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# -*- coding: utf-8 -*-
from __future__ import (absolute_import, division, print_function,
unicode_literals)
from contextlib import contextmanager
from redis import Redis
from .local import LocalStack, release_local
class NoRedisConnectionException(Exception):
pass
@contextmanager
def Connection(connection=None): # noqa
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):
"""Pushes the given connection on the stack."""
_connection_stack.push(redis)
def pop_connection():
"""Pops the topmost connection from the stack."""
return _connection_stack.pop()
def use_connection(redis=None):
"""Clears the stack and uses the given connection. Protects against mixed
use of use_connection() and stacked connection contexts.
"""
assert len(_connection_stack) <= 1, \
'You should not mix Connection contexts with use_connection()'
release_local(_connection_stack)
if redis is None:
redis = Redis()
push_connection(redis)
def get_current_connection():
"""Returns the current Redis connection (i.e. the topmost on the
connection stack).
"""
return _connection_stack.top
def resolve_connection(connection=None):
"""Convenience function to resolve the given or the current connection.
Raises an exception if it cannot resolve a connection now.
"""
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', 'use_connection']
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