Bound MarkAbandoned's compare-and-set retries, giving up after 10 tries (issue 711)

internal/link/calls_kept_test.go

@@ -230,6 +230,40 @@ func TestNatsAFinishRacingTheSweepsWriteWins(t *testing.T) {
 	}
 }
 
+// alwaysMismatchKV wraps a jetstream.KeyValue whose Update always fails with a revision mismatch, as
+// if some other writer kept winning the race forever (novox/hq issue 711 review round 1).
+type alwaysMismatchKV struct {
+	jetstream.KeyValue
+	tries *int
+}
+
+func (a alwaysMismatchKV) Update(ctx context.Context, key string, value []byte, revision uint64) (uint64, error) {
+	*a.tries++
+	return 0, jetstream.ErrKeyRevisionMismatch
+}
+
+// **MarkAbandoned gives up after markAbandonedTries rather than loop forever** (novox/hq issue 711
+// review round 1): a record whose compare-and-set keeps losing is left as it stands, said in an
+// error naming the call, not retried without end.
+func TestNatsAMarkAbandonedGivesUpAfterTenTries(t *testing.T) {
+	keeper := callsBucket(t)
+	running := Call{ID: "call-711-4", Seat: "mesh-controller", Verb: "push", State: CallRunning, Holder: "controller@one"}
+	if err := keeper.Keep(t.Context(), running); err != nil {
+		t.Fatal(err)
+	}
+	waitKept(t, keeper, running.ID, CallRunning)
+
+	tries := 0
+	stuck := &BusCalls{kv: alwaysMismatchKV{KeyValue: keeper.kv, tries: &tries}}
+	_, err := stuck.MarkAbandoned(t.Context(), running.ID)
+	if err == nil || !strings.Contains(err.Error(), running.ID) {
+		t.Fatalf("expected an error naming %s, got %v", running.ID, err)
+	}
+	if tries != markAbandonedTries {
+		t.Fatalf("tried %d times, want %d", tries, markAbandonedTries)
+	}
+}
+
 // The bucket holds the last thousand calls or fourteen days: a call is two keys, so the stream under
 // it holds twice as many messages, and asserting it again keeps the count.
 func TestNatsTheCallsBucketIsBounded(t *testing.T) {