fix: random ticker stops working when no receiver (#1653)

pkg/scheduling/v0/randomticker/ticker.go

@@ -67,13 +67,15 @@ func (rt *RandomTicker) loop() {
 			close(c)
 			return
 		case <-t.C:
+			t.Stop()
+
+			// non-blocking write
 			select {
 			case rt.C <- time.Now():
-				t.Stop()
-				t = time.NewTimer(rt.nextInterval())
 			default:
-				// there could be noone receiving...
 			}
+
+			t = time.NewTimer(rt.nextInterval())
 		}
 	}
 }

pkg/scheduling/v0/randomticker/ticker_test.go

@@ -59,3 +59,47 @@ func TestRandomTicker(t *testing.T) {
 		t.Fatal("expected to receive close channel signal")
 	}
 }
+
+// TestRandomTickerUnblockingIssue is a regression test for a bug in the original implementation
+// where the ticker would stop generating new events if no one was reading from the channel.
+func TestRandomTickerUnblockingIssue(t *testing.T) {
+	minDuration := 50 * time.Millisecond
+	maxDuration := 100 * time.Millisecond
+
+	// Create the random ticker
+	rt := randomticker.NewRandomTicker(minDuration, maxDuration)
+	defer rt.Stop()
+
+	// Get the first tick to make sure it's working
+	select {
+	case <-rt.C:
+		// Good, we got a tick
+	case <-time.After(maxDuration * 2):
+		t.Fatal("didn't receive initial tick in the expected timeframe")
+	}
+
+	// Now simulate a scenario where the consumer isn't reading from the channel
+	// by just waiting without reading from rt.C
+	time.Sleep(maxDuration * 2)
+
+	// After ignoring the channel for a while, now try to read from it again
+	// With the bug, this would hang because no new ticks are generated
+	// With the fix, we should get a new tick within 2*maxDuration
+
+	tickCount := 0
+	timeout := time.After(maxDuration * 5) // Give it plenty of time to tick
+
+	for tickCount < 3 { // Try to get 3 more ticks
+		select {
+		case <-rt.C:
+			tickCount++
+		case <-timeout:
+			// With the original implementation, we'll hit this timeout
+			t.Fatalf("only received %d ticks after ignoring the channel; ticker appears stuck", tickCount)
+			return
+		}
+	}
+
+	// If we get here, the ticker continued to generate events even when
+	// we weren't reading from the channel, which means the fix is working
+}