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from contextlib import contextmanager
from typing import Optional
import warnings
from redis import Redis
from .local import LocalStack
class NoRedisConnectionException(Exception):
pass
@contextmanager
def Connection(connection: Optional['Redis'] = None): # noqa
"""The context manager for handling connections in a clean way.
It will push the connection to the LocalStack, and pop the connection
when leaving the context
Example:
..codeblock:python::
with Connection():
w = Worker()
w.work()
This method is deprecated on version 1.12.0 and will be removed in the future.
Pass the connection to the worker explicitly to handle Redis Connections.
Args:
connection (Optional[Redis], optional): A Redis Connection instance. Defaults to None.
"""
warnings.warn(
"The Conneciton context manager is deprecated. Use the `connection` parameter instead.", DeprecationWarning
)
if connection is None:
connection = Redis()
push_connection(connection)
try:
yield
finally:
popped = pop_connection()
assert popped == connection, (
'Unexpected Redis connection was popped off the stack. ' 'Check your Redis connection setup.'
)
def push_connection(redis: 'Redis'):
"""
Pushes the given connection to the stack.
Args:
redis (Redis): A Redis connection
"""
_connection_stack.push(redis)
def pop_connection() -> 'Redis':
"""
Pops the topmost connection from the stack.
Returns:
redis (Redis): A Redis connection
"""
return _connection_stack.pop()
def get_current_connection() -> 'Redis':
"""
Returns the current Redis connection (i.e. the topmost on the
connection stack).
Returns:
Redis: A Redis Connection
"""
return _connection_stack.top
def resolve_connection(connection: Optional['Redis'] = None) -> 'Redis':
"""
Convenience function to resolve the given or the current connection.
Raises an exception if it cannot resolve a connection now.
Args:
connection (Optional[Redis], optional): A Redis connection. Defaults to None.
Raises:
NoRedisConnectionException: If connection couldn't be resolved.
Returns:
Redis: A Redis Connection
"""
if connection is not None:
return connection
connection = get_current_connection()
if connection is None:
raise NoRedisConnectionException('Could not resolve a Redis connection')
return connection
_connection_stack = LocalStack()
__all__ = ['Connection', 'get_current_connection', 'push_connection', 'pop_connection']
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