if (unlikely(!off)) {
tdb->ecode = TDB_ERR_CORRUPT;
tdb->log(tdb, TDB_DEBUG_FATAL, tdb->log_priv,
- "find_bucket_and_lock: zero hash bucket!\n");
+ "enlarge_hash: zero hash bucket!\n");
goto unlock;
}
tdb_allrecord_unlock(tdb, F_WRLCK);
}
+/* This is the core routine which searches the hashtable for an entry.
+ * On error, no locks are held and TDB_OFF_ERR is returned.
+ * Otherwise, *num_locks locks of type ltype from *start_lock are held.
+ * The bucket where the entry is (or would be) is in *bucket.
+ * If not found, the return value is 0.
+ * If found, the return value is the offset, and *rec is the record. */
+static tdb_off_t find_and_lock(struct tdb_context *tdb,
+ struct tdb_data key,
+ uint64_t h,
+ int ltype,
+ tdb_off_t *start_lock,
+ tdb_len_t *num_locks,
+ tdb_off_t *bucket,
+ struct tdb_used_record *rec)
+{
+ tdb_off_t off;
+
+ /* FIXME: can we avoid locks for some fast paths? */
+ *start_lock = tdb_lock_list(tdb, h, ltype, TDB_LOCK_WAIT);
+ if (*start_lock == TDB_OFF_ERR)
+ return TDB_OFF_ERR;
+
+ /* Fast path. */
+ off = entry_matches(tdb, *start_lock, h, &key, rec);
+ if (likely(off != TDB_OFF_ERR)) {
+ *bucket = *start_lock;
+ *num_locks = 1;
+ return off;
+ }
+
+ /* Slow path, need to grab more locks and search. */
+
+ /* Warning: this may drop the lock on *bucket! */
+ *num_locks = relock_hash_to_zero(tdb, *start_lock, ltype);
+ if (*num_locks == TDB_OFF_ERR)
+ return TDB_OFF_ERR;
+
+ for (*bucket = *start_lock;
+ *bucket < *start_lock + *num_locks;
+ (*bucket)++) {
+ off = entry_matches(tdb, *bucket, h, &key, rec);
+ /* Empty entry or we found it? */
+ if (off == 0 || off != TDB_OFF_ERR)
+ return off;
+ }
+
+ /* We didn't find a zero entry? Something went badly wrong... */
+ unlock_lists(tdb, *start_lock, *start_lock + *num_locks, ltype);
+ tdb->ecode = TDB_ERR_CORRUPT;
+ tdb->log(tdb, TDB_DEBUG_FATAL, tdb->log_priv,
+ "find_and_lock: expected to find an empty hash bucket!\n");
+ return TDB_OFF_ERR;
+}
+
int tdb_store(struct tdb_context *tdb,
struct tdb_data key, struct tdb_data dbuf, int flag)
{
- tdb_off_t new_off, off, old_bucket, start, num_locks = 1;
+ tdb_off_t new_off, off, bucket, start, num;
struct tdb_used_record rec;
uint64_t h;
bool growing = false;
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)
+ off = find_and_lock(tdb, key, h, F_WRLCK, &start, &num, &bucket, &rec);
+ if (unlikely(off == 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)
- break;
- }
- if (i == start + num_locks)
- off = 0;
-
- /* Even if not found, this is where we put the new entry. */
- old_bucket = i;
- }
-
/* Now we have lock on this hash bucket. */
if (flag == TDB_INSERT) {
if (off) {
/* Allocate a new record. */
new_off = alloc(tdb, key.dsize, dbuf.dsize, h, growing);
if (new_off == 0) {
- unlock_lists(tdb, start, num_locks, F_WRLCK);
+ unlock_lists(tdb, start, num, F_WRLCK);
/* Expand, then try again... */
if (tdb_expand(tdb, key.dsize, dbuf.dsize, growing) == -1)
return -1;
}
/* FIXME: Encode extra hash bits! */
- if (tdb_write_off(tdb, hash_off(tdb, old_bucket), new_off) == -1)
+ if (tdb_write_off(tdb, hash_off(tdb, bucket), new_off) == -1)
goto fail;
write:
goto fail;
/* FIXME: tdb_increment_seqnum(tdb); */
- unlock_lists(tdb, start, num_locks, F_WRLCK);
+ unlock_lists(tdb, start, num, F_WRLCK);
/* FIXME: by simple simulation, this approximated 60% full.
* Check in real case! */
- if (unlikely(num_locks > 4 * tdb->header.v.hash_bits - 30))
+ if (unlikely(num > 4 * tdb->header.v.hash_bits - 30))
enlarge_hash(tdb);
return 0;
fail:
- unlock_lists(tdb, start, num_locks, F_WRLCK);
+ unlock_lists(tdb, start, num, F_WRLCK);
return -1;
}
struct tdb_data tdb_fetch(struct tdb_context *tdb, struct tdb_data key)
{
- tdb_off_t off, start, num_locks = 1;
+ tdb_off_t off, start, num, bucket;
struct tdb_used_record rec;
uint64_t h;
struct tdb_data ret;
h = tdb_hash(tdb, key.dptr, key.dsize);
-
- /* 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)
+ off = find_and_lock(tdb, key, h, F_RDLCK, &start, &num, &bucket, &rec);
+ if (unlikely(off == 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;
- }
-
if (!off) {
- unlock_lists(tdb, start, num_locks, F_RDLCK);
tdb->ecode = TDB_ERR_NOEXIST;
- return tdb_null;
+ ret = tdb_null;
+ } else {
+ ret.dsize = rec_data_length(&rec);
+ ret.dptr = tdb_alloc_read(tdb, off + sizeof(rec) + key.dsize,
+ ret.dsize);
}
- ret.dsize = rec_data_length(&rec);
- ret.dptr = tdb_alloc_read(tdb, off + sizeof(rec) + key.dsize,
- ret.dsize);
- unlock_lists(tdb, start, num_locks, F_RDLCK);
+ unlock_lists(tdb, start, num, F_RDLCK);
return ret;
}
int tdb_delete(struct tdb_context *tdb, struct tdb_data key)
{
- tdb_off_t i, old_bucket, off, start, num_locks = 1;
+ tdb_off_t i, bucket, off, start, num;
struct tdb_used_record rec;
uint64_t h;
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)
+ off = find_and_lock(tdb, key, h, F_WRLCK, &start, &num, &bucket, &rec);
+ if (unlikely(off == 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;
-
- 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;
- }
-
if (!off) {
- unlock_lists(tdb, start, num_locks, F_WRLCK);
+ unlock_lists(tdb, start, num, F_WRLCK);
tdb->ecode = TDB_ERR_NOEXIST;
return -1;
}
-delete:
/* This actually unlinks it. */
- if (tdb_write_off(tdb, hash_off(tdb, old_bucket), 0) == -1)
+ if (tdb_write_off(tdb, hash_off(tdb, bucket), 0) == -1)
goto unlock_err;
/* Rehash anything following. */
- for (i = hash_off(tdb, old_bucket+1);
- i != hash_off(tdb, h + num_locks);
+ for (i = hash_off(tdb, bucket+1);
+ i != hash_off(tdb, h + num - 1);
i += sizeof(tdb_off_t)) {
tdb_off_t off2;
uint64_t h2;
if (unlikely(off2 == TDB_OFF_ERR))
goto unlock_err;
+ /* This can happen if we raced. */
+ if (unlikely(off2 == 0))
+ break;
+
/* Maybe use a bit to indicate it is in ideal place? */
h2 = hash_record(tdb, off2);
/* Is it happy where it is? */
+ rec_extra_padding(&rec)) != 0)
goto unlock_err;
- unlock_lists(tdb, start, num_locks, F_WRLCK);
+ unlock_lists(tdb, start, num, F_WRLCK);
return 0;
unlock_err:
- unlock_lists(tdb, start, num_locks, F_WRLCK);
+ unlock_lists(tdb, start, num, F_WRLCK);
return -1;
}
projects / ccan / blobdiff