const (
    // SchedulerSubsystem - subsystem name used by scheduler
    SchedulerSubsystem = "scheduler"
    // SchedulingLatencyName - scheduler latency metric name
    SchedulingLatencyName = "scheduling_duration_seconds"
    // DeprecatedSchedulingLatencyName - scheduler latency metric name which is deprecated
    DeprecatedSchedulingLatencyName = "scheduling_latency_seconds"

    // OperationLabel - operation label name
    OperationLabel = "operation"

    // PredicateEvaluation - predicate evaluation operation label value
    PredicateEvaluation = "predicate_evaluation"
    // PriorityEvaluation - priority evaluation operation label value
    PriorityEvaluation = "priority_evaluation"
    // PreemptionEvaluation - preemption evaluation operation label value (occurs in case of scheduling fitError).
    PreemptionEvaluation = "preemption_evaluation"
    // Binding - binding operation label value
    Binding = "binding"
)

var (

    // PodScheduleSuccesses counts how many pods were scheduled.
    PodScheduleSuccesses = scheduleAttempts.With(prometheus.Labels{"result": "scheduled"})
    // PodScheduleFailures counts how many pods could not be scheduled.
    PodScheduleFailures = scheduleAttempts.With(prometheus.Labels{"result": "unschedulable"})
    // PodScheduleErrors counts how many pods could not be scheduled due to a scheduler error.
    PodScheduleErrors = scheduleAttempts.With(prometheus.Labels{"result": "error"})
    SchedulingLatency = prometheus.NewSummaryVec(
        prometheus.SummaryOpts{
            Subsystem: SchedulerSubsystem,
            Name:      SchedulingLatencyName,
            Help:      "Scheduling latency in seconds split by sub-parts of the scheduling operation",

            MaxAge: 5 * time.Hour,
        },
        []string{OperationLabel},
    )
    DeprecatedSchedulingLatency = prometheus.NewSummaryVec(
        prometheus.SummaryOpts{
            Subsystem: SchedulerSubsystem,
            Name:      DeprecatedSchedulingLatencyName,
            Help:      "(Deprecated) Scheduling latency in seconds split by sub-parts of the scheduling operation",

            MaxAge: 5 * time.Hour,
        },
        []string{OperationLabel},
    )
    E2eSchedulingLatency = prometheus.NewHistogram(
        prometheus.HistogramOpts{
            Subsystem: SchedulerSubsystem,
            Name:      "e2e_scheduling_duration_seconds",
            Help:      "E2e scheduling latency in seconds (scheduling algorithm + binding)",
            Buckets:   prometheus.ExponentialBuckets(0.001, 2, 15),
        },
    )
    DeprecatedE2eSchedulingLatency = prometheus.NewHistogram(
        prometheus.HistogramOpts{
            Subsystem: SchedulerSubsystem,
            Name:      "e2e_scheduling_latency_microseconds",
            Help:      "(Deprecated) E2e scheduling latency in microseconds (scheduling algorithm + binding)",
            Buckets:   prometheus.ExponentialBuckets(1000, 2, 15),
        },
    )
    SchedulingAlgorithmLatency = prometheus.NewHistogram(
        prometheus.HistogramOpts{
            Subsystem: SchedulerSubsystem,
            Name:      "scheduling_algorithm_duration_seconds",
            Help:      "Scheduling algorithm latency in seconds",
            Buckets:   prometheus.ExponentialBuckets(0.001, 2, 15),
        },
    )
    DeprecatedSchedulingAlgorithmLatency = prometheus.NewHistogram(
        prometheus.HistogramOpts{
            Subsystem: SchedulerSubsystem,
            Name:      "scheduling_algorithm_latency_microseconds",
            Help:      "(Deprecated) Scheduling algorithm latency in microseconds",
            Buckets:   prometheus.ExponentialBuckets(1000, 2, 15),
        },
    )
    SchedulingAlgorithmPredicateEvaluationDuration = prometheus.NewHistogram(
        prometheus.HistogramOpts{
            Subsystem: SchedulerSubsystem,
            Name:      "scheduling_algorithm_predicate_evaluation_seconds",
            Help:      "Scheduling algorithm predicate evaluation duration in seconds",
            Buckets:   prometheus.ExponentialBuckets(0.001, 2, 15),
        },
    )
    DeprecatedSchedulingAlgorithmPredicateEvaluationDuration = prometheus.NewHistogram(
        prometheus.HistogramOpts{
            Subsystem: SchedulerSubsystem,
            Name:      "scheduling_algorithm_predicate_evaluation",
            Help:      "(Deprecated) Scheduling algorithm predicate evaluation duration in microseconds",
            Buckets:   prometheus.ExponentialBuckets(1000, 2, 15),
        },
    )
    SchedulingAlgorithmPriorityEvaluationDuration = prometheus.NewHistogram(
        prometheus.HistogramOpts{
            Subsystem: SchedulerSubsystem,
            Name:      "scheduling_algorithm_priority_evaluation_seconds",
            Help:      "Scheduling algorithm priority evaluation duration in seconds",
            Buckets:   prometheus.ExponentialBuckets(0.001, 2, 15),
        },
    )
    DeprecatedSchedulingAlgorithmPriorityEvaluationDuration = prometheus.NewHistogram(
        prometheus.HistogramOpts{
            Subsystem: SchedulerSubsystem,
            Name:      "scheduling_algorithm_priority_evaluation",
            Help:      "(Deprecated) Scheduling algorithm priority evaluation duration in microseconds",
            Buckets:   prometheus.ExponentialBuckets(1000, 2, 15),
        },
    )
    SchedulingAlgorithmPremptionEvaluationDuration = prometheus.NewHistogram(
        prometheus.HistogramOpts{
            Subsystem: SchedulerSubsystem,
            Name:      "scheduling_algorithm_preemption_evaluation_seconds",
            Help:      "Scheduling algorithm preemption evaluation duration in seconds",
            Buckets:   prometheus.ExponentialBuckets(0.001, 2, 15),
        },
    )
    DeprecatedSchedulingAlgorithmPremptionEvaluationDuration = prometheus.NewHistogram(
        prometheus.HistogramOpts{
            Subsystem: SchedulerSubsystem,
            Name:      "scheduling_algorithm_preemption_evaluation",
            Help:      "(Deprecated) Scheduling algorithm preemption evaluation duration in microseconds",
            Buckets:   prometheus.ExponentialBuckets(1000, 2, 15),
        },
    )
    BindingLatency = prometheus.NewHistogram(
        prometheus.HistogramOpts{
            Subsystem: SchedulerSubsystem,
            Name:      "binding_duration_seconds",
            Help:      "Binding latency in seconds",
            Buckets:   prometheus.ExponentialBuckets(0.001, 2, 15),
        },
    )
    DeprecatedBindingLatency = prometheus.NewHistogram(
        prometheus.HistogramOpts{
            Subsystem: SchedulerSubsystem,
            Name:      "binding_latency_microseconds",
            Help:      "(Deprecated) Binding latency in microseconds",
            Buckets:   prometheus.ExponentialBuckets(1000, 2, 15),
        },
    )
    PreemptionVictims = prometheus.NewGauge(
        prometheus.GaugeOpts{
            Subsystem: SchedulerSubsystem,
            Name:      "pod_preemption_victims",
            Help:      "Number of selected preemption victims",
        })
    PreemptionAttempts = prometheus.NewCounter(
        prometheus.CounterOpts{
            Subsystem: SchedulerSubsystem,
            Name:      "total_preemption_attempts",
            Help:      "Total preemption attempts in the cluster till now",
        })

    ActivePods        = pendingPods.With(prometheus.Labels{"queue": "active"})
    BackoffPods       = pendingPods.With(prometheus.Labels{"queue": "backoff"})
    UnschedulablePods = pendingPods.With(prometheus.Labels{"queue": "unschedulable"})
)

type MetricRecorder interface {
    Inc()
    Dec()
    Clear()
}

type PendingPodsRecorder struct {
    // contains filtered or unexported fields
}