diff options
Diffstat (limited to 'source4/lib/tdb/common/tdb.c')
| -rw-r--r-- | source4/lib/tdb/common/tdb.c | 181 |
1 files changed, 175 insertions, 6 deletions
diff --git a/source4/lib/tdb/common/tdb.c b/source4/lib/tdb/common/tdb.c index 03a66804b3..a6b472ae94 100644 --- a/source4/lib/tdb/common/tdb.c +++ b/source4/lib/tdb/common/tdb.c @@ -258,6 +258,66 @@ int tdb_do_delete(struct tdb_context *tdb, tdb_off_t rec_ptr, struct list_struct return 0; } +static int tdb_count_dead(struct tdb_context *tdb, u32 hash) +{ + int res = 0; + tdb_off_t rec_ptr; + struct list_struct rec; + + /* read in the hash top */ + if (tdb_ofs_read(tdb, TDB_HASH_TOP(hash), &rec_ptr) == -1) + return 0; + + while (rec_ptr) { + if (tdb_rec_read(tdb, rec_ptr, &rec) == -1) + return 0; + + if (rec.magic == TDB_DEAD_MAGIC) { + res += 1; + } + rec_ptr = rec.next; + } + return res; +} + +/* + * Purge all DEAD records from a hash chain + */ +static int tdb_purge_dead(struct tdb_context *tdb, u32 hash) +{ + int res = -1; + struct list_struct rec; + tdb_off_t rec_ptr; + + if (tdb_lock(tdb, -1, F_WRLCK) == -1) { + return -1; + } + + /* read in the hash top */ + if (tdb_ofs_read(tdb, TDB_HASH_TOP(hash), &rec_ptr) == -1) + goto fail; + + while (rec_ptr) { + tdb_off_t next; + + if (tdb_rec_read(tdb, rec_ptr, &rec) == -1) { + goto fail; + } + + next = rec.next; + + if (rec.magic == TDB_DEAD_MAGIC + && tdb_do_delete(tdb, rec_ptr, &rec) == -1) { + goto fail; + } + rec_ptr = next; + } + res = 0; + fail: + tdb_unlock(tdb, -1, F_WRLCK); + return res; +} + /* delete an entry in the database given a key */ static int tdb_delete_hash(struct tdb_context *tdb, TDB_DATA key, u32 hash) { @@ -265,9 +325,42 @@ static int tdb_delete_hash(struct tdb_context *tdb, TDB_DATA key, u32 hash) struct list_struct rec; int ret; - if (!(rec_ptr = tdb_find_lock_hash(tdb, key, hash, F_WRLCK, &rec))) - return -1; - ret = tdb_do_delete(tdb, rec_ptr, &rec); + if (tdb->max_dead_records != 0) { + + /* + * Allow for some dead records per hash chain, mainly for + * tdb's with a very high create/delete rate like locking.tdb. + */ + + if (tdb_lock(tdb, BUCKET(hash), F_WRLCK) == -1) + return -1; + + if (tdb_count_dead(tdb, hash) >= tdb->max_dead_records) { + /* + * Don't let the per-chain freelist grow too large, + * delete all existing dead records + */ + tdb_purge_dead(tdb, hash); + } + + if (!(rec_ptr = tdb_find(tdb, key, hash, &rec))) { + tdb_unlock(tdb, BUCKET(hash), F_WRLCK); + return -1; + } + + /* + * Just mark the record as dead. + */ + rec.magic = TDB_DEAD_MAGIC; + ret = tdb_rec_write(tdb, rec_ptr, &rec); + } + else { + if (!(rec_ptr = tdb_find_lock_hash(tdb, key, hash, F_WRLCK, + &rec))) + return -1; + + ret = tdb_do_delete(tdb, rec_ptr, &rec); + } if (ret == 0) { tdb_increment_seqnum(tdb); @@ -284,6 +377,35 @@ int tdb_delete(struct tdb_context *tdb, TDB_DATA key) return tdb_delete_hash(tdb, key, hash); } +/* + * See if we have a dead record around with enough space + */ +static tdb_off_t tdb_find_dead(struct tdb_context *tdb, u32 hash, + struct list_struct *r, tdb_len_t length) +{ + tdb_off_t rec_ptr; + + /* read in the hash top */ + if (tdb_ofs_read(tdb, TDB_HASH_TOP(hash), &rec_ptr) == -1) + return 0; + + /* keep looking until we find the right record */ + while (rec_ptr) { + if (tdb_rec_read(tdb, rec_ptr, r) == -1) + return 0; + + if (TDB_DEAD(r) && r->rec_len >= length) { + /* + * First fit for simple coding, TODO: change to best + * fit + */ + return rec_ptr; + } + rec_ptr = r->next; + } + return 0; +} + /* store an element in the database, replacing any existing element with the same key @@ -316,8 +438,7 @@ int tdb_store(struct tdb_context *tdb, TDB_DATA key, TDB_DATA dbuf, int flag) } else { /* first try in-place update, on modify or replace. */ if (tdb_update_hash(tdb, key, hash, dbuf) == 0) { - ret = 0; - goto fail; /* Well, not really failed */ + goto done; } if (tdb->ecode == TDB_ERR_NOEXIST && flag == TDB_MODIFY) { @@ -347,9 +468,56 @@ int tdb_store(struct tdb_context *tdb, TDB_DATA key, TDB_DATA dbuf, int flag) if (dbuf.dsize) memcpy(p+key.dsize, dbuf.dptr, dbuf.dsize); + if (tdb->max_dead_records != 0) { + /* + * Allow for some dead records per hash chain, look if we can + * find one that can hold the new record. We need enough space + * for key, data and tailer. If we find one, we don't have to + * consult the central freelist. + */ + rec_ptr = tdb_find_dead( + tdb, hash, &rec, + key.dsize + dbuf.dsize + sizeof(tdb_off_t)); + + if (rec_ptr != 0) { + rec.key_len = key.dsize; + rec.data_len = dbuf.dsize; + rec.full_hash = hash; + rec.magic = TDB_MAGIC; + if (tdb_rec_write(tdb, rec_ptr, &rec) == -1 + || tdb->methods->tdb_write( + tdb, rec_ptr + sizeof(rec), + p, key.dsize + dbuf.dsize) == -1) { + goto fail; + } + goto done; + } + } + + /* + * 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 */ - if (!(rec_ptr = tdb_allocate(tdb, key.dsize + dbuf.dsize, &rec))) + rec_ptr = tdb_allocate(tdb, key.dsize + dbuf.dsize, &rec); + + tdb_unlock(tdb, -1, F_WRLCK); + + if (rec_ptr == 0) { goto fail; + } /* Read hash top into next ptr */ if (tdb_ofs_read(tdb, TDB_HASH_TOP(hash), &rec.next) == -1) @@ -368,6 +536,7 @@ int tdb_store(struct tdb_context *tdb, TDB_DATA key, TDB_DATA dbuf, int flag) goto fail; } + done: ret = 0; fail: if (ret == 0) { |