diff options
Diffstat (limited to 'third_party/git/refs/ref-cache.c')
| -rw-r--r-- | third_party/git/refs/ref-cache.c | 551 |
1 files changed, 551 insertions, 0 deletions
diff --git a/third_party/git/refs/ref-cache.c b/third_party/git/refs/ref-cache.c new file mode 100644 index 0000000000..b7052f72e2 --- /dev/null +++ b/third_party/git/refs/ref-cache.c @@ -0,0 +1,551 @@ +#include "../cache.h" +#include "../refs.h" +#include "refs-internal.h" +#include "ref-cache.h" +#include "../iterator.h" + +void add_entry_to_dir(struct ref_dir *dir, struct ref_entry *entry) +{ + ALLOC_GROW(dir->entries, dir->nr + 1, dir->alloc); + dir->entries[dir->nr++] = entry; + /* optimize for the case that entries are added in order */ + if (dir->nr == 1 || + (dir->nr == dir->sorted + 1 && + strcmp(dir->entries[dir->nr - 2]->name, + dir->entries[dir->nr - 1]->name) < 0)) + dir->sorted = dir->nr; +} + +struct ref_dir *get_ref_dir(struct ref_entry *entry) +{ + struct ref_dir *dir; + assert(entry->flag & REF_DIR); + dir = &entry->u.subdir; + if (entry->flag & REF_INCOMPLETE) { + if (!dir->cache->fill_ref_dir) + BUG("incomplete ref_store without fill_ref_dir function"); + + dir->cache->fill_ref_dir(dir->cache->ref_store, dir, entry->name); + entry->flag &= ~REF_INCOMPLETE; + } + return dir; +} + +struct ref_entry *create_ref_entry(const char *refname, + const struct object_id *oid, int flag) +{ + struct ref_entry *ref; + + FLEX_ALLOC_STR(ref, name, refname); + oidcpy(&ref->u.value.oid, oid); + ref->flag = flag; + return ref; +} + +struct ref_cache *create_ref_cache(struct ref_store *refs, + fill_ref_dir_fn *fill_ref_dir) +{ + struct ref_cache *ret = xcalloc(1, sizeof(*ret)); + + ret->ref_store = refs; + ret->fill_ref_dir = fill_ref_dir; + ret->root = create_dir_entry(ret, "", 0, 1); + return ret; +} + +static void clear_ref_dir(struct ref_dir *dir); + +static void free_ref_entry(struct ref_entry *entry) +{ + if (entry->flag & REF_DIR) { + /* + * Do not use get_ref_dir() here, as that might + * trigger the reading of loose refs. + */ + clear_ref_dir(&entry->u.subdir); + } + free(entry); +} + +void free_ref_cache(struct ref_cache *cache) +{ + free_ref_entry(cache->root); + free(cache); +} + +/* + * Clear and free all entries in dir, recursively. + */ +static void clear_ref_dir(struct ref_dir *dir) +{ + int i; + for (i = 0; i < dir->nr; i++) + free_ref_entry(dir->entries[i]); + FREE_AND_NULL(dir->entries); + dir->sorted = dir->nr = dir->alloc = 0; +} + +struct ref_entry *create_dir_entry(struct ref_cache *cache, + const char *dirname, size_t len, + int incomplete) +{ + struct ref_entry *direntry; + + FLEX_ALLOC_MEM(direntry, name, dirname, len); + direntry->u.subdir.cache = cache; + direntry->flag = REF_DIR | (incomplete ? REF_INCOMPLETE : 0); + return direntry; +} + +static int ref_entry_cmp(const void *a, const void *b) +{ + struct ref_entry *one = *(struct ref_entry **)a; + struct ref_entry *two = *(struct ref_entry **)b; + return strcmp(one->name, two->name); +} + +static void sort_ref_dir(struct ref_dir *dir); + +struct string_slice { + size_t len; + const char *str; +}; + +static int ref_entry_cmp_sslice(const void *key_, const void *ent_) +{ + const struct string_slice *key = key_; + const struct ref_entry *ent = *(const struct ref_entry * const *)ent_; + int cmp = strncmp(key->str, ent->name, key->len); + if (cmp) + return cmp; + return '\0' - (unsigned char)ent->name[key->len]; +} + +int search_ref_dir(struct ref_dir *dir, const char *refname, size_t len) +{ + struct ref_entry **r; + struct string_slice key; + + if (refname == NULL || !dir->nr) + return -1; + + sort_ref_dir(dir); + key.len = len; + key.str = refname; + r = bsearch(&key, dir->entries, dir->nr, sizeof(*dir->entries), + ref_entry_cmp_sslice); + + if (r == NULL) + return -1; + + return r - dir->entries; +} + +/* + * Search for a directory entry directly within dir (without + * recursing). Sort dir if necessary. subdirname must be a directory + * name (i.e., end in '/'). If mkdir is set, then create the + * directory if it is missing; otherwise, return NULL if the desired + * directory cannot be found. dir must already be complete. + */ +static struct ref_dir *search_for_subdir(struct ref_dir *dir, + const char *subdirname, size_t len, + int mkdir) +{ + int entry_index = search_ref_dir(dir, subdirname, len); + struct ref_entry *entry; + if (entry_index == -1) { + if (!mkdir) + return NULL; + /* + * Since dir is complete, the absence of a subdir + * means that the subdir really doesn't exist; + * therefore, create an empty record for it but mark + * the record complete. + */ + entry = create_dir_entry(dir->cache, subdirname, len, 0); + add_entry_to_dir(dir, entry); + } else { + entry = dir->entries[entry_index]; + } + return get_ref_dir(entry); +} + +/* + * If refname is a reference name, find the ref_dir within the dir + * tree that should hold refname. If refname is a directory name + * (i.e., it ends in '/'), then return that ref_dir itself. dir must + * represent the top-level directory and must already be complete. + * Sort ref_dirs and recurse into subdirectories as necessary. If + * mkdir is set, then create any missing directories; otherwise, + * return NULL if the desired directory cannot be found. + */ +static struct ref_dir *find_containing_dir(struct ref_dir *dir, + const char *refname, int mkdir) +{ + const char *slash; + for (slash = strchr(refname, '/'); slash; slash = strchr(slash + 1, '/')) { + size_t dirnamelen = slash - refname + 1; + struct ref_dir *subdir; + subdir = search_for_subdir(dir, refname, dirnamelen, mkdir); + if (!subdir) { + dir = NULL; + break; + } + dir = subdir; + } + + return dir; +} + +struct ref_entry *find_ref_entry(struct ref_dir *dir, const char *refname) +{ + int entry_index; + struct ref_entry *entry; + dir = find_containing_dir(dir, refname, 0); + if (!dir) + return NULL; + entry_index = search_ref_dir(dir, refname, strlen(refname)); + if (entry_index == -1) + return NULL; + entry = dir->entries[entry_index]; + return (entry->flag & REF_DIR) ? NULL : entry; +} + +int remove_entry_from_dir(struct ref_dir *dir, const char *refname) +{ + int refname_len = strlen(refname); + int entry_index; + struct ref_entry *entry; + int is_dir = refname[refname_len - 1] == '/'; + if (is_dir) { + /* + * refname represents a reference directory. Remove + * the trailing slash; otherwise we will get the + * directory *representing* refname rather than the + * one *containing* it. + */ + char *dirname = xmemdupz(refname, refname_len - 1); + dir = find_containing_dir(dir, dirname, 0); + free(dirname); + } else { + dir = find_containing_dir(dir, refname, 0); + } + if (!dir) + return -1; + entry_index = search_ref_dir(dir, refname, refname_len); + if (entry_index == -1) + return -1; + entry = dir->entries[entry_index]; + + MOVE_ARRAY(&dir->entries[entry_index], + &dir->entries[entry_index + 1], dir->nr - entry_index - 1); + dir->nr--; + if (dir->sorted > entry_index) + dir->sorted--; + free_ref_entry(entry); + return dir->nr; +} + +int add_ref_entry(struct ref_dir *dir, struct ref_entry *ref) +{ + dir = find_containing_dir(dir, ref->name, 1); + if (!dir) + return -1; + add_entry_to_dir(dir, ref); + return 0; +} + +/* + * Emit a warning and return true iff ref1 and ref2 have the same name + * and the same oid. Die if they have the same name but different + * oids. + */ +static int is_dup_ref(const struct ref_entry *ref1, const struct ref_entry *ref2) +{ + if (strcmp(ref1->name, ref2->name)) + return 0; + + /* Duplicate name; make sure that they don't conflict: */ + + if ((ref1->flag & REF_DIR) || (ref2->flag & REF_DIR)) + /* This is impossible by construction */ + die("Reference directory conflict: %s", ref1->name); + + if (!oideq(&ref1->u.value.oid, &ref2->u.value.oid)) + die("Duplicated ref, and SHA1s don't match: %s", ref1->name); + + warning("Duplicated ref: %s", ref1->name); + return 1; +} + +/* + * Sort the entries in dir non-recursively (if they are not already + * sorted) and remove any duplicate entries. + */ +static void sort_ref_dir(struct ref_dir *dir) +{ + int i, j; + struct ref_entry *last = NULL; + + /* + * This check also prevents passing a zero-length array to qsort(), + * which is a problem on some platforms. + */ + if (dir->sorted == dir->nr) + return; + + QSORT(dir->entries, dir->nr, ref_entry_cmp); + + /* Remove any duplicates: */ + for (i = 0, j = 0; j < dir->nr; j++) { + struct ref_entry *entry = dir->entries[j]; + if (last && is_dup_ref(last, entry)) + free_ref_entry(entry); + else + last = dir->entries[i++] = entry; + } + dir->sorted = dir->nr = i; +} + +enum prefix_state { + /* All refs within the directory would match prefix: */ + PREFIX_CONTAINS_DIR, + + /* Some, but not all, refs within the directory might match prefix: */ + PREFIX_WITHIN_DIR, + + /* No refs within the directory could possibly match prefix: */ + PREFIX_EXCLUDES_DIR +}; + +/* + * Return a `prefix_state` constant describing the relationship + * between the directory with the specified `dirname` and `prefix`. + */ +static enum prefix_state overlaps_prefix(const char *dirname, + const char *prefix) +{ + while (*prefix && *dirname == *prefix) { + dirname++; + prefix++; + } + if (!*prefix) + return PREFIX_CONTAINS_DIR; + else if (!*dirname) + return PREFIX_WITHIN_DIR; + else + return PREFIX_EXCLUDES_DIR; +} + +/* + * Load all of the refs from `dir` (recursively) that could possibly + * contain references matching `prefix` into our in-memory cache. If + * `prefix` is NULL, prime unconditionally. + */ +static void prime_ref_dir(struct ref_dir *dir, const char *prefix) +{ + /* + * The hard work of loading loose refs is done by get_ref_dir(), so we + * just need to recurse through all of the sub-directories. We do not + * even need to care about sorting, as traversal order does not matter + * to us. + */ + int i; + for (i = 0; i < dir->nr; i++) { + struct ref_entry *entry = dir->entries[i]; + if (!(entry->flag & REF_DIR)) { + /* Not a directory; no need to recurse. */ + } else if (!prefix) { + /* Recurse in any case: */ + prime_ref_dir(get_ref_dir(entry), NULL); + } else { + switch (overlaps_prefix(entry->name, prefix)) { + case PREFIX_CONTAINS_DIR: + /* + * Recurse, and from here down we + * don't have to check the prefix + * anymore: + */ + prime_ref_dir(get_ref_dir(entry), NULL); + break; + case PREFIX_WITHIN_DIR: + prime_ref_dir(get_ref_dir(entry), prefix); + break; + case PREFIX_EXCLUDES_DIR: + /* No need to prime this directory. */ + break; + } + } + } +} + +/* + * A level in the reference hierarchy that is currently being iterated + * through. + */ +struct cache_ref_iterator_level { + /* + * The ref_dir being iterated over at this level. The ref_dir + * is sorted before being stored here. + */ + struct ref_dir *dir; + + enum prefix_state prefix_state; + + /* + * The index of the current entry within dir (which might + * itself be a directory). If index == -1, then the iteration + * hasn't yet begun. If index == dir->nr, then the iteration + * through this level is over. + */ + int index; +}; + +/* + * Represent an iteration through a ref_dir in the memory cache. The + * iteration recurses through subdirectories. + */ +struct cache_ref_iterator { + struct ref_iterator base; + + /* + * The number of levels currently on the stack. This is always + * at least 1, because when it becomes zero the iteration is + * ended and this struct is freed. + */ + size_t levels_nr; + + /* The number of levels that have been allocated on the stack */ + size_t levels_alloc; + + /* + * Only include references with this prefix in the iteration. + * The prefix is matched textually, without regard for path + * component boundaries. + */ + const char *prefix; + + /* + * A stack of levels. levels[0] is the uppermost level that is + * being iterated over in this iteration. (This is not + * necessary the top level in the references hierarchy. If we + * are iterating through a subtree, then levels[0] will hold + * the ref_dir for that subtree, and subsequent levels will go + * on from there.) + */ + struct cache_ref_iterator_level *levels; +}; + +static int cache_ref_iterator_advance(struct ref_iterator *ref_iterator) +{ + struct cache_ref_iterator *iter = + (struct cache_ref_iterator *)ref_iterator; + + while (1) { + struct cache_ref_iterator_level *level = + &iter->levels[iter->levels_nr - 1]; + struct ref_dir *dir = level->dir; + struct ref_entry *entry; + enum prefix_state entry_prefix_state; + + if (level->index == -1) + sort_ref_dir(dir); + + if (++level->index == level->dir->nr) { + /* This level is exhausted; pop up a level */ + if (--iter->levels_nr == 0) + return ref_iterator_abort(ref_iterator); + + continue; + } + + entry = dir->entries[level->index]; + + if (level->prefix_state == PREFIX_WITHIN_DIR) { + entry_prefix_state = overlaps_prefix(entry->name, iter->prefix); + if (entry_prefix_state == PREFIX_EXCLUDES_DIR) + continue; + } else { + entry_prefix_state = level->prefix_state; + } + + if (entry->flag & REF_DIR) { + /* push down a level */ + ALLOC_GROW(iter->levels, iter->levels_nr + 1, + iter->levels_alloc); + + level = &iter->levels[iter->levels_nr++]; + level->dir = get_ref_dir(entry); + level->prefix_state = entry_prefix_state; + level->index = -1; + } else { + iter->base.refname = entry->name; + iter->base.oid = &entry->u.value.oid; + iter->base.flags = entry->flag; + return ITER_OK; + } + } +} + +static int cache_ref_iterator_peel(struct ref_iterator *ref_iterator, + struct object_id *peeled) +{ + return peel_object(ref_iterator->oid, peeled); +} + +static int cache_ref_iterator_abort(struct ref_iterator *ref_iterator) +{ + struct cache_ref_iterator *iter = + (struct cache_ref_iterator *)ref_iterator; + + free((char *)iter->prefix); + free(iter->levels); + base_ref_iterator_free(ref_iterator); + return ITER_DONE; +} + +static struct ref_iterator_vtable cache_ref_iterator_vtable = { + cache_ref_iterator_advance, + cache_ref_iterator_peel, + cache_ref_iterator_abort +}; + +struct ref_iterator *cache_ref_iterator_begin(struct ref_cache *cache, + const char *prefix, + int prime_dir) +{ + struct ref_dir *dir; + struct cache_ref_iterator *iter; + struct ref_iterator *ref_iterator; + struct cache_ref_iterator_level *level; + + dir = get_ref_dir(cache->root); + if (prefix && *prefix) + dir = find_containing_dir(dir, prefix, 0); + if (!dir) + /* There's nothing to iterate over. */ + return empty_ref_iterator_begin(); + + if (prime_dir) + prime_ref_dir(dir, prefix); + + iter = xcalloc(1, sizeof(*iter)); + ref_iterator = &iter->base; + base_ref_iterator_init(ref_iterator, &cache_ref_iterator_vtable, 1); + ALLOC_GROW(iter->levels, 10, iter->levels_alloc); + + iter->levels_nr = 1; + level = &iter->levels[0]; + level->index = -1; + level->dir = dir; + + if (prefix && *prefix) { + iter->prefix = xstrdup(prefix); + level->prefix_state = PREFIX_WITHIN_DIR; + } else { + level->prefix_state = PREFIX_CONTAINS_DIR; + } + + return ref_iterator; +} |