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605 lines (491 loc) · 15.8 KB
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/*
* Copyright (C) the libgit2 contributors. All rights reserved.
*
* This file is part of libgit2, distributed under the GNU GPL v2 with
* a Linking Exception. For full terms see the included COPYING file.
*/
#include "common.h"
#include <zlib.h>
#include "git2/repository.h"
#include "git2/oid.h"
#include "fileops.h"
#include "hash.h"
#include "odb.h"
#include "delta-apply.h"
#include "sha1_lookup.h"
#include "mwindow.h"
#include "pack.h"
#include "git2/odb_backend.h"
struct pack_backend {
git_odb_backend parent;
git_vector packs;
struct git_pack_file *last_found;
char *pack_folder;
};
struct pack_writepack {
struct git_odb_writepack parent;
git_indexer_stream *indexer_stream;
};
/**
* The wonderful tale of a Packed Object lookup query
* ===================================================
* A riveting and epic story of epicness and ASCII
* art, presented by yours truly,
* Sir Vicent of Marti
*
*
* Chapter 1: Once upon a time...
* Initialization of the Pack Backend
* --------------------------------------------------
*
* # git_odb_backend_pack
* | Creates the pack backend structure, initializes the
* | callback pointers to our default read() and exist() methods,
* | and tries to preload all the known packfiles in the ODB.
* |
* |-# packfile_load_all
* | Tries to find the `pack` folder, if it exists. ODBs without
* | a pack folder are ignored altogether. If there's a `pack` folder
* | we run a `dirent` callback through every file in the pack folder
* | to find our packfiles. The packfiles are then sorted according
* | to a sorting callback.
* |
* |-# packfile_load__cb
* | | This callback is called from `dirent` with every single file
* | | inside the pack folder. We find the packs by actually locating
* | | their index (ends in ".idx"). From that index, we verify that
* | | the corresponding packfile exists and is valid, and if so, we
* | | add it to the pack list.
* | |
* | |-# packfile_check
* | Make sure that there's a packfile to back this index, and store
* | some very basic information regarding the packfile itself,
* | such as the full path, the size, and the modification time.
* | We don't actually open the packfile to check for internal consistency.
* |
* |-# packfile_sort__cb
* Sort all the preloaded packs according to some specific criteria:
* we prioritize the "newer" packs because it's more likely they
* contain the objects we are looking for, and we prioritize local
* packs over remote ones.
*
*
*
* Chapter 2: To be, or not to be...
* A standard packed `exist` query for an OID
* --------------------------------------------------
*
* # pack_backend__exists
* | Check if the given SHA1 oid exists in any of the packs
* | that have been loaded for our ODB.
* |
* |-# pack_entry_find
* | Iterate through all the packs that have been preloaded
* | (starting by the pack where the latest object was found)
* | to try to find the OID in one of them.
* |
* |-# pack_entry_find1
* | Check the index of an individual pack to see if the SHA1
* | OID can be found. If we can find the offset to that SHA1
* | inside of the index, that means the object is contained
* | inside of the packfile and we can stop searching.
* | Before returning, we verify that the packfile behing the
* | index we are searching still exists on disk.
* |
* |-# pack_entry_find_offset
* | | Mmap the actual index file to disk if it hasn't been opened
* | | yet, and run a binary search through it to find the OID.
* | | See <http://book.git-scm.com/7_the_packfile.html> for specifics
* | | on the Packfile Index format and how do we find entries in it.
* | |
* | |-# pack_index_open
* | | Guess the name of the index based on the full path to the
* | | packfile, open it and verify its contents. Only if the index
* | | has not been opened already.
* | |
* | |-# pack_index_check
* | Mmap the index file and do a quick run through the header
* | to guess the index version (right now we support v1 and v2),
* | and to verify that the size of the index makes sense.
* |
* |-# packfile_open
* See `packfile_open` in Chapter 3
*
*
*
* Chapter 3: The neverending story...
* A standard packed `lookup` query for an OID
* --------------------------------------------------
* TODO
*
*/
/***********************************************************
*
* FORWARD DECLARATIONS
*
***********************************************************/
static int packfile_sort__cb(const void *a_, const void *b_);
static int packfile_load__cb(void *_data, git_buf *path);
static int pack_entry_find(struct git_pack_entry *e,
struct pack_backend *backend, const git_oid *oid);
/* Can find the offset of an object given
* a prefix of an identifier.
* Sets GIT_EAMBIGUOUS if short oid is ambiguous.
* This method assumes that len is between
* GIT_OID_MINPREFIXLEN and GIT_OID_HEXSZ.
*/
static int pack_entry_find_prefix(
struct git_pack_entry *e,
struct pack_backend *backend,
const git_oid *short_oid,
size_t len);
/***********************************************************
*
* PACK WINDOW MANAGEMENT
*
***********************************************************/
static int packfile_sort__cb(const void *a_, const void *b_)
{
const struct git_pack_file *a = a_;
const struct git_pack_file *b = b_;
int st;
/*
* Local packs tend to contain objects specific to our
* variant of the project than remote ones. In addition,
* remote ones could be on a network mounted filesystem.
* Favor local ones for these reasons.
*/
st = a->pack_local - b->pack_local;
if (st)
return -st;
/*
* Younger packs tend to contain more recent objects,
* and more recent objects tend to get accessed more
* often.
*/
if (a->mtime < b->mtime)
return 1;
else if (a->mtime == b->mtime)
return 0;
return -1;
}
static int packfile_load__cb(void *_data, git_buf *path)
{
struct pack_backend *backend = (struct pack_backend *)_data;
struct git_pack_file *pack;
int error;
size_t i;
if (git__suffixcmp(path->ptr, ".idx") != 0)
return 0; /* not an index */
for (i = 0; i < backend->packs.length; ++i) {
struct git_pack_file *p = git_vector_get(&backend->packs, i);
if (memcmp(p->pack_name, git_buf_cstr(path), git_buf_len(path) - strlen(".idx")) == 0)
return 0;
}
error = git_packfile_check(&pack, path->ptr);
if (error == GIT_ENOTFOUND)
/* ignore missing .pack file as git does */
return 0;
else if (error < 0)
return error;
return git_vector_insert(&backend->packs, pack);
}
static int pack_entry_find_inner(
struct git_pack_entry *e,
struct pack_backend *backend,
const git_oid *oid,
struct git_pack_file *last_found)
{
size_t i;
if (last_found &&
git_pack_entry_find(e, last_found, oid, GIT_OID_HEXSZ) == 0)
return 0;
for (i = 0; i < backend->packs.length; ++i) {
struct git_pack_file *p;
p = git_vector_get(&backend->packs, i);
if (p == last_found)
continue;
if (git_pack_entry_find(e, p, oid, GIT_OID_HEXSZ) == 0) {
backend->last_found = p;
return 0;
}
}
return -1;
}
static int pack_entry_find(struct git_pack_entry *e, struct pack_backend *backend, const git_oid *oid)
{
struct git_pack_file *last_found = backend->last_found;
if (backend->last_found &&
git_pack_entry_find(e, backend->last_found, oid, GIT_OID_HEXSZ) == 0)
return 0;
if (!pack_entry_find_inner(e, backend, oid, last_found))
return 0;
return git_odb__error_notfound("failed to find pack entry", oid);
}
static unsigned pack_entry_find_prefix_inner(
struct git_pack_entry *e,
struct pack_backend *backend,
const git_oid *short_oid,
size_t len,
struct git_pack_file *last_found)
{
int error;
size_t i;
unsigned found = 0;
if (last_found) {
error = git_pack_entry_find(e, last_found, short_oid, len);
if (error == GIT_EAMBIGUOUS)
return error;
if (!error)
found = 1;
}
for (i = 0; i < backend->packs.length; ++i) {
struct git_pack_file *p;
p = git_vector_get(&backend->packs, i);
if (p == last_found)
continue;
error = git_pack_entry_find(e, p, short_oid, len);
if (error == GIT_EAMBIGUOUS)
return error;
if (!error) {
if (++found > 1)
break;
backend->last_found = p;
}
}
return found;
}
static int pack_entry_find_prefix(
struct git_pack_entry *e,
struct pack_backend *backend,
const git_oid *short_oid,
size_t len)
{
struct git_pack_file *last_found = backend->last_found;
unsigned int found = pack_entry_find_prefix_inner(e, backend, short_oid, len, last_found);
if (!found)
return git_odb__error_notfound("no matching pack entry for prefix", short_oid);
else if (found > 1)
return git_odb__error_ambiguous("found multiple pack entries");
else
return 0;
}
/***********************************************************
*
* PACKED BACKEND PUBLIC API
*
* Implement the git_odb_backend API calls
*
***********************************************************/
static int pack_backend__refresh(git_odb_backend *_backend)
{
struct pack_backend *backend = (struct pack_backend *)_backend;
int error;
struct stat st;
git_buf path = GIT_BUF_INIT;
if (backend->pack_folder == NULL)
return 0;
if (p_stat(backend->pack_folder, &st) < 0 || !S_ISDIR(st.st_mode))
return git_odb__error_notfound("failed to refresh packfiles", NULL);
git_buf_sets(&path, backend->pack_folder);
/* reload all packs */
error = git_path_direach(&path, packfile_load__cb, (void *)backend);
git_buf_free(&path);
if (error < 0)
return error;
git_vector_sort(&backend->packs);
return 0;
}
static int pack_backend__read_header(size_t *len_p, git_otype *type_p, struct git_odb_backend *backend, const git_oid *oid)
{
struct git_pack_entry e;
int error;
assert(len_p && type_p && backend && oid);
if ((error = pack_entry_find(&e, (struct pack_backend *)backend, oid)) < 0)
return error;
return git_packfile_resolve_header(len_p, type_p, e.p, e.offset);
}
static int pack_backend__read(void **buffer_p, size_t *len_p, git_otype *type_p, git_odb_backend *backend, const git_oid *oid)
{
struct git_pack_entry e;
git_rawobj raw;
int error;
if ((error = pack_entry_find(&e, (struct pack_backend *)backend, oid)) < 0 ||
(error = git_packfile_unpack(&raw, e.p, &e.offset)) < 0)
return error;
*buffer_p = raw.data;
*len_p = raw.len;
*type_p = raw.type;
return 0;
}
static int pack_backend__read_prefix(
git_oid *out_oid,
void **buffer_p,
size_t *len_p,
git_otype *type_p,
git_odb_backend *backend,
const git_oid *short_oid,
size_t len)
{
int error = 0;
if (len < GIT_OID_MINPREFIXLEN)
error = git_odb__error_ambiguous("prefix length too short");
else if (len >= GIT_OID_HEXSZ) {
/* We can fall back to regular read method */
error = pack_backend__read(buffer_p, len_p, type_p, backend, short_oid);
if (!error)
git_oid_cpy(out_oid, short_oid);
} else {
struct git_pack_entry e;
git_rawobj raw;
if ((error = pack_entry_find_prefix(
&e, (struct pack_backend *)backend, short_oid, len)) == 0 &&
(error = git_packfile_unpack(&raw, e.p, &e.offset)) == 0)
{
*buffer_p = raw.data;
*len_p = raw.len;
*type_p = raw.type;
git_oid_cpy(out_oid, &e.sha1);
}
}
return error;
}
static int pack_backend__exists(git_odb_backend *backend, const git_oid *oid)
{
struct git_pack_entry e;
return pack_entry_find(&e, (struct pack_backend *)backend, oid) == 0;
}
static int pack_backend__foreach(git_odb_backend *_backend, git_odb_foreach_cb cb, void *data)
{
int error;
struct git_pack_file *p;
struct pack_backend *backend;
unsigned int i;
assert(_backend && cb);
backend = (struct pack_backend *)_backend;
/* Make sure we know about the packfiles */
if ((error = pack_backend__refresh(_backend)) < 0)
return error;
git_vector_foreach(&backend->packs, i, p) {
if ((error = git_pack_foreach_entry(p, cb, data)) < 0)
return error;
}
return 0;
}
static int pack_backend__writepack_add(struct git_odb_writepack *_writepack, const void *data, size_t size, git_transfer_progress *stats)
{
struct pack_writepack *writepack = (struct pack_writepack *)_writepack;
assert(writepack);
return git_indexer_stream_add(writepack->indexer_stream, data, size, stats);
}
static int pack_backend__writepack_commit(struct git_odb_writepack *_writepack, git_transfer_progress *stats)
{
struct pack_writepack *writepack = (struct pack_writepack *)_writepack;
assert(writepack);
return git_indexer_stream_finalize(writepack->indexer_stream, stats);
}
static void pack_backend__writepack_free(struct git_odb_writepack *_writepack)
{
struct pack_writepack *writepack = (struct pack_writepack *)_writepack;
assert(writepack);
git_indexer_stream_free(writepack->indexer_stream);
git__free(writepack);
}
static int pack_backend__writepack(struct git_odb_writepack **out,
git_odb_backend *_backend,
git_transfer_progress_callback progress_cb,
void *progress_payload)
{
struct pack_backend *backend;
struct pack_writepack *writepack;
assert(out && _backend);
*out = NULL;
backend = (struct pack_backend *)_backend;
writepack = git__calloc(1, sizeof(struct pack_writepack));
GITERR_CHECK_ALLOC(writepack);
if (git_indexer_stream_new(&writepack->indexer_stream,
backend->pack_folder, progress_cb, progress_payload) < 0) {
git__free(writepack);
return -1;
}
writepack->parent.backend = _backend;
writepack->parent.add = pack_backend__writepack_add;
writepack->parent.commit = pack_backend__writepack_commit;
writepack->parent.free = pack_backend__writepack_free;
*out = (git_odb_writepack *)writepack;
return 0;
}
static void pack_backend__free(git_odb_backend *_backend)
{
struct pack_backend *backend;
size_t i;
assert(_backend);
backend = (struct pack_backend *)_backend;
for (i = 0; i < backend->packs.length; ++i) {
struct git_pack_file *p = git_vector_get(&backend->packs, i);
git_packfile_free(p);
}
git_vector_free(&backend->packs);
git__free(backend->pack_folder);
git__free(backend);
}
int git_odb_backend_one_pack(git_odb_backend **backend_out, const char *idx)
{
struct pack_backend *backend = NULL;
struct git_pack_file *packfile = NULL;
if (git_packfile_check(&packfile, idx) < 0)
return -1;
backend = git__calloc(1, sizeof(struct pack_backend));
GITERR_CHECK_ALLOC(backend);
backend->parent.version = GIT_ODB_BACKEND_VERSION;
if (git_vector_init(&backend->packs, 1, NULL) < 0)
goto on_error;
if (git_vector_insert(&backend->packs, packfile) < 0)
goto on_error;
backend->parent.read = &pack_backend__read;
backend->parent.read_prefix = &pack_backend__read_prefix;
backend->parent.read_header = &pack_backend__read_header;
backend->parent.exists = &pack_backend__exists;
backend->parent.refresh = &pack_backend__refresh;
backend->parent.foreach = &pack_backend__foreach;
backend->parent.free = &pack_backend__free;
*backend_out = (git_odb_backend *)backend;
return 0;
on_error:
git_vector_free(&backend->packs);
git__free(backend);
git__free(packfile);
return -1;
}
int git_odb_backend_pack(git_odb_backend **backend_out, const char *objects_dir)
{
struct pack_backend *backend = NULL;
git_buf path = GIT_BUF_INIT;
backend = git__calloc(1, sizeof(struct pack_backend));
GITERR_CHECK_ALLOC(backend);
backend->parent.version = GIT_ODB_BACKEND_VERSION;
if (git_vector_init(&backend->packs, 8, packfile_sort__cb) < 0 ||
git_buf_joinpath(&path, objects_dir, "pack") < 0)
{
git__free(backend);
return -1;
}
if (git_path_isdir(git_buf_cstr(&path)) == true) {
int error;
backend->pack_folder = git_buf_detach(&path);
error = pack_backend__refresh((git_odb_backend *)backend);
if (error < 0)
return error;
}
backend->parent.read = &pack_backend__read;
backend->parent.read_prefix = &pack_backend__read_prefix;
backend->parent.read_header = &pack_backend__read_header;
backend->parent.exists = &pack_backend__exists;
backend->parent.refresh = &pack_backend__refresh;
backend->parent.foreach = &pack_backend__foreach;
backend->parent.writepack = &pack_backend__writepack;
backend->parent.free = &pack_backend__free;
*backend_out = (git_odb_backend *)backend;
git_buf_free(&path);
return 0;
}
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