seastar::logger Class Reference

Detailed Description

Logger class for ostream or syslog.

Java style api for logging.

static seastar::logger logger("lsa-api");
logger.info("Triggering compaction");

The output format is: (depending on level) DEBUG Y-m-d T,%03d [shard 0] - "your msg"
It is possible to rate-limit log messages, see logger::rate_limit.

#include <seastar/util/log.hh>

Classes
class	lambda_log_writer
class	log_writer
class	rate_limit

Public Member Functions
	logger (sstring name)
	logger (logger &&x)
bool	is_shard_zero () noexcept
bool	is_enabled (log_level level) const noexcept
template<typename... Args>
void	log (log_level level, const char *fmt, Args &&... args) noexcept
template<typename... Args>
void	log (log_level level, rate_limit &rl, const char *fmt, Args &&... args) noexcept
template<typename... Args>
void	error (const char *fmt, Args &&... args) noexcept
template<typename... Args>
void	warn (const char *fmt, Args &&... args) noexcept
template<typename... Args>
void	info (const char *fmt, Args &&... args) noexcept
template<typename... Args>
void	info0 (const char *fmt, Args &&... args) noexcept
template<typename... Args>
void	debug (const char *fmt, Args &&... args) noexcept
template<typename... Args>
void	trace (const char *fmt, Args &&... args) noexcept
const sstring &	name () const noexcept
log_level	level () const noexcept
void	set_level (log_level level) noexcept

Static Public Member Functions
static void	set_ostream (std::ostream &out) noexcept
	Set output stream, default is std::cerr.
static void	set_ostream_enabled (bool enabled) noexcept
	Also output to ostream. default is true.
static void	set_stdout_enabled (bool enabled) noexcept
	Also output to stdout. default is true.
static void	set_syslog_enabled (bool enabled) noexcept

Member Function Documentation

debug()

template<typename... Args>

void seastar::logger::debug ( const char *  fmt, Args &&...  args  )

inlinenoexcept

Log with debug tag: DEBUG Y-m-d T,%03d [shard 0] - "your msg"

Parameters

fmt	- {fmt} style format
args	- args to print string

error()

template<typename... Args>

void seastar::logger::error ( const char *  fmt, Args &&...  args  )

inlinenoexcept

Log with error tag: ERROR Y-m-d T,%03d [shard 0] - "your msg"

Parameters

fmt	- {fmt} style format
args	- args to print string

info()

template<typename... Args>

void seastar::logger::info ( const char *  fmt, Args &&...  args  )

inlinenoexcept

Log with info tag: INFO Y-m-d T,%03d [shard 0] - "your msg"

Parameters

fmt	- {fmt} style format
args	- args to print string

info0()

template<typename... Args>

void seastar::logger::info0 ( const char *  fmt, Args &&...  args  )

inlinenoexcept

Log with info tag on shard zero only: INFO Y-m-d T,%03d [shard 0] - "your msg"

Parameters

fmt	- {fmt} style format
args	- args to print string

is_enabled()

bool seastar::logger::is_enabled ( log_level  level ) const

inlinenoexcept

Test if desired log level is enabled

Parameters

level

- enum level value (info|error...)

Returns

true if the log level has been enabled.

level()

log_level seastar::logger::level ( ) const

inlinenoexcept

Returns

current log level for this logger

log() [1/2]

template<typename... Args>

void seastar::logger::log ( log_level  level, const char *  fmt, Args &&...  args  )

inlinenoexcept

logs to desired level if enabled, otherwise we ignore the log line

Parameters

fmt	- {fmt} style format
args	- args to print string

log() [2/2]

template<typename... Args>

void seastar::logger::log ( log_level  level, rate_limit &  rl, const char *  fmt, Args &&...  args  )

inlinenoexcept

logs with a rate limit to desired level if enabled, otherwise we ignore the log line

If there were messages dropped due to rate-limiting the following snippet will be prepended to the first non-dropped log messages:

(rate limiting dropped $N similar messages)

Where $N is the number of messages dropped.

Parameters

rl	- the rate_limit to apply to this log
fmt	- {fmt} style format
args	- args to print string

name()

const sstring& seastar::logger::name ( ) const

inlinenoexcept

Returns

name of the logger. Usually one logger per module

set_level()

void seastar::logger::set_level ( log_level  level )

inlinenoexcept

Parameters

level

- set the log level

set_syslog_enabled()

static void seastar::logger::set_syslog_enabled ( bool  enabled )

staticnoexcept

Also output to syslog. default is false

NOTE: syslog() can block, which will stall the reactor thread. this should be rare (will have to fill the pipe buffer before syslogd can clear it) but can happen.

trace()

template<typename... Args>

void seastar::logger::trace ( const char *  fmt, Args &&...  args  )

inlinenoexcept

Log with trace tag: TRACE Y-m-d T,%03d [shard 0] - "your msg"

Parameters

fmt	- {fmt} style format
args	- args to print string

warn()

template<typename... Args>

void seastar::logger::warn ( const char *  fmt, Args &&...  args  )

inlinenoexcept

Log with warning tag: WARN Y-m-d T,%03d [shard 0] - "your msg"

Parameters

fmt	- {fmt} style format
args	- args to print string

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The documentation for this class was generated from the following file:

• seastar/util/log.hh