Logging

Detailed Description

The OLA logging system.

Example

\#include <ola/Logging.h>

// Call this once
ola::InitLogging(ola::OLA_LOG_WARN, ola::OLA_LOG_STDERR);

OLA_FATAL << "Null pointer!";
OLA_WARN << "Could not connect to server: " << ip_address;
OLA_INFO << "Reading configs from " << config_dir;
OLA_DEBUG << "Counter was " << counter;

Collaboration diagram for Logging:

Files
file	Logging.cpp
file	Logging.h
	Header file for OLA Logging.

Namespaces
	ola
	The namespace containing all OLA symbols.

Classes
class	ola::LogDestination
	The base class for log destinations. More...
class	ola::StdErrorLogDestination
	A LogDestination that writes to stderr. More...
class	ola::SyslogDestination
	An abstract base of LogDestination that writes to syslog. More...
class	ola::UnixSyslogDestination
	A SyslogDestination that writes to Unix syslog. More...

Macros
#define	OLA_LOG(level)
#define	OLA_FATAL   OLA_LOG(ola::OLA_LOG_FATAL)
#define	OLA_WARN   OLA_LOG(ola::OLA_LOG_WARN)
#define	OLA_INFO   OLA_LOG(ola::OLA_LOG_INFO)
#define	OLA_DEBUG   OLA_LOG(ola::OLA_LOG_DEBUG)

Enumerations
enum	ola::log_level {   ola::OLA_LOG_NONE, ola::OLA_LOG_FATAL, ola::OLA_LOG_WARN, ola::OLA_LOG_INFO,   ola::OLA_LOG_DEBUG, OLA_LOG_MAX }
	The OLA log levels. This controls the verbosity of logging. Each level also includes those below it. More...
enum	ola::log_output { ola::OLA_LOG_STDERR, ola::OLA_LOG_SYSLOG, OLA_LOG_NULL }
	The destination to write log messages to. More...

Functions
void	ola::SetLogLevel (log_level level)
	Set the logging level. More...
void	ola::IncrementLogLevel ()
	Increment the log level by one. The log level wraps to OLA_LOG_NONE.
bool	ola::InitLoggingFromFlags ()
	Initialize the OLA logging system from flags. More...
bool	ola::InitLogging (log_level level, log_output output)
	Initialize the OLA logging system. More...
void	ola::InitLogging (log_level level, LogDestination *destination)
	Initialize the OLA logging system using the specified LogDestination. More...
virtual	ola::LogDestination::~LogDestination ()
	Destructor.
virtual void	ola::LogDestination::Write (log_level level, const std::string &log_line)=0
	An abstract function for writing to your log destination. More...
void	ola::StdErrorLogDestination::Write (log_level level, const std::string &log_line)
	Writes a messages out to stderr.
virtual	ola::SyslogDestination::~SyslogDestination ()
	Destructor.
virtual bool	ola::SyslogDestination::Init ()=0
	Initialize the SyslogDestination.
virtual void	ola::SyslogDestination::Write (log_level level, const std::string &log_line)=0
	Write a line to the system logger. More...
bool	ola::UnixSyslogDestination::Init ()
	Initialize the UnixSyslogDestination.
void	ola::UnixSyslogDestination::Write (log_level level, const std::string &log_line)
	Write a line to syslog.
log_level	ola::LogLevel ()
	Fetch the current level of logging. More...

Macro Definition Documentation

#define OLA_DEBUG   OLA_LOG(ola::OLA_LOG_DEBUG)

Provide a stream to log a debug message.

OLA_DEBUG << "Counter was " << counter;

#define OLA_FATAL   OLA_LOG(ola::OLA_LOG_FATAL)

Provide a stream to log a fatal message. e.g.

OLA_FATAL << "Null pointer!";

#define OLA_INFO   OLA_LOG(ola::OLA_LOG_INFO)

Provide a stream to log an infomational message.

OLA_INFO << "Reading configs from " << config_dir;

#define OLA_LOG

(

level

)

Value:

(level <= ola::LogLevel()) && \
 ola::LogLine(__FILE__, __LINE__, level).stream()

Provide a stream interface to log a message at the specified log level. Rather than calling this directly use one of the OLA_FATAL, OLA_WARN, OLA_INFO or OLA_DEBUG macros.

Parameters

level

the log_level to log at.

#define OLA_WARN   OLA_LOG(ola::OLA_LOG_WARN)

Provide a stream to log a warning message.

OLA_WARN << "Could not connect to server: " << ip_address;

Enumeration Type Documentation

enum ola::log_level

The OLA log levels. This controls the verbosity of logging. Each level also includes those below it.

Enumerator
OLA_LOG_NONE	No messages are logged.
OLA_LOG_FATAL	Fatal messages are logged.
OLA_LOG_WARN	Warnings messages are logged.
OLA_LOG_INFO	Informational messages are logged.
OLA_LOG_DEBUG	Debug messages are logged.

enum ola::log_output

The destination to write log messages to.

Enumerator
OLA_LOG_STDERR	Log to stderr.
OLA_LOG_SYSLOG	Log to syslog.

Function Documentation

bool ola::InitLogging	(	log_level	level,
		log_output	output
	)

Initialize the OLA logging system.

Parameters

level	the level to log at
output	the destination for the logs

Returns

true if logging was initialized sucessfully, false otherwise.

void ola::InitLogging	(	log_level	level,
		LogDestination *	destination
	)

Initialize the OLA logging system using the specified LogDestination.

Parameters

level	the level to log at
destination	the LogDestination to use.

bool ola::InitLoggingFromFlags

(

)

Initialize the OLA logging system from flags.

Precondition

ParseFlags() must have been called before calling this.

Returns

true if logging was initialized sucessfully, false otherwise.

log_level ola::LogLevel ( )

inline

Fetch the current level of logging.

Returns

the current log_level.

void ola::SetLogLevel

(

log_level

level

)

Set the logging level.

Parameters

level

the new log_level to use.

virtual void ola::LogDestination::Write ( log_level  level, const std::string &  log_line  )

pure virtual

An abstract function for writing to your log destination.

Note

You must over load this if you want to create a new log destination

Implemented in ola::UnixSyslogDestination, ola::SyslogDestination, and ola::StdErrorLogDestination.

virtual void ola::SyslogDestination::Write ( log_level  level, const std::string &  log_line  )

pure virtual

Write a line to the system logger.

Note

This is syslog on *nix or the event log on windows.

Implements ola::LogDestination.

Implemented in ola::UnixSyslogDestination.