1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
|
from contextlib import contextmanager
from typing import Optional
import warnings
from redis import Redis
from .local import LocalStack, release_local
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 use_connection(redis: Optional['Redis'] = None):
"""
Clears the stack and uses the given connection. Protects against mixed
use of use_connection() and stacked connection contexts.
Args:
redis (Optional[Redis], optional): A Redis Connection. Defaults to None.
"""
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() -> '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', 'use_connection']
|
