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>