class KeyValueStorage:
"""
Key value storage with redis server
"""
def __init__(self, host: str, port: int, retries_limit: int, timeout: int):
self.host = host
self.port = port
self.timeout = timeout
self.retries_limit = retries_limit
self._kv_storage = None
self._connect()
def _connect(self) -> NoReturn:
"""
Connection to redis server with retries
:param retry_counter: counter of times of retrying
:return: Redis connection if it was successful and None otherwise
"""
try:
self._kv_storage = Redis(
host=self.host,
port=self.port,
socket_timeout=self.timeout
)
self._kv_storage.ping()
except Exception:
logging.error(
"Got error while connecting to redis with host %s and port %d.",
self.host,
self.port
)
def _reset_connection(self) -> NoReturn:
"""
Resets connection to redis server
:return:
"""
self._kv_storage.close()
self._connect()
@make_retries
def get(self, key: str) -> str:
"""
Gets value by key as from persistent data storage
:param key: key to get value for
:return: value for specified key
"""
result = self._kv_storage.get(key)
return result.decode("utf-8") if result is not None else result
def cache_get(self, key: str) -> Optional[float]:
"""
Gets value by key from cache
:param key: key to get value for
:return: float value if found some in cache and None otherwise
"""
result = None
try:
result = self.get(key)
except (ConnectionError, TimeoutError) as exception:
logging.error(
"Could not get value from cache. Encountered error: %s",
str(exception)
)
return float(result) if result is not None else result
@make_retries
def _set(self, key: str,
value: Union[float, int],
key_expire_time_sec: int) -> NoReturn:
"""
Sets the value into cache by specified key
:param key: key to set value for
:param value: value for setting
:param key_expire_time_sec: time in which key will be expired
"""
self._kv_storage.set(key, str(value), ex=key_expire_time_sec)
def cache_set(self, key: str,
value: Union[float, int],
key_expire_time_sec: int) -> NoReturn:
"""
Sets the value into cache by specified key
:param key: key to set value for
:param value: value for setting
:param key_expire_time_sec: time in which key will be expired
"""
try:
self._set(key, str(value), key_expire_time_sec=key_expire_time_sec)
except (ConnectionError, TimeoutError) as exception:
logging.error(
"Could not set value to cache. Encountered error: %s",
str(exception)
)
def clear(self) -> NoReturn:
self._kv_storage.flushall()
