diff options
Diffstat (limited to 'commit-graph.c')
| -rw-r--r-- | commit-graph.c | 738 |
1 files changed, 738 insertions, 0 deletions
diff --git a/commit-graph.c b/commit-graph.c new file mode 100644 index 0000000..3ff8c84 --- /dev/null +++ b/commit-graph.c @@ -0,0 +1,738 @@ +#include "cache.h" +#include "config.h" +#include "git-compat-util.h" +#include "lockfile.h" +#include "pack.h" +#include "packfile.h" +#include "commit.h" +#include "object.h" +#include "revision.h" +#include "sha1-lookup.h" +#include "commit-graph.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_FANOUT_SIZE (4 * 256) +#define GRAPH_CHUNKLOOKUP_WIDTH 12 +#define GRAPH_MIN_SIZE (5 * GRAPH_CHUNKLOOKUP_WIDTH + GRAPH_FANOUT_SIZE + \ + GRAPH_OID_LEN + 8) + +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; +} + +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); +} + +/* global storage */ +static struct commit_graph *commit_graph = NULL; + +static void prepare_commit_graph_one(const char *obj_dir) +{ + char *graph_name; + + if (commit_graph) + return; + + graph_name = get_commit_graph_filename(obj_dir); + commit_graph = load_commit_graph_one(graph_name); + + FREE_AND_NULL(graph_name); +} + +static int prepare_commit_graph_run_once = 0; +static void prepare_commit_graph(void) +{ + struct alternate_object_database *alt; + char *obj_dir; + + if (prepare_commit_graph_run_once) + return; + prepare_commit_graph_run_once = 1; + + obj_dir = get_object_directory(); + prepare_commit_graph_one(obj_dir); + prepare_alt_odb(); + for (alt = alt_odb_list; !commit_graph && alt; alt = alt->next) + prepare_commit_graph_one(alt->path); +} + +static void close_commit_graph(void) +{ + if (!commit_graph) + return; + + if (commit_graph->graph_fd >= 0) { + munmap((void *)commit_graph->data, commit_graph->data_len); + commit_graph->data = NULL; + close(commit_graph->graph_fd); + } + + FREE_AND_NULL(commit_graph); +} + +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; + hashcpy(oid.hash, g->chunk_oid_lookup + g->hash_len * pos); + c = lookup_commit(&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 int fill_commit_in_graph(struct commit *item, struct commit_graph *g, uint32_t pos) +{ + struct object_id oid; + 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; + + hashcpy(oid.hash, commit_data); + item->tree = lookup_tree(&oid); + + 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); + + 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; +} + +int parse_commit_in_graph(struct commit *item) +{ + if (!core_commit_graph) + return 0; + if (item->object.parsed) + return 1; + + prepare_commit_graph(); + if (commit_graph) { + uint32_t pos; + int found; + if (item->graph_pos != COMMIT_NOT_FROM_GRAPH) { + pos = item->graph_pos; + found = 1; + } else { + found = bsearch_graph(commit_graph, &(item->object.oid), &pos); + } + + if (found) + return fill_commit_in_graph(item, commit_graph, pos); + } + + return 0; +} + +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, (*list)->tree->object.oid.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[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(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(&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(&oids->list[i]); + + if (commit && !parse_commit(commit)) + add_missing_parents(oids, commit); + } + + for (i = 0; i < oids->nr; i++) { + commit = lookup_commit(&oids->list[i]); + + if (commit) + commit->object.flags &= ~UNINTERESTING; + } +} + +void write_commit_graph(const char *obj_dir, + const char **pack_indexes, + int nr_packs, + const char **commit_hex, + int nr_commits, + int append) +{ + struct packed_oid_list oids; + struct packed_commit_list commits; + struct hashfile *f; + uint32_t i, count_distinct = 0; + char *graph_name; + int fd; + 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; + + oids.nr = 0; + oids.alloc = approximate_object_count() / 4; + + if (append) { + prepare_commit_graph_one(obj_dir); + if (commit_graph) + oids.alloc += commit_graph->num_commits; + } + + if (oids.alloc < 1024) + oids.alloc = 1024; + ALLOC_ARRAY(oids.list, oids.alloc); + + if (append && 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 < nr_packs; i++) { + struct packed_git *p; + strbuf_setlen(&packname, dirlen); + strbuf_addstr(&packname, pack_indexes[i]); + p = add_packed_git(packname.buf, packname.len, 1); + if (!p) + die("error adding pack %s", packname.buf); + if (open_pack_index(p)) + die("error opening index for %s", packname.buf); + for_each_object_in_pack(p, add_packed_commits, &oids); + close_pack(p); + } + strbuf_release(&packname); + } + + if (commit_hex) { + for (i = 0; i < nr_commits; i++) { + const char *end; + struct object_id oid; + struct commit *result; + + if (commit_hex[i] && parse_oid_hex(commit_hex[i], &oid, &end)) + continue; + + result = lookup_commit_reference_gently(&oid, 1); + + if (result) { + ALLOC_GROW(oids.list, oids.nr + 1, oids.alloc); + oidcpy(&oids.list[oids.nr], &(result->object.oid)); + oids.nr++; + } + } + } + + if (!pack_indexes && !commit_hex) + for_each_packed_object(add_packed_commits, &oids, 0); + + close_reachable(&oids); + + QSORT(oids.list, oids.nr, commit_compare); + + count_distinct = 1; + for (i = 1; i < oids.nr; i++) { + if (oidcmp(&oids.list[i-1], &oids.list[i])) + count_distinct++; + } + + if (count_distinct >= GRAPH_PARENT_MISSING) + die(_("the commit graph format cannot write %d commits"), count_distinct); + + commits.nr = 0; + commits.alloc = count_distinct; + ALLOC_ARRAY(commits.list, commits.alloc); + + num_extra_edges = 0; + for (i = 0; i < oids.nr; i++) { + int num_parents = 0; + if (i > 0 && !oidcmp(&oids.list[i-1], &oids.list[i])) + continue; + + commits.list[commits.nr] = lookup_commit(&oids.list[i]); + parse_commit(commits.list[commits.nr]); + + for (parent = commits.list[commits.nr]->parents; + parent; parent = parent->next) + num_parents++; + + if (num_parents > 2) + num_extra_edges += num_parents - 1; + + commits.nr++; + } + num_chunks = num_extra_edges ? 4 : 3; + + if (commits.nr >= GRAPH_PARENT_MISSING) + die(_("too many commits to write graph")); + + graph_name = get_commit_graph_filename(obj_dir); + fd = hold_lock_file_for_update(&lk, graph_name, 0); + + if (fd < 0) { + struct strbuf folder = STRBUF_INIT; + strbuf_addstr(&folder, graph_name); + strbuf_setlen(&folder, strrchr(folder.buf, '/') - folder.buf); + + if (mkdir(folder.buf, 0777) < 0) + die_errno(_("cannot mkdir %s"), folder.buf); + strbuf_release(&folder); + + fd = hold_lock_file_for_update(&lk, graph_name, LOCK_DIE_ON_ERROR); + + if (fd < 0) + die_errno("unable to create '%s'", graph_name); + } + + f = hashfd(lk.tempfile->fd, lk.tempfile->filename.buf); + + hashwrite_be32(f, GRAPH_SIGNATURE); + + hashwrite_u8(f, GRAPH_VERSION); + hashwrite_u8(f, GRAPH_OID_VERSION); + hashwrite_u8(f, num_chunks); + hashwrite_u8(f, 0); /* unused padding byte */ + + chunk_ids[0] = GRAPH_CHUNKID_OIDFANOUT; + chunk_ids[1] = GRAPH_CHUNKID_OIDLOOKUP; + chunk_ids[2] = GRAPH_CHUNKID_DATA; + if (num_extra_edges) + chunk_ids[3] = GRAPH_CHUNKID_LARGEEDGES; + else + chunk_ids[3] = 0; + chunk_ids[4] = 0; + + chunk_offsets[0] = 8 + (num_chunks + 1) * GRAPH_CHUNKLOOKUP_WIDTH; + chunk_offsets[1] = chunk_offsets[0] + GRAPH_FANOUT_SIZE; + chunk_offsets[2] = chunk_offsets[1] + GRAPH_OID_LEN * commits.nr; + chunk_offsets[3] = chunk_offsets[2] + (GRAPH_OID_LEN + 16) * commits.nr; + chunk_offsets[4] = chunk_offsets[3] + 4 * num_extra_edges; + + for (i = 0; i <= num_chunks; i++) { + uint32_t chunk_write[3]; + + chunk_write[0] = htonl(chunk_ids[i]); + chunk_write[1] = htonl(chunk_offsets[i] >> 32); + chunk_write[2] = htonl(chunk_offsets[i] & 0xffffffff); + hashwrite(f, chunk_write, 12); + } + + write_graph_chunk_fanout(f, commits.list, commits.nr); + write_graph_chunk_oids(f, GRAPH_OID_LEN, commits.list, commits.nr); + write_graph_chunk_data(f, GRAPH_OID_LEN, commits.list, commits.nr); + write_graph_chunk_large_edges(f, commits.list, commits.nr); + + close_commit_graph(); + finalize_hashfile(f, NULL, CSUM_HASH_IN_STREAM | CSUM_FSYNC); + commit_lock_file(&lk); + + free(oids.list); + oids.alloc = 0; + oids.nr = 0; +} |