[thirdparty/git.git] / pack-bitmap-write.c

#include "cache.h"
#include "object-store.h"
#include "commit.h"
#include "tag.h"
#include "diff.h"
#include "revision.h"
#include "list-objects.h"
#include "progress.h"
#include "pack-revindex.h"
#include "pack.h"
#include "pack-bitmap.h"
#include "sha1-lookup.h"
#include "pack-objects.h"

struct bitmapped_commit {
	struct commit *commit;
	struct ewah_bitmap *bitmap;
	struct ewah_bitmap *write_as;
	int flags;
	int xor_offset;
	uint32_t commit_pos;
};

struct bitmap_writer {
	struct ewah_bitmap *commits;
	struct ewah_bitmap *trees;
	struct ewah_bitmap *blobs;
	struct ewah_bitmap *tags;

	khash_sha1 *bitmaps;
	khash_sha1 *reused;
	struct packing_data *to_pack;

	struct bitmapped_commit *selected;
	unsigned int selected_nr, selected_alloc;

	struct progress *progress;
	int show_progress;
	unsigned char pack_checksum[20];
};

static struct bitmap_writer writer;

void bitmap_writer_show_progress(int show)
{
	writer.show_progress = show;
}

/**
 * Build the initial type index for the packfile
 */
void bitmap_writer_build_type_index(struct pack_idx_entry **index,
				    uint32_t index_nr)
{
	uint32_t i;

	writer.commits = ewah_new();
	writer.trees = ewah_new();
	writer.blobs = ewah_new();
	writer.tags = ewah_new();

	for (i = 0; i < index_nr; ++i) {
		struct object_entry *entry = (struct object_entry *)index[i];
		enum object_type real_type;

		entry->in_pack_pos = i;

		switch (entry->type) {
		case OBJ_COMMIT:
		case OBJ_TREE:
		case OBJ_BLOB:
		case OBJ_TAG:
			real_type = entry->type;
			break;

		default:
			real_type = oid_object_info(the_repository,
						    &entry->idx.oid, NULL);
			break;
		}

		switch (real_type) {
		case OBJ_COMMIT:
			ewah_set(writer.commits, i);
			break;

		case OBJ_TREE:
			ewah_set(writer.trees, i);
			break;

		case OBJ_BLOB:
			ewah_set(writer.blobs, i);
			break;

		case OBJ_TAG:
			ewah_set(writer.tags, i);
			break;

		default:
			die("Missing type information for %s (%d/%d)",
			    oid_to_hex(&entry->idx.oid), real_type,
			    entry->type);
		}
	}
}

/**
 * Compute the actual bitmaps
 */
static struct object **seen_objects;
static unsigned int seen_objects_nr, seen_objects_alloc;

static inline void push_bitmapped_commit(struct commit *commit, struct ewah_bitmap *reused)
{
	if (writer.selected_nr >= writer.selected_alloc) {
		writer.selected_alloc = (writer.selected_alloc + 32) * 2;
		REALLOC_ARRAY(writer.selected, writer.selected_alloc);
	}

	writer.selected[writer.selected_nr].commit = commit;
	writer.selected[writer.selected_nr].bitmap = reused;
	writer.selected[writer.selected_nr].flags = 0;

	writer.selected_nr++;
}

static inline void mark_as_seen(struct object *object)
{
	ALLOC_GROW(seen_objects, seen_objects_nr + 1, seen_objects_alloc);
	seen_objects[seen_objects_nr++] = object;
}

static inline void reset_all_seen(void)
{
	unsigned int i;
	for (i = 0; i < seen_objects_nr; ++i) {
		seen_objects[i]->flags &= ~(SEEN | ADDED | SHOWN);
	}
	seen_objects_nr = 0;
}

static uint32_t find_object_pos(const unsigned char *sha1)
{
	struct object_entry *entry = packlist_find(writer.to_pack, sha1, NULL);

	if (!entry) {
		die("Failed to write bitmap index. Packfile doesn't have full closure "
			"(object %s is missing)", sha1_to_hex(sha1));
	}

	return entry->in_pack_pos;
}

static void show_object(struct object *object, const char *name, void *data)
{
	struct bitmap *base = data;
	bitmap_set(base, find_object_pos(object->oid.hash));
	mark_as_seen(object);
}

static void show_commit(struct commit *commit, void *data)
{
	mark_as_seen((struct object *)commit);
}

static int
add_to_include_set(struct bitmap *base, struct commit *commit)
{
	khiter_t hash_pos;
	uint32_t bitmap_pos = find_object_pos(commit->object.oid.hash);

	if (bitmap_get(base, bitmap_pos))
		return 0;

	hash_pos = kh_get_sha1(writer.bitmaps, commit->object.oid.hash);
	if (hash_pos < kh_end(writer.bitmaps)) {
		struct bitmapped_commit *bc = kh_value(writer.bitmaps, hash_pos);
		bitmap_or_ewah(base, bc->bitmap);
		return 0;
	}

	bitmap_set(base, bitmap_pos);
	return 1;
}

static int
should_include(struct commit *commit, void *_data)
{
	struct bitmap *base = _data;

	if (!add_to_include_set(base, commit)) {
		struct commit_list *parent = commit->parents;

		mark_as_seen((struct object *)commit);

		while (parent) {
			parent->item->object.flags |= SEEN;
			mark_as_seen((struct object *)parent->item);
			parent = parent->next;
		}

		return 0;
	}

	return 1;
}

static void compute_xor_offsets(void)
{
	static const int MAX_XOR_OFFSET_SEARCH = 10;

	int i, next = 0;

	while (next < writer.selected_nr) {
		struct bitmapped_commit *stored = &writer.selected[next];

		int best_offset = 0;
		struct ewah_bitmap *best_bitmap = stored->bitmap;
		struct ewah_bitmap *test_xor;

		for (i = 1; i <= MAX_XOR_OFFSET_SEARCH; ++i) {
			int curr = next - i;

			if (curr < 0)
				break;

			test_xor = ewah_pool_new();
			ewah_xor(writer.selected[curr].bitmap, stored->bitmap, test_xor);

			if (test_xor->buffer_size < best_bitmap->buffer_size) {
				if (best_bitmap != stored->bitmap)
					ewah_pool_free(best_bitmap);

				best_bitmap = test_xor;
				best_offset = i;
			} else {
				ewah_pool_free(test_xor);
			}
		}

		stored->xor_offset = best_offset;
		stored->write_as = best_bitmap;

		next++;
	}
}

void bitmap_writer_build(struct packing_data *to_pack)
{
	static const double REUSE_BITMAP_THRESHOLD = 0.2;

	int i, reuse_after, need_reset;
	struct bitmap *base = bitmap_new();
	struct rev_info revs;

	writer.bitmaps = kh_init_sha1();
	writer.to_pack = to_pack;

	if (writer.show_progress)
		writer.progress = start_progress("Building bitmaps", writer.selected_nr);

	init_revisions(&revs, NULL);
	revs.tag_objects = 1;
	revs.tree_objects = 1;
	revs.blob_objects = 1;
	revs.no_walk = 0;

	revs.include_check = should_include;
	reset_revision_walk();

	reuse_after = writer.selected_nr * REUSE_BITMAP_THRESHOLD;
	need_reset = 0;

	for (i = writer.selected_nr - 1; i >= 0; --i) {
		struct bitmapped_commit *stored;
		struct object *object;

		khiter_t hash_pos;
		int hash_ret;

		stored = &writer.selected[i];
		object = (struct object *)stored->commit;

		if (stored->bitmap == NULL) {
			if (i < writer.selected_nr - 1 &&
			    (need_reset ||
			     !in_merge_bases(writer.selected[i + 1].commit,
					     stored->commit))) {
			    bitmap_reset(base);
			    reset_all_seen();
			}

			add_pending_object(&revs, object, "");
			revs.include_check_data = base;

			if (prepare_revision_walk(&revs))
				die("revision walk setup failed");

			traverse_commit_list(&revs, show_commit, show_object, base);

			object_array_clear(&revs.pending);

			stored->bitmap = bitmap_to_ewah(base);
			need_reset = 0;
		} else
			need_reset = 1;

		if (i >= reuse_after)
			stored->flags |= BITMAP_FLAG_REUSE;

		hash_pos = kh_put_sha1(writer.bitmaps, object->oid.hash, &hash_ret);
		if (hash_ret == 0)
			die("Duplicate entry when writing index: %s",
			    oid_to_hex(&object->oid));

		kh_value(writer.bitmaps, hash_pos) = stored;
		display_progress(writer.progress, writer.selected_nr - i);
	}

	bitmap_free(base);
	stop_progress(&writer.progress);

	compute_xor_offsets();
}

/**
 * Select the commits that will be bitmapped
 */
static inline unsigned int next_commit_index(unsigned int idx)
{
	static const unsigned int MIN_COMMITS = 100;
	static const unsigned int MAX_COMMITS = 5000;

	static const unsigned int MUST_REGION = 100;
	static const unsigned int MIN_REGION = 20000;

	unsigned int offset, next;

	if (idx <= MUST_REGION)
		return 0;

	if (idx <= MIN_REGION) {
		offset = idx - MUST_REGION;
		return (offset < MIN_COMMITS) ? offset : MIN_COMMITS;
	}

	offset = idx - MIN_REGION;
	next = (offset < MAX_COMMITS) ? offset : MAX_COMMITS;

	return (next > MIN_COMMITS) ? next : MIN_COMMITS;
}

static int date_compare(const void *_a, const void *_b)
{
	struct commit *a = *(struct commit **)_a;
	struct commit *b = *(struct commit **)_b;
	return (long)b->date - (long)a->date;
}

void bitmap_writer_reuse_bitmaps(struct packing_data *to_pack)
{
	if (prepare_bitmap_git() < 0)
		return;

	writer.reused = kh_init_sha1();
	rebuild_existing_bitmaps(to_pack, writer.reused, writer.show_progress);
}

static struct ewah_bitmap *find_reused_bitmap(const unsigned char *sha1)
{
	khiter_t hash_pos;

	if (!writer.reused)
		return NULL;

	hash_pos = kh_get_sha1(writer.reused, sha1);
	if (hash_pos >= kh_end(writer.reused))
		return NULL;

	return kh_value(writer.reused, hash_pos);
}

void bitmap_writer_select_commits(struct commit **indexed_commits,
				  unsigned int indexed_commits_nr,
				  int max_bitmaps)
{
	unsigned int i = 0, j, next;

	QSORT(indexed_commits, indexed_commits_nr, date_compare);

	if (writer.show_progress)
		writer.progress = start_progress("Selecting bitmap commits", 0);

	if (indexed_commits_nr < 100) {
		for (i = 0; i < indexed_commits_nr; ++i)
			push_bitmapped_commit(indexed_commits[i], NULL);
		return;
	}

	for (;;) {
		struct ewah_bitmap *reused_bitmap = NULL;
		struct commit *chosen = NULL;

		next = next_commit_index(i);

		if (i + next >= indexed_commits_nr)
			break;

		if (max_bitmaps > 0 && writer.selected_nr >= max_bitmaps) {
			writer.selected_nr = max_bitmaps;
			break;
		}

		if (next == 0) {
			chosen = indexed_commits[i];
			reused_bitmap = find_reused_bitmap(chosen->object.oid.hash);
		} else {
			chosen = indexed_commits[i + next];

			for (j = 0; j <= next; ++j) {
				struct commit *cm = indexed_commits[i + j];

				reused_bitmap = find_reused_bitmap(cm->object.oid.hash);
				if (reused_bitmap || (cm->object.flags & NEEDS_BITMAP) != 0) {
					chosen = cm;
					break;
				}

				if (cm->parents && cm->parents->next)
					chosen = cm;
			}
		}

		push_bitmapped_commit(chosen, reused_bitmap);

		i += next + 1;
		display_progress(writer.progress, i);
	}

	stop_progress(&writer.progress);
}


static int hashwrite_ewah_helper(void *f, const void *buf, size_t len)
{
	/* hashwrite will die on error */
	hashwrite(f, buf, len);
	return len;
}

/**
 * Write the bitmap index to disk
 */
static inline void dump_bitmap(struct hashfile *f, struct ewah_bitmap *bitmap)
{
	if (ewah_serialize_to(bitmap, hashwrite_ewah_helper, f) < 0)
		die("Failed to write bitmap index");
}

static const unsigned char *sha1_access(size_t pos, void *table)
{
	struct pack_idx_entry **index = table;
	return index[pos]->oid.hash;
}

static void write_selected_commits_v1(struct hashfile *f,
				      struct pack_idx_entry **index,
				      uint32_t index_nr)
{
	int i;

	for (i = 0; i < writer.selected_nr; ++i) {
		struct bitmapped_commit *stored = &writer.selected[i];

		int commit_pos =
			sha1_pos(stored->commit->object.oid.hash, index, index_nr, sha1_access);

		if (commit_pos < 0)
			die("BUG: trying to write commit not in index");

		hashwrite_be32(f, commit_pos);
		hashwrite_u8(f, stored->xor_offset);
		hashwrite_u8(f, stored->flags);

		dump_bitmap(f, stored->write_as);
	}
}

static void write_hash_cache(struct hashfile *f,
			     struct pack_idx_entry **index,
			     uint32_t index_nr)
{
	uint32_t i;

	for (i = 0; i < index_nr; ++i) {
		struct object_entry *entry = (struct object_entry *)index[i];
		uint32_t hash_value = htonl(entry->hash);
		hashwrite(f, &hash_value, sizeof(hash_value));
	}
}

void bitmap_writer_set_checksum(unsigned char *sha1)
{
	hashcpy(writer.pack_checksum, sha1);
}

void bitmap_writer_finish(struct pack_idx_entry **index,
			  uint32_t index_nr,
			  const char *filename,
			  uint16_t options)
{
	static uint16_t default_version = 1;
	static uint16_t flags = BITMAP_OPT_FULL_DAG;
	struct strbuf tmp_file = STRBUF_INIT;
	struct hashfile *f;

	struct bitmap_disk_header header;

	int fd = odb_mkstemp(&tmp_file, "pack/tmp_bitmap_XXXXXX");

	f = hashfd(fd, tmp_file.buf);

	memcpy(header.magic, BITMAP_IDX_SIGNATURE, sizeof(BITMAP_IDX_SIGNATURE));
	header.version = htons(default_version);
	header.options = htons(flags | options);
	header.entry_count = htonl(writer.selected_nr);
	hashcpy(header.checksum, writer.pack_checksum);

	hashwrite(f, &header, sizeof(header));
	dump_bitmap(f, writer.commits);
	dump_bitmap(f, writer.trees);
	dump_bitmap(f, writer.blobs);
	dump_bitmap(f, writer.tags);
	write_selected_commits_v1(f, index, index_nr);

	if (options & BITMAP_OPT_HASH_CACHE)
		write_hash_cache(f, index, index_nr);

	hashclose(f, NULL, CSUM_FSYNC);

	if (adjust_shared_perm(tmp_file.buf))
		die_errno("unable to make temporary bitmap file readable");

	if (rename(tmp_file.buf, filename))
		die_errno("unable to rename temporary bitmap file to '%s'", filename);

	strbuf_release(&tmp_file);
}
Commit	Line	Data
7cc8f971	1	#include "cache.h"
cbd53a21	2	#include "object-store.h"
7cc8f971 VM	3	#include "commit.h"
	4	#include "tag.h"
	5	#include "diff.h"
	6	#include "revision.h"
	7	#include "list-objects.h"
	8	#include "progress.h"
	9	#include "pack-revindex.h"
	10	#include "pack.h"
	11	#include "pack-bitmap.h"
	12	#include "sha1-lookup.h"
	13	#include "pack-objects.h"
	14
	15	struct bitmapped_commit {
	16	struct commit *commit;
	17	struct ewah_bitmap *bitmap;
	18	struct ewah_bitmap *write_as;
	19	int flags;
	20	int xor_offset;
	21	uint32_t commit_pos;
	22	};
	23
	24	struct bitmap_writer {
	25	struct ewah_bitmap *commits;
	26	struct ewah_bitmap *trees;
	27	struct ewah_bitmap *blobs;
	28	struct ewah_bitmap *tags;
	29
	30	khash_sha1 *bitmaps;
	31	khash_sha1 *reused;
	32	struct packing_data *to_pack;
	33
	34	struct bitmapped_commit *selected;
	35	unsigned int selected_nr, selected_alloc;
	36
	37	struct progress *progress;
	38	int show_progress;
	39	unsigned char pack_checksum[20];
	40	};
	41
	42	static struct bitmap_writer writer;
	43
	44	void bitmap_writer_show_progress(int show)
	45	{
	46	writer.show_progress = show;
	47	}
	48
	49	/**
	50	* Build the initial type index for the packfile
	51	*/
	52	void bitmap_writer_build_type_index(struct pack_idx_entry **index,
	53	uint32_t index_nr)
	54	{
	55	uint32_t i;
	56
	57	writer.commits = ewah_new();
	58	writer.trees = ewah_new();
	59	writer.blobs = ewah_new();
	60	writer.tags = ewah_new();
	61
	62	for (i = 0; i < index_nr; ++i) {
	63	struct object_entry entry = (struct object_entry )index[i];
	64	enum object_type real_type;
	65
	66	entry->in_pack_pos = i;
67
68	switch (entry->type) {
69	case OBJ_COMMIT:
70	case OBJ_TREE:
71	case OBJ_BLOB:
72	case OBJ_TAG:
73	real_type = entry->type;
74	break;
75
76	default:
0df8e965 SB	77	real_type = oid_object_info(the_repository,
0df8e965 SB	78	&entry->idx.oid, NULL);
7cc8f971 VM	79	break;
	80	}
	81
	82	switch (real_type) {
	83	case OBJ_COMMIT:
	84	ewah_set(writer.commits, i);
	85	break;
	86
	87	case OBJ_TREE:
	88	ewah_set(writer.trees, i);
	89	break;
	90
	91	case OBJ_BLOB:
	92	ewah_set(writer.blobs, i);
	93	break;
	94
	95	case OBJ_TAG:
	96	ewah_set(writer.tags, i);
	97	break;
	98
	99	default:
	100	die("Missing type information for %s (%d/%d)",
e6a492b7	101	oid_to_hex(&entry->idx.oid), real_type,
e6a492b7	102	entry->type);
7cc8f971 VM	103	}
	104	}
	105	}
	106
	107	/**
	108	* Compute the actual bitmaps
	109	*/
	110	static struct object **seen_objects;
	111	static unsigned int seen_objects_nr, seen_objects_alloc;
	112
	113	static inline void push_bitmapped_commit(struct commit commit, struct ewah_bitmap reused)
	114	{
	115	if (writer.selected_nr >= writer.selected_alloc) {
	116	writer.selected_alloc = (writer.selected_alloc + 32) * 2;
2756ca43	117	REALLOC_ARRAY(writer.selected, writer.selected_alloc);
7cc8f971 VM	118	}
	119
	120	writer.selected[writer.selected_nr].commit = commit;
	121	writer.selected[writer.selected_nr].bitmap = reused;
	122	writer.selected[writer.selected_nr].flags = 0;
	123
	124	writer.selected_nr++;
	125	}
	126
	127	static inline void mark_as_seen(struct object *object)
	128	{
	129	ALLOC_GROW(seen_objects, seen_objects_nr + 1, seen_objects_alloc);
	130	seen_objects[seen_objects_nr++] = object;
	131	}
	132
	133	static inline void reset_all_seen(void)
	134	{
	135	unsigned int i;
	136	for (i = 0; i < seen_objects_nr; ++i) {
	137	seen_objects[i]->flags &= ~(SEEN \| ADDED \| SHOWN);
	138	}
	139	seen_objects_nr = 0;
	140	}
	141
	142	static uint32_t find_object_pos(const unsigned char *sha1)
	143	{
	144	struct object_entry *entry = packlist_find(writer.to_pack, sha1, NULL);
	145
	146	if (!entry) {
	147	die("Failed to write bitmap index. Packfile doesn't have full closure "
	148	"(object %s is missing)", sha1_to_hex(sha1));
	149	}
	150
	151	return entry->in_pack_pos;
	152	}
	153
de1e67d0	154	static void show_object(struct object object, const char name, void *data)
7cc8f971 VM	155	{
7cc8f971 VM	156	struct bitmap *base = data;
ed1c9977	157	bitmap_set(base, find_object_pos(object->oid.hash));
7cc8f971 VM	158	mark_as_seen(object);
	159	}
	160
	161	static void show_commit(struct commit commit, void data)
	162	{
	163	mark_as_seen((struct object *)commit);
	164	}
	165
	166	static int
	167	add_to_include_set(struct bitmap base, struct commit commit)
	168	{
	169	khiter_t hash_pos;
ed1c9977	170	uint32_t bitmap_pos = find_object_pos(commit->object.oid.hash);
7cc8f971 VM	171
	172	if (bitmap_get(base, bitmap_pos))
	173	return 0;
	174
ed1c9977	175	hash_pos = kh_get_sha1(writer.bitmaps, commit->object.oid.hash);
7cc8f971 VM	176	if (hash_pos < kh_end(writer.bitmaps)) {
	177	struct bitmapped_commit *bc = kh_value(writer.bitmaps, hash_pos);
	178	bitmap_or_ewah(base, bc->bitmap);
	179	return 0;
	180	}
	181
	182	bitmap_set(base, bitmap_pos);
	183	return 1;
	184	}
	185
	186	static int
	187	should_include(struct commit commit, void _data)
	188	{
	189	struct bitmap *base = _data;
	190
	191	if (!add_to_include_set(base, commit)) {
	192	struct commit_list *parent = commit->parents;
	193
	194	mark_as_seen((struct object *)commit);
	195
	196	while (parent) {
	197	parent->item->object.flags \|= SEEN;
	198	mark_as_seen((struct object *)parent->item);
	199	parent = parent->next;
	200	}
	201
	202	return 0;
	203	}
	204
	205	return 1;
	206	}
	207
	208	static void compute_xor_offsets(void)
	209	{
	210	static const int MAX_XOR_OFFSET_SEARCH = 10;
	211
	212	int i, next = 0;
	213
	214	while (next < writer.selected_nr) {
	215	struct bitmapped_commit *stored = &writer.selected[next];
	216
	217	int best_offset = 0;
	218	struct ewah_bitmap *best_bitmap = stored->bitmap;
	219	struct ewah_bitmap *test_xor;
	220
	221	for (i = 1; i <= MAX_XOR_OFFSET_SEARCH; ++i) {
	222	int curr = next - i;
	223
	224	if (curr < 0)
	225	break;
	226
	227	test_xor = ewah_pool_new();
	228	ewah_xor(writer.selected[curr].bitmap, stored->bitmap, test_xor);
	229
	230	if (test_xor->buffer_size < best_bitmap->buffer_size) {
	231	if (best_bitmap != stored->bitmap)
	232	ewah_pool_free(best_bitmap);
	233
	234	best_bitmap = test_xor;
	235	best_offset = i;
	236	} else {
	237	ewah_pool_free(test_xor);
	238	}
	239	}
240
241	stored->xor_offset = best_offset;
242	stored->write_as = best_bitmap;
243
244	next++;
245	}
246	}
247
248	void bitmap_writer_build(struct packing_data *to_pack)
249	{
250	static const double REUSE_BITMAP_THRESHOLD = 0.2;
251
252	int i, reuse_after, need_reset;
253	struct bitmap *base = bitmap_new();
254	struct rev_info revs;
255
256	writer.bitmaps = kh_init_sha1();
257	writer.to_pack = to_pack;
258
259	if (writer.show_progress)
260	writer.progress = start_progress("Building bitmaps", writer.selected_nr);
261
262	init_revisions(&revs, NULL);
263	revs.tag_objects = 1;
264	revs.tree_objects = 1;
265	revs.blob_objects = 1;
266	revs.no_walk = 0;
267
268	revs.include_check = should_include;
269	reset_revision_walk();
270
271	reuse_after = writer.selected_nr * REUSE_BITMAP_THRESHOLD;
272	need_reset = 0;
273
274	for (i = writer.selected_nr - 1; i >= 0; --i) {
275	struct bitmapped_commit *stored;
276	struct object *object;
277
278	khiter_t hash_pos;
279	int hash_ret;
280
281	stored = &writer.selected[i];
282	object = (struct object *)stored->commit;
283
284	if (stored->bitmap == NULL) {
285	if (i < writer.selected_nr - 1 &&
286	(need_reset \|\|
287	!in_merge_bases(writer.selected[i + 1].commit,
288	stored->commit))) {
289	bitmap_reset(base);
290	reset_all_seen();
291	}
292
293	add_pending_object(&revs, object, "");
294	revs.include_check_data = base;
295
296	if (prepare_revision_walk(&revs))
297	die("revision walk setup failed");
298
299	traverse_commit_list(&revs, show_commit, show_object, base);
300
4d01a7fa	301	object_array_clear(&revs.pending);
7cc8f971 VM	302
	303	stored->bitmap = bitmap_to_ewah(base);
	304	need_reset = 0;
	305	} else
	306	need_reset = 1;
	307
	308	if (i >= reuse_after)
	309	stored->flags \|= BITMAP_FLAG_REUSE;
	310
ed1c9977	311	hash_pos = kh_put_sha1(writer.bitmaps, object->oid.hash, &hash_ret);
7cc8f971 VM	312	if (hash_ret == 0)
7cc8f971 VM	313	die("Duplicate entry when writing index: %s",
f2fd0760	314	oid_to_hex(&object->oid));
7cc8f971 VM	315
	316	kh_value(writer.bitmaps, hash_pos) = stored;
	317	display_progress(writer.progress, writer.selected_nr - i);
	318	}
	319
	320	bitmap_free(base);
	321	stop_progress(&writer.progress);
	322
	323	compute_xor_offsets();
	324	}
	325
	326	/**
	327	* Select the commits that will be bitmapped
	328	*/
	329	static inline unsigned int next_commit_index(unsigned int idx)
	330	{
	331	static const unsigned int MIN_COMMITS = 100;
	332	static const unsigned int MAX_COMMITS = 5000;
	333
	334	static const unsigned int MUST_REGION = 100;
	335	static const unsigned int MIN_REGION = 20000;
	336
	337	unsigned int offset, next;
	338
	339	if (idx <= MUST_REGION)
	340	return 0;
	341
	342	if (idx <= MIN_REGION) {
	343	offset = idx - MUST_REGION;
	344	return (offset < MIN_COMMITS) ? offset : MIN_COMMITS;
	345	}
	346
	347	offset = idx - MIN_REGION;
	348	next = (offset < MAX_COMMITS) ? offset : MAX_COMMITS;
	349
	350	return (next > MIN_COMMITS) ? next : MIN_COMMITS;
	351	}
	352
	353	static int date_compare(const void _a, const void _b)
	354	{
	355	struct commit a = (struct commit **)_a;
	356	struct commit b = (struct commit **)_b;
	357	return (long)b->date - (long)a->date;
	358	}
	359
	360	void bitmap_writer_reuse_bitmaps(struct packing_data *to_pack)
	361	{
	362	if (prepare_bitmap_git() < 0)
	363	return;
	364
	365	writer.reused = kh_init_sha1();
	366	rebuild_existing_bitmaps(to_pack, writer.reused, writer.show_progress);
	367	}
	368
	369	static struct ewah_bitmap find_reused_bitmap(const unsigned char sha1)
	370	{
	371	khiter_t hash_pos;
	372
	373	if (!writer.reused)
	374	return NULL;
	375
	376	hash_pos = kh_get_sha1(writer.reused, sha1);
	377	if (hash_pos >= kh_end(writer.reused))
	378	return NULL;
379
380	return kh_value(writer.reused, hash_pos);
381	}
382
383	void bitmap_writer_select_commits(struct commit **indexed_commits,
384	unsigned int indexed_commits_nr,
385	int max_bitmaps)
386	{
387	unsigned int i = 0, j, next;
388
9ed0d8d6	389	QSORT(indexed_commits, indexed_commits_nr, date_compare);
7cc8f971 VM	390
	391	if (writer.show_progress)
	392	writer.progress = start_progress("Selecting bitmap commits", 0);
	393
	394	if (indexed_commits_nr < 100) {
	395	for (i = 0; i < indexed_commits_nr; ++i)
	396	push_bitmapped_commit(indexed_commits[i], NULL);
	397	return;
	398	}
	399
	400	for (;;) {
	401	struct ewah_bitmap *reused_bitmap = NULL;
	402	struct commit *chosen = NULL;
	403
	404	next = next_commit_index(i);
	405
	406	if (i + next >= indexed_commits_nr)
	407	break;
	408
	409	if (max_bitmaps > 0 && writer.selected_nr >= max_bitmaps) {
	410	writer.selected_nr = max_bitmaps;
	411	break;
	412	}
	413
	414	if (next == 0) {
	415	chosen = indexed_commits[i];
ed1c9977	416	reused_bitmap = find_reused_bitmap(chosen->object.oid.hash);
7cc8f971 VM	417	} else {
	418	chosen = indexed_commits[i + next];
	419
	420	for (j = 0; j <= next; ++j) {
	421	struct commit *cm = indexed_commits[i + j];
	422
ed1c9977	423	reused_bitmap = find_reused_bitmap(cm->object.oid.hash);
7cc8f971 VM	424	if (reused_bitmap \|\| (cm->object.flags & NEEDS_BITMAP) != 0) {
	425	chosen = cm;
	426	break;
	427	}
	428
	429	if (cm->parents && cm->parents->next)
	430	chosen = cm;
	431	}
	432	}
	433
	434	push_bitmapped_commit(chosen, reused_bitmap);
	435
	436	i += next + 1;
	437	display_progress(writer.progress, i);
	438	}
	439
	440	stop_progress(&writer.progress);
	441	}
	442
	443
98a3beab	444	static int hashwrite_ewah_helper(void f, const void buf, size_t len)
7cc8f971	445	{
98a3beab	446	/* hashwrite will die on error */
98a3beab	447	hashwrite(f, buf, len);
7cc8f971 VM	448	return len;
	449	}
	450
	451	/**
	452	* Write the bitmap index to disk
	453	*/
98a3beab	454	static inline void dump_bitmap(struct hashfile f, struct ewah_bitmap bitmap)
7cc8f971	455	{
98a3beab	456	if (ewah_serialize_to(bitmap, hashwrite_ewah_helper, f) < 0)
7cc8f971 VM	457	die("Failed to write bitmap index");
	458	}
	459
	460	static const unsigned char sha1_access(size_t pos, void table)
	461	{
	462	struct pack_idx_entry **index = table;
e6a492b7	463	return index[pos]->oid.hash;
7cc8f971 VM	464	}
7cc8f971 VM	465
98a3beab	466	static void write_selected_commits_v1(struct hashfile *f,
7cc8f971 VM	467	struct pack_idx_entry **index,
	468	uint32_t index_nr)
	469	{
	470	int i;
	471
	472	for (i = 0; i < writer.selected_nr; ++i) {
	473	struct bitmapped_commit *stored = &writer.selected[i];
7cc8f971 VM	474
7cc8f971 VM	475	int commit_pos =
ed1c9977	476	sha1_pos(stored->commit->object.oid.hash, index, index_nr, sha1_access);
7cc8f971 VM	477
	478	if (commit_pos < 0)
	479	die("BUG: trying to write commit not in index");
	480
98a3beab	481	hashwrite_be32(f, commit_pos);
	482	hashwrite_u8(f, stored->xor_offset);
	483	hashwrite_u8(f, stored->flags);
7cc8f971	484
7cc8f971 VM	485	dump_bitmap(f, stored->write_as);
	486	}
	487	}
	488
98a3beab	489	static void write_hash_cache(struct hashfile *f,
ae4f07fb VM	490	struct pack_idx_entry **index,
	491	uint32_t index_nr)
	492	{
	493	uint32_t i;
	494
	495	for (i = 0; i < index_nr; ++i) {
	496	struct object_entry entry = (struct object_entry )index[i];
	497	uint32_t hash_value = htonl(entry->hash);
98a3beab	498	hashwrite(f, &hash_value, sizeof(hash_value));
ae4f07fb VM	499	}
	500	}
	501
7cc8f971 VM	502	void bitmap_writer_set_checksum(unsigned char *sha1)
	503	{
	504	hashcpy(writer.pack_checksum, sha1);
	505	}
	506
	507	void bitmap_writer_finish(struct pack_idx_entry **index,
	508	uint32_t index_nr,
ae4f07fb VM	509	const char *filename,
ae4f07fb VM	510	uint16_t options)
7cc8f971	511	{
7cc8f971 VM	512	static uint16_t default_version = 1;
7cc8f971 VM	513	static uint16_t flags = BITMAP_OPT_FULL_DAG;
594fa999	514	struct strbuf tmp_file = STRBUF_INIT;
98a3beab	515	struct hashfile *f;
7cc8f971 VM	516
	517	struct bitmap_disk_header header;
	518
594fa999	519	int fd = odb_mkstemp(&tmp_file, "pack/tmp_bitmap_XXXXXX");
7cc8f971	520
98a3beab	521	f = hashfd(fd, tmp_file.buf);
7cc8f971 VM	522
	523	memcpy(header.magic, BITMAP_IDX_SIGNATURE, sizeof(BITMAP_IDX_SIGNATURE));
	524	header.version = htons(default_version);
ae4f07fb	525	header.options = htons(flags \| options);
7cc8f971	526	header.entry_count = htonl(writer.selected_nr);
50546b15	527	hashcpy(header.checksum, writer.pack_checksum);
7cc8f971	528
98a3beab	529	hashwrite(f, &header, sizeof(header));
7cc8f971 VM	530	dump_bitmap(f, writer.commits);
	531	dump_bitmap(f, writer.trees);
	532	dump_bitmap(f, writer.blobs);
	533	dump_bitmap(f, writer.tags);
	534	write_selected_commits_v1(f, index, index_nr);
	535
ae4f07fb VM	536	if (options & BITMAP_OPT_HASH_CACHE)
	537	write_hash_cache(f, index, index_nr);
	538
98a3beab	539	hashclose(f, NULL, CSUM_FSYNC);
7cc8f971	540
594fa999	541	if (adjust_shared_perm(tmp_file.buf))
7cc8f971 VM	542	die_errno("unable to make temporary bitmap file readable");
7cc8f971 VM	543
594fa999	544	if (rename(tmp_file.buf, filename))
7cc8f971	545	die_errno("unable to rename temporary bitmap file to '%s'", filename);
594fa999 JK	546
594fa999 JK	547	strbuf_release(&tmp_file);
7cc8f971	548	}