Remove unused metrics.

Change-Id: Icf03ba4ce92a5e38daf12930f9661daba79c83bb

retrieval/target.go

@@ -141,6 +141,9 @@ type Target interface {
 }
 
 // target is a Target that refers to a singular HTTP or HTTPS endpoint.
+//
+// TODO: The implementation is not yet goroutine safe, but for the web status,
+// methods are called concurrently.
 type target struct {
 	// The current health state of the target.
 	state TargetState

storage/local/instrumentation.go

@@ -45,18 +45,6 @@ var (
 		Help: "The duration of the last storage purge iteration in milliseconds.",
 	})
 
-	numChunks = prometheus.NewGauge(prometheus.GaugeOpts{
-		Name: "prometheus_used_chunks_count",
-		Help: "The current number of chunks in use.",
-	})
-	numChunkGives = prometheus.NewCounter(prometheus.CounterOpts{
-		Name: "prometheus_chunk_gives_total",
-		Help: "The total number of returned (freed) chunks.",
-	})
-	numChunkGets = prometheus.NewCounter(prometheus.CounterOpts{
-		Name: "prometheus_chunk_gets_total",
-		Help: "The total number of retrieved chunks.",
-	})
 	numTranscodes = prometheus.NewCounter(prometheus.CounterOpts{
 		Name: "prometheus_chunk_transcodes_total",
 		Help: "The total number of chunk transcodes.",
@@ -85,9 +73,6 @@ func init() {
 	prometheus.MustRegister(numSamples)
 	prometheus.MustRegister(evictionDuration)
 	prometheus.MustRegister(purgeDuration)
-	prometheus.MustRegister(numChunks)
-	prometheus.MustRegister(numChunkGives)
-	prometheus.MustRegister(numChunkGets)
 	prometheus.MustRegister(numTranscodes)
 	prometheus.MustRegister(numPinnedChunks)
 	prometheus.MustRegister(persistLatencies)