NAME

       pmemlog_create()(DEPRECATED),      pmemlog_open()(DEPRECATED),     pmemlog_close()(DEPRECATED),     pmem‐
       log_check()(DEPRECATED) - 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  trans‐
       actional  nature  of  a  log  memory  pool requires some space overhead in the memory pool, the resulting
       available log size is less than poolsize, and is made available to the caller  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 al‐
       lowed by the library for a log pool is defined in <libpmemlog.h> as PMEMLOG_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  limited  by
       the  capacity  of  a single memory device.  libpmemlog(7) allows building persistent memory resident logs
       spanning multiple memory devices 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_create(); 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 argument 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 argument 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 appli‐
       cation must have permission to open the file and memory map the file or pool set with read/write  permis‐
       sions.

       Be  aware  that  if the pool contains bad blocks inside, opening can be aborted by the SIGBUS signal, be‐
       cause currently the pool is not checked against bad blocks during opening.  It can be turned on  by  set‐
       ting  the  CHECK_BAD_BLOCKS compat feature.  For details see description of this feature in pmempool-fea‐
       ture(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 us‐
       ing 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 memory 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
       returns 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 resident log file is found to be consis‐
       tent.  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 ERROR
       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  sys‐
       tem does not support posix_fallocate(3).

SEE ALSO

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