Commit 84f9894e authored by Julien Muchembled's avatar Julien Muchembled

storage: review search of data serial for undo

- Fix case of empty values: there's no reason to do anything special for them.
- Do not warn about multiple level of indirection to get data serial.
  With the current structure of tables, this does not cause significant
  performance issue as it did before.
parent d562bf8f
......@@ -328,28 +328,20 @@ class DatabaseManager(object):
tid (int)
tid corresponding to received parameters
serial
tid at which actual object data is located
data tid of the found record
If 'tid is None', requested object and transaction could
not be found.
If 'serial is None', requested object exist but has no data (its creation
has been undone).
If 'tid == serial', it means that requested transaction
contains object data.
Otherwise, it's an undo transaction which did not involve conflict
resolution.
(None, None) is returned if requested object and transaction
could not be found.
This method only exists for performance reasons, by not returning data:
_getObject already returns these values but it is slower.
"""
if self.__class__ not in self.__getDataTID:
self.__getDataTID.add(self.__class__)
logging.warning("Fallback to generic/slow implementation"
" of _getDataTID. It should be overriden by backend storage.")
" of _getDataTID. It should be overridden by backend storage.")
r = self._getObject(oid, tid, before_tid)
if r:
serial, _, _, data_id, _, value_serial = r
if value_serial is None and data_id:
return serial, serial
return serial, value_serial
return None, None
return (r[0], r[-1]) if r else (None, None)
def findUndoTID(self, oid, tid, ltid, undone_tid, transaction_object):
"""
......@@ -389,17 +381,17 @@ class DatabaseManager(object):
ltid = u64(ltid)
undone_tid = u64(undone_tid)
def getDataTID(tid=None, before_tid=None):
tid, value_serial = self._getDataTID(oid, tid, before_tid)
if value_serial not in (None, tid):
if value_serial >= tid:
raise ValueError("Incorrect value reference found for"
" oid %d at tid %d: reference = %d"
% (oid, value_serial, tid))
if value_serial != getDataTID(value_serial)[1]:
logging.warning("Multiple levels of indirection"
" when getting data serial for oid %d at tid %d."
" This causes suboptimal performance.", oid, tid)
return tid, value_serial
tid, data_tid = self._getDataTID(oid, tid, before_tid)
current_tid = tid
while data_tid:
if data_tid < tid:
tid, data_tid = self._getDataTID(oid, data_tid)
if tid is not None:
continue
logging.error("Incorrect data serial for oid %s at tid %s",
oid, current_tid)
return current_tid, current_tid
return current_tid, tid
if transaction_object:
current_tid = current_data_tid = u64(transaction_object[2])
else:
......
......@@ -423,7 +423,7 @@ class MySQLDatabaseManager(DatabaseManager):
return self.conn.insert_id()
def _getDataTID(self, oid, tid=None, before_tid=None):
sql = ('SELECT tid, data_id, value_tid FROM obj'
sql = ('SELECT tid, value_tid FROM obj'
' WHERE partition = %d AND oid = %d'
) % (self._getPartition(oid), oid)
if tid is not None:
......@@ -435,12 +435,7 @@ class MySQLDatabaseManager(DatabaseManager):
# MySQL does not use an index for a HAVING clause!
sql += ' ORDER BY tid DESC LIMIT 1'
r = self.query(sql)
if r:
(serial, data_id, value_serial), = r
if value_serial is None and data_id:
return serial, serial
return serial, value_serial
return None, None
return r[0] if r else (None, None)
def finishTransaction(self, tid):
q = self.query
......
......@@ -370,7 +370,7 @@ class SQLiteDatabaseManager(DatabaseManager):
def _getDataTID(self, oid, tid=None, before_tid=None):
partition = self._getPartition(oid)
sql = 'SELECT tid, data_id, value_tid FROM obj' \
sql = 'SELECT tid, value_tid FROM obj' \
' WHERE partition=? AND oid=?'
if tid is not None:
r = self.query(sql + ' AND tid=?', (partition, oid, tid))
......@@ -381,12 +381,7 @@ class SQLiteDatabaseManager(DatabaseManager):
r = self.query(sql + ' ORDER BY tid DESC LIMIT 1',
(partition, oid))
r = r.fetchone()
if r:
serial, data_id, value_serial = r
if value_serial is None and data_id:
return serial, serial
return serial, value_serial
return None, None
return r or (None, None)
def finishTransaction(self, tid):
args = util.u64(tid),
......
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