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 /* A generic reftable; see below. */
  30 struct reftable_table;
  31
  32 /* reftable_new_merged_table creates a new merged table. It takes ownership of
  33    the stack array.
  34 */
  35 int reftable_new_merged_table(struct reftable_merged_table **dest,
  36                               struct reftable_table *stack, int n,
  37                               uint32_t hash_id);
  38
  39 /* returns an iterator positioned just before 'name' */
  40 int reftable_merged_table_seek_ref(struct reftable_merged_table *mt,
  41                                    struct reftable_iterator *it,
  42                                    const char *name);
  43
  44 /* returns an iterator for log entry, at given update_index */
  45 int reftable_merged_table_seek_log_at(struct reftable_merged_table *mt,
  46                                       struct reftable_iterator *it,
  47                                       const char *name, uint64_t update_index);
  48
  49 /* like reftable_merged_table_seek_log_at but look for the newest entry. */
  50 int reftable_merged_table_seek_log(struct reftable_merged_table *mt,
  51                                    struct reftable_iterator *it,
  52                                    const char *name);
  53
  54 /* returns the max update_index covered by this merged table. */
  55 uint64_t
  56 reftable_merged_table_max_update_index(struct reftable_merged_table *mt);
  57
  58 /* returns the min update_index covered by this merged table. */
  59 uint64_t
  60 reftable_merged_table_min_update_index(struct reftable_merged_table *mt);
  61
  62 /* releases memory for the merged_table */
  63 void reftable_merged_table_free(struct reftable_merged_table *m);
  64
  65 /* return the hash ID of the merged table. */
  66 uint32_t reftable_merged_table_hash_id(struct reftable_merged_table *m);
  67
  68 /* create a generic table from reftable_merged_table */
  69 void reftable_table_from_merged_table(struct reftable_table *tab,
  70                                       struct reftable_merged_table *table);
  71
  72 #endif