diff options
| -rw-r--r-- | lib/tdb/common/freelist.c | 100 | ||||
| -rw-r--r-- | lib/tdb/common/tdb.c | 20 | ||||
| -rw-r--r-- | lib/tdb/common/tdb_private.h | 3 |
3 files changed, 93 insertions, 30 deletions
diff --git a/lib/tdb/common/freelist.c b/lib/tdb/common/freelist.c index ea14dd02ab..6f8f812d41 100644 --- a/lib/tdb/common/freelist.c +++ b/lib/tdb/common/freelist.c @@ -273,7 +273,8 @@ static tdb_off_t tdb_allocate_ofs(struct tdb_context *tdb, 0 is returned if the space could not be allocated */ -tdb_off_t tdb_allocate(struct tdb_context *tdb, tdb_len_t length, struct tdb_record *rec) +static tdb_off_t tdb_allocate_from_freelist( + struct tdb_context *tdb, tdb_len_t length, struct tdb_record *rec) { tdb_off_t rec_ptr, last_ptr, newrec_ptr; struct { @@ -282,9 +283,6 @@ tdb_off_t tdb_allocate(struct tdb_context *tdb, tdb_len_t length, struct tdb_rec } bestfit; float multiplier = 1.0; - if (tdb_lock(tdb, -1, F_WRLCK) == -1) - return 0; - /* over-allocate to reduce fragmentation */ length *= 1.25; @@ -297,7 +295,7 @@ tdb_off_t tdb_allocate(struct tdb_context *tdb, tdb_len_t length, struct tdb_rec /* read in the freelist top */ if (tdb_ofs_read(tdb, FREELIST_TOP, &rec_ptr) == -1) - goto fail; + return 0; bestfit.rec_ptr = 0; bestfit.last_ptr = 0; @@ -310,7 +308,7 @@ tdb_off_t tdb_allocate(struct tdb_context *tdb, tdb_len_t length, struct tdb_rec */ while (rec_ptr) { if (tdb_rec_free_read(tdb, rec_ptr, rec) == -1) { - goto fail; + return 0; } if (rec->rec_len >= length) { @@ -344,12 +342,11 @@ tdb_off_t tdb_allocate(struct tdb_context *tdb, tdb_len_t length, struct tdb_rec if (bestfit.rec_ptr != 0) { if (tdb_rec_free_read(tdb, bestfit.rec_ptr, rec) == -1) { - goto fail; + return 0; } newrec_ptr = tdb_allocate_ofs(tdb, length, bestfit.rec_ptr, rec, bestfit.last_ptr); - tdb_unlock(tdb, -1, F_WRLCK); return newrec_ptr; } @@ -357,12 +354,95 @@ tdb_off_t tdb_allocate(struct tdb_context *tdb, tdb_len_t length, struct tdb_rec database and if we can then try again */ if (tdb_expand(tdb, length + sizeof(*rec)) == 0) goto again; - fail: - tdb_unlock(tdb, -1, F_WRLCK); + return 0; } +static bool tdb_alloc_dead( + struct tdb_context *tdb, int hash, tdb_len_t length, + tdb_off_t *rec_ptr, struct tdb_record *rec) +{ + tdb_off_t last_ptr; + + *rec_ptr = tdb_find_dead(tdb, hash, rec, length, &last_ptr); + if (*rec_ptr == 0) { + return false; + } + /* + * Unlink the record from the hash chain, it's about to be moved into + * another one. + */ + return (tdb_ofs_write(tdb, last_ptr, &rec->next) == 0); +} + +/* + * Chain "hash" is assumed to be locked + */ + +tdb_off_t tdb_allocate(struct tdb_context *tdb, int hash, tdb_len_t length, + struct tdb_record *rec) +{ + tdb_off_t ret; + int i; + + if (tdb->max_dead_records == 0) { + /* + * No dead records to expect anywhere. Do the blocking + * freelist lock without trying to steal from others + */ + goto blocking_freelist_allocate; + } + + /* + * The following loop tries to get the freelist lock nonblocking. If + * it gets the lock, allocate from there. If the freelist is busy, + * instead of waiting we try to steal dead records from other hash + * chains. + * + * Be aware that we do nonblocking locks on the other hash chains as + * well and fail gracefully. This way we avoid deadlocks (we block two + * hash chains, something which is pretty bad normally) + */ + + for (i=1; i<tdb->hash_size; i++) { + + int list; + + if (tdb_lock_nonblock(tdb, -1, F_WRLCK) == 0) { + /* + * Under the freelist lock take the chance to give + * back our dead records. + */ + tdb_purge_dead(tdb, hash); + + ret = tdb_allocate_from_freelist(tdb, length, rec); + tdb_unlock(tdb, -1, F_WRLCK); + return ret; + } + + list = BUCKET(hash+i); + + if (tdb_lock_nonblock(tdb, list, F_WRLCK) == 0) { + bool got_dead; + got_dead = tdb_alloc_dead(tdb, list, length, &ret, rec); + tdb_unlock(tdb, list, F_WRLCK); + + if (got_dead) { + return ret; + } + } + } + +blocking_freelist_allocate: + + if (tdb_lock(tdb, -1, F_WRLCK) == -1) { + return 0; + } + ret = tdb_allocate_from_freelist(tdb, length, rec); + tdb_unlock(tdb, -1, F_WRLCK); + return ret; +} /* return the size of the freelist - used to decide if we should repack diff --git a/lib/tdb/common/tdb.c b/lib/tdb/common/tdb.c index a7111dea96..ba1c98edbe 100644 --- a/lib/tdb/common/tdb.c +++ b/lib/tdb/common/tdb.c @@ -550,26 +550,8 @@ static int _tdb_store(struct tdb_context *tdb, TDB_DATA key, } } - /* - * We have to allocate some space from the freelist, so this means we - * have to lock it. Use the chance to purge all the DEAD records from - * the hash chain under the freelist lock. - */ - - if (tdb_lock(tdb, -1, F_WRLCK) == -1) { - goto fail; - } - - if ((tdb->max_dead_records != 0) - && (tdb_purge_dead(tdb, hash) == -1)) { - tdb_unlock(tdb, -1, F_WRLCK); - goto fail; - } - /* we have to allocate some space */ - rec_ptr = tdb_allocate(tdb, key.dsize + dbuf.dsize, &rec); - - tdb_unlock(tdb, -1, F_WRLCK); + rec_ptr = tdb_allocate(tdb, hash, key.dsize + dbuf.dsize, &rec); if (rec_ptr == 0) { goto fail; diff --git a/lib/tdb/common/tdb_private.h b/lib/tdb/common/tdb_private.h index f62c0a3a6f..a672159578 100644 --- a/lib/tdb/common/tdb_private.h +++ b/lib/tdb/common/tdb_private.h @@ -255,7 +255,8 @@ int tdb_ofs_read(struct tdb_context *tdb, tdb_off_t offset, tdb_off_t *d); int tdb_ofs_write(struct tdb_context *tdb, tdb_off_t offset, tdb_off_t *d); void *tdb_convert(void *buf, uint32_t size); int tdb_free(struct tdb_context *tdb, tdb_off_t offset, struct tdb_record *rec); -tdb_off_t tdb_allocate(struct tdb_context *tdb, tdb_len_t length, struct tdb_record *rec); +tdb_off_t tdb_allocate(struct tdb_context *tdb, int hash, tdb_len_t length, + struct tdb_record *rec); int tdb_ofs_read(struct tdb_context *tdb, tdb_off_t offset, tdb_off_t *d); int tdb_ofs_write(struct tdb_context *tdb, tdb_off_t offset, tdb_off_t *d); int tdb_lock_record(struct tdb_context *tdb, tdb_off_t off); |