return NULL;
}
-static int tdb_key_compare(TDB_DATA key, TDB_DATA data, void *private_data)
+static tdb_off_t hash_off(struct tdb_context *tdb, uint64_t list)
{
- return memcmp(data.dptr, key.dptr, data.dsize) == 0;
+ return tdb->header.v.hash_off
+ + ((list & ((1ULL << tdb->header.v.hash_bits) - 1))
+ * sizeof(tdb_off_t));
}
-static void unlock_lists(struct tdb_context *tdb,
- uint64_t start, uint64_t end, int ltype)
+/* Returns 0 if the entry is a zero (definitely not a match).
+ * Returns a valid entry offset if it's a match. Fills in rec.
+ * Otherwise returns TDB_OFF_ERR: keep searching. */
+static tdb_off_t entry_matches(struct tdb_context *tdb,
+ uint64_t list,
+ uint64_t hash,
+ const struct tdb_data *key,
+ struct tdb_used_record *rec)
{
- for (;;) {
- tdb_unlock_list(tdb, start, ltype);
- if (start == end)
- return;
- start = (start + 1) & ((1ULL << tdb->header.v.hash_bits) - 1);
- }
-}
-
-/* FIXME: Return header copy? */
-/* Returns -1 or offset of entry (0 if not found).
- * Locks hash entried from *start to *end (where the entry was found). */
-static tdb_off_t find_bucket_and_lock(struct tdb_context *tdb,
- const struct tdb_data *key,
- uint64_t hash,
- uint64_t *start,
- uint64_t *end,
- uint64_t *room,
- int ltype)
-{
- uint64_t hextra;
tdb_off_t off;
+ uint64_t keylen;
+ const unsigned char *rkey;
- /* FIXME: can we avoid locks for some fast paths? */
- *start = tdb_lock_list(tdb, hash, ltype, TDB_LOCK_WAIT);
- if (*start == TDB_OFF_ERR)
+ off = tdb_read_off(tdb, tdb->header.v.hash_off
+ + list * sizeof(tdb_off_t));
+ if (off == 0 || off == TDB_OFF_ERR)
+ return off;
+
+#if 0 /* FIXME: Check other bits. */
+ unsigned int bits, bitmask, hoffextra;
+ /* Bottom three bits show how many extra hash bits. */
+ bits = (off & ((1 << TDB_EXTRA_HASHBITS_NUM) - 1)) + 1;
+ bitmask = (1 << bits)-1;
+ hoffextra = ((off >> TDB_EXTRA_HASHBITS_NUM) & bitmask);
+ uint64_t hextra = hash >> tdb->header.v.hash_bits;
+ if ((hextra & bitmask) != hoffextra)
return TDB_OFF_ERR;
+ off &= ~...;
+#endif
- *end = *start;
- hextra = hash >> tdb->header.v.hash_bits;
+ if (tdb_read_convert(tdb, off, rec, sizeof(*rec)) == -1)
+ return TDB_OFF_ERR;
- while ((off = tdb_read_off(tdb, tdb->header.v.hash_off
- + *end * sizeof(tdb_off_t)))
- != TDB_OFF_ERR) {
- struct tdb_used_record pad, *r;
- uint64_t keylen;
+ /* FIXME: check extra bits in header! */
+ keylen = rec_key_length(rec);
+ if (keylen != key->dsize)
+ return TDB_OFF_ERR;
- /* Didn't find it? */
- if (!off)
- return 0;
+ rkey = tdb_access_read(tdb, off + sizeof(*rec), keylen);
+ if (!rkey)
+ return TDB_OFF_ERR;
+ if (memcmp(rkey, key->dptr, keylen) != 0)
+ off = TDB_OFF_ERR;
+ tdb_access_release(tdb, rkey);
+ return off;
+}
-#if 0 /* FIXME: Check other bits. */
- unsigned int bits, bitmask, hoffextra;
- /* Bottom three bits show how many extra hash bits. */
- bits = (off & ((1 << TDB_EXTRA_HASHBITS_NUM) - 1)) + 1;
- bitmask = (1 << bits)-1;
- hoffextra = ((off >> TDB_EXTRA_HASHBITS_NUM) & bitmask);
- if ((hextra & bitmask) != hoffextra)
- goto lock_next;
-#endif
+/* FIXME: Optimize? */
+static void unlock_range(struct tdb_context *tdb,
+ tdb_off_t list, tdb_len_t num,
+ int ltype)
+{
+ tdb_off_t i;
- r = tdb_get(tdb, off, &pad, sizeof(*r));
- if (!r)
- goto unlock_err;
+ for (i = list; i < list + num; i++)
+ tdb_unlock_list(tdb, i, ltype);
+}
- if (rec_magic(r) != TDB_MAGIC) {
- tdb->ecode = TDB_ERR_CORRUPT;
- tdb->log(tdb, TDB_DEBUG_FATAL, tdb->log_priv,
- "find_bucket_and_lock: bad magic 0x%llx"
- " at offset %llu!\n",
- (long long)rec_magic(r), (long long)off);
- goto unlock_err;
+/* FIXME: Optimize? */
+static int lock_range(struct tdb_context *tdb,
+ tdb_off_t list, tdb_len_t num,
+ int ltype)
+{
+ tdb_off_t i;
+
+ for (i = list; i < list + num; i++) {
+ if (tdb_lock_list(tdb, i, ltype, TDB_LOCK_WAIT) != 0) {
+ unlock_range(tdb, list, i - list, ltype);
+ return -1;
}
+ }
+ return 0;
+}
- /* FIXME: check extra bits in header! */
- keylen = rec_key_length(r);
- if (keylen != key->dsize)
- goto lock_next;
-
- switch (tdb_parse_data(tdb, *key, off + sizeof(*r), key->dsize,
- tdb_key_compare, NULL)) {
- case 1:
- /* Match! */
- *room = rec_data_length(r) + rec_extra_padding(r);
- return off >> TDB_EXTRA_HASHBITS_NUM;
- case 0:
- break;
- default:
- goto unlock_err;
+/* We lock hashes up to the next empty offset. We already hold the
+ * lock on the start bucket, but we may need to release and re-grab
+ * it. If we fail, we hold no locks at all! */
+static tdb_len_t relock_hash_to_zero(struct tdb_context *tdb,
+ tdb_off_t start, int ltype)
+{
+ tdb_len_t num, len, pre_locks;
+
+again:
+ num = 1ULL << tdb->header.v.hash_bits;
+ len = tdb_find_zero_off(tdb, hash_off(tdb, start), num - start);
+ if (unlikely(len == num - start)) {
+ /* We hit the end of the hash range. Drop lock: we have
+ to lock start of hash first. */
+ tdb_unlock_list(tdb, start, ltype);
+ /* Grab something, so header is stable. */
+ if (tdb_lock_list(tdb, 0, ltype, TDB_LOCK_WAIT))
+ return TDB_OFF_ERR;
+ len = tdb_find_zero_off(tdb, hash_off(tdb, 0), num);
+ if (lock_range(tdb, 1, len, ltype) == -1) {
+ tdb_unlock_list(tdb, 0, ltype);
+ return TDB_OFF_ERR;
}
+ pre_locks = len;
+ len = num - start;
+ } else {
+ /* We already have lock on start. */
+ start++;
+ pre_locks = 0;
+ }
+ if (unlikely(lock_range(tdb, start, len, ltype) == -1)) {
+ if (pre_locks)
+ unlock_range(tdb, 0, pre_locks, ltype);
+ else
+ tdb_unlock_list(tdb, start, ltype);
+ return TDB_OFF_ERR;
+ }
- lock_next:
- /* Lock next bucket. */
- /* FIXME: We can deadlock if this wraps! */
- off = tdb_lock_list(tdb, ++hash, ltype, TDB_LOCK_WAIT);
- if (off == TDB_OFF_ERR)
- goto unlock_err;
- *end = off;
+ /* Now, did we lose the race, and it's not zero any more? */
+ if (unlikely(tdb_read_off(tdb, hash_off(tdb, pre_locks + len)) != 0)) {
+ unlock_range(tdb, 0, pre_locks, ltype);
+ /* Leave the start locked, as expected. */
+ unlock_range(tdb, start + 1, len - 1, ltype);
+ goto again;
}
-unlock_err:
- TEST_IT(*end < *start);
- unlock_lists(tdb, *start, *end, ltype);
- return TDB_OFF_ERR;
+ return pre_locks + len;
}
+/* FIXME: modify, don't rewrite! */
static int update_rec_hdr(struct tdb_context *tdb,
tdb_off_t off,
tdb_len_t keylen,
tdb_len_t datalen,
- tdb_len_t room,
+ struct tdb_used_record *rec,
uint64_t h)
{
- struct tdb_used_record rec;
+ uint64_t room = rec_data_length(rec) + rec_extra_padding(rec);
- if (set_header(tdb, &rec, keylen, datalen, room - datalen, h))
+ if (set_header(tdb, rec, keylen, datalen, room - datalen, h))
return -1;
- return tdb_write_convert(tdb, off, &rec, sizeof(rec));
+ return tdb_write_convert(tdb, off, rec, sizeof(*rec));
}
/* If we fail, others will try after us. */
int tdb_store(struct tdb_context *tdb,
struct tdb_data key, struct tdb_data dbuf, int flag)
{
- tdb_off_t new_off, off, start, end, room;
+ tdb_off_t new_off, off, old_bucket, start, num_locks = 1;
+ struct tdb_used_record rec;
uint64_t h;
bool growing = false;
h = tdb_hash(tdb, key.dptr, key.dsize);
- off = find_bucket_and_lock(tdb, &key, h, &start, &end, &room, F_WRLCK);
- if (off == TDB_OFF_ERR)
+
+ /* FIXME: can we avoid locks for some fast paths? */
+ start = tdb_lock_list(tdb, h, F_WRLCK, TDB_LOCK_WAIT);
+ if (start == TDB_OFF_ERR)
return -1;
+ /* Fast path. */
+ old_bucket = start;
+ off = entry_matches(tdb, start, h, &key, &rec);
+ if (unlikely(off == TDB_OFF_ERR)) {
+ /* Slow path, need to grab more locks and search. */
+ tdb_off_t i;
+
+ /* Warning: this may drop the lock! Does that on error. */
+ num_locks = relock_hash_to_zero(tdb, start, F_WRLCK);
+ if (num_locks == TDB_OFF_ERR)
+ return -1;
+
+ for (i = start; i < start + num_locks; i++) {
+ off = entry_matches(tdb, i, h, &key, &rec);
+ /* Empty entry or we found it? */
+ if (off == 0 || off != TDB_OFF_ERR) {
+ old_bucket = i;
+ break;
+ }
+ }
+ if (i == start + num_locks)
+ off = 0;
+ }
+
/* Now we have lock on this hash bucket. */
if (flag == TDB_INSERT) {
if (off) {
}
} else {
if (off) {
- if (room >= key.dsize + dbuf.dsize) {
+ if (rec_data_length(&rec) + rec_extra_padding(&rec)
+ >= dbuf.dsize) {
new_off = off;
if (update_rec_hdr(tdb, off,
key.dsize, dbuf.dsize,
- room, h))
+ &rec, h))
goto fail;
goto write;
}
/* Allocate a new record. */
new_off = alloc(tdb, key.dsize, dbuf.dsize, h, growing);
if (new_off == 0) {
- unlock_lists(tdb, start, end, F_WRLCK);
+ unlock_range(tdb, start, num_locks, F_WRLCK);
/* Expand, then try again... */
if (tdb_expand(tdb, key.dsize, dbuf.dsize, growing) == -1)
return -1;
/* We didn't like the existing one: remove it. */
if (off) {
add_free_record(tdb, off, sizeof(struct tdb_used_record)
- + key.dsize + room);
+ + rec_key_length(&rec)
+ + rec_data_length(&rec)
+ + rec_extra_padding(&rec));
}
write:
- off = tdb->header.v.hash_off + end * sizeof(tdb_off_t);
/* FIXME: Encode extra hash bits! */
- if (tdb_write_off(tdb, off, new_off) == -1)
+ if (tdb_write_off(tdb, hash_off(tdb, old_bucket), new_off) == -1)
goto fail;
off = new_off + sizeof(struct tdb_used_record);
goto fail;
/* FIXME: tdb_increment_seqnum(tdb); */
- unlock_lists(tdb, start, end, F_WRLCK);
+ unlock_range(tdb, start, num_locks, F_WRLCK);
- /* By simple trial and error, this roughly approximates a 60%
- * full measure. */
- if (unlikely(end - start > 4 * tdb->header.v.hash_bits - 32))
+ /* FIXME: by simple simulation, this approximated 60% full.
+ * Check in real case! */
+ if (unlikely(num_locks > 4 * tdb->header.v.hash_bits - 31))
enlarge_hash(tdb);
return 0;
fail:
- unlock_lists(tdb, start, end, F_WRLCK);
+ unlock_range(tdb, start, num_locks, F_WRLCK);
return -1;
}
struct tdb_data tdb_fetch(struct tdb_context *tdb, struct tdb_data key)
{
- tdb_off_t off, start, end, room;
+ tdb_off_t off, start, num_locks = 1;
+ struct tdb_used_record rec;
uint64_t h;
- struct tdb_used_record pad, *r;
struct tdb_data ret;
h = tdb_hash(tdb, key.dptr, key.dsize);
- off = find_bucket_and_lock(tdb, &key, h, &start, &end, &room, F_RDLCK);
- if (off == TDB_OFF_ERR)
- return tdb_null;
- if (!off) {
- unlock_lists(tdb, start, end, F_RDLCK);
- tdb->ecode = TDB_SUCCESS;
+ /* FIXME: can we avoid locks for some fast paths? */
+ start = tdb_lock_list(tdb, h, F_RDLCK, TDB_LOCK_WAIT);
+ if (start == TDB_OFF_ERR)
return tdb_null;
+
+ /* Fast path. */
+ off = entry_matches(tdb, start, h, &key, &rec);
+ if (unlikely(off == TDB_OFF_ERR)) {
+ /* Slow path, need to grab more locks and search. */
+ tdb_off_t i;
+
+ /* Warning: this may drop the lock! Does that on error. */
+ num_locks = relock_hash_to_zero(tdb, start, F_RDLCK);
+ if (num_locks == TDB_OFF_ERR)
+ return tdb_null;
+
+ for (i = start; i < start + num_locks; i++) {
+ off = entry_matches(tdb, i, h, &key, &rec);
+ /* Empty entry or we found it? */
+ if (off == 0 || off != TDB_OFF_ERR)
+ break;
+ }
+ if (i == start + num_locks)
+ off = 0;
}
- r = tdb_get(tdb, off, &pad, sizeof(*r));
- if (!r) {
- unlock_lists(tdb, start, end, F_RDLCK);
+ if (!off) {
+ unlock_range(tdb, start, num_locks, F_RDLCK);
+ tdb->ecode = TDB_ERR_NOEXIST;
return tdb_null;
}
- ret.dsize = rec_data_length(r);
- ret.dptr = tdb_alloc_read(tdb, off + sizeof(*r) + key.dsize,
+ ret.dsize = rec_data_length(&rec);
+ ret.dptr = tdb_alloc_read(tdb, off + sizeof(rec) + key.dsize,
ret.dsize);
- unlock_lists(tdb, start, end, F_RDLCK);
+ unlock_range(tdb, start, num_locks, F_RDLCK);
return ret;
}
{
tdb_off_t i, hoff, len, num;
+ /* Look for next space. */
i = (h & ((1ULL << tdb->header.v.hash_bits) - 1));
- hoff = tdb->header.v.hash_off + i * sizeof(tdb_off_t);
len = (1ULL << tdb->header.v.hash_bits) - i;
+ num = tdb_find_zero_off(tdb, hash_off(tdb, i), len);
- /* Look for next space. */
- num = tdb_find_zero_off(tdb, hoff, len);
if (unlikely(num == len)) {
- hoff = tdb->header.v.hash_off;
+ /* We wrapped. Look through start of hash table. */
+ hoff = hash_off(tdb, 0);
len = (1ULL << tdb->header.v.hash_bits);
num = tdb_find_zero_off(tdb, hoff, len);
- if (i == len)
+ if (i == len) {
+ tdb->ecode = TDB_ERR_CORRUPT;
+ tdb->log(tdb, TDB_DEBUG_FATAL, tdb->log_priv,
+ "hash_add: full hash table!\n");
return -1;
+ }
}
/* FIXME: Encode extra hash bits! */
- return tdb_write_off(tdb, hoff + num * sizeof(tdb_off_t), off);
+ return tdb_write_off(tdb, hash_off(tdb, i + num), off);
}
-static int unlink_used_record(struct tdb_context *tdb, tdb_off_t chain,
- uint64_t *extra_locks)
+int tdb_delete(struct tdb_context *tdb, struct tdb_data key)
{
- tdb_off_t num, len, i, hoff;
+ tdb_off_t i, old_bucket, off, start, num_locks = 1;
+ struct tdb_used_record rec;
+ uint64_t h;
- /* FIXME: Maybe lock more in search? Maybe don't lock if scan
- * finds none? */
-again:
- len = (1ULL << tdb->header.v.hash_bits) - (chain + 1);
- hoff = tdb->header.v.hash_off + (chain + 1) * sizeof(tdb_off_t);
- num = tdb_find_zero_off(tdb, hoff, len);
-
- /* We want to lock the zero entry, too. In the wrap case,
- * this locks one extra. That's harmless. */
- num++;
-
- for (i = chain + 1; i < chain + 1 + num; i++) {
- if (tdb_lock_list(tdb, i, F_WRLCK, TDB_LOCK_WAIT)
- == TDB_OFF_ERR) {
- if (i != chain + 1)
- unlock_lists(tdb, chain + 1, i-1, F_WRLCK);
+ h = tdb_hash(tdb, key.dptr, key.dsize);
+
+ /* FIXME: can we avoid locks for some fast paths? */
+ start = tdb_lock_list(tdb, h, F_WRLCK, TDB_LOCK_WAIT);
+ if (start == TDB_OFF_ERR)
+ return -1;
+
+ /* Fast path. */
+ old_bucket = start;
+ off = entry_matches(tdb, start, h, &key, &rec);
+ if (off && off != TDB_OFF_ERR) {
+ /* We can only really fastpath delete if next bucket
+ * is 0. Note that we haven't locked it, but our lock
+ * on this bucket stops anyone overflowing into it
+ * while we look. */
+ if (tdb_read_off(tdb, hash_off(tdb, h+1)) == 0)
+ goto delete;
+ /* Slow path. */
+ off = TDB_OFF_ERR;
+ }
+
+ if (unlikely(off == TDB_OFF_ERR)) {
+ /* Slow path, need to grab more locks and search. */
+ tdb_off_t i;
+
+ /* Warning: this may drop the lock! Does that on error. */
+ num_locks = relock_hash_to_zero(tdb, start, F_WRLCK);
+ if (num_locks == TDB_OFF_ERR)
return -1;
- }
- }
- /* The wrap case: we need those locks out of order! */
- if (unlikely(num == len + 1)) {
- *extra_locks = tdb_find_zero_off(tdb, tdb->header.v.hash_off,
- 1ULL << tdb->header.v.hash_bits);
- (*extra_locks)++;
- for (i = 0; i < *extra_locks; i++) {
- if (tdb_lock_list(tdb, i, F_WRLCK, TDB_LOCK_NOWAIT)
- == TDB_OFF_ERR) {
- /* Failed. Caller must lock in order. */
- if (i)
- unlock_lists(tdb, 0, i-1, F_WRLCK);
- unlock_lists(tdb, chain + 1, chain + num,
- F_WRLCK);
- return 1;
+ for (i = start; i < start + num_locks; i++) {
+ off = entry_matches(tdb, i, h, &key, &rec);
+ /* Empty entry or we found it? */
+ if (off == 0 || off != TDB_OFF_ERR) {
+ old_bucket = i;
+ break;
}
}
- num += *extra_locks;
+ if (i == start + num_locks)
+ off = 0;
}
- /* Now we have the locks, be certain that offset is still 0! */
- hoff = tdb->header.v.hash_off
- + (((chain + num) * sizeof(tdb_off_t))
- & ((1ULL << tdb->header.v.hash_bits) - 1));
-
- if (unlikely(tdb_read_off(tdb, hoff) != 0)) {
- unlock_lists(tdb, chain + 1, chain + num, F_WRLCK);
- goto again;
+ if (!off) {
+ unlock_range(tdb, start, num_locks, F_WRLCK);
+ tdb->ecode = TDB_ERR_NOEXIST;
+ return -1;
}
- /* OK, all locked. Unlink first one. */
- hoff = tdb->header.v.hash_off + chain * sizeof(tdb_off_t);
- if (tdb_write_off(tdb, hoff, 0) == -1)
+delete:
+ /* This actually unlinks it. */
+ if (tdb_write_off(tdb, hash_off(tdb, old_bucket), 0) == -1)
goto unlock_err;
- /* Rehash the rest. */
- for (i = 1; i < num; i++) {
- tdb_off_t off;
- uint64_t h;
+ /* Rehash anything following. */
+ for (i = old_bucket+1; i < h + num_locks; i++) {
+ tdb_off_t off2;
+ uint64_t h2;
- hoff = tdb->header.v.hash_off
- + (((chain + i) * sizeof(tdb_off_t))
- & ((1ULL << tdb->header.v.hash_bits) - 1));
- off = tdb_read_off(tdb, hoff);
- if (unlikely(off == TDB_OFF_ERR))
+ off2 = tdb_read_off(tdb, hash_off(tdb, i));
+ if (unlikely(off2 == TDB_OFF_ERR))
goto unlock_err;
/* Maybe use a bit to indicate it is in ideal place? */
- h = hash_record(tdb, off);
+ h2 = hash_record(tdb, off2);
/* Is it happy where it is? */
- if ((h & ((1ULL << tdb->header.v.hash_bits)-1)) == (chain + i))
+ if ((h2 & ((1ULL << tdb->header.v.hash_bits)-1))
+ == (i & ((1ULL << tdb->header.v.hash_bits)-1)))
continue;
/* Remove it. */
- if (tdb_write_off(tdb, hoff, 0) == -1)
+ if (tdb_write_off(tdb, hash_off(tdb, i), 0) == -1)
goto unlock_err;
/* Rehash it. */
- if (hash_add(tdb, h, off) == -1)
+ if (hash_add(tdb, h2, off2) == -1)
goto unlock_err;
}
- unlock_lists(tdb, chain + 1, chain + num, F_WRLCK);
+
+ /* Free the deleted entry. */
+ if (add_free_record(tdb, off,
+ sizeof(struct tdb_used_record)
+ + rec_key_length(&rec)
+ + rec_data_length(&rec)
+ + rec_extra_padding(&rec)) != 0)
+ goto unlock_err;
+
+ unlock_range(tdb, start, num_locks, F_WRLCK);
return 0;
unlock_err:
- unlock_lists(tdb, chain + 1, chain + num, F_WRLCK);
+ unlock_range(tdb, start, num_locks, F_WRLCK);
return -1;
}
-int tdb_delete(struct tdb_context *tdb, struct tdb_data key)
-{
- tdb_off_t off, start, end, room, extra_locks = 0;
- uint64_t h;
- int ret;
-
- h = tdb_hash(tdb, key.dptr, key.dsize);
- off = find_bucket_and_lock(tdb, &key, h, &start, &end, &room, F_WRLCK);
- if (off == TDB_OFF_ERR)
- return -1;
-
- if (off == 0) {
- unlock_lists(tdb, start, end, F_WRLCK);
- tdb->ecode = TDB_ERR_NOEXIST;
- return -1;
- }
-
- ret = unlink_used_record(tdb, end, &extra_locks);
- if (unlikely(ret == 1)) {
- unsigned int i;
-
- unlock_lists(tdb, start, end, F_WRLCK);
-
- /* We need extra locks at the start. */
- for (i = 0; i < extra_locks; i++) {
- if (tdb_lock_list(tdb, i, F_WRLCK, TDB_LOCK_WAIT)
- == TDB_OFF_ERR) {
- if (i)
- unlock_lists(tdb, 0, i-1, F_WRLCK);
- return -1;
- }
- }
- /* Try again now we're holding more locks. */
- ret = tdb_delete(tdb, key);
- unlock_lists(tdb, 0, i, F_WRLCK);
- return ret;
- }
- unlock_lists(tdb, start, end, F_WRLCK);
- return ret;
-}
-
int tdb_close(struct tdb_context *tdb)
{
struct tdb_context **i;
projects / ccan / blobdiff