From a6dace8829ca671d3a8602ef21a6388169ee70bc Mon Sep 17 00:00:00 2001
From: Thomas Jackson <jacksontj.89@gmail.com>
Date: Thu, 21 Jun 2018 14:43:31 -0700
Subject: [PATCH] Check for timeout in each iteration of matrixSelector (#4300)

Signed-off-by: Thomas Jackson <jacksontj.89@gmail.com>

Fixes #4288
---
 promql/engine.go | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/promql/engine.go b/promql/engine.go
index 5953ccabb5..20f2faf229 100644
--- a/promql/engine.go
+++ b/promql/engine.go
@@ -1044,6 +1044,9 @@ func (ev *evaluator) matrixSelector(node *MatrixSelector) Matrix {
 
 	var it *storage.BufferedSeriesIterator
 	for i, s := range node.series {
+		if err := contextDone(ev.ctx, "expression evaluation"); err != nil {
+			ev.error(err)
+		}
 		if it == nil {
 			it = storage.NewBuffer(s.Iterator(), durationMilliseconds(node.Range))
 		} else {