From d1de32ea2773df4c6f8a956678bbd19b6d022475 Mon Sep 17 00:00:00 2001
From: Timo <16718859+toger5@users.noreply.github.com>
Date: Thu, 12 Dec 2024 15:58:50 +0100
Subject: [PATCH] Only re-prepare MatrixrRTC delayed disconnection event on 404
  (#4575)

* Set retry counts of event updating to 1000 (from 1)

 With it being set to one the following issue could occur:

```
// If sending state cancels your own delayed state, prepare another delayed state
// TODO: Remove this once MSC4140 is stable & doesn't cancel own delayed state
if (this.disconnectDelayId !== undefined) {
    try {
        const knownDisconnectDelayId = this.disconnectDelayId;
        await resendIfRateLimited(
            () =>
                this.client._unstable_updateDelayedEvent(
                    knownDisconnectDelayId,
                    UpdateDelayedEventAction.Restart,
                ),
            1000,
        );
    } catch (e) {
        logger.warn("Failed to update delayed disconnection event, prepare it again:", e);
        this.disconnectDelayId = undefined;
        await prepareDelayedDisconnection();
    }
}
```
This code looks like the `catch(e)` could never be triggered with 429 (rate limit) because they would be caught by `await resendIfRateLimited`. EXCEPT that this is only happening once: `resendIfRateLimited<T>(func: () => Promise<T>, numRetriesAllowed: number = 1)`. So as soon as the server sends two rate limits in a row we get the following:
 - we get into the `catch(e)`  because of the rate limit
 - we forget about `this.disconnectDelayId = undefined`
 - we start a new delayed event `await prepareDelayedDisconnection();`
 - we do not anymore update the old delayed event which is still running!
 - the running delay event will make us disconnect from the call (call member becomes `{}`)
 - we get into our outher error catching mechanism that resends the new state event
 - this cancels the newly created delay leave event (`await prepareDelayedDisconnection();`)
 - and create another delay leave event.
 - but if we are still reate limited (chances are really high due to the reconnect), this loop will REPEAT

* also check for M_NOT_FOUND

* Leave retry at current level

---------

Co-authored-by: Hugh Nimmo-Smith <hughns@matrix.org>
---
 src/matrixrtc/MatrixRTCSession.ts | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/src/matrixrtc/MatrixRTCSession.ts b/src/matrixrtc/MatrixRTCSession.ts
index 147a6e0a05e..855596b7976 100644
--- a/src/matrixrtc/MatrixRTCSession.ts
+++ b/src/matrixrtc/MatrixRTCSession.ts
@@ -1189,9 +1189,14 @@ export class MatrixRTCSession extends TypedEventEmitter<MatrixRTCSessionEvent, M
                             ),
                         );
                     } catch (e) {
-                        logger.warn("Failed to update delayed disconnection event, prepare it again:", e);
-                        this.disconnectDelayId = undefined;
-                        await prepareDelayedDisconnection();
+                        if (e instanceof MatrixError && e.errcode === "M_NOT_FOUND") {
+                            // If we get a M_NOT_FOUND we prepare a new delayed event.
+                            // In other error cases we do not want to prepare anything since we do not have the guarantee, that the
+                            // future is not still running.
+                            logger.warn("Failed to update delayed disconnection event, prepare it again:", e);
+                            this.disconnectDelayId = undefined;
+                            await prepareDelayedDisconnection();
+                        }
                     }
                 }
                 if (this.disconnectDelayId !== undefined) {