def incrementCounter(key, property="counter", update_interval=10):
"""Increments a memcached counter.
Args:
key: The key of a datastore entity that contains the counter.
update_interval: Minimum interval between updates.
"""
lock_key = "icl:%s" % key
count_key = "icv:%s" % key
if cache_add(None, lock_key, time=update_interval):
# Time to update the DB
count = int(cache_get(count_key) or 0) + 1
def tx():
entity = db.get(key)
setattr(entity, property, getattr(entity, property) + count)
entity.put()
db.run_in_transaction(tx)
cache_delete(count_key)
else:
# Just update memcache
cache_incr(1, count_key, initial_value=0)
