congress/congress/db/db_ds_table_data.py
Eric K 7db74cbf0f DB operations retry on deadlock
Occassionally, the database backend may experience a deadlock error
in the normal course of operations.
It is standard practice to have the database client retry the
operation.

If retries continue to fail, eventually return to user with 500
error and description.

Closes-Bug: 1746139

Change-Id: Iffc9344d22d1b3c0408eca3cef11767bafd2c7c2
2018-02-07 11:46:23 -08:00

95 lines
3.2 KiB
Python

# Copyright (c) 2016 VMware, Inc. All rights reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License. You may obtain
# a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations
# under the License.
from __future__ import print_function
from __future__ import division
from __future__ import absolute_import
import json
import sqlalchemy as sa
from sqlalchemy.orm import exc as db_exc
from congress.db import api as db
from congress.db import model_base
from congress.db import utils as db_utils
class DSTableData(model_base.BASE):
__tablename__ = 'dstabledata'
ds_id = sa.Column(sa.String(36), nullable=False, primary_key=True)
tablename = sa.Column(sa.String(255), nullable=False, primary_key=True)
# choose long length compatible with MySQL, SQLite, Postgres
tabledata = sa.Column(sa.Text(), nullable=False)
@db_utils.retry_on_db_error
def store_ds_table_data(ds_id, tablename, tabledata, session=None):
session = session or db.get_session()
tabledata = _json_encode_table_data(tabledata)
with session.begin(subtransactions=True):
new_row = session.merge(DSTableData(
ds_id=ds_id,
tablename=tablename,
tabledata=tabledata))
return new_row
@db_utils.retry_on_db_error
def delete_ds_table_data(ds_id, tablename=None, session=None):
session = session or db.get_session()
if tablename is None:
return session.query(DSTableData).filter(
DSTableData.ds_id == ds_id).delete()
else:
return session.query(DSTableData).filter(
DSTableData.ds_id == ds_id,
DSTableData.tablename == tablename).delete()
@db_utils.retry_on_db_error
def get_ds_table_data(ds_id, tablename=None, session=None):
session = session or db.get_session()
try:
if tablename is None:
rows = session.query(DSTableData).filter(
DSTableData.ds_id == ds_id)
return_list = []
for row in rows:
return_list.append(
{'tablename': row.tablename,
'tabledata': _json_decode_table_data(row.tabledata)})
return return_list
else:
return _json_decode_table_data(session.query(DSTableData).filter(
DSTableData.ds_id == ds_id,
DSTableData.tablename == tablename).one().tabledata)
except db_exc.NoResultFound:
pass
def _json_encode_table_data(tabledata):
tabledata = list(tabledata)
for i in range(0, len(tabledata)):
tabledata[i] = list(tabledata[i])
return json.dumps(tabledata)
def _json_decode_table_data(json_tabledata):
tabledata = json.loads(json_tabledata)
for i in range(0, len(tabledata)):
tabledata[i] = tuple(tabledata[i])
return set(tabledata)