DragonFly On-Line Manual Pages

Search: Section:  

MTBL_FILESET(3)                                                MTBL_FILESET(3)


NAME

       mtbl_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)

Search: Section: