Logging

Enumerations
enum	lws_log_levels {   LLL_ERR = 1 << 0, LLL_WARN = 1 << 1, LLL_NOTICE = 1 << 2, LLL_INFO = 1 << 3,   LLL_DEBUG = 1 << 4, LLL_PARSER = 1 << 5, LLL_HEADER = 1 << 6, LLL_EXT = 1 << 7,   LLL_CLIENT = 1 << 8, LLL_LATENCY = 1 << 9, LLL_USER = 1 << 10, LLL_COUNT = 11 }

Functions
LWS_VISIBLE LWS_EXTERN void	_lws_log (int filter, const char *format,...) LWS_FORMAT(2)
LWS_VISIBLE LWS_EXTERN void	_lws_logv (int filter, const char *format, va_list vl)
LWS_VISIBLE LWS_EXTERN int	lwsl_timestamp (int level, char *p, int len)
LWS_VISIBLE LWS_EXTERN void	lwsl_hexdump (void *buf, size_t len)
LWS_VISIBLE LWS_EXTERN void	lws_set_log_level (int level, void(*log_emit_function)(int level, const char *line))
LWS_VISIBLE LWS_EXTERN void	lwsl_emit_syslog (int level, const char *line)
LWS_VISIBLE LWS_EXTERN int	lwsl_visible (int level)

Detailed Description

Logging

Lws provides flexible and filterable logging facilities, which can be used inside lws and in user code.

Log categories may be individually filtered bitwise, and directed to built-in sinks for syslog-compatible logging, or a user-defined function.

Function Documentation

lws_set_log_level()

LWS_VISIBLE LWS_EXTERN void lws_set_log_level	(	int	level,
		void(*)(int level, const char *line)	log_emit_function
	)

#include <lib/libwebsockets.h>

lws_set_log_level() - Set the logging bitfield

Parameters

level	OR together the LLL_ debug contexts you want output from
log_emit_function	NULL to leave it as it is, or a user-supplied function to perform log string emission instead of the default stderr one.

log level defaults to "err", "warn" and "notice" contexts enabled and emission on stderr.

lwsl_emit_syslog()

LWS_VISIBLE LWS_EXTERN void lwsl_emit_syslog	(	int	level,
		const char *	line
	)

#include <lib/libwebsockets.h>

lwsl_emit_syslog() - helper log emit function writes to system log

Parameters

level	one of LLL_ log level indexes
line	log string

You use this by passing the function pointer to lws_set_log_level(), to set it as the log emit function, it is not called directly.

lwsl_hexdump()

LWS_VISIBLE LWS_EXTERN void lwsl_hexdump	(	void *	buf,
		size_t	len
	)

#include <lib/libwebsockets.h>

lwsl_hexdump() - helper to hexdump a buffer (DEBUG builds only)

Parameters

buf	buffer start to dump
len	length of buffer to dump

lwsl_timestamp()

LWS_VISIBLE LWS_EXTERN int lwsl_timestamp	(	int	level,
		char *	p,
		int	len
	)

#include <lib/libwebsockets.h>

lwsl_timestamp: generate logging timestamp string

Parameters

level	logging level
p	char * buffer to take timestamp
len	length of p

returns length written in p

lwsl_visible()

LWS_VISIBLE LWS_EXTERN int lwsl_visible

(

int

level

)

#include <lib/libwebsockets.h>

lwsl_visible() - returns true if the log level should be printed

Parameters

level

one of LLL_ log level indexes

This is useful if you have to do work to generate the log content, you can skip the work if the log level used to print it is not actually enabled at runtime.