NAME

       pmemlog_tell(),  pmemlog_rewind(),  pmemlog_walk()  -  checks  current  write  point for the log or walks
       through the log

SYNOPSIS

              #include <libpmemlog.h>

              long long pmemlog_tell(PMEMlogpool *plp);
              void pmemlog_rewind(PMEMlogpool *plp);
              void pmemlog_walk(PMEMlogpool *plp, size_t chunksize,
                  int (*process_chunk)(const void *buf, size_t len, void *arg),
                  void *arg);

DESCRIPTION

       The pmemlog_tell() function returns the current write point for the log, expressed as a byte offset  into
       the  usable  log space in the memory pool.  This offset starts off as zero on a newly-created log, and is
       incremented by each successful append operation.  This function can be used to determine how much data is
       currently in the log.

       The pmemlog_rewind() function resets the current write point for the log to zero.  After this  call,  the
       next append adds to the beginning of the log.

       The  pmemlog_walk() function walks through the log plp, from beginning to end, calling the callback func‐
       tion process_chunk for each chunksize block of data found.  The argument arg is also passed to the  call‐
       back  to  help  avoid  the  need  for  global  state.   The  chunksize  argument  is useful for logs with
       fixed-length records and may be specified as 0 to cause a single call to the callback with the entire log
       contents passed as the buf argument.  The len argument tells the process_chunk function how much data buf
       is holding.  The callback function should return 1 if pmemlog_walk() should continue walking through  the
       log,  or  0  to terminate the walk.  The callback function is called while holding libpmemlog(7) internal
       locks that make calls atomic, so the callback function must not try to append to the log itself or  dead‐
       lock will occur.

RETURN VALUE

       On success, pmemlog_tell() returns the current write point for the log.  On error, it returns -1 and sets
       errno appropriately.

       The pmemlog_rewind() and pmemlog_walk() functions return no value.

SEE ALSO

       libpmemlog(7) and <https://pmem.io>

PMDK - pmemlog API version 1.1                     2021-09-24                                    PMEMLOG_TELL(3)