fix(buffer): Skip sleep if duration is zero (#4028)

#skip-changelog

---------

Co-authored-by: Riccardo Busetti <riccardo.busetti@sentry.io>

relay-server/src/services/buffer/mod.rs

@@ -147,7 +147,9 @@ impl EnvelopeBufferService {
  );
 
  self.system_ready(buffer).await;
- tokio::time::sleep(self.sleep).await;
+ if self.sleep > Duration::ZERO {
+ tokio::time::sleep(self.sleep).await;
+ }
  if let Some(project_cache_ready) = self.project_cache_ready.as_mut() {
  project_cache_ready.await?;
  self.project_cache_ready = None;
@@ -326,7 +328,6 @@ impl Service for EnvelopeBufferService {
  relay_log::trace!("EnvelopeBufferService received global config");
  self.sleep = Duration::ZERO; // Try to pop
  }
-
  else => break,
  }
 
@@ -486,11 +487,17 @@ mod tests {
  }
  addr.send(EnvelopeBuffer::Ready(project_key));
 
- tokio::time::sleep(Duration::from_millis(1000)).await;
+ tokio::time::sleep(Duration::from_millis(100)).await;
 
- // Project cache received only one envelope:
- assert_eq!(project_cache_rx.len(), 1); // without throttling, this would be 5.
- assert!(project_cache_rx.try_recv().is_ok());
- assert_eq!(project_cache_rx.len(), 0);
+ let mut messages = vec![];
+ project_cache_rx.recv_many(&mut messages, 100).await;
+
+ assert_eq!(
+ messages
+ .iter()
+ .filter(|message| matches!(message, ProjectCache::HandleDequeuedEnvelope(..)))
+ .count(),
+ 1
+ );
  }
 }