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, 20 insertions, 57 deletions

diff --git a/metrics/metrics.go b/metrics/metrics.go
index c82661d80..4e4e3ecb2 100644
--- a/metrics/metrics.go
+++ b/metrics/metrics.go
@@ -1,20 +1,8 @@
-// Copyright 2015 The go-ethereum Authors
-// This file is part of the go-ethereum library.
+// Go port of Coda Hale's Metrics library
 //
-// The go-ethereum library is free software: you can redistribute it and/or modify
-// it under the terms of the GNU Lesser General Public License as published by
-// the Free Software Foundation, either version 3 of the License, or
-// (at your option) any later version.
+// <https://github.com/rcrowley/go-metrics>
 //
-// The go-ethereum library is distributed in the hope that it will be useful,
-// but WITHOUT ANY WARRANTY; without even the implied warranty of
-// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
-// GNU Lesser General Public License for more details.
-//
-// You should have received a copy of the GNU Lesser General Public License
-// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
-
-// Package metrics provides general system and process level metrics collection.
+// Coda Hale's original work: <https://github.com/codahale/metrics>
 package metrics
 
 import (
@@ -24,17 +12,19 @@ import (
 	"time"
 
 	"github.com/ethereum/go-ethereum/log"
-	"github.com/rcrowley/go-metrics"
-	"github.com/rcrowley/go-metrics/exp"
 )
 
+// Enabled is checked by the constructor functions for all of the
+// standard metrics.  If it is true, the metric returned is a stub.
+//
+// This global kill-switch helps quantify the observer effect and makes
+// for less cluttered pprof profiles.
+var Enabled bool = false
+
 // MetricsEnabledFlag is the CLI flag name to use to enable metrics collections.
 const MetricsEnabledFlag = "metrics"
 const DashboardEnabledFlag = "dashboard"
 
-// Enabled is the flag specifying if metrics are enable or not.
-var Enabled = false
-
 // Init enables or disables the metrics system. Since we need this to run before
 // any other code gets to create meters and timers, we'll actually do an ugly hack
 // and peek into the command line args for the metrics flag.
@@ -45,34 +35,7 @@ func init() {
 			Enabled = true
 		}
 	}
-	exp.Exp(metrics.DefaultRegistry)
-}
-
-// NewCounter create a new metrics Counter, either a real one of a NOP stub depending
-// on the metrics flag.
-func NewCounter(name string) metrics.Counter {
-	if !Enabled {
-		return new(metrics.NilCounter)
-	}
-	return metrics.GetOrRegisterCounter(name, metrics.DefaultRegistry)
-}
-
-// NewMeter create a new metrics Meter, either a real one of a NOP stub depending
-// on the metrics flag.
-func NewMeter(name string) metrics.Meter {
-	if !Enabled {
-		return new(metrics.NilMeter)
-	}
-	return metrics.GetOrRegisterMeter(name, metrics.DefaultRegistry)
-}
-
-// NewTimer create a new metrics Timer, either a real one of a NOP stub depending
-// on the metrics flag.
-func NewTimer(name string) metrics.Timer {
-	if !Enabled {
-		return new(metrics.NilTimer)
-	}
-	return metrics.GetOrRegisterTimer(name, metrics.DefaultRegistry)
+	//exp.Exp(DefaultRegistry)
 }
 
 // CollectProcessMetrics periodically collects various metrics about the running
@@ -90,17 +53,17 @@ func CollectProcessMetrics(refresh time.Duration) {
 		diskstats[i] = new(DiskStats)
 	}
 	// Define the various metrics to collect
-	memAllocs := metrics.GetOrRegisterMeter("system/memory/allocs", metrics.DefaultRegistry)
-	memFrees := metrics.GetOrRegisterMeter("system/memory/frees", metrics.DefaultRegistry)
-	memInuse := metrics.GetOrRegisterMeter("system/memory/inuse", metrics.DefaultRegistry)
-	memPauses := metrics.GetOrRegisterMeter("system/memory/pauses", metrics.DefaultRegistry)
+	memAllocs := GetOrRegisterMeter("system/memory/allocs", DefaultRegistry)
+	memFrees := GetOrRegisterMeter("system/memory/frees", DefaultRegistry)
+	memInuse := GetOrRegisterMeter("system/memory/inuse", DefaultRegistry)
+	memPauses := GetOrRegisterMeter("system/memory/pauses", DefaultRegistry)
 
-	var diskReads, diskReadBytes, diskWrites, diskWriteBytes metrics.Meter
+	var diskReads, diskReadBytes, diskWrites, diskWriteBytes Meter
 	if err := ReadDiskStats(diskstats[0]); err == nil {
-		diskReads = metrics.GetOrRegisterMeter("system/disk/readcount", metrics.DefaultRegistry)
-		diskReadBytes = metrics.GetOrRegisterMeter("system/disk/readdata", metrics.DefaultRegistry)
-		diskWrites = metrics.GetOrRegisterMeter("system/disk/writecount", metrics.DefaultRegistry)
-		diskWriteBytes = metrics.GetOrRegisterMeter("system/disk/writedata", metrics.DefaultRegistry)
+		diskReads = GetOrRegisterMeter("system/disk/readcount", DefaultRegistry)
+		diskReadBytes = GetOrRegisterMeter("system/disk/readdata", DefaultRegistry)
+		diskWrites = GetOrRegisterMeter("system/disk/writecount", DefaultRegistry)
+		diskWriteBytes = GetOrRegisterMeter("system/disk/writedata", DefaultRegistry)
 	} else {
 		log.Debug("Failed to read disk metrics", "err", err)
 	}