Update to kube v1.17

Signed-off-by: Humble Chirammal <hchiramm@redhat.com>

vendor/k8s.io/component-base/metrics/metric.go

@@ -0,0 +1,222 @@
+/*
+Copyright 2019 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"
+
+	"github.com/blang/semver"
+	"github.com/prometheus/client_golang/prometheus"
+	dto "github.com/prometheus/client_model/go"
+
+	"k8s.io/klog"
+)
+
+/*
+kubeCollector extends the prometheus.Collector interface to allow customization of the metric
+registration process. Defer metric initialization until Create() is called, which then
+delegates to the underlying metric's initializeMetric or initializeDeprecatedMetric
+method call depending on whether the metric is deprecated or not.
+*/
+type kubeCollector interface {
+	Collector
+	lazyKubeMetric
+	DeprecatedVersion() *semver.Version
+	// Each collector metric should provide an initialization function
+	// for both deprecated and non-deprecated variants of a metric. This
+	// is necessary since metric instantiation will be deferred
+	// until the metric is actually registered somewhere.
+	initializeMetric()
+	initializeDeprecatedMetric()
+}
+
+/*
+lazyKubeMetric defines our metric registration interface. lazyKubeMetric objects are expected
+to lazily instantiate metrics (i.e defer metric instantiation until when
+the Create() function is explicitly called).
+*/
+type lazyKubeMetric interface {
+	Create(*semver.Version) bool
+	IsCreated() bool
+	IsHidden() bool
+	IsDeprecated() bool
+}
+
+/*
+lazyMetric implements lazyKubeMetric. A lazy metric is lazy because it waits until metric
+registration time before instantiation. Add it as an anonymous field to a struct that
+implements kubeCollector to get deferred registration behavior. You must call lazyInit
+with the kubeCollector itself as an argument.
+*/
+type lazyMetric struct {
+	isDeprecated        bool
+	isHidden            bool
+	isCreated           bool
+	createLock          sync.RWMutex
+	markDeprecationOnce sync.Once
+	createOnce          sync.Once
+	self                kubeCollector
+}
+
+func (r *lazyMetric) IsCreated() bool {
+	r.createLock.RLock()
+	defer r.createLock.RUnlock()
+	return r.isCreated
+}
+
+// lazyInit provides the lazyMetric with a reference to the kubeCollector it is supposed
+// to allow lazy initialization for. It should be invoked in the factory function which creates new
+// kubeCollector type objects.
+func (r *lazyMetric) lazyInit(self kubeCollector) {
+	r.self = self
+}
+
+// determineDeprecationStatus figures out whether the lazy metric should be deprecated or not.
+// This method takes a Version argument which should be the version of the binary in which
+// this code is currently being executed.
+func (r *lazyMetric) determineDeprecationStatus(version semver.Version) {
+	selfVersion := r.self.DeprecatedVersion()
+	if selfVersion == nil {
+		return
+	}
+	r.markDeprecationOnce.Do(func() {
+		if selfVersion.LTE(version) {
+			r.isDeprecated = true
+		}
+		if ShouldShowHidden() {
+			klog.Warningf("Hidden metrics have been manually overridden, showing this very deprecated metric.")
+			return
+		}
+		if shouldHide(&version, selfVersion) {
+			// TODO(RainbowMango): Remove this log temporarily. https://github.com/kubernetes/kubernetes/issues/85369
+			// klog.Warningf("This metric has been deprecated for more than one release, hiding.")
+			r.isHidden = true
+		}
+	})
+}
+
+func (r *lazyMetric) IsHidden() bool {
+	return r.isHidden
+}
+
+func (r *lazyMetric) IsDeprecated() bool {
+	return r.isDeprecated
+}
+
+// Create forces the initialization of metric which has been deferred until
+// the point at which this method is invoked. This method will determine whether
+// the metric is deprecated or hidden, no-opting if the metric should be considered
+// hidden. Furthermore, this function no-opts and returns true if metric is already
+// created.
+func (r *lazyMetric) Create(version *semver.Version) bool {
+	if version != nil {
+		r.determineDeprecationStatus(*version)
+	}
+	// let's not create if this metric is slated to be hidden
+	if r.IsHidden() {
+		return false
+	}
+	r.createOnce.Do(func() {
+		r.createLock.Lock()
+		defer r.createLock.Unlock()
+		r.isCreated = true
+		if r.IsDeprecated() {
+			r.self.initializeDeprecatedMetric()
+		} else {
+			r.self.initializeMetric()
+		}
+	})
+	return r.IsCreated()
+}
+
+// ClearState will clear all the states marked by Create.
+// It intends to be used for re-register a hidden metric.
+func (r *lazyMetric) ClearState() {
+	r.createLock.Lock()
+	defer r.createLock.Unlock()
+
+	r.isDeprecated = false
+	r.isHidden = false
+	r.isCreated = false
+	r.markDeprecationOnce = *(new(sync.Once))
+	r.createOnce = *(new(sync.Once))
+}
+
+/*
+This code is directly lifted from the prometheus codebase. It's a convenience struct which
+allows you satisfy the Collector interface automatically if you already satisfy the Metric interface.
+
+For reference: https://github.com/prometheus/client_golang/blob/v0.9.2/prometheus/collector.go#L98-L120
+*/
+type selfCollector struct {
+	metric prometheus.Metric
+}
+
+func (c *selfCollector) initSelfCollection(m prometheus.Metric) {
+	c.metric = m
+}
+
+func (c *selfCollector) Describe(ch chan<- *prometheus.Desc) {
+	ch <- c.metric.Desc()
+}
+
+func (c *selfCollector) Collect(ch chan<- prometheus.Metric) {
+	ch <- c.metric
+}
+
+// no-op vecs for convenience
+var noopCounterVec = &prometheus.CounterVec{}
+var noopHistogramVec = &prometheus.HistogramVec{}
+var noopSummaryVec = &prometheus.SummaryVec{}
+var noopGaugeVec = &prometheus.GaugeVec{}
+var noopObserverVec = &noopObserverVector{}
+
+// just use a convenience struct for all the no-ops
+var noop = &noopMetric{}
+
+type noopMetric struct{}
+
+func (noopMetric) Inc()                             {}
+func (noopMetric) Add(float64)                      {}
+func (noopMetric) Dec()                             {}
+func (noopMetric) Set(float64)                      {}
+func (noopMetric) Sub(float64)                      {}
+func (noopMetric) Observe(float64)                  {}
+func (noopMetric) SetToCurrentTime()                {}
+func (noopMetric) Desc() *prometheus.Desc           { return nil }
+func (noopMetric) Write(*dto.Metric) error          { return nil }
+func (noopMetric) Describe(chan<- *prometheus.Desc) {}
+func (noopMetric) Collect(chan<- prometheus.Metric) {}
+
+type noopObserverVector struct{}
+
+func (noopObserverVector) GetMetricWith(prometheus.Labels) (prometheus.Observer, error) {
+	return noop, nil
+}
+func (noopObserverVector) GetMetricWithLabelValues(...string) (prometheus.Observer, error) {
+	return noop, nil
+}
+func (noopObserverVector) With(prometheus.Labels) prometheus.Observer    { return noop }
+func (noopObserverVector) WithLabelValues(...string) prometheus.Observer { return noop }
+func (noopObserverVector) CurryWith(prometheus.Labels) (prometheus.ObserverVec, error) {
+	return noopObserverVec, nil
+}
+func (noopObserverVector) MustCurryWith(prometheus.Labels) prometheus.ObserverVec {
+	return noopObserverVec
+}
+func (noopObserverVector) Describe(chan<- *prometheus.Desc) {}
+func (noopObserverVector) Collect(chan<- prometheus.Metric) {}