def _set_balance(self, cur, imsi, pncounter):
"""
Sets a subscriber balance to the given PN counter. Subscriber must
exist in the database.
Important: This doesn't do anything about transactions, you need to
make sure the caller appropriately implements that logic.
Arguments:
imsi: Subscriber IMSI
cursor: DB cursor
pncounter: A PNCounter representing the subscriber's balance
Returns: None
Raises:
ValueError: Invalid PNCounter
SubscriberNotFound: No subscriber exists in the DB
"""
bal = pncounter.serialize()
# validate state; raises ValueError if there's a problem
crdt.PNCounter.from_state(pncounter.state)
try:
self._update(cur, imsi, bal)
except KeyError:
# No subscriber affected
raise SubscriberNotFound(imsi)
def _set_credit(self, imsi, new_balance):
"""
Set a subscriber's balance.
Note: behavior of this is somewhat counter-intuitive. Internally, we'll
either increment or decrement the counter such that
balance.value() + X = new_balance.
This kinda breaks the underlying model of the PNCounter representation,
which only supports increment() and decrement() operations. So, if you
run set_credit(imsi, 5) in two places such that those two set_credit's
don't have a causal dependency, the subscriber balance will converge to
a value that is something other than 5 probably, depending on what
operations were necessary to get that value on each device.
Raises:
SubscriberNotFound if the subscriber doesn't exist
"""
try:
self[imsi] = new_balance
except TypeError:
raise IOError('corrupt billing table: multiple records for %s' %
(imsi, ))
except IndexError:
raise SubscriberNotFound(imsi)
def _get_balance(self, cur, imsi):
"""
Get a PN counter representing the subscribers' balance.
Important: This doesn't do anything about transactions, you need to
make sure the caller appropriately implements that logic.
Arguments:
imsi: Subscriber IMSI
cursor: DB cursor
Returns: PNCounter representing subscriber's balance.
Raises:
IOError: Invalid DB state (more than one record for an IMSI)
SubscriberNotFound: No subscriber exists in the DB
"""
try:
res = self._get_option(cur, imsi)
except TypeError:
raise IOError()
else:
if res is None:
raise SubscriberNotFound(imsi)
return crdt.PNCounter.from_json(res)
def get_account_balance(self, imsi):
"""
Gets a subscriber's balance as an integer.
Raises:
SubscriberNotFound if the subscriber doesn't exist
"""
try:
return int(crdt.PNCounter.from_json(self[imsi]).value())
except KeyError:
raise SubscriberNotFound(imsi)