Add cached properties

Cache properties to prevent methods from invoking multiple times per request

mangum/handlers/alb.py

@@ -7,6 +7,7 @@
     handle_base64_response_body,
     handle_exclude_headers,
     maybe_encode_body,
+    TypedCachedProperty,
 )
 from mangum.types import (
     Response,
@@ -95,16 +96,15 @@ def __init__(
         self.context = context
         self.config = config
 
-    @property
+    @TypedCachedProperty
     def body(self) -> bytes:
         return maybe_encode_body(
             self.event.get("body", b""),
             is_base64=self.event.get("isBase64Encoded", False),
         )
 
-    @property
+    @TypedCachedProperty
     def scope(self) -> Scope:
-
         headers = transform_headers(self.event)
         list_headers = [list(x) for x in headers]
         # Unique headers. If there are duplicates, it will use the last defined.

mangum/handlers/api_gateway.py

@@ -1,13 +1,13 @@
 from typing import Dict, List, Tuple
 from urllib.parse import urlencode
-
 from mangum.handlers.utils import (
     get_server_and_port,
     handle_base64_response_body,
     handle_exclude_headers,
     handle_multi_value_headers,
     maybe_encode_body,
     strip_api_gateway_path,
+    TypedCachedProperty,
 )
 from mangum.types import (
     Response,
@@ -78,14 +78,14 @@ def __init__(
         self.context = context
         self.config = config
 
-    @property
+    @TypedCachedProperty
     def body(self) -> bytes:
         return maybe_encode_body(
             self.event.get("body", b""),
             is_base64=self.event.get("isBase64Encoded", False),
         )
 
-    @property
+    @TypedCachedProperty
     def scope(self) -> Scope:
         headers = _handle_multi_value_headers_for_request(self.event)
         return {
@@ -144,14 +144,14 @@ def __init__(
         self.context = context
         self.config = config
 
-    @property
+    @TypedCachedProperty
     def body(self) -> bytes:
         return maybe_encode_body(
             self.event.get("body", b""),
             is_base64=self.event.get("isBase64Encoded", False),
         )
 
-    @property
+    @TypedCachedProperty
     def scope(self) -> Scope:
         request_context = self.event["requestContext"]
         event_version = self.event["version"]

mangum/handlers/lambda_at_edge.py

@@ -1,10 +1,10 @@
 from typing import Dict, List
-
 from mangum.handlers.utils import (
     handle_base64_response_body,
     handle_exclude_headers,
     handle_multi_value_headers,
     maybe_encode_body,
+    TypedCachedProperty,
 )
 from mangum.types import Scope, Response, LambdaConfig, LambdaEvent, LambdaContext
 
@@ -31,15 +31,15 @@ def __init__(
         self.context = context
         self.config = config
 
-    @property
+    @TypedCachedProperty
     def body(self) -> bytes:
         cf_request_body = self.event["Records"][0]["cf"]["request"].get("body", {})
         return maybe_encode_body(
             cf_request_body.get("data"),
             is_base64=cf_request_body.get("encoding", "") == "base64",
         )
 
-    @property
+    @TypedCachedProperty
     def scope(self) -> Scope:
         cf_request = self.event["Records"][0]["cf"]["request"]
         scheme_header = cf_request["headers"].get("cloudfront-forwarded-proto", [{}])

mangum/handlers/utils.py

@@ -1,10 +1,13 @@
 import base64
-from typing import Any, Dict, List, Tuple, Union
+from typing import Any, Dict, List, Tuple, Union, TypeVar, Callable, cast
 from urllib.parse import unquote
-
+from cached_property import cached_property
 from mangum.types import Headers, LambdaConfig
 
 
+F = TypeVar("F", bound=Callable[..., Any])
+
+
 def maybe_encode_body(body: Union[str, bytes], *, is_base64: bool) -> bytes:
     body = body or b""
     if is_base64:
@@ -93,3 +96,8 @@ def handle_exclude_headers(
         finalized_headers[header_key] = header_value
 
     return finalized_headers
+
+
+class TypedCachedProperty(cached_property):
+    def __init__(self, func: F) -> None:
+        super().__init__(func)

mangum/protocols/http.py

@@ -93,7 +93,6 @@ async def send(self, message: Message) -> None:
             self.state is HTTPCycleState.RESPONSE
             and message["type"] == "http.response.body"
         ):
-
             body = message.get("body", b"")
             more_body = message.get("more_body", False)
             self.buffer.write(body)

mangum/protocols/lifespan.py

@@ -98,14 +98,12 @@ async def run(self) -> None:
     async def receive(self) -> Message:
         """Awaited by the application to receive ASGI `lifespan` events."""
         if self.state is LifespanCycleState.CONNECTING:
-
             # Connection established. The next event returned by the queue will be
             # `lifespan.startup` to inform the application that the connection is
             # ready to receive lfiespan messages.
             self.state = LifespanCycleState.STARTUP
 
         elif self.state is LifespanCycleState.STARTUP:
-
             # Connection shutting down. The next event returned by the queue will be
             # `lifespan.shutdown` to inform the application that the connection is now
             # closing so that it may perform cleanup.

requirements.txt

@@ -11,3 +11,4 @@ brotli
 brotli-asgi
 mkdocs
 mkdocs-material
+cached-property

tests/handlers/test_alb.py

@@ -4,6 +4,7 @@
 2. https://docs.aws.amazon.com/elasticloadbalancing/latest/application/lambda-functions.html  # noqa: E501
 """
 from typing import Dict, List, Optional
+from unittest import mock
 
 import pytest
 
@@ -409,3 +410,26 @@ async def app(scope, receive, send):
             "content-type": "text/plain; charset=utf-8",
         }
     assert response == expected_response
+
+
+def test_aws_alb_scope_called_once() -> None:
+    async def app(scope, receive, send):
+        await send(
+            {
+                "type": "http.response.start",
+                "status": 200,
+                "headers": [
+                    [b"content-type", b"text/plain; charset=utf-8"],
+                ],
+            }
+        )
+        await send({"type": "http.response.body", "body": b"Hello, world!"})
+
+    handler = Mangum(app, lifespan="off")
+    event = get_mock_aws_alb_event("GET", "/test", {}, None, None, False, False)
+
+    with mock.patch(
+        "mangum.handlers.alb.transform_headers",
+    ) as mock_func:
+        handler(event, {})
+        mock_func.assert_called_once()

tests/handlers/test_api_gateway.py

@@ -1,4 +1,5 @@
 import urllib.parse
+from unittest import mock
 
 import pytest
 
@@ -429,3 +430,27 @@ async def app(scope, receive, send):
         "multiValueHeaders": {},
         "body": "Hello world",
     }
+
+
+def test_aws_api_gateway_scope_called_once():
+    async def app(scope, receive, send):
+        await send(
+            {
+                "type": "http.response.start",
+                "status": 200,
+                "headers": [
+                    [b"content-type", b"text/plain; charset=utf-8"],
+                ],
+            }
+        )
+        await send({"type": "http.response.body", "body": b"Hello world"})
+
+    event = get_mock_aws_api_gateway_event("GET", "/test", {}, None, False)
+
+    handler = Mangum(app, lifespan="off")
+
+    with mock.patch(
+        "mangum.handlers.api_gateway._handle_multi_value_headers_for_request",
+    ) as mock_func:
+        handler(event, {})
+        mock_func.assert_called_once()

tests/handlers/test_http_gateway.py

@@ -1,4 +1,5 @@
 import urllib.parse
+from unittest import mock
 
 import pytest
 
@@ -687,3 +688,25 @@ async def app(scope, receive, send):
         "headers": {"content-type": content_type.decode()},
         "body": utf_res_body,
     }
+
+
+def test_aws_http_gateway_scope_called_once():
+    async def app(scope, receive, send):
+        await send(
+            {
+                "type": "http.response.start",
+                "status": 200,
+                "headers": [[b"header1", b"value1"], [b"header2", b"value1, value2"]],
+            }
+        )
+        await send({"type": "http.response.body", "body": b"Hello world"})
+
+    event = get_mock_aws_http_gateway_event_v2("GET", "/test", {}, None, False)
+
+    handler = Mangum(app, lifespan="off")
+
+    with mock.patch(
+        "mangum.handlers.api_gateway.strip_api_gateway_path",
+    ) as mock_func:
+        handler(event, {})
+        mock_func.assert_called_once()

tests/handlers/test_lambda_at_edge.py

@@ -1,4 +1,5 @@
 import urllib.parse
+from unittest import mock
 
 import pytest
 
@@ -373,3 +374,24 @@ async def app(scope, receive, send):
         },
         "body": "Hello world",
     }
+
+
+def test_aws_lambda_at_edge_scope_called_once():
+    async def app(scope, receive, send):
+        await send(
+            {
+                "type": "http.response.start",
+                "status": 200,
+                "headers": [[b"content-type", b"text/plain; charset=utf-8"]],
+            }
+        )
+        await send({"type": "http.response.body", "body": b"Hello world"})
+
+    event = mock_lambda_at_edge_event("GET", "/test", {}, None, False)
+    handler = Mangum(app, lifespan="off")
+
+    with mock.patch.object(
+        LambdaAtEdge, "context", new_callable=mock.PropertyMock, create=True
+    ) as mock_ctx:
+        handler(event, {})
+        assert mock_ctx.call_count == 2