[#451] metrics: Move to internal

`metrics` don't look like something others want to import.

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

internal/metrics/writecache.go

@@ -0,0 +1,108 @@
+package metrics
+
+import (
+	"strconv"
+	"time"
+
+	"git.frostfs.info/TrueCloudLab/frostfs-observability/metrics"
+	"github.com/prometheus/client_golang/prometheus"
+)
+
+type WriteCacheMetrics interface {
+	AddMethodDuration(shardID, path, storageType, method string, success bool, d time.Duration)
+	SetActualCount(shardID, path, storageType string, count uint64)
+	SetEstimateSize(shardID, path, storageType string, size uint64)
+	SetMode(shardID, mode string)
+	IncOperationCounter(shardID, path, storageType, operation string, success NullBool)
+	Close(shardID, path string)
+}
+
+type writeCacheMetrics struct {
+	methodDuration   *prometheus.HistogramVec
+	operationCounter *prometheus.CounterVec
+
+	actualCount *prometheus.GaugeVec
+
+	estimatedSize *prometheus.GaugeVec
+
+	mode *shardIDModeValue
+}
+
+func newWriteCacheMetrics() *writeCacheMetrics {
+	return &writeCacheMetrics{
+		methodDuration: metrics.NewHistogramVec(prometheus.HistogramOpts{
+			Namespace: namespace,
+			Subsystem: writeCacheSubsystem,
+			Name:      "request_duration_seconds",
+			Help:      "Writecache request process duration",
+		}, []string{shardIDLabel, successLabel, storageLabel, methodLabel, pathLabel}),
+		operationCounter: metrics.NewCounterVec(prometheus.CounterOpts{
+			Namespace: namespace,
+			Subsystem: writeCacheSubsystem,
+			Name:      "operations_total",
+			Help:      "The number of writecache operations processed",
+		}, []string{shardIDLabel, storageLabel, successLabel, operationLabel, pathLabel}),
+		actualCount:   newWCGaugeVec("actual_objects_total", "Actual objects count in writecache", []string{shardIDLabel, storageLabel, pathLabel}),
+		estimatedSize: newWCGaugeVec("estimated_size_bytes", "Estimated writecache size", []string{shardIDLabel, storageLabel, pathLabel}),
+		mode:          newShardIDMode(writeCacheSubsystem, "mode_info", "Writecache mode value"),
+	}
+}
+
+func (m *writeCacheMetrics) AddMethodDuration(shardID, path, storageType, method string, success bool, d time.Duration) {
+	m.methodDuration.With(
+		prometheus.Labels{
+			shardIDLabel: shardID,
+			successLabel: strconv.FormatBool(success),
+			storageLabel: storageType,
+			methodLabel:  method,
+			pathLabel:    path,
+		},
+	).Observe(d.Seconds())
+}
+
+func (m *writeCacheMetrics) SetActualCount(shardID, path, storageType string, count uint64) {
+	m.actualCount.With(prometheus.Labels{
+		shardIDLabel: shardID,
+		storageLabel: storageType,
+		pathLabel:    path,
+	}).Set(float64(count))
+}
+
+func (m *writeCacheMetrics) SetEstimateSize(shardID, path, storageType string, size uint64) {
+	m.estimatedSize.With(prometheus.Labels{
+		shardIDLabel: shardID,
+		storageLabel: storageType,
+		pathLabel:    path,
+	}).Set(float64(size))
+}
+
+func (m *writeCacheMetrics) SetMode(shardID string, mode string) {
+	m.mode.SetMode(shardID, mode)
+}
+
+func (m *writeCacheMetrics) IncOperationCounter(shardID, path, storageType, operation string, success NullBool) {
+	m.operationCounter.With(prometheus.Labels{
+		shardIDLabel:   shardID,
+		storageLabel:   storageType,
+		operationLabel: operation,
+		successLabel:   success.String(),
+		pathLabel:      path,
+	}).Inc()
+}
+
+func (m *writeCacheMetrics) Close(shardID, path string) {
+	m.mode.Delete(shardID)
+	m.methodDuration.DeletePartialMatch(prometheus.Labels{shardIDLabel: shardID, pathLabel: path})
+	m.operationCounter.DeletePartialMatch(prometheus.Labels{shardIDLabel: shardID, pathLabel: path})
+	m.actualCount.DeletePartialMatch(prometheus.Labels{shardIDLabel: shardID, pathLabel: path})
+	m.estimatedSize.DeletePartialMatch(prometheus.Labels{shardIDLabel: shardID, pathLabel: path})
+}
+
+func newWCGaugeVec(name, help string, labels []string) *prometheus.GaugeVec {
+	return metrics.NewGaugeVec(prometheus.GaugeOpts{
+		Namespace: namespace,
+		Subsystem: writeCacheSubsystem,
+		Name:      name,
+		Help:      help,
+	}, labels)
+}