libwebsockets
Lightweight C library for HTML5 websockets
Logging

Macros

#define lwsl_err(...)   _lws_log(LLL_ERR, __VA_ARGS__)
 
#define lwsl_user(...)   _lws_log(LLL_USER, __VA_ARGS__)
 
#define lwsl_warn(...)   _lws_log(LLL_WARN, __VA_ARGS__)
 
#define lwsl_notice(...)   _lws_log(LLL_NOTICE, __VA_ARGS__)
 
#define lwsl_info(...)   do {} while(0)
 
#define lwsl_debug(...)   do {} while(0)
 
#define lwsl_parser(...)   do {} while(0)
 
#define lwsl_header(...)   do {} while(0)
 
#define lwsl_ext(...)   do {} while(0)
 
#define lwsl_client(...)   do {} while(0)
 
#define lwsl_latency(...)   do {} while(0)
 
#define lwsl_thread(...)   do {} while(0)
 
#define lwsl_hexdump_err(...)   lwsl_hexdump_level(LLL_ERR, __VA_ARGS__)
 
#define lwsl_hexdump_warn(...)   lwsl_hexdump_level(LLL_WARN, __VA_ARGS__)
 
#define lwsl_hexdump_notice(...)   lwsl_hexdump_level(LLL_NOTICE, __VA_ARGS__)
 
#define lwsl_hexdump_info(...)   lwsl_hexdump_level(LLL_INFO, __VA_ARGS__)
 
#define lwsl_hexdump_debug(...)   lwsl_hexdump_level(LLL_DEBUG, __VA_ARGS__)
 
#define lws_list_ptr_container(P, T, M)   ((T *)((char *)(P) - offsetof(T, M)))
 
#define lws_list_ptr_advance(_lp)   _lp = *((void **)_lp)
 

Typedefs

typedef unsigned char * lwsac_cached_file_t
 
typedef void * lws_list_ptr
 
typedef int(* lws_list_ptr_sort_func_t) (lws_list_ptr a, lws_list_ptr b)
 

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_THREAD = 1 << 11,
  LLL_COUNT = 12
}
 

Functions

LWS_VISIBLE LWS_EXTERN int lwsl_timestamp (int level, char *p, int len)
 
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 void lwsl_hexdump_level (int level, const void *vbuf, size_t len)
 
LWS_VISIBLE LWS_EXTERN void lwsl_hexdump (const 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 void lwsl_emit_stderr (int level, const char *line)
 
LWS_VISIBLE LWS_EXTERN void lwsl_emit_stderr_notimestamp (int level, const char *line)
 
LWS_VISIBLE LWS_EXTERN int lwsl_visible (int level)
 
LWS_VISIBLE LWS_EXTERN void lws_list_ptr_insert (lws_list_ptr *phead, lws_list_ptr *add, lws_list_ptr_sort_func_t sort)
 
LWS_VISIBLE LWS_EXTERN void * lwsac_use (struct lwsac **head, size_t ensure, size_t chunk_size)
 
LWS_VISIBLE LWS_EXTERN void lwsac_free (struct lwsac **head)
 
LWS_VISIBLE LWS_EXTERN void lwsac_detach (struct lwsac **head)
 
LWS_VISIBLE LWS_EXTERN void lwsac_reference (struct lwsac *head)
 
LWS_VISIBLE LWS_EXTERN void lwsac_unreference (struct lwsac **head)
 
LWS_VISIBLE LWS_EXTERN void lwsac_use_cached_file_start (lwsac_cached_file_t cache)
 
LWS_VISIBLE LWS_EXTERN void lwsac_use_cached_file_end (lwsac_cached_file_t *cache)
 
LWS_VISIBLE LWS_EXTERN void lwsac_use_cached_file_detach (lwsac_cached_file_t *cache)
 
LWS_VISIBLE LWS_EXTERN int lwsac_cached_file (const char *filepath, lwsac_cached_file_t *cache, size_t *len)
 
LWS_VISIBLE LWS_EXTERN size_t lwsac_sizeof (void)
 
LWS_VISIBLE LWS_EXTERN size_t lwsac_get_tail_pos (struct lwsac *lac)
 
LWS_VISIBLE LWS_EXTERN struct lwsac * lwsac_get_next (struct lwsac *lac)
 
LWS_VISIBLE LWS_EXTERN size_t lwsac_align (size_t length)
 
LWS_VISIBLE LWS_EXTERN void lwsac_info (struct lwsac *head)
 
LWS_VISIBLE LWS_EXTERN uint64_t lwsac_total_alloc (struct lwsac *head)
 

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.

Allocated Chunks

If you know you will be allocating a large, unknown number of same or differently sized objects, it's certainly possible to do it with libc malloc. However the allocation cost in time and memory overhead can add up, and deallocation means walking the structure of every object and freeing them in turn.

lwsac (LWS Allocated Chunks) allocates chunks intended to be larger than your objects (4000 bytes by default) which you linearly allocate from using lwsac_use().

If your next request won't fit in the current chunk, a new chunk is added to the chain of chunks and the allocaton done from there. If the request is larger than the chunk size, an oversize chunk is created to satisfy it.

When you are finished with the allocations, you call lwsac_free() and free all the chunks. So you may have thousands of objects in the chunks, but they are all destroyed with the chunks without having to deallocate them one by one pointlessly.

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 <include/libwebsockets/lws-logs.h>

lws_set_log_level() - Set the logging bitfield

Parameters
levelOR together the LLL_ debug contexts you want output from
log_emit_functionNULL 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. If stderr is a tty (according to isatty()) then the output is coloured according to the log level using ANSI escapes.

◆ lwsac_detach()

LWS_VISIBLE LWS_EXTERN void lwsac_detach ( struct lwsac **  head)

#include <include/libwebsockets/lws-lwsac.h>

lwsac_detach() - destroy an lwsac unless somebody else is referencing it

Parameters
headpointer to the lwsac list object

The creator of the lwsac can all this instead of lwsac_free() when it itself has finished with the lwsac, but other code may be consuming it.

If there are no other references, the lwsac is destroyed, *head is set to NULL and that's the end; however if something else has called lwsac_reference() on the lwsac, it simply returns. When lws_unreference() is called and no references are left, it will be destroyed then.

◆ lwsac_free()

LWS_VISIBLE LWS_EXTERN void lwsac_free ( struct lwsac **  head)

#include <include/libwebsockets/lws-lwsac.h>

lwsac_free - deallocate all chunks in the lwsac and set head NULL

Parameters
headpointer to the lwsac list object

This deallocates all chunks in the lwsac, then sets *head to NULL. All lwsac_use() pointers are invalidated in one hit without individual frees.

◆ lwsac_reference()

LWS_VISIBLE LWS_EXTERN void lwsac_reference ( struct lwsac *  head)

#include <include/libwebsockets/lws-lwsac.h>

lwsac_reference() - increase the lwsac reference count

Parameters
headpointer to the lwsac list object

Increment the reference count on the lwsac to defer destruction.

◆ lwsac_unreference()

LWS_VISIBLE LWS_EXTERN void lwsac_unreference ( struct lwsac **  head)

#include <include/libwebsockets/lws-lwsac.h>

lwsac_reference() - increase the lwsac reference count

Parameters
headpointer to the lwsac list object

Decrement the reference count on the lwsac... if it reached 0 on a detached lwsac then the lwsac is immediately destroyed and *head set to NULL.

◆ lwsac_use()

LWS_VISIBLE LWS_EXTERN void* lwsac_use ( struct lwsac **  head,
size_t  ensure,
size_t  chunk_size 
)

#include <include/libwebsockets/lws-lwsac.h>

lwsac_use - allocate / use some memory from a lwsac

Parameters
headpointer to the lwsac list object
ensurethe number of bytes we want to use
chunk_size0, or the size of the chunk to (over)allocate if what we want won't fit in the current tail chunk. If 0, the default value of 4000 is used. If ensure is larger, it is used instead.

This also serves to init the lwsac if *head is NULL. Basically it does whatever is necessary to return you a pointer to ensure bytes of memory reserved for the caller.

Returns NULL if OOM.

◆ lwsl_emit_stderr()

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

#include <include/libwebsockets/lws-logs.h>

lwsl_emit_stderr() - helper log emit function writes to stderr

Parameters
levelone of LLL_ log level indexes
linelog 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.

It prepends a system timestamp like [2018/11/13 07:41:57:3989]

If stderr is a tty, then ansi colour codes are added.

◆ lwsl_emit_stderr_notimestamp()

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

#include <include/libwebsockets/lws-logs.h>

lwsl_emit_stderr_notimestamp() - helper log emit function writes to stderr

Parameters
levelone of LLL_ log level indexes
linelog 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.

If stderr is a tty, then ansi colour codes are added.

◆ lwsl_emit_syslog()

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

#include <include/libwebsockets/lws-logs.h>

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

Parameters
levelone of LLL_ log level indexes
linelog 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 ( const void *  buf,
size_t  len 
)

#include <include/libwebsockets/lws-logs.h>

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

Parameters
bufbuffer start to dump
lenlength of buffer to dump

Calls through to lwsl_hexdump_level(LLL_DEBUG, ... for compatability. It's better to use lwsl_hexdump_level(level, ... directly so you can control the visibility.

◆ lwsl_hexdump_level()

LWS_VISIBLE LWS_EXTERN void lwsl_hexdump_level ( int  level,
const void *  vbuf,
size_t  len 
)

#include <include/libwebsockets/lws-logs.h>

lwsl_hexdump_level() - helper to hexdump a buffer at a selected debug level

Parameters
levelone of LLL_ constants
vbufbuffer start to dump
lenlength of buffer to dump

If level is visible, does a nice hexdump -C style dump of vbuf for len bytes. This can be extremely convenient while debugging.

◆ lwsl_timestamp()

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

#include <include/libwebsockets/lws-logs.h>

lwsl_timestamp: generate logging timestamp string

Parameters
levellogging level
pchar * buffer to take timestamp
lenlength of p

returns length written in p

◆ lwsl_visible()

LWS_VISIBLE LWS_EXTERN int lwsl_visible ( int  level)

#include <include/libwebsockets/lws-logs.h>

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

Parameters
levelone 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.