blob: a5060808d3c6fc23a400e28aff4564c7165a1a78 (
plain) (
blame)
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
|
# -*- coding: utf-8 -*-
# Copyright 2015 OpenMarket Ltd
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
"""
This module controls the reliability for application service transactions.
The nominal flow through this module looks like:
___________
\O/ --- event -->| | +--------------+
| - event ---->| EventPool |<-- poll 1/s for events ---| EventSorter |
/ \ ---- event ->|___________| +--------------+
USERS ____________________________|
| | |
V V V
ASa ASb ASc
[e,e] [e] [e,e,e]
|
V
-````````- +------------+
|````````|<--StoreTxn-|Transaction |
|Database| | Maker |---> SEND TO AS
`--------` +------------+
What happens on SEND TO AS depends on the state of the Application Service:
- If the AS is marked as DOWN, do nothing.
- If the AS is marked as UP, send the transaction.
* SUCCESS : Increment where the AS is up to txn-wise and nuke the txn
contents from the db.
* FAILURE : Marked AS as DOWN and start Recoverer.
Recoverer attempts to recover ASes who have died. The flow for this looks like:
,--------------------- backoff++ --------------.
V |
START ---> Wait exp ------> Get oldest txn ID from ----> FAILURE
backoff DB and try to send it
^ |__________
Mark AS as | V
UP & quit +---------- YES SUCCESS
| | |
NO <--- Have more txns? <------ Mark txn success & nuke -+
from db; incr AS pos.
"""
class EventPool(object):
pass
class EventSorter(object):
pass
class TransactionMaker(object):
pass
class Recoverer(object):
pass
|
