Navigation

Changeset 153

Timestamp:

04/26/08 15:34:30 (4 months ago)

Author:

njriley

Message:

Handle database failure on reads.

Files:

r152	r153
18	18	class Sucrose(object):
19	19
	20	@db.read_or_die
20	21	def user_from_uin(self, uin):
21	22	return self.users.filter_by(uin=uin).first()
22	23
	24	@db.read_or_die
23	25	def tray_from_location(self, location):
24	26	if not ( ( location[0] in '12345' and location[1] in '1237' ) or
…	…
28	30	return self.trays.filter_by(machine_tray_id=int(location)).first()
29	31
30
	32	@db.read_or_die
31	33	def item_from_tray(self, tray):
32	34	return self.items.filter_by(item_id=tray.item_id).first()
33	35
	36	@db.read_or_die
34	37	def balance_for_user(self, user):
35	38	return self.vending.filter_by(uid=user.uid).first().balance
36	39
	40	@db.read_or_die
37	41	def recent_purchases_for_user(self, user):
38	42	transactions = self.transactions.filter_by(user=user).\
…	…
42	46	return [(t.item_name, t.cost) for t in transactions]
43	47
	48	@db.read_or_die
44	49	def total_spent_by_user(self, user):
45	50	return self.transactions.filter_by(user=user).\

r121	r153
1		from sqlalchemy import create_engine, Table, Column, Integer, Numeric, ~~String,~~ \
2		MetaData, ForeignKey
	1	from sqlalchemy import create_engine, Table, Column, Integer, Numeric, \
	2	String, MetaData, ForeignKey
3	3	from sqlalchemy.databases.mysql import MSEnum, MSInteger
4	4	from sqlalchemy.ext.declarative import declarative_base
…	…
6	6	from sqlalchemy.orm import mapper, relation, sessionmaker
7	7
8		DB_URL = 'mysql://soda:m568EXUFS@db1.acm.uiuc.edu'
	8	DB_URL = 'mysql://soda:m568EXUFS@db2.acm.uiuc.edu'
9	9	# XXX change 'sucrose' to 'vending' once caffeine is migrated
10	10	_sucrose = create_engine('%s/sucrose' % DB_URL)
…	…
72	72	_Session = sessionmaker(transactional=False, autoflush=False, twophase=True)
73	73	session = _Session()
	74
	75	try:
	76	from functools import wraps
	77	except ImportError:
	78	wraps = lambda wrapped: lambda wrapper: wrapper
	79	from sqlalchemy.exceptions import DBAPIError
	80	import logging, os
	81	def read_or_die(f):
	82	"""
	83	Retry a repeatable database read operation a few times before
	84	exiting - handling temporary database failure.
	85	"""
	86	@wraps(f)
	87	def wrapper(self, args, *kw):
	88	for retry_count in xrange(5, 0, -1):
	89	try:
	90	return f(self, args, *kw)
	91	except DBAPIError, e:
	92	logging.warn('Retrying database query - %d left' % retry_count,
	93	exc_info=True)
	94	except ValueError, e: # XXX replace with Sucrose-specific exception
	95	raise
	96	except:
	97	logging.critical('Unexpected exception on DB read',
	98	exc_info=True)
	99	os._exit(1)
	100	logging.critical('No retries left')
	101	os._exit(1)
	102	return wrapper
	103