Merge branch 'ds/commit-graph'
authorJunio C Hamano <gitster@pobox.com>
Tue, 8 May 2018 06:59:20 +0000 (15:59 +0900)
committerJunio C Hamano <gitster@pobox.com>
Tue, 8 May 2018 06:59:20 +0000 (15:59 +0900)
Precompute and store information necessary for ancestry traversal
in a separate file to optimize graph walking.

* ds/commit-graph:
  commit-graph: implement "--append" option
  commit-graph: build graph from starting commits
  commit-graph: read only from specific pack-indexes
  commit: integrate commit graph with commit parsing
  commit-graph: close under reachability
  commit-graph: add core.commitGraph setting
  commit-graph: implement git commit-graph read
  commit-graph: implement git-commit-graph write
  commit-graph: implement write_commit_graph()
  commit-graph: create git-commit-graph builtin
  graph: add commit graph design document
  commit-graph: add format document
  csum-file: refactor finalize_hashfile() method
  csum-file: rename hashclose() to finalize_hashfile()

18 files changed:
1  2 
.gitignore
Documentation/config.txt
Makefile
builtin.h
builtin/index-pack.c
builtin/pack-objects.c
bulk-checkin.c
cache.h
commit-graph.c
commit.c
config.c
contrib/completion/git-completion.bash
environment.c
fast-import.c
git.c
pack-bitmap-write.c
packfile.c
packfile.h

diff --cc .gitignore
Simple merge
Simple merge
diff --cc Makefile
Simple merge
diff --cc builtin.h
Simple merge
Simple merge
Simple merge
diff --cc bulk-checkin.c
Simple merge
diff --cc cache.h
Simple merge
diff --cc commit-graph.c
index 0000000,3ff8c84..3fc1e0d
mode 000000,100644..100644
--- /dev/null
@@@ -1,0 -1,738 +1,741 @@@
 -      prepare_alt_odb();
 -      for (alt = alt_odb_list; !commit_graph && alt; alt = alt->next)
+ #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"
++#include "object-store.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(the_repository);
++      for (alt = the_repository->objects->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;
+ }
diff --cc commit.c
+++ b/commit.c
@@@ -383,7 -384,9 +384,9 @@@ int parse_commit_gently(struct commit *
                return -1;
        if (item->object.parsed)
                return 0;
 -      buffer = read_sha1_file(item->object.oid.hash, &type, &size);
+       if (parse_commit_in_graph(item))
+               return 0;
 +      buffer = read_object_file(&item->object.oid, &type, &size);
        if (!buffer)
                return quiet_on_missing ? -1 :
                        error("Could not read %s",
diff --cc config.c
Simple merge
diff --cc environment.c
Simple merge
diff --cc fast-import.c
Simple merge
diff --cc git.c
--- 1/git.c
--- 2/git.c
+++ b/git.c
@@@ -392,15 -388,16 +392,16 @@@ static struct cmd_struct commands[] = 
        { "clone", cmd_clone },
        { "column", cmd_column, RUN_SETUP_GENTLY },
        { "commit", cmd_commit, RUN_SETUP | NEED_WORK_TREE },
 -      { "commit-tree", cmd_commit_tree, RUN_SETUP },
 -      { "config", cmd_config, RUN_SETUP_GENTLY },
+       { "commit-graph", cmd_commit_graph, RUN_SETUP },
 +      { "commit-tree", cmd_commit_tree, RUN_SETUP | NO_PARSEOPT },
 +      { "config", cmd_config, RUN_SETUP_GENTLY | DELAY_PAGER_CONFIG },
        { "count-objects", cmd_count_objects, RUN_SETUP },
 -      { "credential", cmd_credential, RUN_SETUP_GENTLY },
 +      { "credential", cmd_credential, RUN_SETUP_GENTLY | NO_PARSEOPT },
        { "describe", cmd_describe, RUN_SETUP },
 -      { "diff", cmd_diff },
 -      { "diff-files", cmd_diff_files, RUN_SETUP | NEED_WORK_TREE },
 -      { "diff-index", cmd_diff_index, RUN_SETUP },
 -      { "diff-tree", cmd_diff_tree, RUN_SETUP },
 +      { "diff", cmd_diff, NO_PARSEOPT },
 +      { "diff-files", cmd_diff_files, RUN_SETUP | NEED_WORK_TREE | NO_PARSEOPT },
 +      { "diff-index", cmd_diff_index, RUN_SETUP | NO_PARSEOPT },
 +      { "diff-tree", cmd_diff_tree, RUN_SETUP | NO_PARSEOPT },
        { "difftool", cmd_difftool, RUN_SETUP | NEED_WORK_TREE },
        { "fast-export", cmd_fast_export, RUN_SETUP },
        { "fetch", cmd_fetch, RUN_SETUP },
Simple merge
diff --cc packfile.c
Simple merge
diff --cc packfile.h
@@@ -65,7 -63,8 +65,8 @@@ extern void close_pack_index(struct pac
  
  extern unsigned char *use_pack(struct packed_git *, struct pack_window **, off_t, unsigned long *);
  extern void close_pack_windows(struct packed_git *);
 -extern void close_all_packs(void);
+ extern void close_pack(struct packed_git *);
 +extern void close_all_packs(struct raw_object_store *o);
  extern void unuse_pack(struct pack_window **);
  extern void clear_delta_base_cache(void);
  extern struct packed_git *add_packed_git(const char *path, size_t path_len, int local);