split-index: don't compare cached data of entries already marked for split index
[git/git.git] / split-index.c
CommitLineData
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1#include "cache.h"
2#include "split-index.h"
96a1d8d3 3#include "ewah/ewok.h"
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4
5struct 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
14int 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;
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19 int ret;
20
2182abd9 21 if (sz < the_hash_algo->rawsz)
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22 return error("corrupt link extension (too short)");
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;
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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)
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40 return error("garbage at the end of link extension");
41 return 0;
42}
43
44int 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);
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49 if (!si->delete_bitmap && !si->replace_bitmap)
50 return 0;
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51 ewah_serialize_strbuf(si->delete_bitmap, sb);
52 ewah_serialize_strbuf(si->replace_bitmap, sb);
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53 return 0;
54}
55
56static 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
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64 * entry".
65 */
66 for (i = 0; i < base->cache_nr; i++)
67 base->cache[i]->index = i + 1;
68}
69
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70void move_cache_to_base_index(struct index_state *istate)
71{
72 struct split_index *si = istate->split_index;
73 int i;
74
75 /*
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JM
76 * If there was a previous base index, then transfer ownership of allocated
77 * entries to the parent index.
c18b80a0 78 */
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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
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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;
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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);
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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
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107static 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++;
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115}
116
117static 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
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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];
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134 if (ce_namelen(src))
135 die("corrupt link extension, entry %d should have "
136 "zero length name", (int)pos);
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137 src->index = pos + 1;
138 src->ce_flags |= CE_UPDATE_IN_BASE;
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139 src->ce_namelen = dst->ce_namelen;
140 copy_cache_entry(dst, src);
a849735b 141 discard_cache_entry(src);
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142 si->nr_replacements++;
143}
144
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145void merge_base_index(struct index_state *istate)
146{
147 struct split_index *si = istate->split_index;
76b07b37 148 unsigned int i;
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149
150 mark_base_index_entries(si->base);
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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);
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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++) {
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168 if (!ce_namelen(si->saved_cache[i]))
169 die("corrupt link extension, entry %d should "
170 "have non-zero length name", i);
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171 add_index_entry(istate, si->saved_cache[i],
172 ADD_CACHE_OK_TO_ADD |
ce7c614b 173 ADD_CACHE_KEEP_CACHE_TREE |
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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);
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186 si->delete_bitmap = NULL;
187 si->replace_bitmap = NULL;
76b07b37 188 si->saved_cache_nr = 0;
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189}
190
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191/*
192 * Compare most of the fields in two cache entries, i.e. all except the
193 * hashmap_entry and the name.
194 */
195static 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
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215void prepare_to_write_split_index(struct index_state *istate)
216{
217 struct split_index *si = init_split_index(istate);
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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
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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 }
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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 }
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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);
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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;
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308 ALLOC_GROW(entries, nr_entries+1, nr_alloc);
309 entries[nr_entries++] = ce;
310 }
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TG
311 if (is_null_oid(&ce->oid))
312 istate->drop_cache_tree = 1;
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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));
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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;
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332 istate->cache = entries;
333 istate->cache_nr = nr_entries;
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334}
335
336void finish_writing_split_index(struct index_state *istate)
337{
338 struct split_index *si = init_split_index(istate);
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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;
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346 istate->cache_nr = si->saved_cache_nr;
347}
348
349void 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}
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NTND
364
365void 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}
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NTND
376
377void replace_index_entry_in_base(struct index_state *istate,
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BW
378 struct cache_entry *old_entry,
379 struct cache_entry *new_entry)
078a58e8 380{
75b7b971 381 if (old_entry->index &&
078a58e8
NTND
382 istate->split_index &&
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 }
390}
cef4fc7e
CC
391
392void 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
400void remove_split_index(struct index_state *istate)
401{
64719b11
JH
402 if (istate->split_index) {
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;
430 }
cef4fc7e 431}