Retry send after timer fires, in case no updates occur

agent/proxycfg/state.go

@@ -628,11 +628,6 @@ func (s *state) run() {
 			case s.snapCh <- *snapCopy:
 				s.logger.Trace("Delivered new snapshot to proxy config watchers")
 
-			// avoid blocking if a snapshot is already buffered
-			default:
-				s.logger.Trace("Failed to deliver new snapshot to proxy config watchers")
-			}
-
 				// Allow the next change to trigger a send
 				coalesceTimer = nil
 
@@ -640,6 +635,20 @@ func (s *state) run() {
 				// this iteration
 				continue
 
+			// avoid blocking if a snapshot is already buffered, but queue up a retry with a timer
+			default:
+				s.logger.Trace("Failed to deliver new snapshot to proxy config watchers")
+
+				if coalesceTimer == nil {
+					coalesceTimer = time.AfterFunc(coalesceTimeout, func() {
+						sendCh <- struct{}{}
+					})
+				}
+
+				// Do not reset coalesceTimer since we just queued a timer-based refresh
+				continue
+			}
+
 		case replyCh := <-s.reqCh:
 			s.logger.Trace("A proxy config snapshot was requested")