[thirdparty/git.git] / commit-graph.c

#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)
{
	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;
}

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 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(&oid);

	return c->maybe_tree;
}

struct tree *get_commit_tree_in_graph(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 called from non-commit-graph commit");

	return load_tree_for_commit(commit_graph, (struct commit *)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[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;
}
Commit	Line	Data
08fd81c9 DS	1	#include "cache.h"
	2	#include "config.h"
	3	#include "git-compat-util.h"
	4	#include "lockfile.h"
	5	#include "pack.h"
	6	#include "packfile.h"
	7	#include "commit.h"
	8	#include "object.h"
	9	#include "revision.h"
	10	#include "sha1-lookup.h"
	11	#include "commit-graph.h"
	12
	13	#define GRAPH_SIGNATURE 0x43475048 /* "CGPH" */
	14	#define GRAPH_CHUNKID_OIDFANOUT 0x4f494446 /* "OIDF" */
	15	#define GRAPH_CHUNKID_OIDLOOKUP 0x4f49444c /* "OIDL" */
	16	#define GRAPH_CHUNKID_DATA 0x43444154 /* "CDAT" */
	17	#define GRAPH_CHUNKID_LARGEEDGES 0x45444745 /* "EDGE" */
	18
	19	#define GRAPH_DATA_WIDTH 36
	20
	21	#define GRAPH_VERSION_1 0x1
	22	#define GRAPH_VERSION GRAPH_VERSION_1
	23
	24	#define GRAPH_OID_VERSION_SHA1 1
	25	#define GRAPH_OID_LEN_SHA1 GIT_SHA1_RAWSZ
	26	#define GRAPH_OID_VERSION GRAPH_OID_VERSION_SHA1
	27	#define GRAPH_OID_LEN GRAPH_OID_LEN_SHA1
	28
	29	#define GRAPH_OCTOPUS_EDGES_NEEDED 0x80000000
	30	#define GRAPH_PARENT_MISSING 0x7fffffff
	31	#define GRAPH_EDGE_LAST_MASK 0x7fffffff
	32	#define GRAPH_PARENT_NONE 0x70000000
	33
	34	#define GRAPH_LAST_EDGE 0x80000000
	35
	36	#define GRAPH_FANOUT_SIZE (4 * 256)
	37	#define GRAPH_CHUNKLOOKUP_WIDTH 12
	38	#define GRAPH_MIN_SIZE (5 * GRAPH_CHUNKLOOKUP_WIDTH + GRAPH_FANOUT_SIZE + \
	39	GRAPH_OID_LEN + 8)
	40
2a2e32bd	41	char get_commit_graph_filename(const char obj_dir)
08fd81c9 DS	42	{
	43	return xstrfmt("%s/info/commit-graph", obj_dir);
	44	}
	45
2a2e32bd DS	46	static struct commit_graph *alloc_commit_graph(void)
	47	{
	48	struct commit_graph g = xcalloc(1, sizeof(g));
	49	g->graph_fd = -1;
	50
	51	return g;
	52	}
	53
	54	struct commit_graph load_commit_graph_one(const char graph_file)
	55	{
	56	void *graph_map;
	57	const unsigned char data, chunk_lookup;
	58	size_t graph_size;
	59	struct stat st;
	60	uint32_t i;
	61	struct commit_graph *graph;
	62	int fd = git_open(graph_file);
	63	uint64_t last_chunk_offset;
	64	uint32_t last_chunk_id;
	65	uint32_t graph_signature;
	66	unsigned char graph_version, hash_version;
	67
	68	if (fd < 0)
	69	return NULL;
	70	if (fstat(fd, &st)) {
	71	close(fd);
	72	return NULL;
	73	}
	74	graph_size = xsize_t(st.st_size);
	75
	76	if (graph_size < GRAPH_MIN_SIZE) {
	77	close(fd);
	78	die("graph file %s is too small", graph_file);
	79	}
	80	graph_map = xmmap(NULL, graph_size, PROT_READ, MAP_PRIVATE, fd, 0);
	81	data = (const unsigned char *)graph_map;
	82
	83	graph_signature = get_be32(data);
	84	if (graph_signature != GRAPH_SIGNATURE) {
	85	error("graph signature %X does not match signature %X",
	86	graph_signature, GRAPH_SIGNATURE);
	87	goto cleanup_fail;
	88	}
	89
	90	graph_version = (unsigned char)(data + 4);
	91	if (graph_version != GRAPH_VERSION) {
	92	error("graph version %X does not match version %X",
	93	graph_version, GRAPH_VERSION);
	94	goto cleanup_fail;
	95	}
	96
	97	hash_version = (unsigned char)(data + 5);
	98	if (hash_version != GRAPH_OID_VERSION) {
	99	error("hash version %X does not match version %X",
	100	hash_version, GRAPH_OID_VERSION);
	101	goto cleanup_fail;
	102	}
	103
	104	graph = alloc_commit_graph();
	105
	106	graph->hash_len = GRAPH_OID_LEN;
	107	graph->num_chunks = (unsigned char)(data + 6);
	108	graph->graph_fd = fd;
	109	graph->data = graph_map;
110	graph->data_len = graph_size;
111
112	last_chunk_id = 0;
113	last_chunk_offset = 8;
114	chunk_lookup = data + 8;
115	for (i = 0; i < graph->num_chunks; i++) {
116	uint32_t chunk_id = get_be32(chunk_lookup + 0);
117	uint64_t chunk_offset = get_be64(chunk_lookup + 4);
118	int chunk_repeated = 0;
119
120	chunk_lookup += GRAPH_CHUNKLOOKUP_WIDTH;
121
122	if (chunk_offset > graph_size - GIT_MAX_RAWSZ) {
123	error("improper chunk offset %08x%08x", (uint32_t)(chunk_offset >> 32),
124	(uint32_t)chunk_offset);
125	goto cleanup_fail;
126	}
127
128	switch (chunk_id) {
129	case GRAPH_CHUNKID_OIDFANOUT:
130	if (graph->chunk_oid_fanout)
131	chunk_repeated = 1;
132	else
133	graph->chunk_oid_fanout = (uint32_t*)(data + chunk_offset);
134	break;
135
136	case GRAPH_CHUNKID_OIDLOOKUP:
137	if (graph->chunk_oid_lookup)
138	chunk_repeated = 1;
139	else
140	graph->chunk_oid_lookup = data + chunk_offset;
141	break;
142
143	case GRAPH_CHUNKID_DATA:
144	if (graph->chunk_commit_data)
145	chunk_repeated = 1;
146	else
147	graph->chunk_commit_data = data + chunk_offset;
148	break;
149
150	case GRAPH_CHUNKID_LARGEEDGES:
151	if (graph->chunk_large_edges)
152	chunk_repeated = 1;
153	else
154	graph->chunk_large_edges = data + chunk_offset;
155	break;
156	}
157
158	if (chunk_repeated) {
159	error("chunk id %08x appears multiple times", chunk_id);
160	goto cleanup_fail;
161	}
162
163	if (last_chunk_id == GRAPH_CHUNKID_OIDLOOKUP)
164	{
165	graph->num_commits = (chunk_offset - last_chunk_offset)
166	/ graph->hash_len;
167	}
168
169	last_chunk_id = chunk_id;
170	last_chunk_offset = chunk_offset;
171	}
172
173	return graph;
174
175	cleanup_fail:
176	munmap(graph_map, graph_size);
177	close(fd);
178	exit(1);
179	}
180
177722b3 DS	181	/* global storage */
	182	static struct commit_graph *commit_graph = NULL;
	183
	184	static void prepare_commit_graph_one(const char *obj_dir)
	185	{
	186	char *graph_name;
	187
	188	if (commit_graph)
	189	return;
	190
	191	graph_name = get_commit_graph_filename(obj_dir);
	192	commit_graph = load_commit_graph_one(graph_name);
	193
	194	FREE_AND_NULL(graph_name);
	195	}
	196
	197	static int prepare_commit_graph_run_once = 0;
	198	static void prepare_commit_graph(void)
	199	{
	200	struct alternate_object_database *alt;
	201	char *obj_dir;
	202
	203	if (prepare_commit_graph_run_once)
	204	return;
	205	prepare_commit_graph_run_once = 1;
	206
	207	obj_dir = get_object_directory();
	208	prepare_commit_graph_one(obj_dir);
	209	prepare_alt_odb();
	210	for (alt = alt_odb_list; !commit_graph && alt; alt = alt->next)
	211	prepare_commit_graph_one(alt->path);
	212	}
	213
	214	static void close_commit_graph(void)
	215	{
	216	if (!commit_graph)
	217	return;
	218
	219	if (commit_graph->graph_fd >= 0) {
	220	munmap((void *)commit_graph->data, commit_graph->data_len);
	221	commit_graph->data = NULL;
	222	close(commit_graph->graph_fd);
	223	}
	224
	225	FREE_AND_NULL(commit_graph);
	226	}
	227
	228	static int bsearch_graph(struct commit_graph g, struct object_id oid, uint32_t *pos)
	229	{
	230	return bsearch_hash(oid->hash, g->chunk_oid_fanout,
	231	g->chunk_oid_lookup, g->hash_len, pos);
	232	}
	233
	234	static struct commit_list *insert_parent_or_die(struct commit_graph g,
	235	uint64_t pos,
	236	struct commit_list **pptr)
	237	{
	238	struct commit *c;
	239	struct object_id oid;
	240	hashcpy(oid.hash, g->chunk_oid_lookup + g->hash_len * pos);
	241	c = lookup_commit(&oid);
	242	if (!c)
	243	die("could not find commit %s", oid_to_hex(&oid));
	244	c->graph_pos = pos;
245	return &commit_list_insert(c, pptr)->next;
246	}
247
248	static int fill_commit_in_graph(struct commit item, struct commit_graph g, uint32_t pos)
249	{
177722b3 DS	250	uint32_t edge_value;
	251	uint32_t *parent_data_ptr;
	252	uint64_t date_low, date_high;
	253	struct commit_list **pptr;
	254	const unsigned char commit_data = g->chunk_commit_data + (g->hash_len + 16) pos;
	255
	256	item->object.parsed = 1;
	257	item->graph_pos = pos;
	258
7b8a21db	259	item->maybe_tree = NULL;
177722b3 DS	260
	261	date_high = get_be32(commit_data + g->hash_len + 8) & 0x3;
	262	date_low = get_be32(commit_data + g->hash_len + 12);
	263	item->date = (timestamp_t)((date_high << 32) \| date_low);
	264
83073cc9 DS	265	item->generation = get_be32(commit_data + g->hash_len + 8) >> 2;
83073cc9 DS	266
177722b3 DS	267	pptr = &item->parents;
	268
	269	edge_value = get_be32(commit_data + g->hash_len);
	270	if (edge_value == GRAPH_PARENT_NONE)
	271	return 1;
	272	pptr = insert_parent_or_die(g, edge_value, pptr);
	273
	274	edge_value = get_be32(commit_data + g->hash_len + 4);
	275	if (edge_value == GRAPH_PARENT_NONE)
	276	return 1;
	277	if (!(edge_value & GRAPH_OCTOPUS_EDGES_NEEDED)) {
	278	pptr = insert_parent_or_die(g, edge_value, pptr);
	279	return 1;
	280	}
	281
	282	parent_data_ptr = (uint32_t*)(g->chunk_large_edges +
	283	4 * (uint64_t)(edge_value & GRAPH_EDGE_LAST_MASK));
	284	do {
	285	edge_value = get_be32(parent_data_ptr);
	286	pptr = insert_parent_or_die(g,
	287	edge_value & GRAPH_EDGE_LAST_MASK,
	288	pptr);
	289	parent_data_ptr++;
	290	} while (!(edge_value & GRAPH_LAST_EDGE));
	291
	292	return 1;
	293	}
	294
	295	int parse_commit_in_graph(struct commit *item)
	296	{
	297	if (!core_commit_graph)
	298	return 0;
	299	if (item->object.parsed)
	300	return 1;
	301
	302	prepare_commit_graph();
	303	if (commit_graph) {
	304	uint32_t pos;
	305	int found;
	306	if (item->graph_pos != COMMIT_NOT_FROM_GRAPH) {
	307	pos = item->graph_pos;
	308	found = 1;
	309	} else {
	310	found = bsearch_graph(commit_graph, &(item->object.oid), &pos);
	311	}
	312
	313	if (found)
	314	return fill_commit_in_graph(item, commit_graph, pos);
	315	}
	316
	317	return 0;
	318	}
	319
7b8a21db DS	320	static struct tree load_tree_for_commit(struct commit_graph g, struct commit *c)
	321	{
	322	struct object_id oid;
	323	const unsigned char *commit_data = g->chunk_commit_data +
	324	GRAPH_DATA_WIDTH * (c->graph_pos);
	325
	326	hashcpy(oid.hash, commit_data);
	327	c->maybe_tree = lookup_tree(&oid);
	328
	329	return c->maybe_tree;
	330	}
	331
	332	struct tree get_commit_tree_in_graph(const struct commit c)
	333	{
	334	if (c->maybe_tree)
	335	return c->maybe_tree;
	336	if (c->graph_pos == COMMIT_NOT_FROM_GRAPH)
	337	BUG("get_commit_tree_in_graph called from non-commit-graph commit");
	338
	339	return load_tree_for_commit(commit_graph, (struct commit *)c);
	340	}
	341
08fd81c9 DS	342	static void write_graph_chunk_fanout(struct hashfile *f,
	343	struct commit **commits,
	344	int nr_commits)
	345	{
	346	int i, count = 0;
	347	struct commit **list = commits;
	348
	349	/*
	350	* Write the first-level table (the list is sorted,
	351	* but we use a 256-entry lookup to be able to avoid
	352	* having to do eight extra binary search iterations).
	353	*/
	354	for (i = 0; i < 256; i++) {
	355	while (count < nr_commits) {
	356	if ((*list)->object.oid.hash[0] != i)
	357	break;
	358	count++;
	359	list++;
	360	}
	361
	362	hashwrite_be32(f, count);
	363	}
	364	}
	365
	366	static void write_graph_chunk_oids(struct hashfile *f, int hash_len,
	367	struct commit **commits, int nr_commits)
	368	{
	369	struct commit **list = commits;
	370	int count;
	371	for (count = 0; count < nr_commits; count++, list++)
	372	hashwrite(f, (*list)->object.oid.hash, (int)hash_len);
	373	}
	374
	375	static const unsigned char commit_to_sha1(size_t index, void table)
	376	{
	377	struct commit **commits = table;
	378	return commits[index]->object.oid.hash;
	379	}
	380
	381	static void write_graph_chunk_data(struct hashfile *f, int hash_len,
	382	struct commit **commits, int nr_commits)
	383	{
	384	struct commit **list = commits;
	385	struct commit **last = commits + nr_commits;
	386	uint32_t num_extra_edges = 0;
	387
	388	while (list < last) {
	389	struct commit_list *parent;
	390	int edge_value;
	391	uint32_t packedDate[2];
	392
	393	parse_commit(*list);
2e27bd77	394	hashwrite(f, get_commit_tree_oid(*list)->hash, hash_len);
08fd81c9 DS	395
	396	parent = (*list)->parents;
	397
	398	if (!parent)
	399	edge_value = GRAPH_PARENT_NONE;
	400	else {
	401	edge_value = sha1_pos(parent->item->object.oid.hash,
	402	commits,
	403	nr_commits,
	404	commit_to_sha1);
	405
	406	if (edge_value < 0)
	407	edge_value = GRAPH_PARENT_MISSING;
	408	}
	409
	410	hashwrite_be32(f, edge_value);
	411
	412	if (parent)
	413	parent = parent->next;
	414
	415	if (!parent)
	416	edge_value = GRAPH_PARENT_NONE;
	417	else if (parent->next)
	418	edge_value = GRAPH_OCTOPUS_EDGES_NEEDED \| num_extra_edges;
	419	else {
	420	edge_value = sha1_pos(parent->item->object.oid.hash,
	421	commits,
	422	nr_commits,
	423	commit_to_sha1);
	424	if (edge_value < 0)
	425	edge_value = GRAPH_PARENT_MISSING;
	426	}
	427
	428	hashwrite_be32(f, edge_value);
	429
	430	if (edge_value & GRAPH_OCTOPUS_EDGES_NEEDED) {
	431	do {
	432	num_extra_edges++;
	433	parent = parent->next;
	434	} while (parent);
	435	}
	436
	437	if (sizeof((*list)->date) > 4)
	438	packedDate[0] = htonl(((*list)->date >> 32) & 0x3);
	439	else
	440	packedDate[0] = 0;
	441
	442	packedDate[1] = htonl((*list)->date);
	443	hashwrite(f, packedDate, 8);
	444
	445	list++;
	446	}
	447	}
	448
	449	static void write_graph_chunk_large_edges(struct hashfile *f,
	450	struct commit **commits,
	451	int nr_commits)
	452	{
	453	struct commit **list = commits;
	454	struct commit **last = commits + nr_commits;
	455	struct commit_list *parent;
	456
	457	while (list < last) {
	458	int num_parents = 0;
459	for (parent = (*list)->parents; num_parents < 3 && parent;
460	parent = parent->next)
461	num_parents++;
462
463	if (num_parents <= 2) {
464	list++;
465	continue;
466	}
467
468	/* Since num_parents > 2, this initializer is safe. */
469	for (parent = (*list)->parents->next; parent; parent = parent->next) {
470	int edge_value = sha1_pos(parent->item->object.oid.hash,
471	commits,
472	nr_commits,
473	commit_to_sha1);
474
475	if (edge_value < 0)
476	edge_value = GRAPH_PARENT_MISSING;
477	else if (!parent->next)
478	edge_value \|= GRAPH_LAST_EDGE;
479
480	hashwrite_be32(f, edge_value);
481	}
482
483	list++;
484	}
485	}
486
487	static int commit_compare(const void _a, const void _b)
488	{
489	const struct object_id a = (const struct object_id )_a;
490	const struct object_id b = (const struct object_id )_b;
491	return oidcmp(a, b);
492	}
493
494	struct packed_commit_list {
495	struct commit **list;
496	int nr;
497	int alloc;
498	};
499
500	struct packed_oid_list {
501	struct object_id *list;
502	int nr;
503	int alloc;
504	};
505
506	static int add_packed_commits(const struct object_id *oid,
507	struct packed_git *pack,
508	uint32_t pos,
509	void *data)
510	{
511	struct packed_oid_list list = (struct packed_oid_list)data;
512	enum object_type type;
513	off_t offset = nth_packed_object_offset(pack, pos);
514	struct object_info oi = OBJECT_INFO_INIT;
515
516	oi.typep = &type;
517	if (packed_object_info(pack, offset, &oi) < 0)
518	die("unable to get type of object %s", oid_to_hex(oid));
519
520	if (type != OBJ_COMMIT)
521	return 0;
522
523	ALLOC_GROW(list->list, list->nr + 1, list->alloc);
524	oidcpy(&(list->list[list->nr]), oid);
525	list->nr++;
526
527	return 0;
528	}
529
4f2542b4 DS	530	static void add_missing_parents(struct packed_oid_list oids, struct commit commit)
	531	{
	532	struct commit_list *parent;
	533	for (parent = commit->parents; parent; parent = parent->next) {
	534	if (!(parent->item->object.flags & UNINTERESTING)) {
	535	ALLOC_GROW(oids->list, oids->nr + 1, oids->alloc);
	536	oidcpy(&oids->list[oids->nr], &(parent->item->object.oid));
	537	oids->nr++;
	538	parent->item->object.flags \|= UNINTERESTING;
	539	}
	540	}
	541	}
	542
	543	static void close_reachable(struct packed_oid_list *oids)
	544	{
	545	int i;
	546	struct commit *commit;
	547
	548	for (i = 0; i < oids->nr; i++) {
	549	commit = lookup_commit(&oids->list[i]);
	550	if (commit)
	551	commit->object.flags \|= UNINTERESTING;
	552	}
	553
	554	/*
	555	* As this loop runs, oids->nr may grow, but not more
	556	* than the number of missing commits in the reachable
	557	* closure.
	558	*/
	559	for (i = 0; i < oids->nr; i++) {
	560	commit = lookup_commit(&oids->list[i]);
	561
	562	if (commit && !parse_commit(commit))
	563	add_missing_parents(oids, commit);
	564	}
	565
	566	for (i = 0; i < oids->nr; i++) {
	567	commit = lookup_commit(&oids->list[i]);
	568
	569	if (commit)
	570	commit->object.flags &= ~UNINTERESTING;
	571	}
	572	}
	573
049d51a2 DS	574	void write_commit_graph(const char *obj_dir,
049d51a2 DS	575	const char **pack_indexes,
3d5df01b DS	576	int nr_packs,
3d5df01b DS	577	const char **commit_hex,
7547b95b DS	578	int nr_commits,
7547b95b DS	579	int append)
08fd81c9 DS	580	{
	581	struct packed_oid_list oids;
	582	struct packed_commit_list commits;
	583	struct hashfile *f;
	584	uint32_t i, count_distinct = 0;
	585	char *graph_name;
	586	int fd;
	587	struct lock_file lk = LOCK_INIT;
	588	uint32_t chunk_ids[5];
	589	uint64_t chunk_offsets[5];
	590	int num_chunks;
	591	int num_extra_edges;
	592	struct commit_list *parent;
	593
	594	oids.nr = 0;
	595	oids.alloc = approximate_object_count() / 4;
	596
7547b95b DS	597	if (append) {
	598	prepare_commit_graph_one(obj_dir);
	599	if (commit_graph)
	600	oids.alloc += commit_graph->num_commits;
	601	}
	602
08fd81c9 DS	603	if (oids.alloc < 1024)
	604	oids.alloc = 1024;
	605	ALLOC_ARRAY(oids.list, oids.alloc);
	606
7547b95b DS	607	if (append && commit_graph) {
	608	for (i = 0; i < commit_graph->num_commits; i++) {
	609	const unsigned char *hash = commit_graph->chunk_oid_lookup +
	610	commit_graph->hash_len * i;
	611	hashcpy(oids.list[oids.nr++].hash, hash);
	612	}
	613	}
	614
049d51a2 DS	615	if (pack_indexes) {
	616	struct strbuf packname = STRBUF_INIT;
	617	int dirlen;
	618	strbuf_addf(&packname, "%s/pack/", obj_dir);
	619	dirlen = packname.len;
	620	for (i = 0; i < nr_packs; i++) {
	621	struct packed_git *p;
	622	strbuf_setlen(&packname, dirlen);
	623	strbuf_addstr(&packname, pack_indexes[i]);
	624	p = add_packed_git(packname.buf, packname.len, 1);
	625	if (!p)
	626	die("error adding pack %s", packname.buf);
	627	if (open_pack_index(p))
	628	die("error opening index for %s", packname.buf);
	629	for_each_object_in_pack(p, add_packed_commits, &oids);
	630	close_pack(p);
	631	}
	632	strbuf_release(&packname);
3d5df01b DS	633	}
	634
	635	if (commit_hex) {
	636	for (i = 0; i < nr_commits; i++) {
	637	const char *end;
	638	struct object_id oid;
	639	struct commit *result;
	640
	641	if (commit_hex[i] && parse_oid_hex(commit_hex[i], &oid, &end))
	642	continue;
	643
	644	result = lookup_commit_reference_gently(&oid, 1);
	645
	646	if (result) {
	647	ALLOC_GROW(oids.list, oids.nr + 1, oids.alloc);
	648	oidcpy(&oids.list[oids.nr], &(result->object.oid));
	649	oids.nr++;
	650	}
	651	}
	652	}
	653
	654	if (!pack_indexes && !commit_hex)
049d51a2 DS	655	for_each_packed_object(add_packed_commits, &oids, 0);
049d51a2 DS	656
4f2542b4	657	close_reachable(&oids);
08fd81c9 DS	658
	659	QSORT(oids.list, oids.nr, commit_compare);
	660
	661	count_distinct = 1;
	662	for (i = 1; i < oids.nr; i++) {
	663	if (oidcmp(&oids.list[i-1], &oids.list[i]))
	664	count_distinct++;
	665	}
	666
	667	if (count_distinct >= GRAPH_PARENT_MISSING)
	668	die(_("the commit graph format cannot write %d commits"), count_distinct);
	669
	670	commits.nr = 0;
	671	commits.alloc = count_distinct;
	672	ALLOC_ARRAY(commits.list, commits.alloc);
	673
	674	num_extra_edges = 0;
	675	for (i = 0; i < oids.nr; i++) {
	676	int num_parents = 0;
	677	if (i > 0 && !oidcmp(&oids.list[i-1], &oids.list[i]))
	678	continue;
	679
	680	commits.list[commits.nr] = lookup_commit(&oids.list[i]);
	681	parse_commit(commits.list[commits.nr]);
	682
	683	for (parent = commits.list[commits.nr]->parents;
	684	parent; parent = parent->next)
	685	num_parents++;
	686
	687	if (num_parents > 2)
	688	num_extra_edges += num_parents - 1;
	689
	690	commits.nr++;
	691	}
	692	num_chunks = num_extra_edges ? 4 : 3;
	693
	694	if (commits.nr >= GRAPH_PARENT_MISSING)
	695	die(_("too many commits to write graph"));
	696
	697	graph_name = get_commit_graph_filename(obj_dir);
	698	fd = hold_lock_file_for_update(&lk, graph_name, 0);
	699
	700	if (fd < 0) {
	701	struct strbuf folder = STRBUF_INIT;
	702	strbuf_addstr(&folder, graph_name);
	703	strbuf_setlen(&folder, strrchr(folder.buf, '/') - folder.buf);
	704
	705	if (mkdir(folder.buf, 0777) < 0)
	706	die_errno(_("cannot mkdir %s"), folder.buf);
	707	strbuf_release(&folder);
	708
	709	fd = hold_lock_file_for_update(&lk, graph_name, LOCK_DIE_ON_ERROR);
	710
	711	if (fd < 0)
	712	die_errno("unable to create '%s'", graph_name);
	713	}
	714
	715	f = hashfd(lk.tempfile->fd, lk.tempfile->filename.buf);
	716
	717	hashwrite_be32(f, GRAPH_SIGNATURE);
	718
	719	hashwrite_u8(f, GRAPH_VERSION);
	720	hashwrite_u8(f, GRAPH_OID_VERSION);
	721	hashwrite_u8(f, num_chunks);
722	hashwrite_u8(f, 0); /* unused padding byte */
723
724	chunk_ids[0] = GRAPH_CHUNKID_OIDFANOUT;
725	chunk_ids[1] = GRAPH_CHUNKID_OIDLOOKUP;
726	chunk_ids[2] = GRAPH_CHUNKID_DATA;
727	if (num_extra_edges)
728	chunk_ids[3] = GRAPH_CHUNKID_LARGEEDGES;
729	else
730	chunk_ids[3] = 0;
731	chunk_ids[4] = 0;
732
733	chunk_offsets[0] = 8 + (num_chunks + 1) * GRAPH_CHUNKLOOKUP_WIDTH;
734	chunk_offsets[1] = chunk_offsets[0] + GRAPH_FANOUT_SIZE;
735	chunk_offsets[2] = chunk_offsets[1] + GRAPH_OID_LEN * commits.nr;
736	chunk_offsets[3] = chunk_offsets[2] + (GRAPH_OID_LEN + 16) * commits.nr;
737	chunk_offsets[4] = chunk_offsets[3] + 4 * num_extra_edges;
738
739	for (i = 0; i <= num_chunks; i++) {
740	uint32_t chunk_write[3];
741
742	chunk_write[0] = htonl(chunk_ids[i]);
743	chunk_write[1] = htonl(chunk_offsets[i] >> 32);
744	chunk_write[2] = htonl(chunk_offsets[i] & 0xffffffff);
745	hashwrite(f, chunk_write, 12);
746	}
747
748	write_graph_chunk_fanout(f, commits.list, commits.nr);
749	write_graph_chunk_oids(f, GRAPH_OID_LEN, commits.list, commits.nr);
750	write_graph_chunk_data(f, GRAPH_OID_LEN, commits.list, commits.nr);
751	write_graph_chunk_large_edges(f, commits.list, commits.nr);
752
177722b3	753	close_commit_graph();
08fd81c9 DS	754	finalize_hashfile(f, NULL, CSUM_HASH_IN_STREAM \| CSUM_FSYNC);
	755	commit_lock_file(&lk);
	756
	757	free(oids.list);
	758	oids.alloc = 0;
	759	oids.nr = 0;
	760	}