stats: Add Counts() method to multi counter type.

An existing test used this functionality. When we stopped exporting the
"counters" type, the test lost that functionality. Instead of relying on
an implementation detail, there is a proper public method now.

Signed-off-by: Michael Berlin <mberlin@google.com>

go/stats/counters.go

@@ -419,6 +419,13 @@ func (mc *CountersWithMultiLabels) Reset(names []string) {
 	mc.counters.Reset(mapKey(names))
 }
 
+// Counts returns a copy of the Counters' map.
+// The key is a single string where all labels are joiend by a "." e.g.
+// "label1.label2".
+func (mc *CountersWithMultiLabels) Counts() map[string]int64 {
+	return mc.counters.Counts()
+}
+
 // GaugesWithMultiLabels is a CountersWithMultiLabels implementation where the values can go up and down
 type GaugesWithMultiLabels struct {
 	CountersWithMultiLabels

go/vt/vttablet/tabletserver/query_executor_test.go

@@ -1821,13 +1821,13 @@ func TestQueryExecutorTableAclDryRun(t *testing.T) {
 	qre := newTestQueryExecutor(ctx, tsv, query, 0)
 	defer tsv.StopService()
 	checkPlanID(t, planbuilder.PlanPassSelect, qre.plan.PlanID)
-	beforeCount := tabletenv.TableaclPseudoDenied.Counters.Counts()[tableACLStatsKey]
+	beforeCount := tabletenv.TableaclPseudoDenied.Counts()[tableACLStatsKey]
 	// query should fail because current user do not have read permissions
 	_, err := qre.Execute()
 	if err != nil {
 		t.Fatalf("qre.Execute() = %v, want: nil", err)
 	}
-	afterCount := tabletenv.TableaclPseudoDenied.Counters.Counts()[tableACLStatsKey]
+	afterCount := tabletenv.TableaclPseudoDenied.Counts()[tableACLStatsKey]
 	if afterCount-beforeCount != 1 {
 		t.Fatalf("table acl pseudo denied count should increase by one. got: %d, want: %d", afterCount, beforeCount+1)
 	}