Merge pull request #40 from jimtheyounger/feature/add-dynamodb-backend

Add dynamodb backend support

fastapi_cache/backends/dynamodb.py

@@ -0,0 +1,92 @@
+import datetime
+from typing import Tuple
+
+from aiobotocore.session import get_session
+
+from fastapi_cache.backends import Backend
+
+
+class DynamoBackend(Backend):
+    """
+    Amazon DynamoDB backend provider
+
+    This backend requires an existing table within your AWS environment to be passed during
+    backend init. If ttl is going to be used, this needs to be manually enabled on the table
+    using the `ttl` key. Dynamo will take care of deleting outdated objects, but this is not
+    instant so don't be alarmed when they linger around for a bit.
+
+    As with all AWS clients, credentials will be taken from the environment. Check the AWS SDK
+    for more information.
+
+    Usage:
+        >> dynamodb = DynamoBackend(table_name="your-cache", region="eu-west-1")
+        >> await dynamodb.init()
+        >> FastAPICache.init(dynamodb)
+    """
+
+    def __init__(self, table_name, region=None):
+        self.session = get_session()
+        self.client = None  # Needs async init
+        self.table_name = table_name
+        self.region = region
+
+    async def init(self):
+        self.client = await self.session.create_client(
+            "dynamodb", region_name=self.region
+        ).__aenter__()
+
+    async def close(self):
+        self.client = await self.client.__aexit__(None, None, None)
+
+    async def get_with_ttl(self, key: str) -> Tuple[int, str]:
+        response = await self.client.get_item(TableName=self.table_name, Key={"key": {"S": key}})
+
+        if "Item" in response:
+            value = response["Item"].get("value", {}).get("S")
+            ttl = response["Item"].get("ttl", {}).get("N")
+
+            if not ttl:
+                return -1, value
+
+            # It's only eventually consistent so we need to check ourselves
+            expire = int(ttl) - int(datetime.datetime.now().timestamp())
+            if expire > 0:
+                return expire, value
+
+        return 0, None
+
+    async def get(self, key) -> str:
+        response = await self.client.get_item(TableName=self.table_name, Key={"key": {"S": key}})
+        if "Item" in response:
+            return response["Item"].get("value", {}).get("S")
+
+    async def set(self, key: str, value: str, expire: int = None):
+        ttl = (
+            {
+                "ttl": {
+                    "N": str(
+                        int(
+                            (
+                                datetime.datetime.now() + datetime.timedelta(seconds=expire)
+                            ).timestamp()
+                        )
+                    )
+                }
+            }
+            if expire
+            else {}
+        )
+
+        await self.client.put_item(
+            TableName=self.table_name,
+            Item={
+                **{
+                    "key": {"S": key},
+                    "value": {"S": value},
+                },
+                **ttl,
+            },
+        )
+
+    async def clear(self, namespace: str = None, key: str = None) -> int:
+        raise NotImplementedError

fastapi_cache/backends/inmemory.py

@@ -43,7 +43,7 @@ class InMemoryBackend(Backend):
 
     async def set(self, key: str, value: str, expire: int = None):
         async with self._lock:
-            self._store[key] = Value(value, self._now + expire)
+            self._store[key] = Value(value, self._now + expire or 0)
 
     async def clear(self, namespace: str = None, key: str = None) -> int:
         count = 0