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
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
|
"""DynamoDB cache backend. For usage details, see :ref:`Backends: DynamoDB <dynamodb>`.
.. automodsumm:: requests_cache.backends.dynamodb
:classes-only:
:nosignatures:
"""
from typing import Iterable, Optional
import boto3
from boto3.dynamodb.types import Binary
from boto3.resources.base import ServiceResource
from botocore.exceptions import ClientError
from requests_cache.backends.base import VT
from .._utils import get_valid_kwargs
from ..serializers import SerializerType, dynamodb_document_serializer
from . import BaseCache, BaseStorage, DictStorage
class DynamoDbCache(BaseCache):
"""DynamoDB cache backend.
By default, responses are only partially serialized into a DynamoDB-compatible document format.
Args:
table_name: DynamoDB table name
connection: :boto3:`DynamoDB Resource <services/dynamodb.html#DynamoDB.ServiceResource>`
object to use instead of creating a new one
ttl: Use DynamoDB TTL to automatically remove expired items
kwargs: Additional keyword arguments for :py:meth:`~boto3.session.Session.resource`
"""
def __init__(
self,
table_name: str = 'http_cache',
*,
ttl: bool = True,
connection: Optional[ServiceResource] = None,
decode_content: bool = True,
serializer: Optional[SerializerType] = None,
**kwargs,
):
super().__init__(cache_name=table_name, **kwargs)
skwargs = {'serializer': serializer, **kwargs} if serializer else kwargs
self.responses = DynamoDbDict(
table_name,
ttl=ttl,
connection=connection,
decode_content=decode_content,
**skwargs,
)
# Redirects will be only stored in memory and not persisted
self.redirects: BaseStorage[str, str] = DictStorage()
class DynamoDbDict(BaseStorage):
"""A dictionary-like interface for DynamoDB table
Args:
table_name: DynamoDB table name
connection: :boto3:`DynamoDB Resource <services/dynamodb.html#DynamoDB.ServiceResource>`
object to use instead of creating a new one
ttl: Use DynamoDB TTL to automatically remove expired items
kwargs: Additional keyword arguments for :py:meth:`~boto3.session.Session.resource`
"""
def __init__(
self,
table_name: str,
ttl: bool = True,
connection: Optional[ServiceResource] = None,
serializer: Optional[SerializerType] = dynamodb_document_serializer,
**kwargs,
):
super().__init__(serializer=serializer, **kwargs)
connection_kwargs = get_valid_kwargs(
boto3.Session.__init__, kwargs, extras=['endpoint_url']
)
self.connection = connection or boto3.resource('dynamodb', **connection_kwargs)
self.table_name = table_name
self.ttl = ttl
self._table = self.connection.Table(self.table_name)
self._create_table()
if ttl:
self._enable_ttl()
def _create_table(self):
"""Create a default table if one does not already exist"""
try:
self.connection.create_table(
AttributeDefinitions=[
{'AttributeName': 'key', 'AttributeType': 'S'},
],
TableName=self.table_name,
KeySchema=[
{'AttributeName': 'key', 'KeyType': 'HASH'},
],
BillingMode='PAY_PER_REQUEST',
)
self._table.wait_until_exists()
# Ignore error if table already exists
except ClientError as e:
if e.response['Error']['Code'] != 'ResourceInUseException':
raise
def _enable_ttl(self):
"""Enable TTL, if not already enabled"""
try:
self.connection.meta.client.update_time_to_live(
TableName=self.table_name,
TimeToLiveSpecification={'AttributeName': 'ttl', 'Enabled': True},
)
# Ignore error if TTL is already enabled
except ClientError as e:
if e.response['Error']['Code'] != 'ValidationException':
raise
def __getitem__(self, key):
result = self._table.get_item(Key={'key': key})
if 'Item' not in result:
raise KeyError
return self.deserialize(key, result['Item']['value'])
def __setitem__(self, key, value):
item = {'key': key, 'value': self.serialize(value)}
# If enabled, set TTL value as a timestamp in unix format
if self.ttl and getattr(value, 'expires_unix', None):
item['ttl'] = value.expires_unix
self._table.put_item(Item=item)
def __delitem__(self, key):
response = self._table.delete_item(Key={'key': key}, ReturnValues='ALL_OLD')
if 'Attributes' not in response:
raise KeyError
def __iter__(self):
# Alias 'key' attribute since it's a reserved keyword
results = self._table.scan(
ProjectionExpression='#k',
ExpressionAttributeNames={'#k': 'key'},
)
for item in results['Items']:
yield item['key']
def __len__(self):
"""Get the number of items in the table.
**Note:** This is an estimate, and is updated every 6 hours. A full table scan will use up
your provisioned throughput, so it's not recommended.
"""
return self._table.item_count
def bulk_delete(self, keys: Iterable[str]):
"""Delete multiple keys from the cache. Does not raise errors for missing keys."""
with self._table.batch_writer() as batch:
for key in keys:
batch.delete_item(Key={'key': key})
def clear(self):
self.bulk_delete((k for k in self))
def deserialize(self, key, value: VT):
"""Handle Binary objects from a custom serializer"""
serialized_value = value.value if isinstance(value, Binary) else value
return super().deserialize(key, serialized_value)
# TODO: Support pagination
def values(self):
for item in self._table.scan()['Items']:
yield self.deserialize(item['key'], item['value'])
|
