git/reftable/reftable-merged.h
Han-Wen Nienhuys 1ae2b8cda8 reftable: add merged table view
This adds an abstract, read-only interface to the ref database.

This primitive is used to construct the read view of the ref database
(the read view is constructed by merging several *.ref files). It also
provides the mechanism to provide a unified view of the refs in the main
repository and the per-worktree refs.

Signed-off-by: Han-Wen Nienhuys <hanwen@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-10-08 10:45:48 -07:00

72 lines
2.4 KiB
C

/*
Copyright 2020 Google LLC
Use of this source code is governed by a BSD-style
license that can be found in the LICENSE file or at
https://developers.google.com/open-source/licenses/bsd
*/
#ifndef REFTABLE_MERGED_H
#define REFTABLE_MERGED_H
#include "reftable-iterator.h"
/*
* Merged tables
*
* A ref database kept in a sequence of table files. The merged_table presents a
* unified view to reading (seeking, iterating) a sequence of immutable tables.
*
* The merged tables are on purpose kept disconnected from their actual storage
* (eg. files on disk), because it is useful to merge tables aren't files. For
* example, the per-workspace and global ref namespace can be implemented as a
* merged table of two stacks of file-backed reftables.
*/
/* A merged table is implements seeking/iterating over a stack of tables. */
struct reftable_merged_table;
/* A generic reftable; see below. */
struct reftable_table;
/* reftable_new_merged_table creates a new merged table. It takes ownership of
the stack array.
*/
int reftable_new_merged_table(struct reftable_merged_table **dest,
struct reftable_table *stack, int n,
uint32_t hash_id);
/* returns an iterator positioned just before 'name' */
int reftable_merged_table_seek_ref(struct reftable_merged_table *mt,
struct reftable_iterator *it,
const char *name);
/* returns an iterator for log entry, at given update_index */
int reftable_merged_table_seek_log_at(struct reftable_merged_table *mt,
struct reftable_iterator *it,
const char *name, uint64_t update_index);
/* like reftable_merged_table_seek_log_at but look for the newest entry. */
int reftable_merged_table_seek_log(struct reftable_merged_table *mt,
struct reftable_iterator *it,
const char *name);
/* returns the max update_index covered by this merged table. */
uint64_t
reftable_merged_table_max_update_index(struct reftable_merged_table *mt);
/* returns the min update_index covered by this merged table. */
uint64_t
reftable_merged_table_min_update_index(struct reftable_merged_table *mt);
/* releases memory for the merged_table */
void reftable_merged_table_free(struct reftable_merged_table *m);
/* return the hash ID of the merged table. */
uint32_t reftable_merged_table_hash_id(struct reftable_merged_table *m);
/* create a generic table from reftable_merged_table */
void reftable_table_from_merged_table(struct reftable_table *tab,
struct reftable_merged_table *table);
#endif