reftable/reftable-merged.h

   1 /*
   2 Copyright 2020 Google LLC
   3
   4 Use of this source code is governed by a BSD-style
   5 license that can be found in the LICENSE file or at
   6 https://developers.google.com/open-source/licenses/bsd
   7 */
   8
   9 #ifndef REFTABLE_MERGED_H
  10 #define REFTABLE_MERGED_H
  11
  12 #include "reftable-iterator.h"
  13
  14 /*
  15  * Merged tables
  16  *
  17  * A ref database kept in a sequence of table files. The merged_table presents a
  18  * unified view to reading (seeking, iterating) a sequence of immutable tables.
  19  *
  20  * The merged tables are on purpose kept disconnected from their actual storage
  21  * (eg. files on disk), because it is useful to merge tables aren't files. For
  22  * example, the per-workspace and global ref namespace can be implemented as a
  23  * merged table of two stacks of file-backed reftables.
  24  */
  25
  26 /* A merged table is implements seeking/iterating over a stack of tables. */
  27 struct reftable_merged_table;
  28
  29 struct reftable_reader;
  30
  31 /*
  32  * reftable_merged_table_new creates a new merged table. The readers must be
  33  * kept alive as long as the merged table is still in use.
  34  */
  35 int reftable_merged_table_new(struct reftable_merged_table **dest,
  36                               struct reftable_reader **readers, size_t n,
  37                               uint32_t hash_id);
  38
  39 /* Initialize a merged table iterator for reading refs. */
  40 int reftable_merged_table_init_ref_iterator(struct reftable_merged_table *mt,
  41                                             struct reftable_iterator *it);
  42
  43 /* Initialize a merged table iterator for reading logs. */
  44 int reftable_merged_table_init_log_iterator(struct reftable_merged_table *mt,
  45                                             struct reftable_iterator *it);
  46
  47 /* returns the max update_index covered by this merged table. */
  48 uint64_t
  49 reftable_merged_table_max_update_index(struct reftable_merged_table *mt);
  50
  51 /* returns the min update_index covered by this merged table. */
  52 uint64_t
  53 reftable_merged_table_min_update_index(struct reftable_merged_table *mt);
  54
  55 /* releases memory for the merged_table */
  56 void reftable_merged_table_free(struct reftable_merged_table *m);
  57
  58 /* return the hash ID of the merged table. */
  59 uint32_t reftable_merged_table_hash_id(struct reftable_merged_table *m);
  60
  61 #endif