| #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) { |
| CALLOC_ARRAY(istate->split_index, 1); |
| 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) { |
| istate->ce_mem_pool = xmalloc(sizeof(struct mem_pool)); |
| mem_pool_init(istate->ce_mem_pool, 0); |
| } |
| |
| mem_pool_combine(istate->ce_mem_pool, istate->split_index->base->ce_mem_pool); |
| } |
| |
| CALLOC_ARRAY(si->base, 1); |
| 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, 0); |
| |
| 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) { |
| BUG("ce refers to a shared ce at %d, which is beyond the shared index size %d", |
| ce->index, si->base->cache_nr); |
| } |
| ce->ce_flags |= CE_MATCHED; /* or "shared" */ |
| base = si->base->cache[ce->index - 1]; |
| if (ce == base) { |
| /* The entry is present in the shared 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 there |
| * is already a replacement entry in |
| * the split index. |
| * Nothing more to do here. |
| */ |
| } else if (!ce_uptodate(ce) && |
| is_racy_timestamp(istate, ce)) { |
| /* |
| * A racily clean cache entry stored |
| * only in the shared index: it must |
| * be added to the split index, so |
| * the subsequent do_write_index() |
| * can smudge its stat data. |
| */ |
| ce->ce_flags |= CE_UPDATE_IN_BASE; |
| } else { |
| /* |
| * The entry is only present in the |
| * shared index and it was not |
| * refreshed. |
| * Just leave it there. |
| */ |
| } |
| 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 if (!ce_uptodate(ce) && |
| is_racy_timestamp(istate, ce)) { |
| /* |
| * A copy of a racily clean cache entry from |
| * the shared index. It must be added to |
| * the split index, so the subsequent |
| * do_write_index() can smudge its stat data. |
| */ |
| ce->ce_flags |= CE_UPDATE_IN_BASE; |
| } 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) { |
| if (istate->split_index->base) { |
| /* |
| * 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. |
| */ |
| 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; |
| } |
| } |