SIMPLE SOLUTIONS

MTBL_FILESET(3) - Linux man page online | Library functions

Automatic multiple MTBL data file merger.

Chapter
07/11/2015
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)
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mtbl_fileset(3) referred by mtbl(7)
refer to mtbl_iter(3) | mtbl_merger(3) | mtbl_source(3)
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