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]

mm

maplog 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_basename	Same basename supplied to clib_maplog_init
[in]	fp_arg	Callback 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.