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maplog.h File Reference

mmap-based thread-safe fixed-size record double-buffered logging. More...

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Data Structures

struct  clib_maplog_header_t
 Maplog log file header segment. More...
 
struct  clib_maplog_main_t
 Process-private main data structure. More...
 
struct  clib_maplog_init_args_t
 log initialization structure More...
 

Macros

#define MAPLOG_MAJOR_VERSION   1
 
#define MAPLOG_MINOR_VERSION   1
 
#define MAPLOG_PATCH_VERSION   0
 
#define CLIB_MAPLOG_FLAG_INIT   (1<<0)
 
#define CLIB_MAPLOG_FLAG_CIRCULAR   (1<<1)
 
#define CLIB_MAPLOG_FLAG_WRAPPED   (1<<2)
 

Functions

int clib_maplog_init (clib_maplog_init_args_t *ap)
 Initialize a maplog object. More...
 
void clib_maplog_update_header (clib_maplog_main_t *mm)
 Update a mapped log header file. More...
 
void clib_maplog_close (clib_maplog_main_t *mm)
 Close a mapped log, and update the log header file. More...
 
int clib_maplog_process (char *file_basename, void *fp_arg)
 Process a complete maplog. More...
 
static void * clib_maplog_get_entry (clib_maplog_main_t *mm)
 Obtain a log entry pointer. More...
 

Variables

format_function_t format_maplog_header
 

Detailed Description

mmap-based thread-safe fixed-size record double-buffered logging.

This scheme should be about as fast as practicable. By fiat, log records are rounded to a multiple of CLIB_CACHE_LINE_BYTES. Consumer code calls clib_maplog_get_entry(...) to obtain a pointer to a log entry.

We use an atomic ticket-counter to dole out log entries. Whichever client thread crosses the double-buffer boundary is in charge of replacing the log segment which just filled.

Definition in file maplog.h.

Macro Definition Documentation

◆ CLIB_MAPLOG_FLAG_CIRCULAR

#define CLIB_MAPLOG_FLAG_CIRCULAR   (1<<1)

Definition at line 93 of file maplog.h.

◆ CLIB_MAPLOG_FLAG_INIT

#define CLIB_MAPLOG_FLAG_INIT   (1<<0)

Definition at line 92 of file maplog.h.

◆ CLIB_MAPLOG_FLAG_WRAPPED

#define CLIB_MAPLOG_FLAG_WRAPPED   (1<<2)

Definition at line 94 of file maplog.h.

◆ MAPLOG_MAJOR_VERSION

#define MAPLOG_MAJOR_VERSION   1

Definition at line 62 of file maplog.h.

◆ MAPLOG_MINOR_VERSION

#define MAPLOG_MINOR_VERSION   1

Definition at line 63 of file maplog.h.

◆ MAPLOG_PATCH_VERSION

#define MAPLOG_PATCH_VERSION   0

Definition at line 64 of file maplog.h.

Function Documentation

◆ clib_maplog_close()

void clib_maplog_close ( clib_maplog_main_t mm)

Close a mapped log, and update the log header file.

Unmap the current log segments. Read the log header. Update the number of records, and number of files

Parameters
[in/out]mm mapped log object

Definition at line 299 of file maplog.c.

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◆ clib_maplog_get_entry()

static void* clib_maplog_get_entry ( clib_maplog_main_t mm)
inlinestatic

Obtain a log entry pointer.

Increments the atomic ticket counter, and returns a pointer to the newly-allocated log entry. The slowpath function replaces a full log segment with a new/fresh/empty log segment

Parameters
[in]mmmaplog object pointer
Returns
pointer to the allocated log entry

Definition at line 133 of file maplog.h.

◆ clib_maplog_init()

int clib_maplog_init ( clib_maplog_init_args_t a)

Initialize a maplog object.

Compute record and file size parameters Create and map two log segments to seed the process

Parameters
[in/out]a init args structure
Returns
0 => success, <0 => failure

Definition at line 28 of file maplog.c.

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◆ clib_maplog_process()

int clib_maplog_process ( char *  file_basename,
void *  fp_arg 
)

Process a complete maplog.

Reads the maplog header. Map and process all log segments in order. Calls the callback function once per file with a record count.

Note: if the file header isn't updated by calling clib_maplog_close(), it will appear to have an infinite number of records in an infinite number of files.

So long as the callback function understands that possibility

  • by simply ignoring NULL records - the scheme still works...
Parameters
[in]file_basenameSame basename supplied to clib_maplog_init
[in]fp_argCallback function pointer

Definition at line 384 of file maplog.c.

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◆ clib_maplog_update_header()

void clib_maplog_update_header ( clib_maplog_main_t mm)

Update a mapped log header file.

Read the log header. Update the number of records, and number of files

Parameters
[in/out]mm mapped log object

Definition at line 246 of file maplog.c.

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Variable Documentation

◆ format_maplog_header

format_function_t format_maplog_header

Definition at line 117 of file maplog.h.