NDOJ/judge/dblock.py

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692 B
Python
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2020-01-21 06:35:58 +00:00
from itertools import chain
from django.db import connection, transaction
class LockModel(object):
def __init__(self, write, read=()):
self.tables = ', '.join(chain(
('`%s` WRITE' % model._meta.db_table for model in write),
('`%s` READ' % model._meta.db_table for model in read),
))
self.cursor = connection.cursor()
def __enter__(self):
self.cursor.execute('LOCK TABLES ' + self.tables)
def __exit__(self, exc_type, exc_val, exc_tb):
if exc_type is None:
transaction.commit()
else:
transaction.rollback()
self.cursor.execute('UNLOCK TABLES')
self.cursor.close()