NAME

       pmempool_feature_query(),  pmempool_feature_enable(),  pmempool_feature_disable() - toggle
       or query pool set features

SYNOPSIS

              #include <libpmempool.h>

              int pmempool_feature_query(const char *path, enum pmempool_feature feature, unsigned flags);

              int pmempool_feature_enable(const char *path, enum pmempool_feature feature, unsigned flags);

              int pmempool_feature_disable(const char *path, enum pmempool_feature feature, unsigned flags);

DESCRIPTION

       The feature argument accepts following values:

       • PMEMPOOL_FEAT_SINGLEHDR - only the first part in each replica  contains  the  pool  part
         internal  metadata.   This value can be used only with pmempool_feature_query().  It can
         not be enabled or disabled.  For details see poolset(5).

       • PMEMPOOL_FEAT_CKSUM_2K -  only  the  first  2KiB  of  pool  part  internal  metadata  is
         checksummed.   Other  features  may  depend  on this one to store additional metadata in
         otherwise unused second 2KiB part of a header.  When PMEMPOOL_FEAT_CKSUM_2K is  disabled
         whole 4KiB is checksummed.

       • PMEMPOOL_FEAT_SHUTDOWN_STATE - enables additional check performed during pool open which
         verifies pool consistency in the presence of dirty shutdown.  PMEMPOOL_FEAT_CKSUM_2K has
         to    be    enabled    prior    to   PMEMPOOL_FEAT_SHUTDOWN_STATE   otherwise   enabling
         PMEMPOOL_FEAT_SHUTDOWN_STATE will fail.

       • PMEMPOOL_FEAT_CHECK_BAD_BLOCKS - enables checking bad blocks performed during opening  a
         pool  and  fixing  bad  blocks  performed  by  pmempool-sync during syncing a pool.  For
         details see pmempool-feature(1).

       The pmempool_feature_query() function checks state of feature in the pool set  pointed  by
       path.

       The pmempool_feature_enable() function enables feature in the pool set pointed by path.

       The pmempool_feature_disable() function disables feature in the pool set pointed by path.

COMPATIBILITY

       Poolsets  with  features  not defined in this document (e.g. enabled by the newer software
       version) are not supported.

DISCLAIMER

       pmempool_feature_query(), pmempool_feature_enable() and pmempool_feature_disable() are not
       fail safe.

RETURN VALUE

       On  success,  pmempool_feature_query()  returns  0  if  feature  is disabled or 1 if it is
       enabled.  On error, it returns -1 and sets errno accordingly.

       On success, pmempool_feature_enable() returns 0.  On error, it returns -1 and  sets  errno
       accordingly.

       On  success, pmempool_feature_disable() returns 0.  On error, it returns -1 and sets errno
       accordingly.

       If non zero flags are provided errno is set to EINVAL and function returns -1.

SEE ALSO

       poolset(5) and <https://pmem.io>