[git/git.git] / split-index.c

#include "cache.h"
#include "split-index.h"
#include "ewah/ewok.h"

struct split_index *init_split_index(struct index_state *istate)
{
	if (!istate->split_index) {
		istate->split_index = xcalloc(1, sizeof(*istate->split_index));
		istate->split_index->refcount = 1;
	}
	return istate->split_index;
}

int read_link_extension(struct index_state *istate,
			 const void *data_, unsigned long sz)
{
	const unsigned char *data = data_;
	struct split_index *si;
	int ret;

	if (sz < the_hash_algo->rawsz)
		return error("corrupt link extension (too short)");
	si = init_split_index(istate);
	hashcpy(si->base_oid.hash, data);
	data += the_hash_algo->rawsz;
	sz -= the_hash_algo->rawsz;
	if (!sz)
		return 0;
	si->delete_bitmap = ewah_new();
	ret = ewah_read_mmap(si->delete_bitmap, data, sz);
	if (ret < 0)
		return error("corrupt delete bitmap in link extension");
	data += ret;
	sz -= ret;
	si->replace_bitmap = ewah_new();
	ret = ewah_read_mmap(si->replace_bitmap, data, sz);
	if (ret < 0)
		return error("corrupt replace bitmap in link extension");
	if (ret != sz)
		return error("garbage at the end of link extension");
	return 0;
}

int write_link_extension(struct strbuf *sb,
			 struct index_state *istate)
{
	struct split_index *si = istate->split_index;
	strbuf_add(sb, si->base_oid.hash, the_hash_algo->rawsz);
	if (!si->delete_bitmap && !si->replace_bitmap)
		return 0;
	ewah_serialize_strbuf(si->delete_bitmap, sb);
	ewah_serialize_strbuf(si->replace_bitmap, sb);
	return 0;
}

static void mark_base_index_entries(struct index_state *base)
{
	int i;
	/*
	 * To keep track of the shared entries between
	 * istate->base->cache[] and istate->cache[], base entry
	 * position is stored in each base entry. All positions start
	 * from 1 instead of 0, which is reserved to say "this is a new
	 * entry".
	 */
	for (i = 0; i < base->cache_nr; i++)
		base->cache[i]->index = i + 1;
}

void move_cache_to_base_index(struct index_state *istate)
{
	struct split_index *si = istate->split_index;
	int i;

	/*
	 * If there was a previous base index, then transfer ownership of allocated
	 * entries to the parent index.
	 */
	if (si->base &&
		si->base->ce_mem_pool) {

		if (!istate->ce_mem_pool)
			mem_pool_init(&istate->ce_mem_pool, 0);

		mem_pool_combine(istate->ce_mem_pool, istate->split_index->base->ce_mem_pool);
	}

	si->base = xcalloc(1, sizeof(*si->base));
	si->base->version = istate->version;
	/* zero timestamp disables racy test in ce_write_index() */
	si->base->timestamp = istate->timestamp;
	ALLOC_GROW(si->base->cache, istate->cache_nr, si->base->cache_alloc);
	si->base->cache_nr = istate->cache_nr;

	/*
	 * The mem_pool needs to move with the allocated entries.
	 */
	si->base->ce_mem_pool = istate->ce_mem_pool;
	istate->ce_mem_pool = NULL;

	COPY_ARRAY(si->base->cache, istate->cache, istate->cache_nr);
	mark_base_index_entries(si->base);
	for (i = 0; i < si->base->cache_nr; i++)
		si->base->cache[i]->ce_flags &= ~CE_UPDATE_IN_BASE;
}

static void mark_entry_for_delete(size_t pos, void *data)
{
	struct index_state *istate = data;
	if (pos >= istate->cache_nr)
		die("position for delete %d exceeds base index size %d",
		    (int)pos, istate->cache_nr);
	istate->cache[pos]->ce_flags |= CE_REMOVE;
	istate->split_index->nr_deletions++;
}

static void replace_entry(size_t pos, void *data)
{
	struct index_state *istate = data;
	struct split_index *si = istate->split_index;
	struct cache_entry *dst, *src;

	if (pos >= istate->cache_nr)
		die("position for replacement %d exceeds base index size %d",
		    (int)pos, istate->cache_nr);
	if (si->nr_replacements >= si->saved_cache_nr)
		die("too many replacements (%d vs %d)",
		    si->nr_replacements, si->saved_cache_nr);
	dst = istate->cache[pos];
	if (dst->ce_flags & CE_REMOVE)
		die("entry %d is marked as both replaced and deleted",
		    (int)pos);
	src = si->saved_cache[si->nr_replacements];
	if (ce_namelen(src))
		die("corrupt link extension, entry %d should have "
		    "zero length name", (int)pos);
	src->index = pos + 1;
	src->ce_flags |= CE_UPDATE_IN_BASE;
	src->ce_namelen = dst->ce_namelen;
	copy_cache_entry(dst, src);
	discard_cache_entry(src);
	si->nr_replacements++;
}

void merge_base_index(struct index_state *istate)
{
	struct split_index *si = istate->split_index;
	unsigned int i;

	mark_base_index_entries(si->base);

	si->saved_cache	    = istate->cache;
	si->saved_cache_nr  = istate->cache_nr;
	istate->cache_nr    = si->base->cache_nr;
	istate->cache	    = NULL;
	istate->cache_alloc = 0;
	ALLOC_GROW(istate->cache, istate->cache_nr, istate->cache_alloc);
	COPY_ARRAY(istate->cache, si->base->cache, istate->cache_nr);

	si->nr_deletions = 0;
	si->nr_replacements = 0;
	ewah_each_bit(si->replace_bitmap, replace_entry, istate);
	ewah_each_bit(si->delete_bitmap, mark_entry_for_delete, istate);
	if (si->nr_deletions)
		remove_marked_cache_entries(istate);

	for (i = si->nr_replacements; i < si->saved_cache_nr; i++) {
		if (!ce_namelen(si->saved_cache[i]))
			die("corrupt link extension, entry %d should "
			    "have non-zero length name", i);
		add_index_entry(istate, si->saved_cache[i],
				ADD_CACHE_OK_TO_ADD |
				ADD_CACHE_KEEP_CACHE_TREE |
				/*
				 * we may have to replay what
				 * merge-recursive.c:update_stages()
				 * does, which has this flag on
				 */
				ADD_CACHE_SKIP_DFCHECK);
		si->saved_cache[i] = NULL;
	}

	ewah_free(si->delete_bitmap);
	ewah_free(si->replace_bitmap);
	FREE_AND_NULL(si->saved_cache);
	si->delete_bitmap  = NULL;
	si->replace_bitmap = NULL;
	si->saved_cache_nr = 0;
}

/*
 * Compare most of the fields in two cache entries, i.e. all except the
 * hashmap_entry and the name.
 */
static int compare_ce_content(struct cache_entry *a, struct cache_entry *b)
{
	const unsigned int ondisk_flags = CE_STAGEMASK | CE_VALID |
					  CE_EXTENDED_FLAGS;
	unsigned int ce_flags = a->ce_flags;
	unsigned int base_flags = b->ce_flags;
	int ret;

	/* only on-disk flags matter */
	a->ce_flags &= ondisk_flags;
	b->ce_flags &= ondisk_flags;
	ret = memcmp(&a->ce_stat_data, &b->ce_stat_data,
		     offsetof(struct cache_entry, name) -
		     offsetof(struct cache_entry, ce_stat_data));
	a->ce_flags = ce_flags;
	b->ce_flags = base_flags;

	return ret;
}

void prepare_to_write_split_index(struct index_state *istate)
{
	struct split_index *si = init_split_index(istate);
	struct cache_entry **entries = NULL, *ce;
	int i, nr_entries = 0, nr_alloc = 0;

	si->delete_bitmap = ewah_new();
	si->replace_bitmap = ewah_new();

	if (si->base) {
		/* Go through istate->cache[] and mark CE_MATCHED to
		 * entry with positive index. We'll go through
		 * base->cache[] later to delete all entries in base
		 * that are not marked with either CE_MATCHED or
		 * CE_UPDATE_IN_BASE. If istate->cache[i] is a
		 * duplicate, deduplicate it.
		 */
		for (i = 0; i < istate->cache_nr; i++) {
			struct cache_entry *base;
			ce = istate->cache[i];
			if (!ce->index) {
				/*
				 * During simple update index operations this
				 * is a cache entry that is not present in
				 * the shared index.  It will be added to the
				 * split index.
				 *
				 * However, it might also represent a file
				 * that already has a cache entry in the
				 * shared index, but a new index has just
				 * been constructed by unpack_trees(), and
				 * this entry now refers to different content
				 * than what was recorded in the original
				 * index, e.g. during 'read-tree -m HEAD^' or
				 * 'checkout HEAD^'.  In this case the
				 * original entry in the shared index will be
				 * marked as deleted, and this entry will be
				 * added to the split index.
				 */
				continue;
			}
			if (ce->index > si->base->cache_nr) {
				ce->index = 0;
				continue;
			}
			ce->ce_flags |= CE_MATCHED; /* or "shared" */
			base = si->base->cache[ce->index - 1];
			if (ce == base)
				continue;
			if (ce->ce_namelen != base->ce_namelen ||
			    strcmp(ce->name, base->name)) {
				ce->index = 0;
				continue;
			}
			/*
			 * This is the copy of a cache entry that is present
			 * in the shared index, created by unpack_trees()
			 * while it constructed a new index.
			 */
			if (ce->ce_flags & CE_UPDATE_IN_BASE) {
				/*
				 * Already marked for inclusion in the split
				 * index, either because the corresponding
				 * file was modified and the cached stat data
				 * was refreshed, or because the original
				 * entry already had a replacement entry in
				 * the split index.
				 * Nothing to do.
				 */
			} else {
				/*
				 * Thoroughly compare the cached data to see
				 * whether it should be marked for inclusion
				 * in the split index.
				 *
				 * This comparison might be unnecessary, as
				 * code paths modifying the cached data do
				 * set CE_UPDATE_IN_BASE as well.
				 */
				if (compare_ce_content(ce, base))
					ce->ce_flags |= CE_UPDATE_IN_BASE;
			}
			discard_cache_entry(base);
			si->base->cache[ce->index - 1] = ce;
		}
		for (i = 0; i < si->base->cache_nr; i++) {
			ce = si->base->cache[i];
			if ((ce->ce_flags & CE_REMOVE) ||
			    !(ce->ce_flags & CE_MATCHED))
				ewah_set(si->delete_bitmap, i);
			else if (ce->ce_flags & CE_UPDATE_IN_BASE) {
				ewah_set(si->replace_bitmap, i);
				ce->ce_flags |= CE_STRIP_NAME;
				ALLOC_GROW(entries, nr_entries+1, nr_alloc);
				entries[nr_entries++] = ce;
			}
			if (is_null_oid(&ce->oid))
				istate->drop_cache_tree = 1;
		}
	}

	for (i = 0; i < istate->cache_nr; i++) {
		ce = istate->cache[i];
		if ((!si->base || !ce->index) && !(ce->ce_flags & CE_REMOVE)) {
			assert(!(ce->ce_flags & CE_STRIP_NAME));
			ALLOC_GROW(entries, nr_entries+1, nr_alloc);
			entries[nr_entries++] = ce;
		}
		ce->ce_flags &= ~CE_MATCHED;
	}

	/*
	 * take cache[] out temporarily, put entries[] in its place
	 * for writing
	 */
	si->saved_cache = istate->cache;
	si->saved_cache_nr = istate->cache_nr;
	istate->cache = entries;
	istate->cache_nr = nr_entries;
}

void finish_writing_split_index(struct index_state *istate)
{
	struct split_index *si = init_split_index(istate);

	ewah_free(si->delete_bitmap);
	ewah_free(si->replace_bitmap);
	si->delete_bitmap = NULL;
	si->replace_bitmap = NULL;
	free(istate->cache);
	istate->cache = si->saved_cache;
	istate->cache_nr = si->saved_cache_nr;
}

void discard_split_index(struct index_state *istate)
{
	struct split_index *si = istate->split_index;
	if (!si)
		return;
	istate->split_index = NULL;
	si->refcount--;
	if (si->refcount)
		return;
	if (si->base) {
		discard_index(si->base);
		free(si->base);
	}
	free(si);
}

void save_or_free_index_entry(struct index_state *istate, struct cache_entry *ce)
{
	if (ce->index &&
	    istate->split_index &&
	    istate->split_index->base &&
	    ce->index <= istate->split_index->base->cache_nr &&
	    ce == istate->split_index->base->cache[ce->index - 1])
		ce->ce_flags |= CE_REMOVE;
	else
		discard_cache_entry(ce);
}

void replace_index_entry_in_base(struct index_state *istate,
				 struct cache_entry *old_entry,
				 struct cache_entry *new_entry)
{
	if (old_entry->index &&
	    istate->split_index &&
	    istate->split_index->base &&
	    old_entry->index <= istate->split_index->base->cache_nr) {
		new_entry->index = old_entry->index;
		if (old_entry != istate->split_index->base->cache[new_entry->index - 1])
			discard_cache_entry(istate->split_index->base->cache[new_entry->index - 1]);
		istate->split_index->base->cache[new_entry->index - 1] = new_entry;
	}
}

void add_split_index(struct index_state *istate)
{
	if (!istate->split_index) {
		init_split_index(istate);
		istate->cache_changed |= SPLIT_INDEX_ORDERED;
	}
}

void remove_split_index(struct index_state *istate)
{
	if (istate->split_index) {
		/*
		 * When removing the split index, we need to move
		 * ownership of the mem_pool associated with the
		 * base index to the main index. There may be cache entries
		 * allocated from the base's memory pool that are shared with
		 * the_index.cache[].
		 */
		mem_pool_combine(istate->ce_mem_pool, istate->split_index->base->ce_mem_pool);

		/*
		 * The split index no longer owns the mem_pool backing
		 * its cache array. As we are discarding this index,
		 * mark the index as having no cache entries, so it
		 * will not attempt to clean up the cache entries or
		 * validate them.
		 */
		if (istate->split_index->base)
			istate->split_index->base->cache_nr = 0;

		/*
		 * We can discard the split index because its
		 * memory pool has been incorporated into the
		 * memory pool associated with the the_index.
		 */
		discard_split_index(istate);

		istate->cache_changed |= SOMETHING_CHANGED;
	}
}
Commit	Line	Data
5fc2fc8f NTND	1	#include "cache.h"
5fc2fc8f NTND	2	#include "split-index.h"
96a1d8d3	3	#include "ewah/ewok.h"
5fc2fc8f NTND	4
	5	struct split_index init_split_index(struct index_state istate)
	6	{
	7	if (!istate->split_index) {
	8	istate->split_index = xcalloc(1, sizeof(*istate->split_index));
	9	istate->split_index->refcount = 1;
	10	}
	11	return istate->split_index;
	12	}
	13
	14	int read_link_extension(struct index_state *istate,
	15	const void *data_, unsigned long sz)
	16	{
	17	const unsigned char *data = data_;
	18	struct split_index *si;
76b07b37 NTND	19	int ret;
76b07b37 NTND	20
2182abd9	21	if (sz < the_hash_algo->rawsz)
5fc2fc8f NTND	22	return error("corrupt link extension (too short)");
5fc2fc8f NTND	23	si = init_split_index(istate);
2182abd9	24	hashcpy(si->base_oid.hash, data);
	25	data += the_hash_algo->rawsz;
	26	sz -= the_hash_algo->rawsz;
76b07b37 NTND	27	if (!sz)
	28	return 0;
	29	si->delete_bitmap = ewah_new();
	30	ret = ewah_read_mmap(si->delete_bitmap, data, sz);
	31	if (ret < 0)
	32	return error("corrupt delete bitmap in link extension");
	33	data += ret;
	34	sz -= ret;
	35	si->replace_bitmap = ewah_new();
	36	ret = ewah_read_mmap(si->replace_bitmap, data, sz);
	37	if (ret < 0)
	38	return error("corrupt replace bitmap in link extension");
	39	if (ret != sz)
5fc2fc8f NTND	40	return error("garbage at the end of link extension");
	41	return 0;
	42	}
	43
	44	int write_link_extension(struct strbuf *sb,
	45	struct index_state *istate)
	46	{
	47	struct split_index *si = istate->split_index;
2182abd9	48	strbuf_add(sb, si->base_oid.hash, the_hash_algo->rawsz);
96a1d8d3 NTND	49	if (!si->delete_bitmap && !si->replace_bitmap)
96a1d8d3 NTND	50	return 0;
be0d9d53 NTND	51	ewah_serialize_strbuf(si->delete_bitmap, sb);
be0d9d53 NTND	52	ewah_serialize_strbuf(si->replace_bitmap, sb);
5fc2fc8f NTND	53	return 0;
	54	}
	55
	56	static void mark_base_index_entries(struct index_state *base)
	57	{
	58	int i;
	59	/*
	60	* To keep track of the shared entries between
	61	* istate->base->cache[] and istate->cache[], base entry
	62	* position is stored in each base entry. All positions start
832c0e5e	63	* from 1 instead of 0, which is reserved to say "this is a new
5fc2fc8f NTND	64	* entry".
	65	*/
	66	for (i = 0; i < base->cache_nr; i++)
	67	base->cache[i]->index = i + 1;
	68	}
	69
c18b80a0 NTND	70	void move_cache_to_base_index(struct index_state *istate)
	71	{
	72	struct split_index *si = istate->split_index;
	73	int i;
	74
	75	/*
8e72d675 JM	76	* If there was a previous base index, then transfer ownership of allocated
8e72d675 JM	77	* entries to the parent index.
c18b80a0	78	*/
8e72d675 JM	79	if (si->base &&
	80	si->base->ce_mem_pool) {
	81
	82	if (!istate->ce_mem_pool)
	83	mem_pool_init(&istate->ce_mem_pool, 0);
	84
	85	mem_pool_combine(istate->ce_mem_pool, istate->split_index->base->ce_mem_pool);
	86	}
	87
c18b80a0 NTND	88	si->base = xcalloc(1, sizeof(*si->base));
	89	si->base->version = istate->version;
	90	/* zero timestamp disables racy test in ce_write_index() */
	91	si->base->timestamp = istate->timestamp;
	92	ALLOC_GROW(si->base->cache, istate->cache_nr, si->base->cache_alloc);
	93	si->base->cache_nr = istate->cache_nr;
8e72d675 JM	94
	95	/*
	96	* The mem_pool needs to move with the allocated entries.
	97	*/
	98	si->base->ce_mem_pool = istate->ce_mem_pool;
	99	istate->ce_mem_pool = NULL;
	100
45ccef87	101	COPY_ARRAY(si->base->cache, istate->cache, istate->cache_nr);
c18b80a0 NTND	102	mark_base_index_entries(si->base);
	103	for (i = 0; i < si->base->cache_nr; i++)
	104	si->base->cache[i]->ce_flags &= ~CE_UPDATE_IN_BASE;
	105	}
	106
76b07b37 NTND	107	static void mark_entry_for_delete(size_t pos, void *data)
	108	{
	109	struct index_state *istate = data;
	110	if (pos >= istate->cache_nr)
	111	die("position for delete %d exceeds base index size %d",
	112	(int)pos, istate->cache_nr);
	113	istate->cache[pos]->ce_flags \|= CE_REMOVE;
2034e848	114	istate->split_index->nr_deletions++;
76b07b37 NTND	115	}
	116
	117	static void replace_entry(size_t pos, void *data)
	118	{
	119	struct index_state *istate = data;
	120	struct split_index *si = istate->split_index;
	121	struct cache_entry dst, src;
b3c96fb1	122
76b07b37 NTND	123	if (pos >= istate->cache_nr)
	124	die("position for replacement %d exceeds base index size %d",
	125	(int)pos, istate->cache_nr);
	126	if (si->nr_replacements >= si->saved_cache_nr)
	127	die("too many replacements (%d vs %d)",
	128	si->nr_replacements, si->saved_cache_nr);
	129	dst = istate->cache[pos];
	130	if (dst->ce_flags & CE_REMOVE)
	131	die("entry %d is marked as both replaced and deleted",
	132	(int)pos);
	133	src = si->saved_cache[si->nr_replacements];
b3c96fb1 NTND	134	if (ce_namelen(src))
	135	die("corrupt link extension, entry %d should have "
	136	"zero length name", (int)pos);
76b07b37 NTND	137	src->index = pos + 1;
76b07b37 NTND	138	src->ce_flags \|= CE_UPDATE_IN_BASE;
b3c96fb1 NTND	139	src->ce_namelen = dst->ce_namelen;
b3c96fb1 NTND	140	copy_cache_entry(dst, src);
a849735b	141	discard_cache_entry(src);
76b07b37 NTND	142	si->nr_replacements++;
	143	}
	144
5fc2fc8f NTND	145	void merge_base_index(struct index_state *istate)
	146	{
	147	struct split_index *si = istate->split_index;
76b07b37	148	unsigned int i;
5fc2fc8f NTND	149
5fc2fc8f NTND	150	mark_base_index_entries(si->base);
76b07b37 NTND	151
	152	si->saved_cache = istate->cache;
	153	si->saved_cache_nr = istate->cache_nr;
	154	istate->cache_nr = si->base->cache_nr;
	155	istate->cache = NULL;
	156	istate->cache_alloc = 0;
5fc2fc8f	157	ALLOC_GROW(istate->cache, istate->cache_nr, istate->cache_alloc);
45ccef87	158	COPY_ARRAY(istate->cache, si->base->cache, istate->cache_nr);
76b07b37 NTND	159
	160	si->nr_deletions = 0;
	161	si->nr_replacements = 0;
	162	ewah_each_bit(si->replace_bitmap, replace_entry, istate);
	163	ewah_each_bit(si->delete_bitmap, mark_entry_for_delete, istate);
	164	if (si->nr_deletions)
	165	remove_marked_cache_entries(istate);
	166
	167	for (i = si->nr_replacements; i < si->saved_cache_nr; i++) {
b3c96fb1 NTND	168	if (!ce_namelen(si->saved_cache[i]))
	169	die("corrupt link extension, entry %d should "
	170	"have non-zero length name", i);
76b07b37 NTND	171	add_index_entry(istate, si->saved_cache[i],
76b07b37 NTND	172	ADD_CACHE_OK_TO_ADD \|
ce7c614b	173	ADD_CACHE_KEEP_CACHE_TREE \|
76b07b37 NTND	174	/*
	175	* we may have to replay what
	176	* merge-recursive.c:update_stages()
	177	* does, which has this flag on
	178	*/
	179	ADD_CACHE_SKIP_DFCHECK);
	180	si->saved_cache[i] = NULL;
	181	}
	182
	183	ewah_free(si->delete_bitmap);
	184	ewah_free(si->replace_bitmap);
88ce3ef6	185	FREE_AND_NULL(si->saved_cache);
76b07b37 NTND	186	si->delete_bitmap = NULL;
76b07b37 NTND	187	si->replace_bitmap = NULL;
76b07b37	188	si->saved_cache_nr = 0;
5fc2fc8f NTND	189	}
5fc2fc8f NTND	190
e3d83798 SG	191	/*
	192	* Compare most of the fields in two cache entries, i.e. all except the
	193	* hashmap_entry and the name.
	194	*/
	195	static int compare_ce_content(struct cache_entry a, struct cache_entry b)
	196	{
	197	const unsigned int ondisk_flags = CE_STAGEMASK \| CE_VALID \|
	198	CE_EXTENDED_FLAGS;
	199	unsigned int ce_flags = a->ce_flags;
	200	unsigned int base_flags = b->ce_flags;
	201	int ret;
	202
	203	/* only on-disk flags matter */
	204	a->ce_flags &= ondisk_flags;
	205	b->ce_flags &= ondisk_flags;
	206	ret = memcmp(&a->ce_stat_data, &b->ce_stat_data,
	207	offsetof(struct cache_entry, name) -
	208	offsetof(struct cache_entry, ce_stat_data));
	209	a->ce_flags = ce_flags;
	210	b->ce_flags = base_flags;
	211
	212	return ret;
	213	}
	214
5fc2fc8f NTND	215	void prepare_to_write_split_index(struct index_state *istate)
	216	{
	217	struct split_index *si = init_split_index(istate);
96a1d8d3 NTND	218	struct cache_entry *entries = NULL, ce;
	219	int i, nr_entries = 0, nr_alloc = 0;
	220
	221	si->delete_bitmap = ewah_new();
	222	si->replace_bitmap = ewah_new();
	223
	224	if (si->base) {
	225	/* Go through istate->cache[] and mark CE_MATCHED to
	226	* entry with positive index. We'll go through
	227	* base->cache[] later to delete all entries in base
753c4515	228	* that are not marked with either CE_MATCHED or
96a1d8d3 NTND	229	* CE_UPDATE_IN_BASE. If istate->cache[i] is a
	230	* duplicate, deduplicate it.
	231	*/
	232	for (i = 0; i < istate->cache_nr; i++) {
	233	struct cache_entry *base;
96a1d8d3	234	ce = istate->cache[i];
e3d83798 SG	235	if (!ce->index) {
	236	/*
	237	* During simple update index operations this
	238	* is a cache entry that is not present in
	239	* the shared index. It will be added to the
	240	* split index.
	241	*
	242	* However, it might also represent a file
	243	* that already has a cache entry in the
	244	* shared index, but a new index has just
	245	* been constructed by unpack_trees(), and
	246	* this entry now refers to different content
	247	* than what was recorded in the original
	248	* index, e.g. during 'read-tree -m HEAD^' or
	249	* 'checkout HEAD^'. In this case the
	250	* original entry in the shared index will be
	251	* marked as deleted, and this entry will be
	252	* added to the split index.
	253	*/
96a1d8d3	254	continue;
e3d83798	255	}
96a1d8d3 NTND	256	if (ce->index > si->base->cache_nr) {
	257	ce->index = 0;
	258	continue;
	259	}
	260	ce->ce_flags \|= CE_MATCHED; /* or "shared" */
	261	base = si->base->cache[ce->index - 1];
	262	if (ce == base)
	263	continue;
	264	if (ce->ce_namelen != base->ce_namelen \|\|
	265	strcmp(ce->name, base->name)) {
	266	ce->index = 0;
	267	continue;
	268	}
e3d83798 SG	269	/*
	270	* This is the copy of a cache entry that is present
	271	* in the shared index, created by unpack_trees()
	272	* while it constructed a new index.
	273	*/
	274	if (ce->ce_flags & CE_UPDATE_IN_BASE) {
	275	/*
	276	* Already marked for inclusion in the split
	277	* index, either because the corresponding
	278	* file was modified and the cached stat data
	279	* was refreshed, or because the original
	280	* entry already had a replacement entry in
	281	* the split index.
	282	* Nothing to do.
	283	*/
	284	} else {
	285	/*
	286	* Thoroughly compare the cached data to see
	287	* whether it should be marked for inclusion
	288	* in the split index.
	289	*
	290	* This comparison might be unnecessary, as
	291	* code paths modifying the cached data do
	292	* set CE_UPDATE_IN_BASE as well.
	293	*/
	294	if (compare_ce_content(ce, base))
	295	ce->ce_flags \|= CE_UPDATE_IN_BASE;
	296	}
a849735b	297	discard_cache_entry(base);
96a1d8d3 NTND	298	si->base->cache[ce->index - 1] = ce;
	299	}
	300	for (i = 0; i < si->base->cache_nr; i++) {
	301	ce = si->base->cache[i];
	302	if ((ce->ce_flags & CE_REMOVE) \|\|
	303	!(ce->ce_flags & CE_MATCHED))
	304	ewah_set(si->delete_bitmap, i);
	305	else if (ce->ce_flags & CE_UPDATE_IN_BASE) {
	306	ewah_set(si->replace_bitmap, i);
b3c96fb1	307	ce->ce_flags \|= CE_STRIP_NAME;
96a1d8d3 NTND	308	ALLOC_GROW(entries, nr_entries+1, nr_alloc);
	309	entries[nr_entries++] = ce;
	310	}
4bddd983 TG	311	if (is_null_oid(&ce->oid))
4bddd983 TG	312	istate->drop_cache_tree = 1;
96a1d8d3 NTND	313	}
	314	}
	315
	316	for (i = 0; i < istate->cache_nr; i++) {
	317	ce = istate->cache[i];
	318	if ((!si->base \|\| !ce->index) && !(ce->ce_flags & CE_REMOVE)) {
b3c96fb1	319	assert(!(ce->ce_flags & CE_STRIP_NAME));
96a1d8d3 NTND	320	ALLOC_GROW(entries, nr_entries+1, nr_alloc);
	321	entries[nr_entries++] = ce;
	322	}
	323	ce->ce_flags &= ~CE_MATCHED;
	324	}
	325
	326	/*
	327	* take cache[] out temporarily, put entries[] in its place
	328	* for writing
	329	*/
	330	si->saved_cache = istate->cache;
5fc2fc8f	331	si->saved_cache_nr = istate->cache_nr;
96a1d8d3 NTND	332	istate->cache = entries;
96a1d8d3 NTND	333	istate->cache_nr = nr_entries;
5fc2fc8f NTND	334	}
	335
	336	void finish_writing_split_index(struct index_state *istate)
	337	{
	338	struct split_index *si = init_split_index(istate);
96a1d8d3 NTND	339
	340	ewah_free(si->delete_bitmap);
	341	ewah_free(si->replace_bitmap);
	342	si->delete_bitmap = NULL;
	343	si->replace_bitmap = NULL;
	344	free(istate->cache);
	345	istate->cache = si->saved_cache;
5fc2fc8f NTND	346	istate->cache_nr = si->saved_cache_nr;
	347	}
	348
	349	void discard_split_index(struct index_state *istate)
	350	{
	351	struct split_index *si = istate->split_index;
	352	if (!si)
	353	return;
	354	istate->split_index = NULL;
	355	si->refcount--;
	356	if (si->refcount)
	357	return;
	358	if (si->base) {
	359	discard_index(si->base);
	360	free(si->base);
	361	}
	362	free(si);
	363	}
045113a5 NTND	364
	365	void save_or_free_index_entry(struct index_state istate, struct cache_entry ce)
	366	{
	367	if (ce->index &&
	368	istate->split_index &&
	369	istate->split_index->base &&
	370	ce->index <= istate->split_index->base->cache_nr &&
	371	ce == istate->split_index->base->cache[ce->index - 1])
	372	ce->ce_flags \|= CE_REMOVE;
	373	else
a849735b	374	discard_cache_entry(ce);
045113a5	375	}
078a58e8 NTND	376
078a58e8 NTND	377	void replace_index_entry_in_base(struct index_state *istate,
75b7b971 BW	378	struct cache_entry *old_entry,
75b7b971 BW	379	struct cache_entry *new_entry)
078a58e8	380	{
75b7b971	381	if (old_entry->index &&
078a58e8 NTND	382	istate->split_index &&
078a58e8 NTND	383	istate->split_index->base &&
75b7b971 BW	384	old_entry->index <= istate->split_index->base->cache_nr) {
	385	new_entry->index = old_entry->index;
	386	if (old_entry != istate->split_index->base->cache[new_entry->index - 1])
a849735b	387	discard_cache_entry(istate->split_index->base->cache[new_entry->index - 1]);
75b7b971	388	istate->split_index->base->cache[new_entry->index - 1] = new_entry;
078a58e8 NTND	389	}
078a58e8 NTND	390	}
cef4fc7e CC	391
	392	void add_split_index(struct index_state *istate)
	393	{
	394	if (!istate->split_index) {
	395	init_split_index(istate);
	396	istate->cache_changed \|= SPLIT_INDEX_ORDERED;
	397	}
	398	}
	399
	400	void remove_split_index(struct index_state *istate)
	401	{
64719b11 JH	402	if (istate->split_index) {
64719b11 JH	403	/*
8e72d675 JM	404	* When removing the split index, we need to move
	405	* ownership of the mem_pool associated with the
	406	* base index to the main index. There may be cache entries
	407	* allocated from the base's memory pool that are shared with
	408	* the_index.cache[].
64719b11	409	*/
8e72d675 JM	410	mem_pool_combine(istate->ce_mem_pool, istate->split_index->base->ce_mem_pool);
	411
	412	/*
	413	* The split index no longer owns the mem_pool backing
	414	* its cache array. As we are discarding this index,
	415	* mark the index as having no cache entries, so it
	416	* will not attempt to clean up the cache entries or
	417	* validate them.
	418	*/
	419	if (istate->split_index->base)
	420	istate->split_index->base->cache_nr = 0;
	421
	422	/*
	423	* We can discard the split index because its
	424	* memory pool has been incorporated into the
	425	* memory pool associated with the the_index.
	426	*/
	427	discard_split_index(istate);
	428
64719b11 JH	429	istate->cache_changed \|= SOMETHING_CHANGED;
64719b11 JH	430	}
cef4fc7e	431	}