From d89692ea843f5c67c87ac4c992575015b359c5a0 Mon Sep 17 00:00:00 2001
From: Patrick Cloke <clokep@users.noreply.github.com>
Date: Wed, 19 Aug 2020 07:09:24 -0400
Subject: [PATCH] Convert runWithConnection to async. (#8121)

---
 changelog.d/8121.misc                         |  1 +
 synapse/metrics/background_process_metrics.py |  2 +-
 synapse/storage/database.py                   | 27 +++++++++----------
 3 files changed, 15 insertions(+), 15 deletions(-)
 create mode 100644 changelog.d/8121.misc

diff --git a/changelog.d/8121.misc b/changelog.d/8121.misc
new file mode 100644
index 000000000..dfe4c0317
--- /dev/null
+++ b/changelog.d/8121.misc
@@ -0,0 +1 @@
+Convert various parts of the codebase to async/await.
diff --git a/synapse/metrics/background_process_metrics.py b/synapse/metrics/background_process_metrics.py
index f766d16db..4cd7932e5 100644
--- a/synapse/metrics/background_process_metrics.py
+++ b/synapse/metrics/background_process_metrics.py
@@ -175,7 +175,7 @@ def run_as_background_process(desc: str, func, *args, **kwargs):
     It returns a Deferred which completes when the function completes, but it doesn't
     follow the synapse logcontext rules, which makes it appropriate for passing to
     clock.looping_call and friends (or for firing-and-forgetting in the middle of a
-    normal synapse inlineCallbacks function).
+    normal synapse async function).
 
     Args:
         desc: a description for this background process type
diff --git a/synapse/storage/database.py b/synapse/storage/database.py
index 8a9e06efc..b9aef96b0 100644
--- a/synapse/storage/database.py
+++ b/synapse/storage/database.py
@@ -516,14 +516,16 @@ class DatabasePool(object):
             logger.warning("Starting db txn '%s' from sentinel context", desc)
 
         try:
-            result = yield self.runWithConnection(
-                self.new_transaction,
-                desc,
-                after_callbacks,
-                exception_callbacks,
-                func,
-                *args,
-                **kwargs
+            result = yield defer.ensureDeferred(
+                self.runWithConnection(
+                    self.new_transaction,
+                    desc,
+                    after_callbacks,
+                    exception_callbacks,
+                    func,
+                    *args,
+                    **kwargs
+                )
             )
 
             for after_callback, after_args, after_kwargs in after_callbacks:
@@ -535,8 +537,7 @@ class DatabasePool(object):
 
         return result
 
-    @defer.inlineCallbacks
-    def runWithConnection(self, func: Callable, *args: Any, **kwargs: Any):
+    async def runWithConnection(self, func: Callable, *args: Any, **kwargs: Any) -> Any:
         """Wraps the .runWithConnection() method on the underlying db_pool.
 
         Arguments:
@@ -547,7 +548,7 @@ class DatabasePool(object):
             kwargs: named args to pass to `func`
 
         Returns:
-            Deferred: The result of func
+            The result of func
         """
         parent_context = current_context()  # type: Optional[LoggingContextOrSentinel]
         if not parent_context:
@@ -570,12 +571,10 @@ class DatabasePool(object):
 
                 return func(conn, *args, **kwargs)
 
-        result = yield make_deferred_yieldable(
+        return await make_deferred_yieldable(
             self._db_pool.runWithConnection(inner_func, *args, **kwargs)
         )
 
-        return result
-
     @staticmethod
     def cursor_to_dict(cursor):
         """Converts a SQL cursor into an list of dicts.