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96 lines
2.4 KiB
Python
96 lines
2.4 KiB
Python
from contextlib import contextmanager
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import typing as t
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from redis import Redis
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from .local import LocalStack, release_local
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class NoRedisConnectionException(Exception):
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pass
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@contextmanager
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def Connection(connection: t.Optional['Redis'] = None): # noqa
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if connection is None:
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connection = Redis()
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push_connection(connection)
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try:
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yield
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finally:
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popped = pop_connection()
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assert popped == connection, \
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'Unexpected Redis connection was popped off the stack. ' \
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'Check your Redis connection setup.'
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def push_connection(redis: 'Redis'):
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"""
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Pushes the given connection on the stack.
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Args:
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redis (Redis): A Redis connection
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"""
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_connection_stack.push(redis)
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def pop_connection():
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"""
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Pops the topmost connection from the stack.
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"""
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return _connection_stack.pop()
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def use_connection(redis: t.Optional['Redis'] = None):
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"""
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Clears the stack and uses the given connection. Protects against mixed
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use of use_connection() and stacked connection contexts.
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Args:
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redis (t.Optional[Redis], optional): A Redis Connection. Defaults to None.
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"""
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assert len(_connection_stack) <= 1, \
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'You should not mix Connection contexts with use_connection()'
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release_local(_connection_stack)
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if redis is None:
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redis = Redis()
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push_connection(redis)
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def get_current_connection():
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"""
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Returns the current Redis connection (i.e. the topmost on the
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connection stack).
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"""
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return _connection_stack.top
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def resolve_connection(connection: t.Optional['Redis'] = None) -> 'Redis':
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"""
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Convenience function to resolve the given or the current connection.
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Raises an exception if it cannot resolve a connection now.
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Args:
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connection (t.Optional[Redis], optional): A Redis connection. Defaults to None.
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Raises:
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NoRedisConnectionException: If connection couldn't be resolved.
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Returns:
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Redis: A Redis Connection
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"""
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if connection is not None:
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return connection
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connection = get_current_connection()
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if connection is None:
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raise NoRedisConnectionException('Could not resolve a Redis connection')
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return connection
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_connection_stack = LocalStack()
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__all__ = ['Connection', 'get_current_connection', 'push_connection',
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'pop_connection', 'use_connection']
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