Add `StreamKeyType` class and replace string literals with constants (#12567)

1 files changed, 20 insertions, 19 deletions

diff --git a/synapse/handlers/appservice.py b/synapse/handlers/appservice.py
index 85bd5e4768..1da7bcc85b 100644
--- a/synapse/handlers/appservice.py
+++ b/synapse/handlers/appservice.py
@@ -38,6 +38,7 @@ from synapse.types import (
     JsonDict,
     RoomAlias,
     RoomStreamToken,
+    StreamKeyType,
     UserID,
 )
 from synapse.util.async_helpers import Linearizer
@@ -213,8 +214,8 @@ class ApplicationServicesHandler:
         Args:
             stream_key: The stream the event came from.
 
-                `stream_key` can be "typing_key", "receipt_key", "presence_key",
-                "to_device_key" or "device_list_key". Any other value for `stream_key`
+                `stream_key` can be StreamKeyType.TYPING, StreamKeyType.RECEIPT, StreamKeyType.PRESENCE,
+                StreamKeyType.TO_DEVICE or StreamKeyType.DEVICE_LIST. Any other value for `stream_key`
                 will cause this function to return early.
 
                 Ephemeral events will only be pushed to appservices that have opted into
@@ -235,11 +236,11 @@ class ApplicationServicesHandler:
         # Only the following streams are currently supported.
         # FIXME: We should use constants for these values.
         if stream_key not in (
-            "typing_key",
-            "receipt_key",
-            "presence_key",
-            "to_device_key",
-            "device_list_key",
+            StreamKeyType.TYPING,
+            StreamKeyType.RECEIPT,
+            StreamKeyType.PRESENCE,
+            StreamKeyType.TO_DEVICE,
+            StreamKeyType.DEVICE_LIST,
         ):
             return
 
@@ -258,14 +259,14 @@ class ApplicationServicesHandler:
 
         # Ignore to-device messages if the feature flag is not enabled
         if (
-            stream_key == "to_device_key"
+            stream_key == StreamKeyType.TO_DEVICE
             and not self._msc2409_to_device_messages_enabled
         ):
             return
 
         # Ignore device lists if the feature flag is not enabled
         if (
-            stream_key == "device_list_key"
+            stream_key == StreamKeyType.DEVICE_LIST
             and not self._msc3202_transaction_extensions_enabled
         ):
             return
@@ -283,15 +284,15 @@ class ApplicationServicesHandler:
             if (
                 stream_key
                 in (
-                    "typing_key",
-                    "receipt_key",
-                    "presence_key",
-                    "to_device_key",
+                    StreamKeyType.TYPING,
+                    StreamKeyType.RECEIPT,
+                    StreamKeyType.PRESENCE,
+                    StreamKeyType.TO_DEVICE,
                 )
                 and service.supports_ephemeral
             )
             or (
-                stream_key == "device_list_key"
+                stream_key == StreamKeyType.DEVICE_LIST
                 and service.msc3202_transaction_extensions
             )
         ]
@@ -317,7 +318,7 @@ class ApplicationServicesHandler:
         logger.debug("Checking interested services for %s", stream_key)
         with Measure(self.clock, "notify_interested_services_ephemeral"):
             for service in services:
-                if stream_key == "typing_key":
+                if stream_key == StreamKeyType.TYPING:
                     # Note that we don't persist the token (via set_appservice_stream_type_pos)
                     # for typing_key due to performance reasons and due to their highly
                     # ephemeral nature.
@@ -333,7 +334,7 @@ class ApplicationServicesHandler:
                 async with self._ephemeral_events_linearizer.queue(
                     (service.id, stream_key)
                 ):
-                    if stream_key == "receipt_key":
+                    if stream_key == StreamKeyType.RECEIPT:
                         events = await self._handle_receipts(service, new_token)
                         self.scheduler.enqueue_for_appservice(service, ephemeral=events)
 
@@ -342,7 +343,7 @@ class ApplicationServicesHandler:
                             service, "read_receipt", new_token
                         )
 
-                    elif stream_key == "presence_key":
+                    elif stream_key == StreamKeyType.PRESENCE:
                         events = await self._handle_presence(service, users, new_token)
                         self.scheduler.enqueue_for_appservice(service, ephemeral=events)
 
@@ -351,7 +352,7 @@ class ApplicationServicesHandler:
                             service, "presence", new_token
                         )
 
-                    elif stream_key == "to_device_key":
+                    elif stream_key == StreamKeyType.TO_DEVICE:
                         # Retrieve a list of to-device message events, as well as the
                         # maximum stream token of the messages we were able to retrieve.
                         to_device_messages = await self._get_to_device_messages(
@@ -366,7 +367,7 @@ class ApplicationServicesHandler:
                             service, "to_device", new_token
                         )
 
-                    elif stream_key == "device_list_key":
+                    elif stream_key == StreamKeyType.DEVICE_LIST:
                         device_list_summary = await self._get_device_list_summary(
                             service, new_token
                         )