1 files changed, 12 insertions, 0 deletions
diff --git a/synapse/util/async_helpers.py b/synapse/util/async_helpers.py
index 581dffd8a0..f7af2bca7f 100644
--- a/synapse/util/async_helpers.py
+++ b/synapse/util/async_helpers.py
@@ -225,6 +225,18 @@ class Linearizer(object):
             {}
         )  # type: Dict[str, Sequence[Union[int, Dict[defer.Deferred, int]]]]
 
+    def is_queued(self, key) -> bool:
+        """Checks whether there is a process queued up waiting
+        """
+        entry = self.key_to_defer.get(key)
+        if not entry:
+            # No entry so nothing is waiting.
+            return False
+
+        # There are waiting deferreds only in the OrderedDict of deferreds is
+        # non-empty.
+        return bool(entry[1])
+
     def queue(self, key):
         # we avoid doing defer.inlineCallbacks here, so that cancellation works correctly.
         # (https://twistedmatrix.com/trac/ticket/4632 meant that cancellations were not