[#373] metrics: Add FSTree metrics

Signed-off-by: Dmitrii Stepanov <d.stepanov@yadro.com>

pkg/metrics/mode.go

@@ -37,3 +37,39 @@ func (m *shardIDModeValue) Delete(shardID string) {
 		wcShardID: shardID,
 	})
 }
+
+type shardIDPathModeValue struct {
+	modeValue *prometheus.GaugeVec
+}
+
+func newShardIDPathMode(subsystem, name, help string) *shardIDPathModeValue {
+	return &shardIDPathModeValue{
+		modeValue: metrics.NewGaugeVec(
+			prometheus.GaugeOpts{
+				Namespace: namespace,
+				Subsystem: subsystem,
+				Name:      name,
+				Help:      help,
+			}, []string{shardIDLabel, pathLabel, modeLabel}),
+	}
+}
+
+func (m *shardIDPathModeValue) SetMode(shardID, path string, mode string) {
+	m.modeValue.DeletePartialMatch(prometheus.Labels{
+		shardIDLabel: shardID,
+		pathLabel:    path,
+	})
+
+	m.modeValue.With(prometheus.Labels{
+		shardIDLabel: shardID,
+		pathLabel:    path,
+		modeLabel:    mode,
+	}).Set(1)
+}
+
+func (m *shardIDPathModeValue) Delete(shardID, path string) {
+	m.modeValue.DeletePartialMatch(prometheus.Labels{
+		shardIDLabel: shardID,
+		pathLabel:    path,
+	})
+}