TDB_DATA tdb_null;
+/*
+ increment the tdb sequence number if the tdb has been opened using
+ the TDB_SEQNUM flag
+*/
+static void tdb_increment_seqnum(struct tdb_context *tdb)
+{
+ tdb_off_t seqnum=0;
+
+ if (!(tdb->flags & TDB_SEQNUM)) {
+ return;
+ }
+
+ if (tdb_brlock(tdb, TDB_SEQNUM_OFS, F_WRLCK, F_SETLKW, 1, 1) != 0) {
+ return;
+ }
+
+ /* we ignore errors from this, as we have no sane way of
+ dealing with them.
+ */
+ tdb_ofs_read(tdb, TDB_SEQNUM_OFS, &seqnum);
+ seqnum++;
+ tdb_ofs_write(tdb, TDB_SEQNUM_OFS, &seqnum);
+
+ tdb_brlock(tdb, TDB_SEQNUM_OFS, F_UNLCK, F_SETLKW, 1, 1);
+}
+
+static int tdb_key_compare(TDB_DATA key, TDB_DATA data, void *private_data)
+{
+ return memcmp(data.dptr, key.dptr, data.dsize);
+}
+
/* Returns 0 on fail. On success, return offset of record, and fills
in rec */
static tdb_off_t tdb_find(struct tdb_context *tdb, TDB_DATA key, u32 hash,
if (tdb_rec_read(tdb, rec_ptr, r) == -1)
return 0;
- if (!TDB_DEAD(r) && hash==r->full_hash && key.dsize==r->key_len) {
- unsigned char *k;
- /* a very likely hit - read the key */
- k = tdb_alloc_read(tdb, rec_ptr + sizeof(*r),
- r->key_len);
- if (!k)
- return 0;
-
- if (memcmp(key.dptr, k, key.dsize) == 0) {
- SAFE_FREE(k);
- return rec_ptr;
- }
- SAFE_FREE(k);
+ if (!TDB_DEAD(r) && hash==r->full_hash
+ && key.dsize==r->key_len
+ && tdb_parse_data(tdb, key, rec_ptr + sizeof(*r),
+ r->key_len, tdb_key_compare,
+ NULL) == 0) {
+ return rec_ptr;
}
rec_ptr = r->next;
}
return -1;
}
- if (tdb_write(tdb, rec_ptr + sizeof(rec) + rec.key_len,
+ if (tdb->methods->tdb_write(tdb, rec_ptr + sizeof(rec) + rec.key_len,
dbuf.dptr, dbuf.dsize) == -1)
return -1;
return ret;
}
+/*
+ * Find an entry in the database and hand the record's data to a parsing
+ * function. The parsing function is executed under the chain read lock, so it
+ * should be fast and should not block on other syscalls.
+ *
+ * DONT CALL OTHER TDB CALLS FROM THE PARSER, THIS MIGHT LEAD TO SEGFAULTS.
+ *
+ * For mmapped tdb's that do not have a transaction open it points the parsing
+ * function directly at the mmap area, it avoids the malloc/memcpy in this
+ * case. If a transaction is open or no mmap is available, it has to do
+ * malloc/read/parse/free.
+ *
+ * This is interesting for all readers of potentially large data structures in
+ * the tdb records, ldb indexes being one example.
+ */
+
+int tdb_parse_record(struct tdb_context *tdb, TDB_DATA key,
+ int (*parser)(TDB_DATA key, TDB_DATA data,
+ void *private_data),
+ void *private_data)
+{
+ tdb_off_t rec_ptr;
+ struct list_struct rec;
+ int ret;
+ u32 hash;
+
+ /* find which hash bucket it is in */
+ hash = tdb->hash_fn(&key);
+
+ if (!(rec_ptr = tdb_find_lock_hash(tdb,key,hash,F_RDLCK,&rec))) {
+ return TDB_ERRCODE(TDB_ERR_NOEXIST, 0);
+ }
+
+ ret = tdb_parse_data(tdb, key, rec_ptr + sizeof(rec) + rec.key_len,
+ rec.data_len, parser, private_data);
+
+ tdb_unlock(tdb, BUCKET(rec.full_hash), F_RDLCK);
+
+ return ret;
+}
+
/* check if an entry in the database exists
note that 1 is returned if the key is found and 0 is returned if not found
tdb_off_t last_ptr, i;
struct list_struct lastrec;
- if (tdb->read_only) return -1;
+ if (tdb->read_only || tdb->traverse_read) return -1;
if (tdb_write_lock_record(tdb, rec_ptr) == -1) {
/* Someone traversing here: mark it as dead */
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)
{
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);
+ }
+
if (tdb_unlock(tdb, BUCKET(rec.full_hash), F_WRLCK) != 0)
- TDB_LOG((tdb, 0, "tdb_delete: WARNING tdb_unlock failed!\n"));
+ TDB_LOG((tdb, TDB_DEBUG_WARNING, "tdb_delete: WARNING tdb_unlock failed!\n"));
return ret;
}
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
u32 hash;
tdb_off_t rec_ptr;
char *p = NULL;
- int ret = 0;
+ int ret = -1;
+
+ if (tdb->read_only || tdb->traverse_read) {
+ tdb->ecode = TDB_ERR_RDONLY;
+ return -1;
+ }
/* find which hash bucket it is in */
hash = tdb->hash_fn(&key);
}
} else {
/* first try in-place update, on modify or replace. */
- if (tdb_update_hash(tdb, key, hash, dbuf) == 0)
- goto out;
+ if (tdb_update_hash(tdb, key, hash, dbuf) == 0) {
+ goto done;
+ }
if (tdb->ecode == TDB_ERR_NOEXIST &&
flag == TDB_MODIFY) {
/* if the record doesn't exist and we are in TDB_MODIFY mode then
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)
/* write out and point the top of the hash chain at it */
if (tdb_rec_write(tdb, rec_ptr, &rec) == -1
- || tdb_write(tdb, rec_ptr+sizeof(rec), p, key.dsize+dbuf.dsize)==-1
+ || tdb->methods->tdb_write(tdb, rec_ptr+sizeof(rec), p, key.dsize+dbuf.dsize)==-1
|| tdb_ofs_write(tdb, TDB_HASH_TOP(hash), &rec_ptr) == -1) {
/* Need to tdb_unallocate() here */
goto fail;
}
- out:
+
+ done:
+ ret = 0;
+ fail:
+ if (ret == 0) {
+ tdb_increment_seqnum(tdb);
+ }
+
SAFE_FREE(p);
tdb_unlock(tdb, BUCKET(hash), F_WRLCK);
return ret;
-fail:
- ret = -1;
- goto out;
}
dbuf = tdb_fetch(tdb, key);
if (dbuf.dptr == NULL) {
- dbuf.dptr = malloc(new_dbuf.dsize);
+ dbuf.dptr = (unsigned char *)malloc(new_dbuf.dsize);
} else {
- dbuf.dptr = realloc(dbuf.dptr, dbuf.dsize + new_dbuf.dsize);
+ dbuf.dptr = (unsigned char *)realloc(dbuf.dptr,
+ dbuf.dsize + new_dbuf.dsize);
}
if (dbuf.dptr == NULL) {
*/
tdb_log_func tdb_log_fn(struct tdb_context *tdb)
{
- return tdb->log_fn;
+ return tdb->log.log_fn;
+}
+
+
+/*
+ get the tdb sequence number. Only makes sense if the writers opened
+ with TDB_SEQNUM set. Note that this sequence number will wrap quite
+ quickly, so it should only be used for a 'has something changed'
+ test, not for code that relies on the count of the number of changes
+ made. If you want a counter then use a tdb record.
+
+ The aim of this sequence number is to allow for a very lightweight
+ test of a possible tdb change.
+*/
+int tdb_get_seqnum(struct tdb_context *tdb)
+{
+ tdb_off_t seqnum=0;
+
+ tdb_ofs_read(tdb, TDB_SEQNUM_OFS, &seqnum);
+ return seqnum;
+}
+
+int tdb_hash_size(struct tdb_context *tdb)
+{
+ return tdb->header.hash_size;
+}
+
+size_t tdb_map_size(struct tdb_context *tdb)
+{
+ return tdb->map_size;
}
+
+int tdb_get_flags(struct tdb_context *tdb)
+{
+ return tdb->flags;
+}
+
git.samba.org / ira / wip.git / blobdiff