/*
Copyright 2023 The Kubernetes Authors.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package metrics

import (
	"sync"

	"k8s.io/component-base/metrics"
	"k8s.io/component-base/metrics/legacyregistry"
)

const taintEvictionControllerSubsystem = "taint_eviction_controller"

var (
	// PodDeletionsTotal counts the number of Pods deleted by TaintEvictionController since its start.
	PodDeletionsTotal = metrics.NewCounter(
		&metrics.CounterOpts{
			Subsystem:      taintEvictionControllerSubsystem,
			Name:           "pod_deletions_total",
			Help:           "Total number of Pods deleted by TaintEvictionController since its start.",
			StabilityLevel: metrics.ALPHA,
		},
	)

	// PodDeletionsLatency tracks the latency, in seconds, between the time when a taint effect has been activated
	// for the Pod and its deletion.
	PodDeletionsLatency = metrics.NewHistogram(
		&metrics.HistogramOpts{
			Subsystem:      taintEvictionControllerSubsystem,
			Name:           "pod_deletion_duration_seconds",
			Help:           "Latency, in seconds, between the time when a taint effect has been activated for the Pod and its deletion via TaintEvictionController.",
			Buckets:        []float64{0.005, 0.025, 0.1, 0.5, 1, 2.5, 10, 30, 60, 120, 180, 240}, // 5ms to 4m
			StabilityLevel: metrics.ALPHA,
		},
	)
)

var registerMetrics sync.Once

// Register registers TaintEvictionController metrics.
func Register() {
	registerMetrics.Do(func() {
		legacyregistry.MustRegister(PodDeletionsTotal)
		legacyregistry.MustRegister(PodDeletionsLatency)
	})
}