Stricter requirements to consider a client healthy

A healthy client must not only have a sync task running, but also have
finished its initial sync and have been succesful in its last sync
attempt.

The previous weak requirement caused this issue:
Have two clients, one on a failing server, and try to fetch a media,
thumbnail or profile: since these functions don't need auth, any
healthy client is picked to do the request, but the previous
requirement made it possible to pick the failing client.

src/backend/backend.py

@@ -258,7 +258,8 @@ class Backend:
 
         while True:
             for client in self.clients.values():
-                if client.syncing:
+                if client.healthy:
+                    print( client, client.first_sync_done)
                     return client
 
             if failures and failures % 300 == 0:

src/backend/matrix_client.py

@@ -191,6 +191,7 @@ class MatrixClient(nio.AsyncClient):
 
         self.first_sync_done: asyncio.Event       = asyncio.Event()
         self.first_sync_date: Optional[datetime]  = None
+        self.last_sync_error: Optional[Exception] = None
 
         self.past_tokens:          Dict[str, str] = {}     # {room_id: token}
         self.fully_loaded_rooms:   Set[str]       = set()  # {room_id}
@@ -324,13 +325,15 @@ class MatrixClient(nio.AsyncClient):
         await self.close()
 
     @property
-    def syncing(self) -> bool:
-        """Return whether this client is currently syncing with the server."""
+    def healthy(self) -> bool:
+        """Return whether we're syncing and last sync was successful."""
 
-        if not self.sync_task:
+        task = self.sync_task
+
+        if not task or not self.first_sync_date or self.last_sync_error:
             return False
 
-        return not self.sync_task.done()
+        return not task.done()
 
 
     async def _start(self) -> None:
@@ -395,6 +398,8 @@ class MatrixClient(nio.AsyncClient):
                 await self.sync_task
                 break  # task cancelled
             except Exception as err:
+                self.last_sync_error = err
+
                 trace = traceback.format_exc().rstrip()
 
                 if isinstance(err, MatrixError) and err.http_code >= 500:
@@ -405,6 +410,8 @@ class MatrixClient(nio.AsyncClient):
                     )
                 else:
                     LoopException(str(err), err, trace)
+            else:
+                self.last_sync_error = None
 
             await asyncio.sleep(5)
 

src/icons/thin/image-rotate-left.svg

@@ -0,0 +1,3 @@
+<svg height="1792" viewBox="0 0 1792 1792" width="1792" xmlns="http://www.w3.org/2000/svg">
+    <path d="m1664 896q0 156-61 298t-164 245-245 164-298 61q-172 0-327-72.5t-264-204.5q-7-10-6.5-22.5t8.5-20.5l137-138q10-9 25-9 16 2 23 12 73 95 179 147t225 52q104 0 198.5-40.5t163.5-109.5 109.5-163.5 40.5-198.5-40.5-198.5-109.5-163.5-163.5-109.5-198.5-40.5q-98 0-188 35.5t-160 101.5l137 138q31 30 14 69-17 40-59 40h-448q-26 0-45-19t-19-45v-448q0-42 40-59 39-17 69 14l130 129q107-101 244.5-156.5t284.5-55.5q156 0 298 61t245 164 164 245 61 298z"/>
+</svg>

src/icons/thin/image-rotate-right.svg

@@ -0,0 +1,3 @@
+<svg height="1792" viewBox="0 0 1792 1792" width="1792" xmlns="http://www.w3.org/2000/svg">
+    <path d="m1664 256v448q0 26-19 45t-45 19h-448q-42 0-59-40-17-39 14-69l138-138q-148-137-349-137-104 0-198.5 40.5t-163.5 109.5-109.5 163.5-40.5 198.5 40.5 198.5 109.5 163.5 163.5 109.5 198.5 40.5q119 0 225-52t179-147q7-10 23-12 14 0 25 9l137 138q9 8 9.5 20.5t-7.5 22.5q-109 132-264 204.5t-327 72.5q-156 0-298-61t-245-164-164-245-61-298 61-298 164-245 245-164 298-61q147 0 284.5 55.5t244.5 156.5l130-129q29-31 70-14 39 17 39 59z"/>
+</svg>