src/midx.h

   1 /*
   2  * Copyright (C) the libgit2 contributors. All rights reserved.
   3  *
   4  * This file is part of libgit2, distributed under the GNU GPL v2 with
   5  * a Linking Exception. For full terms see the included COPYING file.
   6  */
   7
   8 #ifndef INCLUDE_midx_h__
   9 #define INCLUDE_midx_h__
  10
  11 #include "common.h"
  12
  13 #include <ctype.h>
  14
  15 #include "git2/sys/midx.h"
  16
  17 #include "map.h"
  18 #include "mwindow.h"
  19 #include "odb.h"
  20
  21 /*
  22  * A multi-pack-index file.
  23  *
  24  * This file contains a merged index for multiple independent .pack files. This
  25  * can help speed up locating objects without requiring a garbage collection
  26  * cycle to create a single .pack file.
  27  *
  28  * Support for this feature was added in git 2.21, and requires the
  29  * `core.multiPackIndex` config option to be set.
  30  */
  31 typedef struct git_midx_file {
  32         git_map index_map;
  33
  34         /* The table of Packfile Names. */
  35         git_vector packfile_names;
  36
  37         /* The OID Fanout table. */
  38         const uint32_t *oid_fanout;
  39         /* The total number of objects in the index. */
  40         uint32_t num_objects;
  41
  42         /* The OID Lookup table. */
  43         git_oid *oid_lookup;
  44
  45         /* The Object Offsets table. Each entry has two 4-byte fields with the pack index and the offset. */
  46         const unsigned char *object_offsets;
  47
  48         /* The Object Large Offsets table. */
  49         const unsigned char *object_large_offsets;
  50         /* The number of entries in the Object Large Offsets table. Each entry has an 8-byte with an offset */
  51         size_t num_object_large_offsets;
  52
  53         /* The trailer of the file. Contains the SHA1-checksum of the whole file. */
  54         git_oid checksum;
  55
  56         /* something like ".git/objects/pack/multi-pack-index". */
  57         git_buf filename;
  58 } git_midx_file;
  59
  60 /*
  61  * An entry in the multi-pack-index file. Similar in purpose to git_pack_entry.
  62  */
  63 typedef struct git_midx_entry {
  64         /* The index within idx->packfile_names where the packfile name can be found. */
  65         size_t pack_index;
  66         /* The offset within the .pack file where the requested object is found. */
  67         off64_t offset;
  68         /* The SHA-1 hash of the requested object. */
  69         git_oid sha1;
  70 } git_midx_entry;
  71
  72 /*
  73  * A writer for `multi-pack-index` files.
  74  */
  75 struct git_midx_writer {
  76         /*
  77          * The path of the directory where the .pack/.idx files are stored. The
  78          * `multi-pack-index` file will be written to the same directory.
  79          */
  80         git_buf pack_dir;
  81
  82         /* The list of `git_pack_file`s. */
  83         git_vector packs;
  84 };
  85
  86 int git_midx_open(
  87                 git_midx_file **idx_out,
  88                 const char *path);
  89 bool git_midx_needs_refresh(
  90                 const git_midx_file *idx,
  91                 const char *path);
  92 int git_midx_entry_find(
  93                 git_midx_entry *e,
  94                 git_midx_file *idx,
  95                 const git_oid *short_oid,
  96                 size_t len);
  97 int git_midx_foreach_entry(
  98                 git_midx_file *idx,
  99                 git_odb_foreach_cb cb,
 100                 void *data);
 101 int git_midx_close(git_midx_file *idx);
 102 void git_midx_free(git_midx_file *idx);
 103
 104 /* This is exposed for use in the fuzzers. */
 105 int git_midx_parse(
 106                 git_midx_file *idx,
 107                 const unsigned char *data,
 108                 size_t size);
 109
 110 #endif