Merge branch 'es/doc-worktree-guessremote-config'
[git.git] / split-index.c
blob5820412dc5203032d1247575d79c6107a163295a
1 #include "cache.h"
2 #include "split-index.h"
3 #include "ewah/ewok.h"
5 struct split_index *init_split_index(struct index_state *istate)
7 if (!istate->split_index) {
8 istate->split_index = xcalloc(1, sizeof(*istate->split_index));
9 istate->split_index->refcount = 1;
11 return istate->split_index;
14 int read_link_extension(struct index_state *istate,
15 const void *data_, unsigned long sz)
17 const unsigned char *data = data_;
18 struct split_index *si;
19 int ret;
21 if (sz < the_hash_algo->rawsz)
22 return error("corrupt link extension (too short)");
23 si = init_split_index(istate);
24 hashcpy(si->base_oid.hash, data);
25 data += the_hash_algo->rawsz;
26 sz -= the_hash_algo->rawsz;
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)
40 return error("garbage at the end of link extension");
41 return 0;
44 int write_link_extension(struct strbuf *sb,
45 struct index_state *istate)
47 struct split_index *si = istate->split_index;
48 strbuf_add(sb, si->base_oid.hash, the_hash_algo->rawsz);
49 if (!si->delete_bitmap && !si->replace_bitmap)
50 return 0;
51 ewah_serialize_strbuf(si->delete_bitmap, sb);
52 ewah_serialize_strbuf(si->replace_bitmap, sb);
53 return 0;
56 static void mark_base_index_entries(struct index_state *base)
58 int i;
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
63 * from 1 instead of 0, which is reserved to say "this is a new
64 * entry".
66 for (i = 0; i < base->cache_nr; i++)
67 base->cache[i]->index = i + 1;
70 void move_cache_to_base_index(struct index_state *istate)
72 struct split_index *si = istate->split_index;
73 int i;
76 * If there was a previous base index, then transfer ownership of allocated
77 * entries to the parent index.
79 if (si->base &&
80 si->base->ce_mem_pool) {
82 if (!istate->ce_mem_pool)
83 mem_pool_init(&istate->ce_mem_pool, 0);
85 mem_pool_combine(istate->ce_mem_pool, istate->split_index->base->ce_mem_pool);
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;
96 * The mem_pool needs to move with the allocated entries.
98 si->base->ce_mem_pool = istate->ce_mem_pool;
99 istate->ce_mem_pool = NULL;
101 COPY_ARRAY(si->base->cache, istate->cache, istate->cache_nr);
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;
107 static void mark_entry_for_delete(size_t pos, void *data)
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;
114 istate->split_index->nr_deletions++;
117 static void replace_entry(size_t pos, void *data)
119 struct index_state *istate = data;
120 struct split_index *si = istate->split_index;
121 struct cache_entry *dst, *src;
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];
134 if (ce_namelen(src))
135 die("corrupt link extension, entry %d should have "
136 "zero length name", (int)pos);
137 src->index = pos + 1;
138 src->ce_flags |= CE_UPDATE_IN_BASE;
139 src->ce_namelen = dst->ce_namelen;
140 copy_cache_entry(dst, src);
141 discard_cache_entry(src);
142 si->nr_replacements++;
145 void merge_base_index(struct index_state *istate)
147 struct split_index *si = istate->split_index;
148 unsigned int i;
150 mark_base_index_entries(si->base);
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;
157 ALLOC_GROW(istate->cache, istate->cache_nr, istate->cache_alloc);
158 COPY_ARRAY(istate->cache, si->base->cache, istate->cache_nr);
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);
167 for (i = si->nr_replacements; i < si->saved_cache_nr; i++) {
168 if (!ce_namelen(si->saved_cache[i]))
169 die("corrupt link extension, entry %d should "
170 "have non-zero length name", i);
171 add_index_entry(istate, si->saved_cache[i],
172 ADD_CACHE_OK_TO_ADD |
173 ADD_CACHE_KEEP_CACHE_TREE |
175 * we may have to replay what
176 * merge-recursive.c:update_stages()
177 * does, which has this flag on
179 ADD_CACHE_SKIP_DFCHECK);
180 si->saved_cache[i] = NULL;
183 ewah_free(si->delete_bitmap);
184 ewah_free(si->replace_bitmap);
185 FREE_AND_NULL(si->saved_cache);
186 si->delete_bitmap = NULL;
187 si->replace_bitmap = NULL;
188 si->saved_cache_nr = 0;
192 * Compare most of the fields in two cache entries, i.e. all except the
193 * hashmap_entry and the name.
195 static int compare_ce_content(struct cache_entry *a, struct cache_entry *b)
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;
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;
212 return ret;
215 void prepare_to_write_split_index(struct index_state *istate)
217 struct split_index *si = init_split_index(istate);
218 struct cache_entry **entries = NULL, *ce;
219 int i, nr_entries = 0, nr_alloc = 0;
221 si->delete_bitmap = ewah_new();
222 si->replace_bitmap = ewah_new();
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
228 * that are not marked with either CE_MATCHED or
229 * CE_UPDATE_IN_BASE. If istate->cache[i] is a
230 * duplicate, deduplicate it.
232 for (i = 0; i < istate->cache_nr; i++) {
233 struct cache_entry *base;
234 ce = istate->cache[i];
235 if (!ce->index) {
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.
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.
254 continue;
256 if (ce->index > si->base->cache_nr) {
257 BUG("ce refers to a shared ce at %d, which is beyond the shared index size %d",
258 ce->index, si->base->cache_nr);
260 ce->ce_flags |= CE_MATCHED; /* or "shared" */
261 base = si->base->cache[ce->index - 1];
262 if (ce == base) {
263 /* The entry is present in the shared index. */
264 if (ce->ce_flags & CE_UPDATE_IN_BASE) {
266 * Already marked for inclusion in
267 * the split index, either because
268 * the corresponding file was
269 * modified and the cached stat data
270 * was refreshed, or because there
271 * is already a replacement entry in
272 * the split index.
273 * Nothing more to do here.
275 } else if (!ce_uptodate(ce) &&
276 is_racy_timestamp(istate, ce)) {
278 * A racily clean cache entry stored
279 * only in the shared index: it must
280 * be added to the split index, so
281 * the subsequent do_write_index()
282 * can smudge its stat data.
284 ce->ce_flags |= CE_UPDATE_IN_BASE;
285 } else {
287 * The entry is only present in the
288 * shared index and it was not
289 * refreshed.
290 * Just leave it there.
293 continue;
295 if (ce->ce_namelen != base->ce_namelen ||
296 strcmp(ce->name, base->name)) {
297 ce->index = 0;
298 continue;
301 * This is the copy of a cache entry that is present
302 * in the shared index, created by unpack_trees()
303 * while it constructed a new index.
305 if (ce->ce_flags & CE_UPDATE_IN_BASE) {
307 * Already marked for inclusion in the split
308 * index, either because the corresponding
309 * file was modified and the cached stat data
310 * was refreshed, or because the original
311 * entry already had a replacement entry in
312 * the split index.
313 * Nothing to do.
315 } else if (!ce_uptodate(ce) &&
316 is_racy_timestamp(istate, ce)) {
318 * A copy of a racily clean cache entry from
319 * the shared index. It must be added to
320 * the split index, so the subsequent
321 * do_write_index() can smudge its stat data.
323 ce->ce_flags |= CE_UPDATE_IN_BASE;
324 } else {
326 * Thoroughly compare the cached data to see
327 * whether it should be marked for inclusion
328 * in the split index.
330 * This comparison might be unnecessary, as
331 * code paths modifying the cached data do
332 * set CE_UPDATE_IN_BASE as well.
334 if (compare_ce_content(ce, base))
335 ce->ce_flags |= CE_UPDATE_IN_BASE;
337 discard_cache_entry(base);
338 si->base->cache[ce->index - 1] = ce;
340 for (i = 0; i < si->base->cache_nr; i++) {
341 ce = si->base->cache[i];
342 if ((ce->ce_flags & CE_REMOVE) ||
343 !(ce->ce_flags & CE_MATCHED))
344 ewah_set(si->delete_bitmap, i);
345 else if (ce->ce_flags & CE_UPDATE_IN_BASE) {
346 ewah_set(si->replace_bitmap, i);
347 ce->ce_flags |= CE_STRIP_NAME;
348 ALLOC_GROW(entries, nr_entries+1, nr_alloc);
349 entries[nr_entries++] = ce;
351 if (is_null_oid(&ce->oid))
352 istate->drop_cache_tree = 1;
356 for (i = 0; i < istate->cache_nr; i++) {
357 ce = istate->cache[i];
358 if ((!si->base || !ce->index) && !(ce->ce_flags & CE_REMOVE)) {
359 assert(!(ce->ce_flags & CE_STRIP_NAME));
360 ALLOC_GROW(entries, nr_entries+1, nr_alloc);
361 entries[nr_entries++] = ce;
363 ce->ce_flags &= ~CE_MATCHED;
367 * take cache[] out temporarily, put entries[] in its place
368 * for writing
370 si->saved_cache = istate->cache;
371 si->saved_cache_nr = istate->cache_nr;
372 istate->cache = entries;
373 istate->cache_nr = nr_entries;
376 void finish_writing_split_index(struct index_state *istate)
378 struct split_index *si = init_split_index(istate);
380 ewah_free(si->delete_bitmap);
381 ewah_free(si->replace_bitmap);
382 si->delete_bitmap = NULL;
383 si->replace_bitmap = NULL;
384 free(istate->cache);
385 istate->cache = si->saved_cache;
386 istate->cache_nr = si->saved_cache_nr;
389 void discard_split_index(struct index_state *istate)
391 struct split_index *si = istate->split_index;
392 if (!si)
393 return;
394 istate->split_index = NULL;
395 si->refcount--;
396 if (si->refcount)
397 return;
398 if (si->base) {
399 discard_index(si->base);
400 free(si->base);
402 free(si);
405 void save_or_free_index_entry(struct index_state *istate, struct cache_entry *ce)
407 if (ce->index &&
408 istate->split_index &&
409 istate->split_index->base &&
410 ce->index <= istate->split_index->base->cache_nr &&
411 ce == istate->split_index->base->cache[ce->index - 1])
412 ce->ce_flags |= CE_REMOVE;
413 else
414 discard_cache_entry(ce);
417 void replace_index_entry_in_base(struct index_state *istate,
418 struct cache_entry *old_entry,
419 struct cache_entry *new_entry)
421 if (old_entry->index &&
422 istate->split_index &&
423 istate->split_index->base &&
424 old_entry->index <= istate->split_index->base->cache_nr) {
425 new_entry->index = old_entry->index;
426 if (old_entry != istate->split_index->base->cache[new_entry->index - 1])
427 discard_cache_entry(istate->split_index->base->cache[new_entry->index - 1]);
428 istate->split_index->base->cache[new_entry->index - 1] = new_entry;
432 void add_split_index(struct index_state *istate)
434 if (!istate->split_index) {
435 init_split_index(istate);
436 istate->cache_changed |= SPLIT_INDEX_ORDERED;
440 void remove_split_index(struct index_state *istate)
442 if (istate->split_index) {
444 * When removing the split index, we need to move
445 * ownership of the mem_pool associated with the
446 * base index to the main index. There may be cache entries
447 * allocated from the base's memory pool that are shared with
448 * the_index.cache[].
450 mem_pool_combine(istate->ce_mem_pool, istate->split_index->base->ce_mem_pool);
453 * The split index no longer owns the mem_pool backing
454 * its cache array. As we are discarding this index,
455 * mark the index as having no cache entries, so it
456 * will not attempt to clean up the cache entries or
457 * validate them.
459 if (istate->split_index->base)
460 istate->split_index->base->cache_nr = 0;
463 * We can discard the split index because its
464 * memory pool has been incorporated into the
465 * memory pool associated with the the_index.
467 discard_split_index(istate);
469 istate->cache_changed |= SOMETHING_CHANGED;