metrics: pull library and introduce ResettingTimer and InfluxDB reporter (#15910)

* go-metrics: fork library and introduce ResettingTimer and InfluxDB reporter.

* vendor: change nonsense/go-metrics to ethersphere/go-metrics

* go-metrics: add tests. move ResettingTimer logic from reporter to type.

* all, metrics: pull in metrics package in go-ethereum

* metrics/test: make sure metrics are enabled for tests

* metrics: apply gosimple rules

* metrics/exp, internal/debug: init expvar endpoint when starting pprof server

* internal/debug: tiny comment formatting fix

1 files changed, 0 insertions, 120 deletions

diff --git a/vendor/github.com/rcrowley/go-metrics/gauge.go b/vendor/github.com/rcrowley/go-metrics/gauge.go
deleted file mode 100644
index cb57a9388..000000000
--- a/vendor/github.com/rcrowley/go-metrics/gauge.go
+++ /dev/null
@@ -1,120 +0,0 @@
-package metrics
-
-import "sync/atomic"
-
-// Gauges hold an int64 value that can be set arbitrarily.
-type Gauge interface {
-	Snapshot() Gauge
-	Update(int64)
-	Value() int64
-}
-
-// GetOrRegisterGauge returns an existing Gauge or constructs and registers a
-// new StandardGauge.
-func GetOrRegisterGauge(name string, r Registry) Gauge {
-	if nil == r {
-		r = DefaultRegistry
-	}
-	return r.GetOrRegister(name, NewGauge).(Gauge)
-}
-
-// NewGauge constructs a new StandardGauge.
-func NewGauge() Gauge {
-	if UseNilMetrics {
-		return NilGauge{}
-	}
-	return &StandardGauge{0}
-}
-
-// NewRegisteredGauge constructs and registers a new StandardGauge.
-func NewRegisteredGauge(name string, r Registry) Gauge {
-	c := NewGauge()
-	if nil == r {
-		r = DefaultRegistry
-	}
-	r.Register(name, c)
-	return c
-}
-
-// NewFunctionalGauge constructs a new FunctionalGauge.
-func NewFunctionalGauge(f func() int64) Gauge {
-	if UseNilMetrics {
-		return NilGauge{}
-	}
-	return &FunctionalGauge{value: f}
-}
-
-// NewRegisteredFunctionalGauge constructs and registers a new StandardGauge.
-func NewRegisteredFunctionalGauge(name string, r Registry, f func() int64) Gauge {
-	c := NewFunctionalGauge(f)
-	if nil == r {
-		r = DefaultRegistry
-	}
-	r.Register(name, c)
-	return c
-}
-
-// GaugeSnapshot is a read-only copy of another Gauge.
-type GaugeSnapshot int64
-
-// Snapshot returns the snapshot.
-func (g GaugeSnapshot) Snapshot() Gauge { return g }
-
-// Update panics.
-func (GaugeSnapshot) Update(int64) {
-	panic("Update called on a GaugeSnapshot")
-}
-
-// Value returns the value at the time the snapshot was taken.
-func (g GaugeSnapshot) Value() int64 { return int64(g) }
-
-// NilGauge is a no-op Gauge.
-type NilGauge struct{}
-
-// Snapshot is a no-op.
-func (NilGauge) Snapshot() Gauge { return NilGauge{} }
-
-// Update is a no-op.
-func (NilGauge) Update(v int64) {}
-
-// Value is a no-op.
-func (NilGauge) Value() int64 { return 0 }
-
-// StandardGauge is the standard implementation of a Gauge and uses the
-// sync/atomic package to manage a single int64 value.
-type StandardGauge struct {
-	value int64
-}
-
-// Snapshot returns a read-only copy of the gauge.
-func (g *StandardGauge) Snapshot() Gauge {
-	return GaugeSnapshot(g.Value())
-}
-
-// Update updates the gauge's value.
-func (g *StandardGauge) Update(v int64) {
-	atomic.StoreInt64(&g.value, v)
-}
-
-// Value returns the gauge's current value.
-func (g *StandardGauge) Value() int64 {
-	return atomic.LoadInt64(&g.value)
-}
-
-// FunctionalGauge returns value from given function
-type FunctionalGauge struct {
-	value func() int64
-}
-
-// Value returns the gauge's current value.
-func (g FunctionalGauge) Value() int64 {
-	return g.value()
-}
-
-// Snapshot returns the snapshot.
-func (g FunctionalGauge) Snapshot() Gauge { return GaugeSnapshot(g.Value()) }
-
-// Update panics.
-func (FunctionalGauge) Update(int64) {
-	panic("Update called on a FunctionalGauge")
-}