astrid-runtime/astrid · error · anyhow::Error

event bus closed before response on

Error message

event bus closed before response on {want_response}

What it means

BusAdminClient::request subscribes to the response topic before publishing the request. If receiver.recv() returns Ok(None), the broadcast channel's sender side has been dropped — the event bus shut down — so no response can ever arrive. This error reports that the bus closed while the request was still in flight for the given response topic.

Solutions

  1. Ensure the event bus outlives all in-flight admin requests (hold the sender until requests complete)
  2. Check for premature shutdown/teardown ordering in the gateway startup/shutdown code
  3. Retry the request after the bus is re-established, or surface a clean 'shutting down' state to the caller
  4. In tests, await requests before dropping the bus fixture

Example fix

// before
drop(bus); // sender dropped while request in flight
let resp = client.request(kind).await?;
// after
let resp = client.request(kind).await?; // keep bus alive until response
drop(bus);
Defensive patterns

Strategy: try-catch

Validate before calling

// Check the bus is alive before issuing:
if bus_sender_count() == 0 { return Err(anyhow!("event bus unavailable")); }

Try / catch

match client.request(kind).await {
    Ok(resp) => resp,
    Err(e) if e.to_string().contains("event bus closed") => {
        // treat as shutdown: stop issuing requests, surface clean shutdown state
        Err(anyhow!("gateway is shutting down"))
    }
    Err(e) => return Err(e),
}

Prevention

When it happens

Trigger: Calling request() while the event bus / its publisher is being shut down; the bus handle holding the sender is dropped mid-request (e.g. process teardown, a test dropping the bus); recv on a broadcast Receiver whose Sender has gone away.

Common situations: Graceful shutdown racing an in-flight admin request; unit/integration tests dropping the bus fixture before awaiting the response; kernel process exit closing the shared bus.

Related errors

AI-assisted analysis of astrid-runtime/astrid@affd8760f4 (2026-09-09). Data as JSON: /api/errors/4e385484bdaca9b4. Report an issue: GitHub.

Appendix: source

Thrown at crates/astrid-gateway/src/bus_admin.rs:157

            message: msg,
        });

        let deadline = tokio::time::Instant::now()
            .checked_add(self.timeout)
            .unwrap_or_else(tokio::time::Instant::now);

        loop {
            let remaining = deadline.saturating_duration_since(tokio::time::Instant::now());
            if remaining.is_zero() {
                return Err(anyhow!(
                    "bus admin request timed out after {:?} waiting for {want_response}",
                    self.timeout
                ));
            }
            let event = match tokio::time::timeout(remaining, receiver.recv()).await {
                Ok(Some(ev)) => ev,
                Ok(None) => {
                    return Err(anyhow!(
                        "event bus closed before response on {want_response}"
                    ));
                },
                Err(_) => {
                    return Err(anyhow!(
                        "bus admin request timed out after {:?} waiting for {want_response}",
                        self.timeout
                    ));
                },
            };

            let AstridEvent::Ipc { message, .. } = &*event else {
                continue;
            };
            if message.source_id != self.expected_source_id {
                continue;
            }
            // The kernel's `publish_response` wraps the

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