poco/Foundation/include/Poco/Logger.h

//
// Logger.h
//
// $Id: //poco/svn/Foundation/include/Poco/Logger.h#2 $
//
// Library: Foundation
// Package: Logging
// Module:  Logger
//
// Definition of the Logger class.
//
// Copyright (c) 2004-2006, Applied Informatics Software Engineering GmbH.
// and Contributors.
//
// Permission is hereby granted, free of charge, to any person or organization
// obtaining a copy of the software and accompanying documentation covered by
// this license (the "Software") to use, reproduce, display, distribute,
// execute, and transmit the Software, and to prepare derivative works of the
// Software, and to permit third-parties to whom the Software is furnished to
// do so, all subject to the following:
// 
// The copyright notices in the Software and this entire statement, including
// the above license grant, this restriction and the following disclaimer,
// must be included in all copies of the Software, in whole or in part, and
// all derivative works of the Software, unless such copies or derivative
// works are solely in the form of machine-executable object code generated by
// a source language processor.
// 
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
// SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
// FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
// ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
// DEALINGS IN THE SOFTWARE.
//


#ifndef Foundation_Logger_INCLUDED
#define Foundation_Logger_INCLUDED


#include "Poco/Foundation.h"
#include "Poco/Channel.h"
#include "Poco/Message.h"
#include <map>
#include <vector>
#include <cstddef>


namespace Poco {


class Exception;


class Foundation_API Logger: public Channel
	/// Logger is a special Channel that acts as the main
	/// entry point into the logging framework.
	///
	/// An application uses instances of the Logger class to generate its log messages
	/// and send them on their way to their final destination. Logger instances
	/// are organized in a hierarchical, tree-like manner and are maintained by
	/// the framework. Every Logger object has exactly one direct ancestor, with
	/// the exception of the root logger. A newly created logger inherits its properties -
	/// channel and level - from its direct ancestor. Every logger is connected
	/// to a channel, to which it passes on its messages. Furthermore, every logger
	/// has a log level, which is used for filtering messages based on their priority.
	/// Only messages with a priority equal to or higher than the specified level
	/// are passed on. For example, if the level of a logger is set to three (PRIO_ERROR),
	/// only messages with priority PRIO_ERROR, PRIO_CRITICAL and PRIO_FATAL will
	/// propagate. If the level is set to zero, the logger is effectively disabled.
	///
	/// The name of a logger determines the logger's place within the logger hierarchy.
	/// The name of the root logger is always "", the empty string. For all other
	/// loggers, the name is made up of one or more components, separated by a period.
	/// For example, the loggers with the name HTTPServer.RequestHandler and HTTPServer.Listener
	/// are descendants of the logger HTTPServer, which itself is a descendant of
	/// the root logger. There is not limit as to how deep
	/// the logger hierarchy can become. Once a logger has been created and it has
	/// inherited the channel and level from its ancestor, it loses the connection
	/// to it. So changes to the level or channel of a logger do not affect its
	/// descendants. This greatly simplifies the implementation of the framework
	/// and is no real restriction, because almost always levels and channels are
	/// set up at application startup and never changed afterwards. Nevertheless,
	/// there are methods to simultaneously change the level and channel of all
	/// loggers in a certain hierarchy.
{
public:
	const std::string& name() const;
		/// Returns the name of the logger, which is set as the
		/// message source on all messages created by the logger.

	void setChannel(Channel* pChannel);
		/// Attaches the given Channel to the Logger.
		
	Channel* getChannel() const;
		/// Returns the Channel attached to the logger.
		
	void setLevel(int level);
		/// Sets the Logger's log level.
		
	int getLevel() const;
		/// Returns the Logger's log level.
		
	void setLevel(const std::string& level);
		/// Sets the Logger's log level using a symbolic value.
		///
		/// Valid values are:
		///   - fatal
		///   - critical
		///   - error
		///   - warning
		///   - notice
		///   - information
		///   - debug
		///   - trace

	void setProperty(const std::string& name, const std::string& value);
		/// Sets or changes a configuration property.
		///
		/// Only the "channel" and "level" properties are supported, which allow
		/// setting the target channel and log level, respectively, via the LoggingRegistry.
		/// The "channel" and "level" properties are set-only.

	void log(const Message& msg);
		/// Logs the given message if its priority is
		/// greater than or equal to the Logger's log level.
		
	void log(const Exception& exc);
		/// Logs the given exception with priority PRIO_ERROR.	
		
	void fatal(const std::string& msg);
		/// If the Logger's log level is at least PRIO_FATAL,
		/// creates a Message with priority PRIO_FATAL
		/// and the given message text and sends it
		/// to the attached channel.

	void critical(const std::string& msg);
		/// If the Logger's log level is at least PRIO_CRITICAL,
		/// creates a Message with priority PRIO_CRITICAL
		/// and the given message text and sends it
		/// to the attached channel.

	void error(const std::string& msg);
		/// If the Logger's log level is at least PRIO_ERROR,
		/// creates a Message with priority PRIO_ERROR
		/// and the given message text and sends it
		/// to the attached channel.

	void warning(const std::string& msg);
		/// If the Logger's log level is at least PRIO_WARNING,
		/// creates a Message with priority PRIO_WARNING
		/// and the given message text and sends it
		/// to the attached channel.

	void notice(const std::string& msg);
		/// If the Logger's log level is at least PRIO_NOTICE,
		/// creates a Message with priority PRIO_NOTICE
		/// and the given message text and sends it
		/// to the attached channel.

	void information(const std::string& msg);
		/// If the Logger's log level is at least PRIO_INFORMATION,
		/// creates a Message with priority PRIO_INFORMATION
		/// and the given message text and sends it
		/// to the attached channel.

	void debug(const std::string& msg);
		/// If the Logger's log level is at least PRIO_DEBUG,
		/// creates a Message with priority PRIO_DEBUG
		/// and the given message text and sends it
		/// to the attached channel.

	void trace(const std::string& msg);
		/// If the Logger's log level is at least PRIO_TRACE,
		/// creates a Message with priority PRIO_TRACE
		/// and the given message text and sends it
		/// to the attached channel.
		
	void dump(const std::string& msg, const void* buffer, std::size_t length, Message::Priority prio = Message::PRIO_DEBUG);
		/// Logs the given message, followed by the data in buffer.
		///
		/// The data in buffer is written in canonical hex+ASCII form:
		/// Offset (4 bytes) in hexadecimal, followed by sixteen 
		/// space-separated, two column, hexadecimal bytes,
		/// followed by the same sixteen bytes as ASCII characters.
		/// For bytes outside the range 32 .. 127, a dot is printed.

	bool is(int level) const;
		/// Returns true if at least the given log level is set.
		
	bool fatal() const;
		/// Returns true if the log level is at least PRIO_FATAL.
		
	bool critical() const;
		/// Returns true if the log level is at least PRIO_CRITICAL.

	bool error() const;
		/// Returns true if the log level is at least PRIO_ERROR.

	bool warning() const;
		/// Returns true if the log level is at least PRIO_WARNING.

	bool notice() const;
		/// Returns true if the log level is at least PRIO_NOTICE.

	bool information() const;
		/// Returns true if the log level is at least PRIO_INFORMATION.

	bool debug() const;
		/// Returns true if the log level is at least PRIO_DEBUG.

	bool trace() const;
		/// Returns true if the log level is at least PRIO_TRACE.

	static std::string format(const std::string& fmt, const std::string& arg);
		/// Replaces all occurences of $0 in fmt with the string given in arg and
		/// returns the result. To include a dollar sign in the result string,
		/// specify two dollar signs ($$) in the format string.
		
	static std::string format(const std::string& fmt, const std::string& arg0, const std::string& arg1);
		/// Replaces all occurences of $<n> in fmt with the string given in arg<n> and
		/// returns the result. To include a dollar sign in the result string,
		/// specify two dollar signs ($$) in the format string.

	static std::string format(const std::string& fmt, const std::string& arg0, const std::string& arg1, const std::string& arg2);	
		/// Replaces all occurences of $<n> in fmt with the string given in arg<n> and
		/// returns the result. To include a dollar sign in the result string,
		/// specify two dollar signs ($$) in the format string.

	static std::string format(const std::string& fmt, const std::string& arg0, const std::string& arg1, const std::string& arg2, const std::string& arg3);	
		/// Replaces all occurences of $<n> in fmt with the string given in arg<n> and
		/// returns the result. To include a dollar sign in the result string,
		/// specify two dollar signs ($$) in the format string.

	static void setLevel(const std::string& name, int level);
		/// Sets the given log level on all loggers that are
		/// descendants of the Logger with the given name.
		
	static void setChannel(const std::string& name, Channel* pChannel);
		/// Attaches the given Channel to all loggers that are
		/// descendants of the Logger with the given name.

	static void setProperty(const std::string& loggerName, const std::string& propertyName, const std::string& value);
		/// Sets or changes a configuration property for all loggers
		/// that are descendants of the Logger with the given name.

	static Logger& get(const std::string& name);
		/// Returns a reference to the Logger with the given name.
		/// If the Logger does not yet exist, it is created, based
		/// on its parent logger.

	static Logger& unsafeGet(const std::string& name);
		/// Returns a reference to the Logger with the given name.
		/// If the Logger does not yet exist, it is created, based
		/// on its parent logger.
		///
		/// WARNING: This method is not thread safe. You should
		/// probably use get() instead.
		/// The only time this method should be used is during
		/// program initialization, when only one thread is running.
		
	static Logger& create(const std::string& name, Channel* pChannel, int level = Message::PRIO_INFORMATION);
		/// Creates and returns a reference to a Logger with the
		/// given name. The Logger's Channel and log level as set as
		/// specified.
		
	static Logger& root();
		/// Returns a reference to the root logger, which is the ultimate
		/// ancestor of all Loggers.
		
	static Logger* has(const std::string& name);
		/// Returns a pointer to the Logger with the given name if it
		/// exists, or a null pointer otherwse.
		
	static void destroy(const std::string& name);
		/// Destroys the logger with the specified name. Does nothing
		/// if the logger is not found.
		///
		/// After a logger has been destroyed, all references to it
		/// become invalid.	
		
	static void shutdown();
		/// Shuts down the logging framework and releases all
		/// Loggers.
		
	static void names(std::vector<std::string>& names);
		/// Fills the given vector with the names
		/// of all currently defined loggers.
		
	static const std::string ROOT; /// The name of the root logger ("").	
		
protected:
	typedef std::map<std::string, Logger*> LoggerMap;

	Logger(const std::string& name, Channel* pChannel, int level);
	~Logger();
	
	void log(const std::string& text, Message::Priority prio);

	static std::string format(const std::string& fmt, int argc, std::string argv[]);
	static void formatDump(std::string& message, const void* buffer, std::size_t length);
	static Logger& parent(const std::string& name);
	static void add(Logger* pLogger);
	static Logger* find(const std::string& name);

private:
	Logger();
	Logger(const Logger&);
	Logger& operator = (const Logger&);
	
	std::string _name;
	Channel*    _pChannel;
	int         _level;

	static LoggerMap* _pLoggerMap;
	static Mutex      _mapMtx;
};


//
// convenience macros
//
#define poco_fatal(logger, msg) \
	if ((logger).fatal()) (logger).fatal(msg) else (void) 0

#define poco_critical(logger, msg) \
	if ((logger).critical()) (logger).critical(msg) else (void) 0

#define poco_error(logger, msg) \
	if ((logger).error()) (logger).error(msg) else (void) 0

#define poco_warning(logger, msg) \
	if ((logger).warning()) (logger).warning(msg) else (void) 0
	
#define poco_notice(logger, msg) \
	if ((logger).notice()) (logger).notice(msg) else (void) 0

#define poco_information(logger, msg) \
	if ((logger).information()) (logger).information(msg) else (void) 0

#if defined(_DEBUG)
	#define poco_debug(logger, msg) \
		if ((logger).debug()) (logger).debug(msg) else (void) 0

	#define poco_trace(logger, msg) \
		if ((logger).trace()) (logger).trace(msg) else (void) 0
#else
	#define poco_debug(logger, msg)
	#define poco_trace(logger, msg)
#endif


//
// inlines
//
inline const std::string& Logger::name() const
{
	return _name;
}


inline int Logger::getLevel() const
{
	return _level;
}


inline void Logger::log(const std::string& text, Message::Priority prio)
{
	if (_level >= prio && _pChannel)
	{
		_pChannel->log(Message(_name, text, prio));
	}
}


inline void Logger::fatal(const std::string& msg)
{
	log(msg, Message::PRIO_FATAL);
}


inline void Logger::critical(const std::string& msg)
{
	log(msg, Message::PRIO_CRITICAL);
}


inline void Logger::error(const std::string& msg)
{
	log(msg, Message::PRIO_ERROR);
}


inline void Logger::warning(const std::string& msg)
{
	log(msg, Message::PRIO_WARNING);
}


inline void Logger::notice(const std::string& msg)
{
	log(msg, Message::PRIO_NOTICE);
}


inline void Logger::information(const std::string& msg)
{
	log(msg, Message::PRIO_INFORMATION);
}


inline void Logger::debug(const std::string& msg)
{
	log(msg, Message::PRIO_DEBUG);
}


inline void Logger::trace(const std::string& msg)
{
	log(msg, Message::PRIO_TRACE);
}


inline bool Logger::is(int level) const
{
	return _level >= level;
}


inline bool Logger::fatal() const
{
	return _level >= Message::PRIO_FATAL;
}


inline bool Logger::critical() const
{
	return _level >= Message::PRIO_CRITICAL;
}


inline bool Logger::error() const
{
	return _level >= Message::PRIO_ERROR;
}


inline bool Logger::warning() const
{
	return _level >= Message::PRIO_WARNING;
}


inline bool Logger::notice() const
{
	return _level >= Message::PRIO_NOTICE;
}


inline bool Logger::information() const
{
	return _level >= Message::PRIO_INFORMATION;
}


inline bool Logger::debug() const
{
	return _level >= Message::PRIO_DEBUG;
}


inline bool Logger::trace() const
{
	return _level >= Message::PRIO_TRACE;
}


} // namespace Poco


#endif // Foundation_Logger_INCLUDED