Fix thumbnailing remote files

synapse/rest/media/v1/media_repository.py

@@ -227,6 +227,34 @@ class MediaRepository(object):
         else:
             respond_404(request)
 
+    @defer.inlineCallbacks
+    def get_remote_media_info(self, server_name, media_id):
+        """Gets the media info associated with the remote file, downloading
+        if necessary.
+
+        Args:
+            server_name (str): Remote server_name where the media originated.
+            media_id (str): The media ID of the content (as defined by the
+                remote server).
+
+        Returns:
+            Deferred[dict]: The media_info of the file
+        """
+        # We linearize here to ensure that we don't try and download remote
+        # media multiple times concurrently
+        key = (server_name, media_id)
+        with (yield self.remote_media_linearizer.queue(key)):
+            responder, media_info = yield self._get_remote_media_impl(
+                server_name, media_id,
+            )
+
+        # Ensure we actually use the responder so that it releases resources
+        if responder:
+            with responder:
+                pass
+
+        defer.returnValue(media_info)
+
     @defer.inlineCallbacks
     def _get_remote_media_impl(self, server_name, media_id):
         """Looks for media in local cache, if not there then attempt to

synapse/rest/media/v1/thumbnail_resource.py

@@ -165,7 +165,7 @@ class ThumbnailResource(Resource):
     def _select_or_generate_remote_thumbnail(self, request, server_name, media_id,
                                              desired_width, desired_height,
                                              desired_method, desired_type):
-        media_info = yield self.media_repo.get_remote_media(server_name, media_id)
+        media_info = yield self.media_repo.get_remote_media_info(server_name, media_id)
 
         thumbnail_infos = yield self.store.get_remote_media_thumbnails(
             server_name, media_id,
@@ -216,7 +216,7 @@ class ThumbnailResource(Resource):
         # TODO: Don't download the whole remote file
         # We should proxy the thumbnail from the remote server instead of
         # downloading the remote file and generating our own thumbnails.
-        yield self.media_repo.get_remote_media(server_name, media_id)
+        yield self.media_repo.get_remote_media_info(server_name, media_id)
 
         thumbnail_infos = yield self.store.get_remote_media_thumbnails(
             server_name, media_id,