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, 118 deletions

diff --git a/vendor/github.com/rcrowley/go-metrics/ewma.go b/vendor/github.com/rcrowley/go-metrics/ewma.go
deleted file mode 100644
index 694a1d033..000000000
--- a/vendor/github.com/rcrowley/go-metrics/ewma.go
+++ /dev/null
@@ -1,118 +0,0 @@
-package metrics
-
-import (
-	"math"
-	"sync"
-	"sync/atomic"
-)
-
-// EWMAs continuously calculate an exponentially-weighted moving average
-// based on an outside source of clock ticks.
-type EWMA interface {
-	Rate() float64
-	Snapshot() EWMA
-	Tick()
-	Update(int64)
-}
-
-// NewEWMA constructs a new EWMA with the given alpha.
-func NewEWMA(alpha float64) EWMA {
-	if UseNilMetrics {
-		return NilEWMA{}
-	}
-	return &StandardEWMA{alpha: alpha}
-}
-
-// NewEWMA1 constructs a new EWMA for a one-minute moving average.
-func NewEWMA1() EWMA {
-	return NewEWMA(1 - math.Exp(-5.0/60.0/1))
-}
-
-// NewEWMA5 constructs a new EWMA for a five-minute moving average.
-func NewEWMA5() EWMA {
-	return NewEWMA(1 - math.Exp(-5.0/60.0/5))
-}
-
-// NewEWMA15 constructs a new EWMA for a fifteen-minute moving average.
-func NewEWMA15() EWMA {
-	return NewEWMA(1 - math.Exp(-5.0/60.0/15))
-}
-
-// EWMASnapshot is a read-only copy of another EWMA.
-type EWMASnapshot float64
-
-// Rate returns the rate of events per second at the time the snapshot was
-// taken.
-func (a EWMASnapshot) Rate() float64 { return float64(a) }
-
-// Snapshot returns the snapshot.
-func (a EWMASnapshot) Snapshot() EWMA { return a }
-
-// Tick panics.
-func (EWMASnapshot) Tick() {
-	panic("Tick called on an EWMASnapshot")
-}
-
-// Update panics.
-func (EWMASnapshot) Update(int64) {
-	panic("Update called on an EWMASnapshot")
-}
-
-// NilEWMA is a no-op EWMA.
-type NilEWMA struct{}
-
-// Rate is a no-op.
-func (NilEWMA) Rate() float64 { return 0.0 }
-
-// Snapshot is a no-op.
-func (NilEWMA) Snapshot() EWMA { return NilEWMA{} }
-
-// Tick is a no-op.
-func (NilEWMA) Tick() {}
-
-// Update is a no-op.
-func (NilEWMA) Update(n int64) {}
-
-// StandardEWMA is the standard implementation of an EWMA and tracks the number
-// of uncounted events and processes them on each tick.  It uses the
-// sync/atomic package to manage uncounted events.
-type StandardEWMA struct {
-	uncounted int64 // /!\ this should be the first member to ensure 64-bit alignment
-	alpha     float64
-	rate      float64
-	init      bool
-	mutex     sync.Mutex
-}
-
-// Rate returns the moving average rate of events per second.
-func (a *StandardEWMA) Rate() float64 {
-	a.mutex.Lock()
-	defer a.mutex.Unlock()
-	return a.rate * float64(1e9)
-}
-
-// Snapshot returns a read-only copy of the EWMA.
-func (a *StandardEWMA) Snapshot() EWMA {
-	return EWMASnapshot(a.Rate())
-}
-
-// Tick ticks the clock to update the moving average.  It assumes it is called
-// every five seconds.
-func (a *StandardEWMA) Tick() {
-	count := atomic.LoadInt64(&a.uncounted)
-	atomic.AddInt64(&a.uncounted, -count)
-	instantRate := float64(count) / float64(5e9)
-	a.mutex.Lock()
-	defer a.mutex.Unlock()
-	if a.init {
-		a.rate += a.alpha * (instantRate - a.rate)
-	} else {
-		a.init = true
-		a.rate = instantRate
-	}
-}
-
-// Update adds n uncounted events.
-func (a *StandardEWMA) Update(n int64) {
-	atomic.AddInt64(&a.uncounted, n)
-}