diff --git a/ChangeLog b/ChangeLog
index f741687c..c88e9076 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,15 @@
+2009-07-18  Tatsuhiro Tsujikawa  <t-tujikawa@users.sourceforge.net>
+
+	Rewritten Logger to avoiding constly virtual call.
+	* src/LogFactory.cc
+	* src/LogFactory.h
+	* src/Logger.h
+	* src/Makefile.am
+	* src/Makefile.in
+	* src/NullLogger.h: Removed.
+	* src/SimpleLogger.cc
+	* src/SimpleLogger.h
+
 2009-07-17  Tatsuhiro Tsujikawa  <t-tujikawa@users.sourceforge.net>
 
 	Updated doc
diff --git a/src/LogFactory.cc b/src/LogFactory.cc
index aacbb43b..13f104b7 100644
--- a/src/LogFactory.cc
+++ b/src/LogFactory.cc
@@ -36,7 +36,6 @@
 #include "SimpleLogger.h"
 #include "a2io.h"
 #include "prefs.h"
-#include <cstring>
 
 namespace aria2 {
 
@@ -46,7 +45,7 @@ bool LogFactory::_consoleOutput = true;
 Logger::LEVEL LogFactory::_logLevel = Logger::DEBUG;
 
 Logger* LogFactory::getInstance() {
-  if(logger == NULL) {
+  if(!logger) {
     SimpleLogger* slogger = new SimpleLogger();
     if(filename != DEV_NULL) {
       // don't open file DEV_NULL for performance sake.
@@ -55,9 +54,9 @@ Logger* LogFactory::getInstance() {
     }
     slogger->setLogLevel(_logLevel);
     if(_consoleOutput) {
-      slogger->setStdout(Logger::NOTICE, true);
-      slogger->setStdout(Logger::WARN, true);
-      slogger->setStdout(Logger::ERROR, true);
+      slogger->setStdoutLogLevel(Logger::NOTICE, true);
+      slogger->setStdoutLogLevel(Logger::WARN, true);
+      slogger->setStdoutLogLevel(Logger::ERROR, true);
     }
     logger = slogger;
   }
diff --git a/src/LogFactory.h b/src/LogFactory.h
index 7ebfb037..cb71eaeb 100644
--- a/src/LogFactory.h
+++ b/src/LogFactory.h
@@ -36,9 +36,11 @@
 #define _D_LOG_FACTORY_H_
 
 #include "common.h"
-#include "Logger.h"
+
 #include <string>
 
+#include "Logger.h"
+
 namespace aria2 {
 
 class LogFactory {
diff --git a/src/Logger.h b/src/Logger.h
index 7119df59..fe141ffd 100644
--- a/src/Logger.h
+++ b/src/Logger.h
@@ -37,24 +37,17 @@
 
 #include "common.h"
 
+#include <cstdarg>
+#include <string>
+#include <fstream>
+#include <iostream>
+
 namespace aria2 {
 
 class Exception;
 
 class Logger {
 public:
-  virtual ~Logger() {}
-  virtual void debug(const char* msg, ...) = 0;
-  virtual void debug(const char* msg, const Exception& ex, ...) = 0;
-  virtual void info(const char* msg, ...) = 0;
-  virtual void info(const char* msg, const Exception& ex, ...) = 0;
-  virtual void notice(const char* msg, ...) = 0;
-  virtual void notice(const char* msg, const Exception& ex, ...) = 0;
-  virtual void warn(const char* msg, ...) = 0;
-  virtual void warn(const char* msg, const Exception& ex, ...) = 0;
-  virtual void error(const char*  msg, ...) = 0;
-  virtual void error(const char* msg, const Exception& ex, ...) = 0;
-
   enum LEVEL {
     DEBUG  = 1 << 0,
     INFO   = 1 << 1,
@@ -63,7 +56,137 @@ public:
     ERROR  = 1 << 4,
   };
 
-  virtual void setLogLevel(LEVEL level) = 0;
+  static const std::string DEBUG_LABEL;
+
+  static const std::string NOTICE_LABEL;
+
+  static const std::string WARN_LABEL;
+
+  static const std::string ERROR_LABEL;
+
+  static const std::string INFO_LABEL;
+private:
+  LEVEL _logLevel;
+
+  std::ofstream _file;
+
+  int _stdoutField;
+protected:
+  virtual void writeLog
+  (std::ostream& o, LEVEL logLevel, const std::string& logLevelLabel,
+   const char* msg, va_list ap) = 0;
+
+  virtual void writeStackTrace
+  (std::ostream& o, LEVEL logLevel, const std::string& logLevelLabel,
+   const Exception& ex) = 0;
+public:
+  Logger();
+
+  virtual ~Logger();
+
+#define WRITE_LOG(LEVEL, LEVEL_LABEL, MSG)				\
+  if(LEVEL >= _logLevel && _file.is_open()) {				\
+    va_list ap;								\
+    va_start(ap, MSG);							\
+    writeLog(_file, LEVEL, LEVEL_LABEL, MSG, ap);			\
+    va_end(ap);								\
+    _file << std::flush;						\
+  }									\
+  if(_stdoutField&LEVEL) {						\
+    std::cout << "\n";							\
+    va_list ap;								\
+    va_start(ap, MSG);							\
+    writeLog(std::cout, LEVEL, LEVEL_LABEL, MSG, ap);			\
+    va_end(ap);								\
+    std::cout << std::flush;						\
+  }									\
+
+#define WRITE_LOG_EX(LEVEL, LEVEL_LABEL, MSG, EX)			\
+  if(LEVEL >= _logLevel && _file.is_open()) {				\
+    va_list ap;								\
+    va_start(ap, EX);							\
+    writeLog(_file, LEVEL, LEVEL_LABEL, MSG, ap);			\
+    va_end(ap);								\
+    writeStackTrace(_file, LEVEL, LEVEL_LABEL, EX);			\
+    _file << std::flush;						\
+  }									\
+  if(_stdoutField&LEVEL) {						\
+    std::cout << "\n";							\
+    va_list ap;								\
+    va_start(ap, EX);							\
+    writeLog(std::cout, LEVEL, LEVEL_LABEL, MSG, ap);			\
+    va_end(ap);								\
+    writeStackTrace(std::cout, LEVEL, LEVEL_LABEL, EX);			\
+    std::cout << std::flush;						\
+  }									\
+
+  void debug(const char* msg, ...)
+  {
+    WRITE_LOG(DEBUG, DEBUG_LABEL, msg);
+  }
+
+  void debug(const char* msg, const Exception& ex, ...)
+  {
+    WRITE_LOG_EX(DEBUG, DEBUG_LABEL, msg, ex);
+  }
+
+  void info(const char* msg, ...)
+  {
+    WRITE_LOG(INFO, INFO_LABEL, msg);
+  }
+
+  void info(const char* msg, const Exception& ex, ...)
+  {
+    WRITE_LOG_EX(INFO, INFO_LABEL, msg, ex);
+  }
+
+  void notice(const char* msg, ...)
+  {
+    WRITE_LOG(NOTICE, NOTICE_LABEL, msg);
+  }
+
+  void notice(const char* msg, const Exception& ex, ...)
+  {
+    WRITE_LOG_EX(NOTICE, NOTICE_LABEL, msg, ex);
+  }
+
+  void warn(const char* msg, ...)
+  {
+    WRITE_LOG(WARN, WARN_LABEL, msg);
+  }
+
+  void warn(const char* msg, const Exception& ex, ...)
+  {
+    WRITE_LOG_EX(WARN, WARN_LABEL, msg, ex);
+  }
+
+  void error(const char*  msg, ...)
+  {
+    WRITE_LOG(ERROR, ERROR_LABEL, msg);
+  }
+
+  void error(const char* msg, const Exception& ex, ...)
+  {
+    WRITE_LOG_EX(ERROR, ERROR_LABEL, msg, ex);
+  }
+
+  void openFile(const std::string& filename);
+
+  void closeFile();
+
+  void setLogLevel(LEVEL level)
+  {
+    _logLevel = level;
+  }
+
+  void setStdoutLogLevel(Logger::LEVEL level, bool enabled)
+  {
+    if(enabled) {
+      _stdoutField |= level;
+    } else {
+      _stdoutField &= ~level;
+    }
+  }
 };
 
 } // namespace aria2
diff --git a/src/Makefile.am b/src/Makefile.am
index 993e9331..b84623ac 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -40,7 +40,7 @@ SRCS =  Socket.h\
 	DlAbortEx.h\
 	DlRetryEx.h\
 	DownloadFailureException.h\
-	Logger.h\
+	Logger.cc Logger.h\
 	SimpleLogger.cc SimpleLogger.h\
 	DiskWriter.h\
 	DiskWriterFactory.h\
@@ -51,7 +51,6 @@ SRCS =  Socket.h\
 	Option.cc Option.h\
 	Base64.cc Base64.h\
 	LogFactory.cc LogFactory.h\
-	NullLogger.h\
 	TimeA2.cc TimeA2.h\
 	SharedHandle.h\
 	HandleRegistry.h\
diff --git a/src/Makefile.in b/src/Makefile.in
index 00806a3a..af944299 100644
--- a/src/Makefile.in
+++ b/src/Makefile.in
@@ -329,13 +329,13 @@ am__libaria2c_a_SOURCES_DIST = Socket.h SocketCore.cc SocketCore.h \
 	SegmentMan.h Util.cc Util.h Request.cc Request.h common.h \
 	message.h Exception.cc Exception.h FatalException.h \
 	RecoverableException.h DlAbortEx.h DlRetryEx.h \
-	DownloadFailureException.h Logger.h SimpleLogger.cc \
+	DownloadFailureException.h Logger.cc Logger.h SimpleLogger.cc \
 	SimpleLogger.h DiskWriter.h DiskWriterFactory.h \
 	AbstractDiskWriter.cc AbstractDiskWriter.h \
 	DefaultDiskWriter.cc DefaultDiskWriter.h \
 	DefaultDiskWriterFactory.cc DefaultDiskWriterFactory.h File.cc \
 	File.h Option.cc Option.h Base64.cc Base64.h LogFactory.cc \
-	LogFactory.h NullLogger.h TimeA2.cc TimeA2.h SharedHandle.h \
+	LogFactory.h TimeA2.cc TimeA2.h SharedHandle.h \
 	HandleRegistry.h FeatureConfig.cc FeatureConfig.h \
 	DownloadEngineFactory.cc DownloadEngineFactory.h SpeedCalc.cc \
 	SpeedCalc.h PeerStat.h BitfieldMan.cc BitfieldMan.h \
@@ -787,11 +787,11 @@ am__objects_26 = SocketCore.$(OBJEXT) Command.$(OBJEXT) \
 	FtpTunnelResponseCommand.$(OBJEXT) SleepCommand.$(OBJEXT) \
 	DownloadEngine.$(OBJEXT) GrowSegment.$(OBJEXT) \
 	PiecedSegment.$(OBJEXT) SegmentMan.$(OBJEXT) Util.$(OBJEXT) \
-	Request.$(OBJEXT) Exception.$(OBJEXT) SimpleLogger.$(OBJEXT) \
-	AbstractDiskWriter.$(OBJEXT) DefaultDiskWriter.$(OBJEXT) \
-	DefaultDiskWriterFactory.$(OBJEXT) File.$(OBJEXT) \
-	Option.$(OBJEXT) Base64.$(OBJEXT) LogFactory.$(OBJEXT) \
-	TimeA2.$(OBJEXT) FeatureConfig.$(OBJEXT) \
+	Request.$(OBJEXT) Exception.$(OBJEXT) Logger.$(OBJEXT) \
+	SimpleLogger.$(OBJEXT) AbstractDiskWriter.$(OBJEXT) \
+	DefaultDiskWriter.$(OBJEXT) DefaultDiskWriterFactory.$(OBJEXT) \
+	File.$(OBJEXT) Option.$(OBJEXT) Base64.$(OBJEXT) \
+	LogFactory.$(OBJEXT) TimeA2.$(OBJEXT) FeatureConfig.$(OBJEXT) \
 	DownloadEngineFactory.$(OBJEXT) SpeedCalc.$(OBJEXT) \
 	BitfieldMan.$(OBJEXT) BitfieldManFactory.$(OBJEXT) \
 	SimpleRandomizer.$(OBJEXT) HttpResponse.$(OBJEXT) \
@@ -1085,13 +1085,13 @@ SRCS = Socket.h SocketCore.cc SocketCore.h BinaryStream.h Command.cc \
 	SegmentMan.h Util.cc Util.h Request.cc Request.h common.h \
 	message.h Exception.cc Exception.h FatalException.h \
 	RecoverableException.h DlAbortEx.h DlRetryEx.h \
-	DownloadFailureException.h Logger.h SimpleLogger.cc \
+	DownloadFailureException.h Logger.cc Logger.h SimpleLogger.cc \
 	SimpleLogger.h DiskWriter.h DiskWriterFactory.h \
 	AbstractDiskWriter.cc AbstractDiskWriter.h \
 	DefaultDiskWriter.cc DefaultDiskWriter.h \
 	DefaultDiskWriterFactory.cc DefaultDiskWriterFactory.h File.cc \
 	File.h Option.cc Option.h Base64.cc Base64.h LogFactory.cc \
-	LogFactory.h NullLogger.h TimeA2.cc TimeA2.h SharedHandle.h \
+	LogFactory.h TimeA2.cc TimeA2.h SharedHandle.h \
 	HandleRegistry.h FeatureConfig.cc FeatureConfig.h \
 	DownloadEngineFactory.cc DownloadEngineFactory.h SpeedCalc.cc \
 	SpeedCalc.h PeerStat.h BitfieldMan.cc BitfieldMan.h \
@@ -1469,6 +1469,7 @@ distclean-compile:
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/LibgnutlsTLSContext.Po@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/LibsslTLSContext.Po@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/LogFactory.Po@am__quote@
+@AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/Logger.Po@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/LongestSequencePieceSelector.Po@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/MSEHandshake.Po@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/MemoryBufferPreDownloadHandler.Po@am__quote@
diff --git a/src/NullLogger.h b/src/NullLogger.h
deleted file mode 100644
index d113d2f8..00000000
--- a/src/NullLogger.h
+++ /dev/null
@@ -1,56 +0,0 @@
-/* <!-- copyright */
-/*
- * aria2 - The high speed download utility
- *
- * Copyright (C) 2006 Tatsuhiro Tsujikawa
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
- *
- * In addition, as a special exception, the copyright holders give
- * permission to link the code of portions of this program with the
- * OpenSSL library under certain conditions as described in each
- * individual source file, and distribute linked combinations
- * including the two.
- * You must obey the GNU General Public License in all respects
- * for all of the code used other than OpenSSL.  If you modify
- * file(s) with this exception, you may extend this exception to your
- * version of the file(s), but you are not obligated to do so.  If you
- * do not wish to do so, delete this exception statement from your
- * version.  If you delete this exception statement from all source
- * files in the program, then also delete it here.
- */
-/* copyright --> */
-#ifndef _D_NULL_LOGGER_H_
-#define _D_NULL_LOGGER_H_
-
-#include "Logger.h"
-
-class NullLogger : public Logger {
-public:
-  NullLogger() {}
-  virtual ~NullLogger() {}
-  virtual void debug(const char* msg, ...) const {}
-  virtual void debug(const char* msg, Exception& ex, ...) const {}
-  virtual void info(const char* msg, ...) const {}
-  virtual void info(const char* msg, Exception& ex, ...) const {}
-  virtual void notice(const char* msg, ...) const {}
-  virtual void notice(const char* msg, Exception& ex, ...) const {}
-  virtual void warn(const char* msg, ...) const {}
-  virtual void warn(const char* msg, Exception& ex, ...) const {}
-  virtual void error(const char*  msg, ...) const {}
-  virtual void error(const char* msg, Exception& ex, ...) const {}
-};
-
-#endif // _D_NULL_LOGGER_H_
diff --git a/src/SimpleLogger.cc b/src/SimpleLogger.cc
index 0a16d344..c3be2526 100644
--- a/src/SimpleLogger.cc
+++ b/src/SimpleLogger.cc
@@ -33,116 +33,27 @@
  */
 /* copyright --> */
 #include "SimpleLogger.h"
-#include "Util.h"
-#include "DlAbortEx.h"
-#include "message.h"
-#include "a2io.h"
-#include "a2time.h"
-#include "StringFormat.h"
-#include "A2STR.h"
-#include <cerrno>
-#include <cstring>
-#include <iostream>
-#include <cstdlib>
+
 #include <cassert>
 
+#include "Util.h"
+#include "a2time.h"
+#include "A2STR.h"
+#include "StringFormat.h"
+#include "Exception.h"
+
 namespace aria2 {
 
-#if !defined(va_copy)
-# if defined(__va_copy)
-#  define va_copy(dest, src) __va_copy(dest, src)
-# else
-#  define va_copy(dest, src) (dest = src)
-# endif
-#endif
-
-#define WRITE_LOG(LEVEL, MSG)						\
-  if(LEVEL >= _logLevel && (stdoutField&LEVEL || file.is_open())) {	\
-    va_list ap;								\
-    va_start(ap, MSG);							\
-    writeFile(LEVEL, MSG, ap);						\
-    flush();								\
-    va_end(ap);								\
-  }
-
-#define WRITE_LOG_EX(LEVEL, MSG, EX)					\
-  if(LEVEL >= _logLevel && (stdoutField&LEVEL || file.is_open())) {	\
-    va_list ap;								\
-    va_start(ap, EX);							\
-    writeFile(LEVEL, MSG, ap);						\
-    writeStackTrace(LEVEL, EX);						\
-    flush();								\
-    va_end(ap);								\
-}
-
-const std::string SimpleLogger::DEBUG("DEBUG");
-
-const std::string SimpleLogger::NOTICE("NOTICE");
-
-const std::string SimpleLogger::WARN("WARN");
-
-const std::string SimpleLogger::ERROR("ERROR");
-
-const std::string SimpleLogger::INFO("INFO");
-
-SimpleLogger::SimpleLogger():stdoutField(0), _logLevel(Logger::DEBUG) {}
-
-SimpleLogger::~SimpleLogger() {
-  closeFile();
-}
-
-void SimpleLogger::openFile(const std::string& filename) {
-  file.open(filename.c_str(), std::ios::app|std::ios::binary);
-  if(!file) {
-    throw DL_ABORT_EX
-      (StringFormat(EX_FILE_OPEN, filename.c_str(), strerror(errno)).str());
-  }
-}
-
-void SimpleLogger::closeFile() {
-  if(file.is_open()) {
-    file.close();
-  }
-}
-
-void SimpleLogger::setStdout(Logger::LEVEL level, bool enabled) {
-  if(enabled) {
-    stdoutField |= level;
-  } else {
-    stdoutField &= ~level;
-  }
-}
-
-void SimpleLogger::writeHeader(std::ostream& o, const std::string& date,
-			       const std::string& level)
+static void writeHeader
+(std::ostream& o, const std::string& date, const std::string& logLevelLabel)
 {
-  o << StringFormat("%s %s - ", date.c_str(), level.c_str());
+  o << StringFormat("%s %s - ", date.c_str(), logLevelLabel.c_str());
 }
 
-void SimpleLogger::writeLog(std::ostream& o, Logger::LEVEL level,
-			    const char* msg, va_list ap,
-			    bool printHeader)
+void SimpleLogger::writeLog
+(std::ostream& o, Logger::LEVEL level, const std::string& logLevelLabel,
+ const char* msg, va_list ap)
 {
-  va_list apCopy;
-  va_copy(apCopy, ap);
-  std::string levelStr;
-  switch(level) {
-  case Logger::DEBUG:
-    levelStr = DEBUG;
-    break;
-  case Logger::NOTICE:
-    levelStr = NOTICE;
-    break;
-  case Logger::WARN:
-    levelStr = WARN;
-    break;
-  case Logger::ERROR:
-    levelStr = ERROR;
-    break;
-  case Logger::INFO:
-  default:
-    levelStr = INFO;
-  }
   struct timeval tv;
   gettimeofday(&tv, 0);
   char datestr[27]; // 'YYYY-MM-DD hh:mm:ss.uuuuuu'+'\0' = 27 bytes
@@ -155,88 +66,24 @@ void SimpleLogger::writeLog(std::ostream& o, Logger::LEVEL level,
   assert(dateLength <= (size_t)20);
   snprintf(datestr+dateLength, sizeof(datestr)-dateLength,
 	   ".%06ld", tv.tv_usec);
-
-  // TODO a quick hack not to print header in console
-  if(printHeader) {
-    writeHeader(o, datestr, levelStr);
-  }
+  writeHeader(o, datestr, logLevelLabel);
   {
     char buf[1024];
-    if(vsnprintf(buf, sizeof(buf), std::string(Util::replace(msg, A2STR::CR_C, A2STR::NIL)+A2STR::LF_C).c_str(), apCopy) < 0) {
+    std::string body = Util::replace(msg, A2STR::CR_C, A2STR::NIL);
+    body += A2STR::LF_C;
+    if(vsnprintf(buf, sizeof(buf), body.c_str(), ap) < 0) {
       o << "SimpleLogger error, failed to format message.\n";
     } else {
       o << buf;
     }
   }
-  va_end(apCopy);
 }
 
-void SimpleLogger::writeFile(Logger::LEVEL level, const char* msg, va_list ap)
+void SimpleLogger::writeStackTrace
+(std::ostream& o, Logger::LEVEL level, const std::string& logLevelLabel,
+ const Exception& e)
 {
-  writeLog(file, level, msg, ap);
-  if(stdoutField&level) {
-    std::cout << "\n";
-    writeLog(std::cout, level, msg, ap);
-  }
-}
-
-void SimpleLogger::writeStackTrace(Logger::LEVEL level, const Exception& e)
-{
-  file << e.stackTrace();
-  if(stdoutField&level) {
-    std::cout << e.stackTrace();
-  }
-}
-
-void SimpleLogger::flush()
-{
-  file << std::flush;
-  std::cout << std::flush;
-}
-
-void SimpleLogger::debug(const char* msg, ...) {
-  WRITE_LOG(Logger::DEBUG, msg);
-}
-
-void SimpleLogger::debug(const char* msg, const Exception& e, ...) {
-  WRITE_LOG_EX(Logger::DEBUG, msg, e);
-}
-
-void SimpleLogger::info(const char* msg, ...) {
-  WRITE_LOG(Logger::INFO, msg);
-}
-
-void SimpleLogger::info(const char* msg, const Exception& e, ...) {
-  WRITE_LOG_EX(Logger::INFO, msg, e);
-}
-
-void SimpleLogger::notice(const char* msg, ...) {
-  WRITE_LOG(Logger::NOTICE, msg);
-}
-
-void SimpleLogger::notice(const char* msg, const Exception& e, ...) {
-  WRITE_LOG_EX(Logger::INFO, msg, e);
-}
-
-void SimpleLogger::warn(const char* msg, ...) {
-  WRITE_LOG(Logger::WARN, msg);
-}
-
-void SimpleLogger::warn(const char* msg, const Exception& e, ...) {
-  WRITE_LOG_EX(Logger::WARN, msg, e);
-}
-
-void SimpleLogger::error(const char* msg, ...) {
-  WRITE_LOG(Logger::ERROR, msg);
-}
-
-void SimpleLogger::error(const char* msg, const Exception& e, ...) {
-  WRITE_LOG_EX(Logger::ERROR, msg, e);
-}
-
-void SimpleLogger::setLogLevel(Logger::LEVEL level)
-{
-  _logLevel = level;
+  o << e.stackTrace();
 }
 
 } // namespace aria2
diff --git a/src/SimpleLogger.h b/src/SimpleLogger.h
index 5789b3dc..ebd0e450 100644
--- a/src/SimpleLogger.h
+++ b/src/SimpleLogger.h
@@ -36,61 +36,18 @@
 #define _D_SIMPLE_LOGGER_H_
 
 #include "Logger.h"
-#include <cstdarg>
-#include <string>
-#include <fstream>
 
 namespace aria2 {
 
 class SimpleLogger:public Logger {
-private:
-  void writeFile(Logger::LEVEL level, const char* msg, va_list ap);
+protected:
+  virtual void writeLog
+  (std::ostream& out, Logger::LEVEL logLevel, const std::string& logLevelLabel,
+   const char* msg, va_list ap);
 
-  void writeStackTrace(Logger::LEVEL level, const Exception& e);
-
-  void flush();
-
-  void writeHeader(std::ostream& out,
-		   const std::string& date, const std::string& level);
-
-  void writeLog(std::ostream& out, Logger::LEVEL level,
-		const char* msg, va_list ap,
-		bool printHeader = true);
-
-  std::ofstream file;
-  int stdoutField;
-
-  Logger::LEVEL _logLevel;
-
-  static const std::string DEBUG;
-
-  static const std::string NOTICE;
-
-  static const std::string WARN;
-
-  static const std::string ERROR;
-
-  static const std::string INFO;
-public:
-  SimpleLogger();
-  ~SimpleLogger();
-
-  void openFile(const std::string& filename);
-  void closeFile();
-  virtual void debug(const char* msg, ...);
-  virtual void debug(const char* msg, const Exception& ex, ...);
-  virtual void info(const char* msg, ...);
-  virtual void info(const char* msg, const Exception& ex, ...);
-  virtual void notice(const char* msg, ...);
-  virtual void notice(const char* msg, const Exception& ex, ...);
-  virtual void warn(const char* msg, ...);
-  virtual void warn(const char* msg, const Exception& ex, ...);
-  virtual void error(const char* msg, ...);
-  virtual void error(const char* msg, const Exception& ex, ...);
-
-  virtual void setLogLevel(Logger::LEVEL level);
-
-  void setStdout(Logger::LEVEL level, bool enabled);
+  virtual void writeStackTrace
+  (std::ostream& out, Logger::LEVEL logLevel, const std::string& logLevelLabel,
+   const Exception& e);
 };
 
 } // namespace aria2