Disable Contains metrics

It is hard to make any conclusions from the Contains metrics because
they are increased not only directly from externa requests, but also
by internal invocations, such as the grpc_bytestream pre-existing
check. The inlining logic in grpc_ac also affects the metrics, and
I'm not sure if I think that is good or bad.

Disabling the Contains metrics, at least temporary while considering
alternatives, to avoid confusion and potential overhead of counters
that are not useful at the moment.

cache/disk/disk_test.go

@@ -1263,8 +1263,8 @@ func TestMetricsUnvalidatedAC(t *testing.T) {
 	}
 
 	acHits := count(testCache.counter, acKind, hitStatus)
-	if acHits != 1 {
-		t.Fatalf("Expected acHit counter to be 1, found %f", acHits)
+	if acHits != 0 {
+		t.Fatalf("Expected acHit counter to be 0, found %f", acHits)
 	}
 
 	acMiss := count(testCache.counter, acKind, missStatus)
@@ -1301,8 +1301,8 @@ func TestMetricsUnvalidatedAC(t *testing.T) {
 	}
 
 	acHits = count(testCache.counter, acKind, hitStatus)
-	if acHits != 2 {
-		t.Fatalf("Expected acHit counter to be 2, found %f", acHits)
+	if acHits != 1 {
+		t.Fatalf("Expected acHit counter to be 1, found %f", acHits)
 	}
 	acMiss = count(testCache.counter, acKind, missStatus)
 	if acMiss != 0 {

cache/disk/metrics.go

@@ -95,54 +95,6 @@ func (m *metricsDecorator) GetZstd(ctx context.Context, hash string, size int64,
 	return rc, size, nil
 }
 
-func (m *metricsDecorator) Contains(ctx context.Context, kind cache.EntryKind, hash string, size int64) (bool, int64) {
-	ok, size := m.diskCache.Contains(ctx, kind, hash, size)
-
-	lbls := prometheus.Labels{"method": containsMethod, "kind": kind.String()}
-	if ok {
-		lbls["status"] = hitStatus
-	} else {
-		lbls["status"] = missStatus
-	}
-	m.addCategoryLabels(ctx, lbls)
-	m.counter.With(lbls).Inc()
-
-	return ok, size
-}
-
-func (m *metricsDecorator) FindMissingCasBlobs(ctx context.Context, blobs []*pb.Digest) ([]*pb.Digest, error) {
-	numLooking := len(blobs)
-	digests, err := m.diskCache.FindMissingCasBlobs(ctx, blobs)
-	if err != nil {
-		return digests, err
-	}
-
-	numMissing := len(digests)
-
-	numFound := numLooking - numMissing
-
-	hitLabels := prometheus.Labels{
-		"method": containsMethod,
-		"kind":   "cas",
-		"status": hitStatus,
-	}
-	m.addCategoryLabels(ctx, hitLabels)
-	hits := m.counter.With(hitLabels)
-
-	missLabels := prometheus.Labels{
-		"method": containsMethod,
-		"kind":   "cas",
-		"status": missStatus,
-	}
-	m.addCategoryLabels(ctx, missLabels)
-	misses := m.counter.With(missLabels)
-
-	hits.Add(float64(numFound))
-	misses.Add(float64(numMissing))
-
-	return digests, nil
-}
-
 func (m *metricsDecorator) Put(ctx context.Context, kind cache.EntryKind, hash string, size int64, r io.Reader) error {
 	err := m.diskCache.Put(ctx, kind, hash, size, r)
 	if err != nil {