Preserve log context over when deferring to thread pool in media repo

synapse/rest/media/v1/base_resource.py

@@ -28,6 +28,7 @@ from twisted.protocols.basic import FileSender
 
 from synapse.util.async import ObservableDeferred
 from synapse.util.stringutils import is_ascii
+from synapse.util.logcontext import preserve_context_over_fn
 
 import os
 
@@ -276,7 +277,8 @@ class BaseMediaResource(Resource):
         )
         self._makedirs(t_path)
 
-        t_len = yield threads.deferToThread(
+        t_len = yield preserve_context_over_fn(
+            threads.deferToThread,
             self._generate_thumbnail,
             input_path, t_path, t_width, t_height, t_method, t_type
         )
@@ -298,7 +300,8 @@ class BaseMediaResource(Resource):
         )
         self._makedirs(t_path)
 
-        t_len = yield threads.deferToThread(
+        t_len = yield preserve_context_over_fn(
+            threads.deferToThread,
             self._generate_thumbnail,
             input_path, t_path, t_width, t_height, t_method, t_type
         )
@@ -372,7 +375,7 @@ class BaseMediaResource(Resource):
                     media_id, t_width, t_height, t_type, t_method, t_len
                 ))
 
-        yield threads.deferToThread(generate_thumbnails)
+        yield preserve_context_over_fn(threads.deferToThread, generate_thumbnails)
 
         for l in local_thumbnails:
             yield self.store.store_local_thumbnail(*l)
@@ -445,7 +448,7 @@ class BaseMediaResource(Resource):
                     t_width, t_height, t_type, t_method, t_len
                 ])
 
-        yield threads.deferToThread(generate_thumbnails)
+        yield preserve_context_over_fn(threads.deferToThread, generate_thumbnails)
 
         for r in remote_thumbnails:
             yield self.store.store_remote_media_thumbnail(*r)