diff options
Diffstat (limited to 'attr.c')
| -rw-r--r-- | attr.c | 173 |
1 files changed, 128 insertions, 45 deletions
@@ -14,6 +14,7 @@ #include "dir.h" #include "utf8.h" #include "quote.h" +#include "thread-utils.h" const char git_attr__true[] = "(builtin)true"; const char git_attr__false[] = "\0(builtin)false"; @@ -23,28 +24,17 @@ static const char git_attr__unknown[] = "(builtin)unknown"; #define ATTR__UNSET NULL #define ATTR__UNKNOWN git_attr__unknown -/* This is a randomly chosen prime. */ -#define HASHSIZE 257 - #ifndef DEBUG_ATTR #define DEBUG_ATTR 0 #endif -/* - * NEEDSWORK: the global dictionary of the interned attributes - * must stay a singleton even after we become thread-ready. - * Access to these must be surrounded with mutex when it happens. - */ struct git_attr { - struct git_attr *next; - unsigned h; - int attr_nr; + int attr_nr; /* unique attribute number */ int maybe_macro; int maybe_real; - char name[FLEX_ARRAY]; + char name[FLEX_ARRAY]; /* attribute name */ }; static int attr_nr; -static struct git_attr *(git_attr_hash[HASHSIZE]); /* * NEEDSWORK: maybe-real, maybe-macro are not property of @@ -63,15 +53,94 @@ const char *git_attr_name(const struct git_attr *attr) return attr->name; } -static unsigned hash_name(const char *name, int namelen) +struct attr_hashmap { + struct hashmap map; +#ifndef NO_PTHREADS + pthread_mutex_t mutex; +#endif +}; + +static inline void hashmap_lock(struct attr_hashmap *map) +{ +#ifndef NO_PTHREADS + pthread_mutex_lock(&map->mutex); +#endif +} + +static inline void hashmap_unlock(struct attr_hashmap *map) { - unsigned val = 0, c; +#ifndef NO_PTHREADS + pthread_mutex_unlock(&map->mutex); +#endif +} - while (namelen--) { - c = *name++; - val = ((val << 7) | (val >> 22)) ^ c; - } - return val; +/* + * The global dictionary of all interned attributes. This + * is a singleton object which is shared between threads. + * Access to this dictionary must be surrounded with a mutex. + */ +static struct attr_hashmap g_attr_hashmap; + +/* The container for objects stored in "struct attr_hashmap" */ +struct attr_hash_entry { + struct hashmap_entry ent; /* must be the first member! */ + const char *key; /* the key; memory should be owned by value */ + size_t keylen; /* length of the key */ + void *value; /* the stored value */ +}; + +/* attr_hashmap comparison function */ +static int attr_hash_entry_cmp(const struct attr_hash_entry *a, + const struct attr_hash_entry *b, + void *unused) +{ + return (a->keylen != b->keylen) || strncmp(a->key, b->key, a->keylen); +} + +/* Initialize an 'attr_hashmap' object */ +static void attr_hashmap_init(struct attr_hashmap *map) +{ + hashmap_init(&map->map, (hashmap_cmp_fn) attr_hash_entry_cmp, 0); +} + +/* + * Retrieve the 'value' stored in a hashmap given the provided 'key'. + * If there is no matching entry, return NULL. + */ +static void *attr_hashmap_get(struct attr_hashmap *map, + const char *key, size_t keylen) +{ + struct attr_hash_entry k; + struct attr_hash_entry *e; + + if (!map->map.tablesize) + attr_hashmap_init(map); + + hashmap_entry_init(&k, memhash(key, keylen)); + k.key = key; + k.keylen = keylen; + e = hashmap_get(&map->map, &k, NULL); + + return e ? e->value : NULL; +} + +/* Add 'value' to a hashmap based on the provided 'key'. */ +static void attr_hashmap_add(struct attr_hashmap *map, + const char *key, size_t keylen, + void *value) +{ + struct attr_hash_entry *e; + + if (!map->map.tablesize) + attr_hashmap_init(map); + + e = xmalloc(sizeof(struct attr_hash_entry)); + hashmap_entry_init(e, memhash(key, keylen)); + e->key = key; + e->keylen = keylen; + e->value = value; + + hashmap_add(&map->map, e); } static int attr_name_valid(const char *name, size_t namelen) @@ -103,37 +172,44 @@ static void report_invalid_attr(const char *name, size_t len, strbuf_release(&err); } -static struct git_attr *git_attr_internal(const char *name, int len) +/* + * Given a 'name', lookup and return the corresponding attribute in the global + * dictionary. If no entry is found, create a new attribute and store it in + * the dictionary. + */ +static struct git_attr *git_attr_internal(const char *name, int namelen) { - unsigned hval = hash_name(name, len); - unsigned pos = hval % HASHSIZE; struct git_attr *a; - for (a = git_attr_hash[pos]; a; a = a->next) { - if (a->h == hval && - !memcmp(a->name, name, len) && !a->name[len]) - return a; - } - - if (!attr_name_valid(name, len)) + if (!attr_name_valid(name, namelen)) return NULL; - FLEX_ALLOC_MEM(a, name, name, len); - a->h = hval; - a->next = git_attr_hash[pos]; - a->attr_nr = attr_nr++; - a->maybe_macro = 0; - a->maybe_real = 0; - git_attr_hash[pos] = a; + hashmap_lock(&g_attr_hashmap); + + a = attr_hashmap_get(&g_attr_hashmap, name, namelen); + + if (!a) { + FLEX_ALLOC_MEM(a, name, name, namelen); + a->attr_nr = g_attr_hashmap.map.size; + a->maybe_real = 0; + a->maybe_macro = 0; + + attr_hashmap_add(&g_attr_hashmap, a->name, namelen, a); + assert(a->attr_nr == (g_attr_hashmap.map.size - 1)); + + /* + * NEEDSWORK: per git_attr_check check_all_attr + * will be initialized a lot more lazily, not + * like this, and not here. + */ + REALLOC_ARRAY(check_all_attr, ++attr_nr); + check_all_attr[a->attr_nr].attr = a; + check_all_attr[a->attr_nr].value = ATTR__UNKNOWN; + assert(a->attr_nr == (attr_nr - 1)); + } + + hashmap_unlock(&g_attr_hashmap); - /* - * NEEDSWORK: per git_attr_check check_all_attr - * will be initialized a lot more lazily, not - * like this, and not here. - */ - REALLOC_ARRAY(check_all_attr, attr_nr); - check_all_attr[a->attr_nr].attr = a; - check_all_attr[a->attr_nr].value = ATTR__UNKNOWN; return a; } @@ -941,3 +1017,10 @@ void git_attr_set_direction(enum git_attr_direction new, struct index_state *ist drop_attr_stack(); use_index = istate; } + +void attr_start(void) +{ +#ifndef NO_PTHREADS + pthread_mutex_init(&g_attr_hashmap.mutex, NULL); +#endif +} |