NAME

       pmem2_get_flush_fn() - get a flush function

SYNOPSIS

              #include <libpmem2.h>

              typedef void (*pmem2_flush_fn)(const void *ptr, size_t size);

              struct pmem2_map;

              pmem2_flush_fn pmem2_get_flush_fn(struct pmem2_map *map);

DESCRIPTION

       The  pmem2_get_flush_fn()  function  returns  a  pointer  to  a  function  responsible for
       efficiently flushing data in the range owned by the map.

       Flushing data using pmem2_flush_fn does not guarantee that the data is stored  durably  by
       the  time  it  returns.   To get this guarantee, application should either use the persist
       operation (see pmem2_get_persist_fn(3)) or follow pmem2_flush_fn by a drain operation (see
       pmem2_get_drain_fn(3)).

       There  are  no  alignment  restrictions  on  the  range  described  by  ptr  and size, but
       pmem2_flush_fn may expand the range as necessary to meet platform alignment requirements.

       There is nothing atomic or transactional about pmem2_flush_fn.  Any  unwritten  stores  in
       the  given  range will be written, but some stores may have already been written by virtue
       of normal cache eviction/replacement policies.  Correctly written code must not depend  on
       stores  waiting  until pmem2_flush_fn is called to be flushed – they can be flushed at any
       time before pmem2_flush_fn is called.

       If two (or more) mappings share the same pmem2_flush_fn and  they  are  adjacent  to  each
       other, it is safe to call this function for a range spanning those mappings.

RETURN VALUE

       The pmem2_get_flush_fn() function never returns NULL.

       The  pmem2_get_flush_fn()  for  the same map always returns the same function.  This means
       that it's safe to cache its return value.  However, this function is very  cheap  (because
       it returns a precomputed value), so caching may not be necessary.

SEE ALSO

       pmem2_get_drain_fn(3),    pmem2_get_persist_fn(3),   pmem2_map_new(3),   libpmem2(7)   and
       <https://pmem.io>