override {
+class CompositorLogExtractor {
+ public:
+  static void ExtractFields(const BlimpMessage& message, LogFields* output) {

[Wez, 2016/06/01 21:35:15]

Looks like this, and the other static member methods below, can just become
static LogFooFields functions in this .cc?

[Kevin M, 2016/06/02 18:05:00]

Done.

     AddField("render_widget_id", message.compositor().render_widget_id(),
              output);
   }
 };
 
 // Logs fields from INPUT messages.
-class InputLogExtractor : public LogExtractor {
-  void ExtractFields(const BlimpMessage& message,
-                     LogFields* output) const override {
+class InputLogExtractor {
+ public:
+  static void ExtractFields(const BlimpMessage& message, LogFields* output) {
     AddField("render_widget_id", message.input().render_widget_id(), output);
     AddField("timestamp_seconds", message.input().timestamp_seconds(), output);
     switch (message.input().type()) {
@@ -121,9 +120,9 @@ class InputLogExtractor : public LogExtractor {
 };
 
 // Logs fields from NAVIGATION messages.
-class NavigationLogExtractor : public LogExtractor {
-  void ExtractFields(const BlimpMessage& message,
-                     LogFields* output) const override {
+class NavigationLogExtractor {
+ public:
+  static void ExtractFields(const BlimpMessage& message, LogFields* output) {
     switch (message.navigation().type()) {
       case NavigationMessage::NAVIGATION_STATE_CHANGED:
         AddField("subtype", "NAVIGATION_STATE_CHANGED", output);
@@ -168,9 +167,9 @@ class NavigationLogExtractor : public LogExtractor {
 };
 
 // Logs fields from PROTOCOL_CONTROL messages.
-class ProtocolControlLogExtractor : public LogExtractor {
-  void ExtractFields(const BlimpMessage& message,
-                     LogFields* output) const override {
+class ProtocolControlLogExtractor {
+ public:
+  static void ExtractFields(const BlimpMessage& message, LogFields* output) {
     switch (message.protocol_control().connection_message_case()) {
       case ProtocolControlMessage::kStartConnection:
         AddField("subtype", "START_CONNECTION", output);
@@ -195,9 +194,9 @@ class ProtocolControlLogExtractor : public LogExtractor {
 };
 
 // Logs fields from RENDER_WIDGET messages.
-class RenderWidgetLogExtractor : public LogExtractor {
-  void ExtractFields(const BlimpMessage& message,
-                     LogFields* output) const override {
+class RenderWidgetLogExtractor {
+ public:
+  static void ExtractFields(const BlimpMessage& message, LogFields* output) {
     switch (message.render_widget().type()) {
       case RenderWidgetMessage::INITIALIZE:
         AddField("subtype", "INITIALIZE", output);
@@ -215,9 +214,9 @@ class RenderWidgetLogExtractor : public LogExtractor {
 };
 
 // Logs fields from SETTINGS messages.
-class SettingsLogExtractor : public LogExtractor {
-  void ExtractFields(const BlimpMessage& message,
-                     LogFields* output) const override {
+class SettingsLogExtractor {
+ public:
+  static void ExtractFields(const BlimpMessage& message, LogFields* output) {
     if (message.settings().has_engine_settings()) {
       const EngineSettingsMessage& engine_settings =
           message.settings().engine_settings();
@@ -230,9 +229,9 @@ class SettingsLogExtractor : public LogExtractor {
 };
 
 // Logs fields from TAB_CONTROL messages.
-class TabControlLogExtractor : public LogExtractor {
-  void ExtractFields(const BlimpMessage& message,
-                     LogFields* output) const override {
+class TabControlLogExtractor {
+ public:
+  static void ExtractFields(const BlimpMessage& message, LogFields* output) {
     switch (message.tab_control().tab_control_case()) {
       case TabControlMessage::kCreateTab:
         AddField("subtype", "CREATE_TAB", output);
@@ -251,9 +250,9 @@ class TabControlLogExtractor : public LogExtractor {
 };
 
 // Logs fields from BLOB_CHANNEL messages.
-class BlobChannelLogExtractor : public LogExtractor {
-  void ExtractFields(const BlimpMessage& message,
-                     LogFields* output) const override {
+class BlobChannelLogExtractor {
+ public:
+  static void ExtractFields(const BlimpMessage& message, LogFields* output) {
     switch (message.blob_channel().type_case()) {
       case BlobChannelMessage::TypeCase::kTransferBlob:
         AddField("subtype", "TRANSFER_BLOB", output);
@@ -272,57 +271,48 @@ class BlobChannelLogExtractor : public LogExtractor {
   }
 };
 
-// No fields are extracted from |message|.
-class NullLogExtractor : public LogExtractor {
-  void ExtractFields(const BlimpMessage& message,
-                     LogFields* output) const override {}
-};
-
-}  // namespace
-
-BlimpMessageLogger::BlimpMessageLogger() {
-  AddHandler("COMPOSITOR", BlimpMessage::kCompositor,
-             base::WrapUnique(new CompositorLogExtractor));
-  AddHandler("INPUT", BlimpMessage::kInput,
-             base::WrapUnique(new InputLogExtractor));
-  AddHandler("NAVIGATION", BlimpMessage::kNavigation,
-             base::WrapUnique(new NavigationLogExtractor));
-  AddHandler("PROTOCOL_CONTROL", BlimpMessage::kProtocolControl,
-             base::WrapUnique(new ProtocolControlLogExtractor));
-  AddHandler("RENDER_WIDGET", BlimpMessage::kRenderWidget,
-             base::WrapUnique(new RenderWidgetLogExtractor));
-  AddHandler("SETTINGS", BlimpMessage::kSettings,
-             base::WrapUnique(new SettingsLogExtractor));
-  AddHandler("TAB_CONTROL", BlimpMessage::kTabControl,
-             base::WrapUnique(new TabControlLogExtractor));
-  AddHandler("BLOB_CHANNEL", BlimpMessage::kBlobChannel,
-             base::WrapUnique(new BlobChannelLogExtractor));
-}
-
-BlimpMessageLogger::~BlimpMessageLogger() {}
-
-void BlimpMessageLogger::AddHandler(const std::string& feature_name,
-                                    BlimpMessage::FeatureCase feature_case,
-                                    std::unique_ptr<LogExtractor> extractor) {
-  DCHECK(extractors_.find(feature_case) == extractors_.end());
-  DCHECK(!feature_name.empty());
-  extractors_[feature_case] = make_pair(feature_name, std::move(extractor));
-}
-
-void BlimpMessageLogger::LogMessageToStream(const BlimpMessage& message,
-                                            std::ostream* out) const {
+void LogMessageToStream(const BlimpMessage& message, std::ostream* out) {
   LogFields fields;
 
-  auto extractor = extractors_.find(message.feature_case());
-  if (extractor != extractors_.end()) {
-    // An extractor is registered for |message|.
-    // Add the human-readable name of |message.type|.
-    fields.push_back(make_pair("type", extractor->second.first));
-    extractor->second.second->ExtractFields(message, &fields);
-  } else {
-    // Don't know the human-readable name of |message.type|.
-    // Just represent it using its numeric form instead.
-    AddField("type", message.feature_case(), &fields);
+  switch (message.feature_case()) {
+    case BlimpMessage::kCompositor:
+      fields.push_back(std::make_pair("type", "COMPOSITOR"));
+      CompositorLogExtractor::ExtractFields(message, &fields);
+      break;
+    case BlimpMessage::kInput:
+      fields.push_back(std::make_pair("type", "INPUT"));
+      InputLogExtractor::ExtractFields(message, &fields);
+      break;
+    case BlimpMessage::kNavigation:
+      fields.push_back(std::make_pair("type", "NAVIGATION"));
+      NavigationLogExtractor::ExtractFields(message, &fields);
+      break;
+    case BlimpMessage::kProtocolControl:
+      fields.push_back(std::make_pair("type", "PROTOCOL_CONTROL"));
+      ProtocolControlLogExtractor::ExtractFields(message, &fields);
+      break;
+    case BlimpMessage::kRenderWidget:
+      fields.push_back(std::make_pair("type", "RENDER_WIDGET"));
+      RenderWidgetLogExtractor::ExtractFields(message, &fields);
+      break;
+    case BlimpMessage::kSettings:
+      fields.push_back(std::make_pair("type", "SETTINGS"));
+      SettingsLogExtractor::ExtractFields(message, &fields);
+      break;
+    case BlimpMessage::kTabControl:
+      fields.push_back(std::make_pair("type", "TAB_CONTROL"));
+      TabControlLogExtractor::ExtractFields(message, &fields);
+      break;
+    case BlimpMessage::kBlobChannel:
+      fields.push_back(std::make_pair("type", "BLOB_CHANNEL"));
+      BlobChannelLogExtractor::ExtractFields(message, &fields);
+      break;
+    case BlimpMessage::kIme:
+      fields.push_back(std::make_pair("type", "IME"));
+      break;
+    case BlimpMessage::FEATURE_NOT_SET:
+      fields.push_back(std::make_pair("type", "<UNKNOWN>"));
+      break;
   }
 
   // Append "target_tab_id" (if present) and "byte_size" to the field set.
@@ -341,8 +331,10 @@ void BlimpMessageLogger::LogMessageToStream(const BlimpMessage& message,
   *out << ">";
 }
 
+}  // namespace
+
 std::ostream& operator<<(std::ostream& out, const BlimpMessage& message) {
-  g_logger.Get().LogMessageToStream(message, &out);
+  LogMessageToStream(message, &out);
   return out;
 }