Git Source Code Mirror - This is a publish-only repository and all pull requests are ignored. Please follow Documentation/SubmittingPatches procedure for any of your improvements. https://git-scm.com/
You can not select more than 25 topics Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
git/commit-graph.c

1071 lines
28 KiB

#include "cache.h"
#include "config.h"
#include "dir.h"
#include "git-compat-util.h"
#include "lockfile.h"
#include "pack.h"
#include "packfile.h"
#include "commit.h"
#include "object.h"
#include "refs.h"
#include "revision.h"
#include "sha1-lookup.h"
#include "commit-graph.h"
#include "object-store.h"
#include "alloc.h"
#include "hashmap.h"
#include "replace-object.h"
#define GRAPH_SIGNATURE 0x43475048 /* "CGPH" */
#define GRAPH_CHUNKID_OIDFANOUT 0x4f494446 /* "OIDF" */
#define GRAPH_CHUNKID_OIDLOOKUP 0x4f49444c /* "OIDL" */
#define GRAPH_CHUNKID_DATA 0x43444154 /* "CDAT" */
#define GRAPH_CHUNKID_LARGEEDGES 0x45444745 /* "EDGE" */
#define GRAPH_DATA_WIDTH 36
#define GRAPH_VERSION_1 0x1
#define GRAPH_VERSION GRAPH_VERSION_1
#define GRAPH_OID_VERSION_SHA1 1
#define GRAPH_OID_LEN_SHA1 GIT_SHA1_RAWSZ
#define GRAPH_OID_VERSION GRAPH_OID_VERSION_SHA1
#define GRAPH_OID_LEN GRAPH_OID_LEN_SHA1
#define GRAPH_OCTOPUS_EDGES_NEEDED 0x80000000
#define GRAPH_PARENT_MISSING 0x7fffffff
#define GRAPH_EDGE_LAST_MASK 0x7fffffff
#define GRAPH_PARENT_NONE 0x70000000
#define GRAPH_LAST_EDGE 0x80000000
#define GRAPH_HEADER_SIZE 8
#define GRAPH_FANOUT_SIZE (4 * 256)
#define GRAPH_CHUNKLOOKUP_WIDTH 12
#define GRAPH_MIN_SIZE (GRAPH_HEADER_SIZE + 4 * GRAPH_CHUNKLOOKUP_WIDTH \
+ GRAPH_FANOUT_SIZE + GRAPH_OID_LEN)
char *get_commit_graph_filename(const char *obj_dir)
{
return xstrfmt("%s/info/commit-graph", obj_dir);
}
static struct commit_graph *alloc_commit_graph(void)
{
struct commit_graph *g = xcalloc(1, sizeof(*g));
g->graph_fd = -1;
return g;
}
extern int read_replace_refs;
static int commit_graph_compatible(struct repository *r)
{
if (read_replace_refs) {
prepare_replace_object(r);
if (hashmap_get_size(&r->objects->replace_map->map))
return 0;
}
prepare_commit_graft(r);
if (r->parsed_objects && r->parsed_objects->grafts_nr)
return 0;
if (is_repository_shallow(r))
return 0;
return 1;
}
struct commit_graph *load_commit_graph_one(const char *graph_file)
{
void *graph_map;
const unsigned char *data, *chunk_lookup;
size_t graph_size;
struct stat st;
uint32_t i;
struct commit_graph *graph;
int fd = git_open(graph_file);
uint64_t last_chunk_offset;
uint32_t last_chunk_id;
uint32_t graph_signature;
unsigned char graph_version, hash_version;
if (fd < 0)
return NULL;
if (fstat(fd, &st)) {
close(fd);
return NULL;
}
graph_size = xsize_t(st.st_size);
if (graph_size < GRAPH_MIN_SIZE) {
close(fd);
die("graph file %s is too small", graph_file);
}
graph_map = xmmap(NULL, graph_size, PROT_READ, MAP_PRIVATE, fd, 0);
data = (const unsigned char *)graph_map;
graph_signature = get_be32(data);
if (graph_signature != GRAPH_SIGNATURE) {
error("graph signature %X does not match signature %X",
graph_signature, GRAPH_SIGNATURE);
goto cleanup_fail;
}
graph_version = *(unsigned char*)(data + 4);
if (graph_version != GRAPH_VERSION) {
error("graph version %X does not match version %X",
graph_version, GRAPH_VERSION);
goto cleanup_fail;
}
hash_version = *(unsigned char*)(data + 5);
if (hash_version != GRAPH_OID_VERSION) {
error("hash version %X does not match version %X",
hash_version, GRAPH_OID_VERSION);
goto cleanup_fail;
}
graph = alloc_commit_graph();
graph->hash_len = GRAPH_OID_LEN;
graph->num_chunks = *(unsigned char*)(data + 6);
graph->graph_fd = fd;
graph->data = graph_map;
graph->data_len = graph_size;
last_chunk_id = 0;
last_chunk_offset = 8;
chunk_lookup = data + 8;
for (i = 0; i < graph->num_chunks; i++) {
uint32_t chunk_id = get_be32(chunk_lookup + 0);
uint64_t chunk_offset = get_be64(chunk_lookup + 4);
int chunk_repeated = 0;
chunk_lookup += GRAPH_CHUNKLOOKUP_WIDTH;
if (chunk_offset > graph_size - GIT_MAX_RAWSZ) {
error("improper chunk offset %08x%08x", (uint32_t)(chunk_offset >> 32),
(uint32_t)chunk_offset);
goto cleanup_fail;
}
switch (chunk_id) {
case GRAPH_CHUNKID_OIDFANOUT:
if (graph->chunk_oid_fanout)
chunk_repeated = 1;
else
graph->chunk_oid_fanout = (uint32_t*)(data + chunk_offset);
break;
case GRAPH_CHUNKID_OIDLOOKUP:
if (graph->chunk_oid_lookup)
chunk_repeated = 1;
else
graph->chunk_oid_lookup = data + chunk_offset;
break;
case GRAPH_CHUNKID_DATA:
if (graph->chunk_commit_data)
chunk_repeated = 1;
else
graph->chunk_commit_data = data + chunk_offset;
break;
case GRAPH_CHUNKID_LARGEEDGES:
if (graph->chunk_large_edges)
chunk_repeated = 1;
else
graph->chunk_large_edges = data + chunk_offset;
break;
}
if (chunk_repeated) {
error("chunk id %08x appears multiple times", chunk_id);
goto cleanup_fail;
}
if (last_chunk_id == GRAPH_CHUNKID_OIDLOOKUP)
{
graph->num_commits = (chunk_offset - last_chunk_offset)
/ graph->hash_len;
}
last_chunk_id = chunk_id;
last_chunk_offset = chunk_offset;
}
return graph;
cleanup_fail:
munmap(graph_map, graph_size);
close(fd);
exit(1);
}
static void prepare_commit_graph_one(struct repository *r, const char *obj_dir)
{
char *graph_name;
if (r->objects->commit_graph)
return;
graph_name = get_commit_graph_filename(obj_dir);
r->objects->commit_graph =
load_commit_graph_one(graph_name);
FREE_AND_NULL(graph_name);
}
/*
* Return 1 if commit_graph is non-NULL, and 0 otherwise.
*
* On the first invocation, this function attemps to load the commit
* graph if the_repository is configured to have one.
*/
static int prepare_commit_graph(struct repository *r)
{
struct alternate_object_database *alt;
char *obj_dir;
int config_value;
if (r->objects->commit_graph_attempted)
return !!r->objects->commit_graph;
r->objects->commit_graph_attempted = 1;
if (repo_config_get_bool(r, "core.commitgraph", &config_value) ||
!config_value)
/*
* This repository is not configured to use commit graphs, so
* do not load one. (But report commit_graph_attempted anyway
* so that commit graph loading is not attempted again for this
* repository.)
*/
return 0;
if (!commit_graph_compatible(r))
return 0;
obj_dir = r->objects->objectdir;
prepare_commit_graph_one(r, obj_dir);
prepare_alt_odb(r);
for (alt = r->objects->alt_odb_list;
!r->objects->commit_graph && alt;
alt = alt->next)
prepare_commit_graph_one(r, alt->path);
return !!r->objects->commit_graph;
}
static void close_commit_graph(void)
{
free_commit_graph(the_repository->objects->commit_graph);
the_repository->objects->commit_graph = NULL;
}
static int bsearch_graph(struct commit_graph *g, struct object_id *oid, uint32_t *pos)
{
return bsearch_hash(oid->hash, g->chunk_oid_fanout,
g->chunk_oid_lookup, g->hash_len, pos);
}
static struct commit_list **insert_parent_or_die(struct commit_graph *g,
uint64_t pos,
struct commit_list **pptr)
{
struct commit *c;
struct object_id oid;
if (pos >= g->num_commits)
die("invalid parent position %"PRIu64, pos);
hashcpy(oid.hash, g->chunk_oid_lookup + g->hash_len * pos);
c = lookup_commit(the_repository, &oid);
if (!c)
die("could not find commit %s", oid_to_hex(&oid));
c->graph_pos = pos;
return &commit_list_insert(c, pptr)->next;
}
static void fill_commit_graph_info(struct commit *item, struct commit_graph *g, uint32_t pos)
{
const unsigned char *commit_data = g->chunk_commit_data + GRAPH_DATA_WIDTH * pos;
item->graph_pos = pos;
item->generation = get_be32(commit_data + g->hash_len + 8) >> 2;
}
static int fill_commit_in_graph(struct commit *item, struct commit_graph *g, uint32_t pos)
{
uint32_t edge_value;
uint32_t *parent_data_ptr;
uint64_t date_low, date_high;
struct commit_list **pptr;
const unsigned char *commit_data = g->chunk_commit_data + (g->hash_len + 16) * pos;
item->object.parsed = 1;
item->graph_pos = pos;
item->maybe_tree = NULL;
date_high = get_be32(commit_data + g->hash_len + 8) & 0x3;
date_low = get_be32(commit_data + g->hash_len + 12);
item->date = (timestamp_t)((date_high << 32) | date_low);
item->generation = get_be32(commit_data + g->hash_len + 8) >> 2;
pptr = &item->parents;
edge_value = get_be32(commit_data + g->hash_len);
if (edge_value == GRAPH_PARENT_NONE)
return 1;
pptr = insert_parent_or_die(g, edge_value, pptr);
edge_value = get_be32(commit_data + g->hash_len + 4);
if (edge_value == GRAPH_PARENT_NONE)
return 1;
if (!(edge_value & GRAPH_OCTOPUS_EDGES_NEEDED)) {
pptr = insert_parent_or_die(g, edge_value, pptr);
return 1;
}
parent_data_ptr = (uint32_t*)(g->chunk_large_edges +
4 * (uint64_t)(edge_value & GRAPH_EDGE_LAST_MASK));
do {
edge_value = get_be32(parent_data_ptr);
pptr = insert_parent_or_die(g,
edge_value & GRAPH_EDGE_LAST_MASK,
pptr);
parent_data_ptr++;
} while (!(edge_value & GRAPH_LAST_EDGE));
return 1;
}
static int find_commit_in_graph(struct commit *item, struct commit_graph *g, uint32_t *pos)
{
if (item->graph_pos != COMMIT_NOT_FROM_GRAPH) {
*pos = item->graph_pos;
return 1;
} else {
return bsearch_graph(g, &(item->object.oid), pos);
}
}
static int parse_commit_in_graph_one(struct commit_graph *g, struct commit *item)
{
uint32_t pos;
if (item->object.parsed)
return 1;
if (find_commit_in_graph(item, g, &pos))
return fill_commit_in_graph(item, g, pos);
return 0;
}
int parse_commit_in_graph(struct repository *r, struct commit *item)
{
if (!prepare_commit_graph(r))
return 0;
return parse_commit_in_graph_one(r->objects->commit_graph, item);
}
void load_commit_graph_info(struct repository *r, struct commit *item)
{
uint32_t pos;
if (!prepare_commit_graph(r))
return;
if (find_commit_in_graph(item, r->objects->commit_graph, &pos))
fill_commit_graph_info(item, r->objects->commit_graph, pos);
}
static struct tree *load_tree_for_commit(struct commit_graph *g, struct commit *c)
{
struct object_id oid;
const unsigned char *commit_data = g->chunk_commit_data +
GRAPH_DATA_WIDTH * (c->graph_pos);
hashcpy(oid.hash, commit_data);
c->maybe_tree = lookup_tree(the_repository, &oid);
return c->maybe_tree;
}
static struct tree *get_commit_tree_in_graph_one(struct commit_graph *g,
const struct commit *c)
{
if (c->maybe_tree)
return c->maybe_tree;
if (c->graph_pos == COMMIT_NOT_FROM_GRAPH)
BUG("get_commit_tree_in_graph_one called from non-commit-graph commit");
return load_tree_for_commit(g, (struct commit *)c);
}
struct tree *get_commit_tree_in_graph(struct repository *r, const struct commit *c)
{
return get_commit_tree_in_graph_one(r->objects->commit_graph, c);
}
static void write_graph_chunk_fanout(struct hashfile *f,
struct commit **commits,
int nr_commits)
{
int i, count = 0;
struct commit **list = commits;
/*
* Write the first-level table (the list is sorted,
* but we use a 256-entry lookup to be able to avoid
* having to do eight extra binary search iterations).
*/
for (i = 0; i < 256; i++) {
while (count < nr_commits) {
if ((*list)->object.oid.hash[0] != i)
break;
count++;
list++;
}
hashwrite_be32(f, count);
}
}
static void write_graph_chunk_oids(struct hashfile *f, int hash_len,
struct commit **commits, int nr_commits)
{
struct commit **list = commits;
int count;
for (count = 0; count < nr_commits; count++, list++)
hashwrite(f, (*list)->object.oid.hash, (int)hash_len);
}
static const unsigned char *commit_to_sha1(size_t index, void *table)
{
struct commit **commits = table;
return commits[index]->object.oid.hash;
}
static void write_graph_chunk_data(struct hashfile *f, int hash_len,
struct commit **commits, int nr_commits)
{
struct commit **list = commits;
struct commit **last = commits + nr_commits;
uint32_t num_extra_edges = 0;
while (list < last) {
struct commit_list *parent;
int edge_value;
uint32_t packedDate[2];
parse_commit(*list);
hashwrite(f, get_commit_tree_oid(*list)->hash, hash_len);
parent = (*list)->parents;
if (!parent)
edge_value = GRAPH_PARENT_NONE;
else {
edge_value = sha1_pos(parent->item->object.oid.hash,
commits,
nr_commits,
commit_to_sha1);
if (edge_value < 0)
edge_value = GRAPH_PARENT_MISSING;
}
hashwrite_be32(f, edge_value);
if (parent)
parent = parent->next;
if (!parent)
edge_value = GRAPH_PARENT_NONE;
else if (parent->next)
edge_value = GRAPH_OCTOPUS_EDGES_NEEDED | num_extra_edges;
else {
edge_value = sha1_pos(parent->item->object.oid.hash,
commits,
nr_commits,
commit_to_sha1);
if (edge_value < 0)
edge_value = GRAPH_PARENT_MISSING;
}
hashwrite_be32(f, edge_value);
if (edge_value & GRAPH_OCTOPUS_EDGES_NEEDED) {
do {
num_extra_edges++;
parent = parent->next;
} while (parent);
}
if (sizeof((*list)->date) > 4)
packedDate[0] = htonl(((*list)->date >> 32) & 0x3);
else
packedDate[0] = 0;
packedDate[0] |= htonl((*list)->generation << 2);
packedDate[1] = htonl((*list)->date);
hashwrite(f, packedDate, 8);
list++;
}
}
static void write_graph_chunk_large_edges(struct hashfile *f,
struct commit **commits,
int nr_commits)
{
struct commit **list = commits;
struct commit **last = commits + nr_commits;
struct commit_list *parent;
while (list < last) {
int num_parents = 0;
for (parent = (*list)->parents; num_parents < 3 && parent;
parent = parent->next)
num_parents++;
if (num_parents <= 2) {
list++;
continue;
}
/* Since num_parents > 2, this initializer is safe. */
for (parent = (*list)->parents->next; parent; parent = parent->next) {
int edge_value = sha1_pos(parent->item->object.oid.hash,
commits,
nr_commits,
commit_to_sha1);
if (edge_value < 0)
edge_value = GRAPH_PARENT_MISSING;
else if (!parent->next)
edge_value |= GRAPH_LAST_EDGE;
hashwrite_be32(f, edge_value);
}
list++;
}
}
static int commit_compare(const void *_a, const void *_b)
{
const struct object_id *a = (const struct object_id *)_a;
const struct object_id *b = (const struct object_id *)_b;
return oidcmp(a, b);
}
struct packed_commit_list {
struct commit **list;
int nr;
int alloc;
};
struct packed_oid_list {
struct object_id *list;
int nr;
int alloc;
};
static int add_packed_commits(const struct object_id *oid,
struct packed_git *pack,
uint32_t pos,
void *data)
{
struct packed_oid_list *list = (struct packed_oid_list*)data;
enum object_type type;
off_t offset = nth_packed_object_offset(pack, pos);
struct object_info oi = OBJECT_INFO_INIT;
oi.typep = &type;
if (packed_object_info(the_repository, pack, offset, &oi) < 0)
die("unable to get type of object %s", oid_to_hex(oid));
if (type != OBJ_COMMIT)
return 0;
ALLOC_GROW(list->list, list->nr + 1, list->alloc);
oidcpy(&(list->list[list->nr]), oid);
list->nr++;
return 0;
}
static void add_missing_parents(struct packed_oid_list *oids, struct commit *commit)
{
struct commit_list *parent;
for (parent = commit->parents; parent; parent = parent->next) {
if (!(parent->item->object.flags & UNINTERESTING)) {
ALLOC_GROW(oids->list, oids->nr + 1, oids->alloc);
oidcpy(&oids->list[oids->nr], &(parent->item->object.oid));
oids->nr++;
parent->item->object.flags |= UNINTERESTING;
}
}
}
static void close_reachable(struct packed_oid_list *oids)
{
int i;
struct commit *commit;
for (i = 0; i < oids->nr; i++) {
commit = lookup_commit(the_repository, &oids->list[i]);
if (commit)
commit->object.flags |= UNINTERESTING;
}
/*
* As this loop runs, oids->nr may grow, but not more
* than the number of missing commits in the reachable
* closure.
*/
for (i = 0; i < oids->nr; i++) {
commit = lookup_commit(the_repository, &oids->list[i]);
if (commit && !parse_commit(commit))
add_missing_parents(oids, commit);
}
for (i = 0; i < oids->nr; i++) {
commit = lookup_commit(the_repository, &oids->list[i]);
if (commit)
commit->object.flags &= ~UNINTERESTING;
}
}
static void compute_generation_numbers(struct packed_commit_list* commits)
{
int i;
struct commit_list *list = NULL;
for (i = 0; i < commits->nr; i++) {
if (commits->list[i]->generation != GENERATION_NUMBER_INFINITY &&
commits->list[i]->generation != GENERATION_NUMBER_ZERO)
continue;
commit_list_insert(commits->list[i], &list);
while (list) {
struct commit *current = list->item;
struct commit_list *parent;
int all_parents_computed = 1;
uint32_t max_generation = 0;
for (parent = current->parents; parent; parent = parent->next) {
if (parent->item->generation == GENERATION_NUMBER_INFINITY ||
parent->item->generation == GENERATION_NUMBER_ZERO) {
all_parents_computed = 0;
commit_list_insert(parent->item, &list);
break;
} else if (parent->item->generation > max_generation) {
max_generation = parent->item->generation;
}
}
if (all_parents_computed) {
current->generation = max_generation + 1;
pop_commit(&list);
if (current->generation > GENERATION_NUMBER_MAX)
current->generation = GENERATION_NUMBER_MAX;
}
}
}
}
static int add_ref_to_list(const char *refname,
const struct object_id *oid,
int flags, void *cb_data)
{
struct string_list *list = (struct string_list *)cb_data;
string_list_append(list, oid_to_hex(oid));
return 0;
}
void write_commit_graph_reachable(const char *obj_dir, int append)
{
struct string_list list;
string_list_init(&list, 1);
for_each_ref(add_ref_to_list, &list);
write_commit_graph(obj_dir, NULL, &list, append);
}
void write_commit_graph(const char *obj_dir,
struct string_list *pack_indexes,
struct string_list *commit_hex,
int append)
{
struct packed_oid_list oids;
struct packed_commit_list commits;
struct hashfile *f;
uint32_t i, count_distinct = 0;
char *graph_name;
struct lock_file lk = LOCK_INIT;
uint32_t chunk_ids[5];
uint64_t chunk_offsets[5];
int num_chunks;
int num_extra_edges;
struct commit_list *parent;
if (!commit_graph_compatible(the_repository))
return;
oids.nr = 0;
oids.alloc = approximate_object_count() / 4;
if (append) {
prepare_commit_graph_one(the_repository, obj_dir);
if (the_repository->objects->commit_graph)
oids.alloc += the_repository->objects->commit_graph->num_commits;
}
if (oids.alloc < 1024)
oids.alloc = 1024;
ALLOC_ARRAY(oids.list, oids.alloc);
if (append && the_repository->objects->commit_graph) {
struct commit_graph *commit_graph =
the_repository->objects->commit_graph;
for (i = 0; i < commit_graph->num_commits; i++) {
const unsigned char *hash = commit_graph->chunk_oid_lookup +
commit_graph->hash_len * i;
hashcpy(oids.list[oids.nr++].hash, hash);
}
}
if (pack_indexes) {
struct strbuf packname = STRBUF_INIT;
int dirlen;
strbuf_addf(&packname, "%s/pack/", obj_dir);
dirlen = packname.len;
for (i = 0; i < pack_indexes->nr; i++) {