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1 | #include "cache.h" | |
2 | #include "split-index.h" | |
3 | #include "ewah/ewok.h" | |
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; | |
19 | int ret; | |
20 | ||
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; | |
42 | } | |
43 | ||
44 | int write_link_extension(struct strbuf *sb, | |
45 | struct index_state *istate) | |
46 | { | |
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; | |
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 | |
63 | * from 1 instead of 0, which is reserved to say "this is a new | |
64 | * entry". | |
65 | */ | |
66 | for (i = 0; i < base->cache_nr; i++) | |
67 | base->cache[i]->index = i + 1; | |
68 | } | |
69 | ||
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 | /* | |
76 | * If there was a previous base index, then transfer ownership of allocated | |
77 | * entries to the parent index. | |
78 | */ | |
79 | if (si->base && | |
80 | si->base->ce_mem_pool) { | |
81 | ||
82 | if (!istate->ce_mem_pool) { | |
83 | istate->ce_mem_pool = xmalloc(sizeof(struct mem_pool)); | |
84 | mem_pool_init(istate->ce_mem_pool, 0); | |
85 | } | |
86 | ||
87 | mem_pool_combine(istate->ce_mem_pool, istate->split_index->base->ce_mem_pool); | |
88 | } | |
89 | ||
90 | si->base = xcalloc(1, sizeof(*si->base)); | |
91 | si->base->version = istate->version; | |
92 | /* zero timestamp disables racy test in ce_write_index() */ | |
93 | si->base->timestamp = istate->timestamp; | |
94 | ALLOC_GROW(si->base->cache, istate->cache_nr, si->base->cache_alloc); | |
95 | si->base->cache_nr = istate->cache_nr; | |
96 | ||
97 | /* | |
98 | * The mem_pool needs to move with the allocated entries. | |
99 | */ | |
100 | si->base->ce_mem_pool = istate->ce_mem_pool; | |
101 | istate->ce_mem_pool = NULL; | |
102 | ||
103 | COPY_ARRAY(si->base->cache, istate->cache, istate->cache_nr); | |
104 | mark_base_index_entries(si->base); | |
105 | for (i = 0; i < si->base->cache_nr; i++) | |
106 | si->base->cache[i]->ce_flags &= ~CE_UPDATE_IN_BASE; | |
107 | } | |
108 | ||
109 | static void mark_entry_for_delete(size_t pos, void *data) | |
110 | { | |
111 | struct index_state *istate = data; | |
112 | if (pos >= istate->cache_nr) | |
113 | die("position for delete %d exceeds base index size %d", | |
114 | (int)pos, istate->cache_nr); | |
115 | istate->cache[pos]->ce_flags |= CE_REMOVE; | |
116 | istate->split_index->nr_deletions++; | |
117 | } | |
118 | ||
119 | static void replace_entry(size_t pos, void *data) | |
120 | { | |
121 | struct index_state *istate = data; | |
122 | struct split_index *si = istate->split_index; | |
123 | struct cache_entry *dst, *src; | |
124 | ||
125 | if (pos >= istate->cache_nr) | |
126 | die("position for replacement %d exceeds base index size %d", | |
127 | (int)pos, istate->cache_nr); | |
128 | if (si->nr_replacements >= si->saved_cache_nr) | |
129 | die("too many replacements (%d vs %d)", | |
130 | si->nr_replacements, si->saved_cache_nr); | |
131 | dst = istate->cache[pos]; | |
132 | if (dst->ce_flags & CE_REMOVE) | |
133 | die("entry %d is marked as both replaced and deleted", | |
134 | (int)pos); | |
135 | src = si->saved_cache[si->nr_replacements]; | |
136 | if (ce_namelen(src)) | |
137 | die("corrupt link extension, entry %d should have " | |
138 | "zero length name", (int)pos); | |
139 | src->index = pos + 1; | |
140 | src->ce_flags |= CE_UPDATE_IN_BASE; | |
141 | src->ce_namelen = dst->ce_namelen; | |
142 | copy_cache_entry(dst, src); | |
143 | discard_cache_entry(src); | |
144 | si->nr_replacements++; | |
145 | } | |
146 | ||
147 | void merge_base_index(struct index_state *istate) | |
148 | { | |
149 | struct split_index *si = istate->split_index; | |
150 | unsigned int i; | |
151 | ||
152 | mark_base_index_entries(si->base); | |
153 | ||
154 | si->saved_cache = istate->cache; | |
155 | si->saved_cache_nr = istate->cache_nr; | |
156 | istate->cache_nr = si->base->cache_nr; | |
157 | istate->cache = NULL; | |
158 | istate->cache_alloc = 0; | |
159 | ALLOC_GROW(istate->cache, istate->cache_nr, istate->cache_alloc); | |
160 | COPY_ARRAY(istate->cache, si->base->cache, istate->cache_nr); | |
161 | ||
162 | si->nr_deletions = 0; | |
163 | si->nr_replacements = 0; | |
164 | ewah_each_bit(si->replace_bitmap, replace_entry, istate); | |
165 | ewah_each_bit(si->delete_bitmap, mark_entry_for_delete, istate); | |
166 | if (si->nr_deletions) | |
167 | remove_marked_cache_entries(istate, 0); | |
168 | ||
169 | for (i = si->nr_replacements; i < si->saved_cache_nr; i++) { | |
170 | if (!ce_namelen(si->saved_cache[i])) | |
171 | die("corrupt link extension, entry %d should " | |
172 | "have non-zero length name", i); | |
173 | add_index_entry(istate, si->saved_cache[i], | |
174 | ADD_CACHE_OK_TO_ADD | | |
175 | ADD_CACHE_KEEP_CACHE_TREE | | |
176 | /* | |
177 | * we may have to replay what | |
178 | * merge-recursive.c:update_stages() | |
179 | * does, which has this flag on | |
180 | */ | |
181 | ADD_CACHE_SKIP_DFCHECK); | |
182 | si->saved_cache[i] = NULL; | |
183 | } | |
184 | ||
185 | ewah_free(si->delete_bitmap); | |
186 | ewah_free(si->replace_bitmap); | |
187 | FREE_AND_NULL(si->saved_cache); | |
188 | si->delete_bitmap = NULL; | |
189 | si->replace_bitmap = NULL; | |
190 | si->saved_cache_nr = 0; | |
191 | } | |
192 | ||
193 | /* | |
194 | * Compare most of the fields in two cache entries, i.e. all except the | |
195 | * hashmap_entry and the name. | |
196 | */ | |
197 | static int compare_ce_content(struct cache_entry *a, struct cache_entry *b) | |
198 | { | |
199 | const unsigned int ondisk_flags = CE_STAGEMASK | CE_VALID | | |
200 | CE_EXTENDED_FLAGS; | |
201 | unsigned int ce_flags = a->ce_flags; | |
202 | unsigned int base_flags = b->ce_flags; | |
203 | int ret; | |
204 | ||
205 | /* only on-disk flags matter */ | |
206 | a->ce_flags &= ondisk_flags; | |
207 | b->ce_flags &= ondisk_flags; | |
208 | ret = memcmp(&a->ce_stat_data, &b->ce_stat_data, | |
209 | offsetof(struct cache_entry, name) - | |
210 | offsetof(struct cache_entry, ce_stat_data)); | |
211 | a->ce_flags = ce_flags; | |
212 | b->ce_flags = base_flags; | |
213 | ||
214 | return ret; | |
215 | } | |
216 | ||
217 | void prepare_to_write_split_index(struct index_state *istate) | |
218 | { | |
219 | struct split_index *si = init_split_index(istate); | |
220 | struct cache_entry **entries = NULL, *ce; | |
221 | int i, nr_entries = 0, nr_alloc = 0; | |
222 | ||
223 | si->delete_bitmap = ewah_new(); | |
224 | si->replace_bitmap = ewah_new(); | |
225 | ||
226 | if (si->base) { | |
227 | /* Go through istate->cache[] and mark CE_MATCHED to | |
228 | * entry with positive index. We'll go through | |
229 | * base->cache[] later to delete all entries in base | |
230 | * that are not marked with either CE_MATCHED or | |
231 | * CE_UPDATE_IN_BASE. If istate->cache[i] is a | |
232 | * duplicate, deduplicate it. | |
233 | */ | |
234 | for (i = 0; i < istate->cache_nr; i++) { | |
235 | struct cache_entry *base; | |
236 | ce = istate->cache[i]; | |
237 | if (!ce->index) { | |
238 | /* | |
239 | * During simple update index operations this | |
240 | * is a cache entry that is not present in | |
241 | * the shared index. It will be added to the | |
242 | * split index. | |
243 | * | |
244 | * However, it might also represent a file | |
245 | * that already has a cache entry in the | |
246 | * shared index, but a new index has just | |
247 | * been constructed by unpack_trees(), and | |
248 | * this entry now refers to different content | |
249 | * than what was recorded in the original | |
250 | * index, e.g. during 'read-tree -m HEAD^' or | |
251 | * 'checkout HEAD^'. In this case the | |
252 | * original entry in the shared index will be | |
253 | * marked as deleted, and this entry will be | |
254 | * added to the split index. | |
255 | */ | |
256 | continue; | |
257 | } | |
258 | if (ce->index > si->base->cache_nr) { | |
259 | BUG("ce refers to a shared ce at %d, which is beyond the shared index size %d", | |
260 | ce->index, si->base->cache_nr); | |
261 | } | |
262 | ce->ce_flags |= CE_MATCHED; /* or "shared" */ | |
263 | base = si->base->cache[ce->index - 1]; | |
264 | if (ce == base) { | |
265 | /* The entry is present in the shared index. */ | |
266 | if (ce->ce_flags & CE_UPDATE_IN_BASE) { | |
267 | /* | |
268 | * Already marked for inclusion in | |
269 | * the split index, either because | |
270 | * the corresponding file was | |
271 | * modified and the cached stat data | |
272 | * was refreshed, or because there | |
273 | * is already a replacement entry in | |
274 | * the split index. | |
275 | * Nothing more to do here. | |
276 | */ | |
277 | } else if (!ce_uptodate(ce) && | |
278 | is_racy_timestamp(istate, ce)) { | |
279 | /* | |
280 | * A racily clean cache entry stored | |
281 | * only in the shared index: it must | |
282 | * be added to the split index, so | |
283 | * the subsequent do_write_index() | |
284 | * can smudge its stat data. | |
285 | */ | |
286 | ce->ce_flags |= CE_UPDATE_IN_BASE; | |
287 | } else { | |
288 | /* | |
289 | * The entry is only present in the | |
290 | * shared index and it was not | |
291 | * refreshed. | |
292 | * Just leave it there. | |
293 | */ | |
294 | } | |
295 | continue; | |
296 | } | |
297 | if (ce->ce_namelen != base->ce_namelen || | |
298 | strcmp(ce->name, base->name)) { | |
299 | ce->index = 0; | |
300 | continue; | |
301 | } | |
302 | /* | |
303 | * This is the copy of a cache entry that is present | |
304 | * in the shared index, created by unpack_trees() | |
305 | * while it constructed a new index. | |
306 | */ | |
307 | if (ce->ce_flags & CE_UPDATE_IN_BASE) { | |
308 | /* | |
309 | * Already marked for inclusion in the split | |
310 | * index, either because the corresponding | |
311 | * file was modified and the cached stat data | |
312 | * was refreshed, or because the original | |
313 | * entry already had a replacement entry in | |
314 | * the split index. | |
315 | * Nothing to do. | |
316 | */ | |
317 | } else if (!ce_uptodate(ce) && | |
318 | is_racy_timestamp(istate, ce)) { | |
319 | /* | |
320 | * A copy of a racily clean cache entry from | |
321 | * the shared index. It must be added to | |
322 | * the split index, so the subsequent | |
323 | * do_write_index() can smudge its stat data. | |
324 | */ | |
325 | ce->ce_flags |= CE_UPDATE_IN_BASE; | |
326 | } else { | |
327 | /* | |
328 | * Thoroughly compare the cached data to see | |
329 | * whether it should be marked for inclusion | |
330 | * in the split index. | |
331 | * | |
332 | * This comparison might be unnecessary, as | |
333 | * code paths modifying the cached data do | |
334 | * set CE_UPDATE_IN_BASE as well. | |
335 | */ | |
336 | if (compare_ce_content(ce, base)) | |
337 | ce->ce_flags |= CE_UPDATE_IN_BASE; | |
338 | } | |
339 | discard_cache_entry(base); | |
340 | si->base->cache[ce->index - 1] = ce; | |
341 | } | |
342 | for (i = 0; i < si->base->cache_nr; i++) { | |
343 | ce = si->base->cache[i]; | |
344 | if ((ce->ce_flags & CE_REMOVE) || | |
345 | !(ce->ce_flags & CE_MATCHED)) | |
346 | ewah_set(si->delete_bitmap, i); | |
347 | else if (ce->ce_flags & CE_UPDATE_IN_BASE) { | |
348 | ewah_set(si->replace_bitmap, i); | |
349 | ce->ce_flags |= CE_STRIP_NAME; | |
350 | ALLOC_GROW(entries, nr_entries+1, nr_alloc); | |
351 | entries[nr_entries++] = ce; | |
352 | } | |
353 | if (is_null_oid(&ce->oid)) | |
354 | istate->drop_cache_tree = 1; | |
355 | } | |
356 | } | |
357 | ||
358 | for (i = 0; i < istate->cache_nr; i++) { | |
359 | ce = istate->cache[i]; | |
360 | if ((!si->base || !ce->index) && !(ce->ce_flags & CE_REMOVE)) { | |
361 | assert(!(ce->ce_flags & CE_STRIP_NAME)); | |
362 | ALLOC_GROW(entries, nr_entries+1, nr_alloc); | |
363 | entries[nr_entries++] = ce; | |
364 | } | |
365 | ce->ce_flags &= ~CE_MATCHED; | |
366 | } | |
367 | ||
368 | /* | |
369 | * take cache[] out temporarily, put entries[] in its place | |
370 | * for writing | |
371 | */ | |
372 | si->saved_cache = istate->cache; | |
373 | si->saved_cache_nr = istate->cache_nr; | |
374 | istate->cache = entries; | |
375 | istate->cache_nr = nr_entries; | |
376 | } | |
377 | ||
378 | void finish_writing_split_index(struct index_state *istate) | |
379 | { | |
380 | struct split_index *si = init_split_index(istate); | |
381 | ||
382 | ewah_free(si->delete_bitmap); | |
383 | ewah_free(si->replace_bitmap); | |
384 | si->delete_bitmap = NULL; | |
385 | si->replace_bitmap = NULL; | |
386 | free(istate->cache); | |
387 | istate->cache = si->saved_cache; | |
388 | istate->cache_nr = si->saved_cache_nr; | |
389 | } | |
390 | ||
391 | void discard_split_index(struct index_state *istate) | |
392 | { | |
393 | struct split_index *si = istate->split_index; | |
394 | if (!si) | |
395 | return; | |
396 | istate->split_index = NULL; | |
397 | si->refcount--; | |
398 | if (si->refcount) | |
399 | return; | |
400 | if (si->base) { | |
401 | discard_index(si->base); | |
402 | free(si->base); | |
403 | } | |
404 | free(si); | |
405 | } | |
406 | ||
407 | void save_or_free_index_entry(struct index_state *istate, struct cache_entry *ce) | |
408 | { | |
409 | if (ce->index && | |
410 | istate->split_index && | |
411 | istate->split_index->base && | |
412 | ce->index <= istate->split_index->base->cache_nr && | |
413 | ce == istate->split_index->base->cache[ce->index - 1]) | |
414 | ce->ce_flags |= CE_REMOVE; | |
415 | else | |
416 | discard_cache_entry(ce); | |
417 | } | |
418 | ||
419 | void replace_index_entry_in_base(struct index_state *istate, | |
420 | struct cache_entry *old_entry, | |
421 | struct cache_entry *new_entry) | |
422 | { | |
423 | if (old_entry->index && | |
424 | istate->split_index && | |
425 | istate->split_index->base && | |
426 | old_entry->index <= istate->split_index->base->cache_nr) { | |
427 | new_entry->index = old_entry->index; | |
428 | if (old_entry != istate->split_index->base->cache[new_entry->index - 1]) | |
429 | discard_cache_entry(istate->split_index->base->cache[new_entry->index - 1]); | |
430 | istate->split_index->base->cache[new_entry->index - 1] = new_entry; | |
431 | } | |
432 | } | |
433 | ||
434 | void add_split_index(struct index_state *istate) | |
435 | { | |
436 | if (!istate->split_index) { | |
437 | init_split_index(istate); | |
438 | istate->cache_changed |= SPLIT_INDEX_ORDERED; | |
439 | } | |
440 | } | |
441 | ||
442 | void remove_split_index(struct index_state *istate) | |
443 | { | |
444 | if (istate->split_index) { | |
445 | if (istate->split_index->base) { | |
446 | /* | |
447 | * When removing the split index, we need to move | |
448 | * ownership of the mem_pool associated with the | |
449 | * base index to the main index. There may be cache entries | |
450 | * allocated from the base's memory pool that are shared with | |
451 | * the_index.cache[]. | |
452 | */ | |
453 | mem_pool_combine(istate->ce_mem_pool, | |
454 | istate->split_index->base->ce_mem_pool); | |
455 | ||
456 | /* | |
457 | * The split index no longer owns the mem_pool backing | |
458 | * its cache array. As we are discarding this index, | |
459 | * mark the index as having no cache entries, so it | |
460 | * will not attempt to clean up the cache entries or | |
461 | * validate them. | |
462 | */ | |
463 | istate->split_index->base->cache_nr = 0; | |
464 | } | |
465 | ||
466 | /* | |
467 | * We can discard the split index because its | |
468 | * memory pool has been incorporated into the | |
469 | * memory pool associated with the the_index. | |
470 | */ | |
471 | discard_split_index(istate); | |
472 | ||
473 | istate->cache_changed |= SOMETHING_CHANGED; | |
474 | } | |
475 | } |