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  function process_chunk for each chunksize block of data found.  The argument arg
       is also passed to the callback 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 deadlock 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 <http://pmem.io>