def increase_shards(name, num):
"""
Increase the number of shards for a given sharded counter.
Will never decrease the number of shards.
Parameters:
name - The name of the counter
num - How many shards to use
"""
config = GeneralCounterShardConfig.get_or_insert(name, name=name)
def txn():
if config.num_shards < num:
config.num_shards = num
config.put()
db.run_in_transaction(txn)
def increment(name):
"""
Increment the value for a given sharded counter.
Parameters:
name - The name of the counter
"""
config = GeneralCounterShardConfig.get_or_insert(name, name=name)
def txn():
index = random.randint(0, config.num_shards - 1)
shard_name = name + str(index)
counter = GeneralCounterShard.get_by_key_name(shard_name)
if counter is None:
counter = GeneralCounterShard(key_name=shard_name, name=name)
counter.count += 1
counter.put()
db.run_in_transaction(txn)
# does nothing if the key does not exist
memcache.incr(name)
