fix: prevent error log when pgcoord query is canceled.

coadler · coadler · commit 97ac7b9b799b · 2023-07-19T20:11:29.000Z
I believe this is what has been causing the `TestReplicas` flakes.
There's a race condition where if a query was in flight while the
`pgcoord` was closing, it would log an error. The error log then fails
the test since somewhere along the line we're creating a `slogtest`
logger.
diff --git a/enterprise/tailnet/pgcoord.go b/enterprise/tailnet/pgcoord.go
@@ -424,7 +424,7 @@ func (b *binder) writeOne(bnd binding) error {
 	default:
 		panic("unhittable")
 	}
-	if err != nil {
+	if err != nil && !pqErrIsCanceled(err) {
 		b.logger.Error(b.ctx, "failed to write binding to database",
 			slog.F("client_id", bnd.client),
 			slog.F("agent_id", bnd.agent),
@@ -434,6 +434,12 @@ func (b *binder) writeOne(bnd binding) error {
 	return err
 }
 
+// This is returned when the context is canceled on a running query. pq does not
+// export an error for this.
+func pqErrIsCanceled(err error) bool {
+	return err.Error() == "pq: canceling statement due to user request"
+}
+
 // storeBinding stores the latest binding, where we interpret node == nil as removing the binding. This keeps the map
 // from growing without bound.
 func (b *binder) storeBinding(bnd binding) {
