From a197834f64385ea836cbac56761913b01da72f6c Mon Sep 17 00:00:00 2001
From: glightfoot <glightfoot@rsglab.com>
Date: Fri, 19 Feb 2021 14:13:03 -0500
Subject: [PATCH] Add comments about thread-safety

Signed-off-by: glightfoot <glightfoot@rsglab.com>
---
 pkg/mapper/mapper.go       | 2 ++
 pkg/mapper/mapper_cache.go | 2 +-
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/pkg/mapper/mapper.go b/pkg/mapper/mapper.go
index e610e1a..33ea5c3 100644
--- a/pkg/mapper/mapper.go
+++ b/pkg/mapper/mapper.go
@@ -263,6 +263,8 @@ func (m *MetricMapper) InitFromFile(fileName string) error {
 	return m.InitFromYAMLString(string(mappingStr))
 }
 
+// UseCache tells the mapper to use a cache that implements the MetricMapperCache interface.
+// This cache MUST be thread-safe!
 func (m *MetricMapper) UseCache(cache MetricMapperCache) {
 	m.mutex.Lock()
 	defer m.mutex.Unlock()
diff --git a/pkg/mapper/mapper_cache.go b/pkg/mapper/mapper_cache.go
index 2c37fa3..9d65f8c 100644
--- a/pkg/mapper/mapper_cache.go
+++ b/pkg/mapper/mapper_cache.go
@@ -59,7 +59,7 @@ type MetricMapperCacheResult struct {
 	Labels  prometheus.Labels
 }
 
-// MetricMapperCache must be thread-safe and should be instrumented with CacheMetrics
+// MetricMapperCache MUST be thread-safe and should be instrumented with CacheMetrics
 type MetricMapperCache interface {
 	// Get a cached result
 	Get(metricKey string) (interface{}, bool)