From dbafe64bdc62f6a76523f992443b5b04797ed579 Mon Sep 17 00:00:00 2001
From: Goutham Veeramachaneni <gouthamve@gmail.com>
Date: Wed, 29 Aug 2018 22:59:12 +0530
Subject: [PATCH] Print error on Sampler Query failure

Signed-off-by: Goutham Veeramachaneni <gouthamve@gmail.com>
---
 sampler.go      |  1 +
 sampler_test.go | 13 +++++++++++++
 2 files changed, 14 insertions(+)

diff --git a/sampler.go b/sampler.go
index e6a32b38..3e163095 100644
--- a/sampler.go
+++ b/sampler.go
@@ -511,6 +511,7 @@ func (s *RemotelyControlledSampler) updateSampler() {
 	res, err := s.manager.GetSamplingStrategy(s.serviceName)
 	if err != nil {
 		s.metrics.SamplerQueryFailure.Inc(1)
+		s.logger.Infof("Unable to query sampling strategy: %v", err)
 		return
 	}
 	s.Lock()
diff --git a/sampler_test.go b/sampler_test.go
index 3faea035..cf33ee84 100644
--- a/sampler_test.go
+++ b/sampler_test.go
@@ -18,6 +18,7 @@ import (
 	"errors"
 	"fmt"
 	"runtime"
+	"strings"
 	"sync"
 	"testing"
 	"time"
@@ -649,6 +650,18 @@ func getSamplingStrategyResponse(strategyType sampling.SamplingStrategyType, val
 	return nil
 }
 
+func TestRemotelyControlledSampler_printErrorForBrokenUpstream(t *testing.T) {
+	logger := &log.BytesBufferLogger{}
+	sampler := NewRemotelyControlledSampler(
+		"client app",
+		SamplerOptions.Logger(logger),
+	)
+	sampler.Close() // stop timer-based updates, we want to call them manually
+	sampler.updateSampler()
+
+	assert.True(t, strings.Contains(logger.String(), "Unable to query sampling strategy:"))
+}
+
 func TestAdaptiveSampler_lockRaceCondition(t *testing.T) {
 	agent, remoteSampler, _ := initAgent(t)
 	defer agent.Close()