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PMEMLOG_CREATE(3)	   PMDK	Programmer's Manual	     PMEMLOG_CREATE(3)

NAME
       pmemlog_create(),  pmemlog_open(),  pmemlog_close(),  pmemlog_check() -
       create, open, close and validate	persistent memory resident log file

SYNOPSIS
	      #include <libpmemlog.h>

	      PMEMlogpool *pmemlog_open(const char *path);
	      PMEMlogpool *pmemlog_create(const	char *path, size_t poolsize, mode_t mode);
	      void pmemlog_close(PMEMlogpool *plp);
	      int pmemlog_check(const char *path);

DESCRIPTION
       The pmemlog_create() function creates a log memory pool with the	 given
       total  poolsize.	  Since	 the transactional nature of a log memory pool
       requires	some space overhead in the memory pool,	the  resulting	avail-
       able log	size is	less than poolsize, and	is made	available to the call-
       er via the pmemlog_nbyte(3) function.  path specifies the name  of  the
       memory  pool file to be created.	 mode specifies	the permissions	to use
       when creating the file as described by creat(2).	 The memory pool  file
       is  fully allocated to the size poolsize	using posix_fallocate(3).  The
       caller may choose to take responsibility	for creating the  memory  pool
       file by creating	it before calling pmemlog_create() and then specifying
       poolsize	as zero.  In this case pmemlog_create()	 will  take  the  pool
       size  from  the size of the existing file and will verify that the file
       appears to be empty by searching	for any	 non-zero  data	 in  the  pool
       header  at the beginning	of the file.  The net pool size	of a pool file
       is equal	to the file size.  The minimum net pool	size  allowed  by  the
       library	 for  a	 log  pool  is	defined	 in  <libpmemlog.h>  as	 PMEM-
       LOG_MIN_POOL.

       Depending  on  the  configuration  of   the   system,   the   available
       non-volatile  memory space may be divided into multiple memory devices.
       In such case, the maximum size of the pmemlog memory pool could be lim-
       ited  by	 the capacity of a single memory device.  libpmemlog(7)	allows
       building	persistent memory resident logs	spanning multiple  memory  de-
       vices  by  creation  of	persistent memory pools	consisting of multiple
       files, where each part of such a	pool set may be	stored on a  different
       memory device or	pmem-aware filesystem.

       Creation	of all the parts of the	pool set can be	done with pmemlog_cre-
       ate(); however, the recommended method for creating pool	sets  is  with
       the pmempool(1) utility.

       When  creating  a pool set consisting of	multiple files,	the path argu-
       ment passed to pmemlog_create() must point to the special set file that
       defines	the  pool layout and the location of all the parts of the pool
       set.  The poolsize argument must	be 0.  The meaning of the  mode	 argu-
       ment does not change, except that the same mode is used for creation of
       all the parts of	the pool set.

       The set file is a plain text file, the structure	of which is  described
       in poolset(5).

       The pmemlog_open() function opens an existing log memory	pool.  Similar
       to pmemlog_create(), path must identify either an existing  log	memory
       pool  file, or the set file used	to create a pool set.  The application
       must have permission to open the	file and memory	map the	file  or  pool
       set with	read/write permissions.

       Be  aware  that	if the pool contains bad blocks	inside,	opening	can be
       aborted by the SIGBUS signal, because currently the pool	is not checked
       against	bad blocks during opening.  It can be turned on	by setting the
       CHECK_BAD_BLOCKS	compat feature.	 For details see description  of  this
       feature in pmempool-feature(1).

       The  pmemlog_close()  function  closes the memory pool indicated	by plp
       and deletes the memory pool handle.  The	log memory pool	 itself	 lives
       on  in  the  file that contains it and may be re-opened at a later time
       using pmemlog_open() as described above.

       The pmemlog_check() function performs a consistency check of  the  file
       indicated  by  path.  pmemlog_check() opens the given path read-only so
       it never	makes any changes to the file.	This function is not supported
       on Device DAX.

RETURN VALUE
       On success, pmemlog_create() returns a PMEMlogpool* handle to the memo-
       ry pool that is used with most of the functions from libpmemlog(7).  If
       an  error prevents any of the pool set files from being created,	it re-
       turns NULL and sets errno appropriately.

       On success, pmemlog_open() returns a PMEMlogpool* handle	to the	memory
       pool that is used with most of the functions from libpmemlog(7).	 If an
       error prevents the pool from being opened,  or  a  pool	set  is	 being
       opened and the actual size of any file does not match the corresponding
       part size defined in the	set file, pmemlog_open() returns NULL and sets
       errno appropriately.

       The pmemlog_close() function returns no value.

       The  pmemlog_check()  function returns 1	if the persistent memory resi-
       dent log	file is	found to  be  consistent.   Any	 inconsistencies  will
       cause  pmemlog_check()  to  return 0, in	which case the use of the file
       with libpmemlog will result in undefined	behavior.  The	debug  version
       of  libpmemlog  will provide additional details on inconsistencies when
       PMEMLOG_LOG_LEVEL is at least 1,	as described in	the DEBUGGING AND  ER-
       ROR  HANDLING section in	libpmemlog(7).	pmemlog_check()	will return -1
       and set errno if	it cannot perform the consistency check	due  to	 other
       errors.

CAVEATS
       Not all file systems support posix_fallocate(3).	 pmemlog_create() will
       fail if the underlying file system does not support posix_fallocate(3).

SEE ALSO
       pmempool(1),    creat(2),     posix_fallocate(3),     pmemlog_nbyte(3),
       poolset(5), libpmemlog(7) and <http://pmem.io>

PMDK - pmemlog API version 1.1	  2019-07-10		     PMEMLOG_CREATE(3)

NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | CAVEATS | SEE ALSO

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