From fa3cb7fa5ae27f977d426e4c3ddda13f6afe2588 Mon Sep 17 00:00:00 2001
From: Patrick Cloke <patrickc@matrix.org>
Date: Fri, 28 Aug 2020 08:43:03 -0400
Subject: [PATCH 1/2] Convert runInteraction to async.

---
 changelog.d/8156.misc       |  1 +
 synapse/storage/database.py | 26 ++++++++++++--------------
 2 files changed, 13 insertions(+), 14 deletions(-)
 create mode 100644 changelog.d/8156.misc

diff --git a/changelog.d/8156.misc b/changelog.d/8156.misc
new file mode 100644
index 000000000000..dfe4c03171d6
--- /dev/null
+++ b/changelog.d/8156.misc
@@ -0,0 +1 @@
+Convert various parts of the codebase to async/await.
diff --git a/synapse/storage/database.py b/synapse/storage/database.py
index 7ab370efef15..41d2291e848a 100644
--- a/synapse/storage/database.py
+++ b/synapse/storage/database.py
@@ -35,7 +35,6 @@
 from typing_extensions import Literal
 
 from twisted.enterprise import adbapi
-from twisted.internet import defer
 
 from synapse.api.errors import StoreError
 from synapse.config.database import DatabaseConnectionConfig
@@ -507,8 +506,9 @@ def new_transaction(
             self._txn_perf_counters.update(desc, duration)
             sql_txn_timer.labels(desc).observe(duration)
 
-    @defer.inlineCallbacks
-    def runInteraction(self, desc: str, func: Callable, *args: Any, **kwargs: Any):
+    async def runInteraction(
+        self, desc: str, func: Callable, *args: Any, **kwargs: Any
+    ) -> Any:
         """Starts a transaction on the database and runs a given function
 
         Arguments:
@@ -521,7 +521,7 @@ def runInteraction(self, desc: str, func: Callable, *args: Any, **kwargs: Any):
             kwargs: named args to pass to `func`
 
         Returns:
-            Deferred: The result of func
+            The result of func
         """
         after_callbacks = []  # type: List[_CallbackListEntry]
         exception_callbacks = []  # type: List[_CallbackListEntry]
@@ -530,16 +530,14 @@ def runInteraction(self, desc: str, func: Callable, *args: Any, **kwargs: Any):
             logger.warning("Starting db txn '%s' from sentinel context", desc)
 
         try:
-            result = yield defer.ensureDeferred(
-                self.runWithConnection(
-                    self.new_transaction,
-                    desc,
-                    after_callbacks,
-                    exception_callbacks,
-                    func,
-                    *args,
-                    **kwargs
-                )
+            result = await self.runWithConnection(
+                self.new_transaction,
+                desc,
+                after_callbacks,
+                exception_callbacks,
+                func,
+                *args,
+                **kwargs
             )
 
             for after_callback, after_args, after_kwargs in after_callbacks:

From ca31cfeb5572d3abda2790ccdc9995b79502dd0a Mon Sep 17 00:00:00 2001
From: Patrick Cloke <patrickc@matrix.org>
Date: Wed, 2 Sep 2020 07:19:09 -0400
Subject: [PATCH 2/2] Add additional typing.

---
 synapse/storage/database.py | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/synapse/storage/database.py b/synapse/storage/database.py
index 41d2291e848a..41a399a49efb 100644
--- a/synapse/storage/database.py
+++ b/synapse/storage/database.py
@@ -28,6 +28,7 @@
     Optional,
     Tuple,
     TypeVar,
+    cast,
     overload,
 )
 
@@ -507,8 +508,8 @@ def new_transaction(
             sql_txn_timer.labels(desc).observe(duration)
 
     async def runInteraction(
-        self, desc: str, func: Callable, *args: Any, **kwargs: Any
-    ) -> Any:
+        self, desc: str, func: "Callable[..., R]", *args: Any, **kwargs: Any
+    ) -> R:
         """Starts a transaction on the database and runs a given function
 
         Arguments:
@@ -547,7 +548,7 @@ async def runInteraction(
                 after_callback(*after_args, **after_kwargs)
             raise
 
-        return result
+        return cast(R, result)
 
     async def runWithConnection(
         self, func: "Callable[..., R]", *args: Any, **kwargs: Any