Improve the performance of logging. (#1142)

src/input_output/FGLog.cpp

@@ -37,6 +37,8 @@ HISTORY
 INCLUDES
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
 
+#include <iostream>
+
 #include "FGLog.h"
 #include "input_output/FGXMLElement.h"
 
@@ -53,10 +55,9 @@ void FGLogging::Flush(void)
   if (!message.empty()) {
     logger->Message(message);
     buffer.str("");
-    logger->Flush();
   }
 
-  buffer.clear();
+  logger->Flush();
 }
 
 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@@ -83,19 +84,22 @@ FGXMLLogging::FGXMLLogging(std::shared_ptr<FGLogger> logger, Element* el, LogLev
 
 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 
-void FGLogConsole::SetLevel(LogLevel level) {
-  FGLogger::SetLevel(level);
+void FGLogConsole::Flush(void) {
   switch (level)
   {
   case LogLevel::BULK:
   case LogLevel::DEBUG:
   case LogLevel::INFO:
-    out.tie(&std::cout);
+    std::cout << buffer.str();
+    std::cout.flush(); // Force the message to be immediately displayed in the console
     break;
   default:
-    out.tie(&std::cerr);
+    std::cerr << buffer.str();
+    std::cerr.flush(); // Force the message to be immediately displayed in the console
     break;
   }
+
+  buffer.str("");
 }
 
 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@@ -104,29 +108,29 @@ void FGLogConsole::Format(LogFormat format) {
   switch (format)
   {
   case LogFormat::RED:
-    out << FGJSBBase::fgred;
+    buffer << FGJSBBase::fgred;
     break;
   case LogFormat::BLUE:
-    out << FGJSBBase::fgblue;
+    buffer << FGJSBBase::fgblue;
     break;
   case LogFormat::BOLD:
-    out << FGJSBBase::highint;
+    buffer << FGJSBBase::highint;
     break;
   case LogFormat::NORMAL:
-    out << FGJSBBase::normint;
+    buffer << FGJSBBase::normint;
     break;
   case LogFormat::UNDERLINE_ON:
-    out << FGJSBBase::underon;
+    buffer << FGJSBBase::underon;
     break;
   case LogFormat::UNDERLINE_OFF:
-    out << FGJSBBase::underoff;
+    buffer << FGJSBBase::underoff;
     break;
   case LogFormat::DEFAULT:
-    out << FGJSBBase::fgdef;
+    buffer << FGJSBBase::fgdef;
     break;
   case LogFormat::RESET:
   default:
-    out << FGJSBBase::reset;
+    buffer << FGJSBBase::reset;
     break;
   }
 }

src/input_output/FGLog.h

@@ -39,7 +39,6 @@ INCLUDES
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
 
 #include <iomanip>
-#include <iostream>
 #include <memory>
 #include <sstream>
 #include <string>
@@ -148,24 +147,18 @@ class JSBSIM_API FGXMLLogging : public FGLogging
 class JSBSIM_API FGLogConsole : public FGLogger
 {
 public:
-  FGLogConsole() : out(std::cout.rdbuf()) {}
-
-  void SetLevel(LogLevel level) override;
   void FileLocation(const std::string& filename, int line) override
-  { out << std::endl << "In file " << filename << ": line" << line << std::endl; }
+  { buffer << std::endl << "In file " << filename << ": line" << line << std::endl; }
   void Format(LogFormat format) override;
-  void Flush(void) override {
-    out.flush();
-    out.clear();
-  }
+  void Flush(void) override;
 
   void Message(const std::string& message) override {
     // if (level < min_level) return;
-    out << message;
+    buffer << message;
   }
 
 private:
-  std::ostream out;
+  std::ostringstream buffer;
 };
 } // namespace JSBSim
 #endif