MTBL_FILESET(3)MTBL_FILESET(3)NAMEmtbl_fileset - automatic multiple MTBL data file merger
SYNOPSIS
#include <mtbl.h>
Fileset objects:
struct mtbl_fileset *
mtbl_fileset_init(const char *fname, const struct mtbl_fileset_options *fopt);
void
mtbl_fileset_destroy(struct mtbl_fileset **f);
void
mtbl_fileset_reload(struct mtbl_fileset *f);
void
mtbl_fileset_reload_now(struct mtbl_fileset *f);
const struct mtbl_source *
mtbl_fileset_source(struct mtbl_fileset *f);
Fileset options:
struct mtbl_fileset_options *
mtbl_fileset_options_init(void);
void
mtbl_fileset_options_destroy(struct mtbl_fileset_options **fopt);
void
mtbl_fileset_options_set_merge_func(
struct mtbl_fileset_options *fopt,
mtbl_merge_func fp,
void *clos);
void
mtbl_fileset_options_set_reload_interval(
struct mtbl_fileset_options *fopt,
uint32_t reload_interval);
DESCRIPTION
The mtbl_fileset is a convenience interface for automatically
maintaining a merged view of a set of MTBL data files. The merged
entries may be consumed via the mtbl_source(3) and mtbl_iter(3)
interfaces.
mtbl_fileset objects are initialized from a "setfile", which specifies
a list of filenames of MTBL data files, one per line. Internally, an
mtbl_reader object is initialized from each filename and added to an
mtbl_merger object. The setfile is watched for changes and the addition
or removal of filenames from the setfile will result in the
corresponding addition or removal of mtbl_reader objects.
Because the MTBL format does not allow duplicate keys, the caller must
provide a function which will accept a key and two conflicting values
for that key and return a replacement value. This function may be
called multiple times for the same key if the same key is inserted more
than twice. See mtbl_merger(3) for further details about the merge
function.
mtbl_fileset objects are created with the mtbl_fileset_init() function,
which requires the path to a "setfile", fname, and a non-NULL fopt
argument which has been configured with a merge function fp.
mtbl_fileset_source() should then be called in order to consume output
via the mtbl_source(3) interface.
Accesses via the mtbl_source(3) interface will implicitly check for
updates to the setfile. However, it may be necessary to explicitly call
the mtbl_fileset_reload() function in order to check for updates,
especially if files are being removed from the setfile and the
mtbl_source is infrequently accessed.
The mtbl_fileset_reload() function avoids checking for updates more
frequently than every reload_interval seconds. The
mtbl_fileset_reload_now() function can be called to bypass the
reload_interval check.
Fileset options
merge_func
See mtbl_merger(3). An mtbl_merger object is used internally for
the external sort.
reload_interval
Specifies the interval between checks for updates to the setfile,
in seconds. Defaults to 60 seconds.
07/11/2015 MTBL_FILESET(3)
