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, 62 insertions, 0 deletions

diff --git a/vendor/github.com/influxdata/influxdb/models/rows.go b/vendor/github.com/influxdata/influxdb/models/rows.go
new file mode 100644
index 000000000..c087a4882
--- /dev/null
+++ b/vendor/github.com/influxdata/influxdb/models/rows.go
@@ -0,0 +1,62 @@
+package models
+
+import (
+	"sort"
+)
+
+// Row represents a single row returned from the execution of a statement.
+type Row struct {
+	Name    string            `json:"name,omitempty"`
+	Tags    map[string]string `json:"tags,omitempty"`
+	Columns []string          `json:"columns,omitempty"`
+	Values  [][]interface{}   `json:"values,omitempty"`
+	Partial bool              `json:"partial,omitempty"`
+}
+
+// SameSeries returns true if r contains values for the same series as o.
+func (r *Row) SameSeries(o *Row) bool {
+	return r.tagsHash() == o.tagsHash() && r.Name == o.Name
+}
+
+// tagsHash returns a hash of tag key/value pairs.
+func (r *Row) tagsHash() uint64 {
+	h := NewInlineFNV64a()
+	keys := r.tagsKeys()
+	for _, k := range keys {
+		h.Write([]byte(k))
+		h.Write([]byte(r.Tags[k]))
+	}
+	return h.Sum64()
+}
+
+// tagKeys returns a sorted list of tag keys.
+func (r *Row) tagsKeys() []string {
+	a := make([]string, 0, len(r.Tags))
+	for k := range r.Tags {
+		a = append(a, k)
+	}
+	sort.Strings(a)
+	return a
+}
+
+// Rows represents a collection of rows. Rows implements sort.Interface.
+type Rows []*Row
+
+// Len implements sort.Interface.
+func (p Rows) Len() int { return len(p) }
+
+// Less implements sort.Interface.
+func (p Rows) Less(i, j int) bool {
+	// Sort by name first.
+	if p[i].Name != p[j].Name {
+		return p[i].Name < p[j].Name
+	}
+
+	// Sort by tag set hash. Tags don't have a meaningful sort order so we
+	// just compute a hash and sort by that instead. This allows the tests
+	// to receive rows in a predictable order every time.
+	return p[i].tagsHash() < p[j].tagsHash()
+}
+
+// Swap implements sort.Interface.
+func (p Rows) Swap(i, j int) { p[i], p[j] = p[j], p[i] }