def try_add_stolen_flag(flag: models.Flag, attacker: int, current_round: int) -> bool:
"""
Flag validation function.
Checks that flag is valid for current round, adds it to cache for team,
atomically checking if it's already submitted by the attacker.
:param flag: Flag model instance
:param attacker: attacker team id
:param current_round: current round
"""
stolen_key = CacheKeys.team_stolen_flags(attacker)
with utils.redis_pipeline(transaction=True) as pipe:
# optimization of redis request count
cached_stolen = pipe.exists(stolen_key).execute()
if not cached_stolen:
cache_helper(
pipeline=pipe,
cache_key=stolen_key,
cache_func=caching.cache_last_stolen,
cache_args=(attacker, current_round, pipe),
)
is_new, = pipe.sadd(stolen_key, flag.id).execute()
return bool(is_new)
def cache_last_stolen(team_id: int, current_round: int,
pipe: Pipeline) -> None:
"""
Caches stolen flags from "flag_lifetime" rounds.
Just adds commands to pipeline stack, don't forget to execute afterwards.
:param team_id: attacker team id
:param current_round: current round
:param pipe: redis connection to add command to
"""
game_config = game.get_current_game_config()
with utils.db_cursor() as (_, curs):
curs.execute(
_SELECT_LAST_STOLEN_TEAM_FLAGS_QUERY,
{
'round': current_round - game_config.flag_lifetime,
'attacker_id': team_id,
},
)
flags = curs.fetchall()
key = CacheKeys.team_stolen_flags(team_id)
pipe.delete(key)
if flags:
pipe.sadd(key, *(flag[0] for flag in flags))
