1PMEM2_GET_FLUSH_FN(3)      PMDK Programmer's Manual      PMEM2_GET_FLUSH_FN(3)
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NAME

6       pmem2_get_flush_fn() - get a flush function
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SYNOPSIS

9              #include <libpmem2.h>
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11              typedef void (*pmem2_flush_fn)(const void *ptr, size_t size);
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13              struct pmem2_map;
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15              pmem2_flush_fn pmem2_get_flush_fn(struct pmem2_map *map);
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DESCRIPTION

18       The  pmem2_get_flush_fn()  function returns a pointer to a function re‐
19       sponsible for efficiently flushing data in the range owned by the map.
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21       Flushing data using pmem2_flush_fn does not guarantee that the data  is
22       stored durably by the time it returns.  To get this guarantee, applica‐
23       tion should  either  use  the  persist  operation  (see  pmem2_get_per‐
24       sist_fn(3))   or  follow  pmem2_flush_fn  by  a  drain  operation  (see
25       pmem2_get_drain_fn(3)).
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27       There are no alignment restrictions on the range described by  ptr  and
28       size,  but  pmem2_flush_fn  may  expand  the range as necessary to meet
29       platform alignment requirements.
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31       There is nothing atomic or transactional about pmem2_flush_fn.  Any un‐
32       written  stores in the given range will be written, but some stores may
33       have already been written by virtue of normal  cache  eviction/replace‐
34       ment  policies.  Correctly written code must not depend on stores wait‐
35       ing until pmem2_flush_fn is called to be flushed – they can be  flushed
36       at any time before pmem2_flush_fn is called.
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38       If  two  (or  more) mappings share the same pmem2_flush_fn and they are
39       adjacent to each other, it is safe to call this function  for  a  range
40       spanning those mappings.
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RETURN VALUE

43       The pmem2_get_flush_fn() function never returns NULL.
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45       The pmem2_get_flush_fn() for the same map always returns the same func‐
46       tion.  This means that it's safe to cache its return  value.   However,
47       this  function  is very cheap (because it returns a precomputed value),
48       so caching may not be necessary.
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SEE ALSO

51       pmem2_get_drain_fn(3), pmem2_get_persist_fn(3), pmem2_map_new(3), libp‐
52       mem2(7) and <https://pmem.io>
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56PMDK - pmem2 API version 1.0      2022-08-25             PMEM2_GET_FLUSH_FN(3)
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