7dc100714d
This PR adds counter metrics for the CPU system and the Geth process. Currently the only metrics available for these items are gauges. Gauges are fine when the consumer scrapes metrics data at the same interval as Geth produces new values (every 3 seconds), but it is likely that most consumers will not scrape that often. Intervals of 10, 15, or maybe even 30 seconds are probably more common. So the problem is, how does the consumer estimate what the CPU was doing in between scrapes. With a counter, it's easy ... you just subtract two successive values and divide by the time to get a nice, accurate average. But with a gauge, you can't do that. A gauge reading is an instantaneous picture of what was happening at that moment, but it gives you no idea about what was going on between scrapes. Taking an average of values is meaningless.
71 lines
2.3 KiB
Go
71 lines
2.3 KiB
Go
// Copyright 2019 The go-ethereum Authors
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// This file is part of the go-ethereum library.
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//
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// The go-ethereum library is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Lesser General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// The go-ethereum library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public License
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// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
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// Package prometheus exposes go-metrics into a Prometheus format.
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package prometheus
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import (
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"fmt"
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"net/http"
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"sort"
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"github.com/ethereum/go-ethereum/log"
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"github.com/ethereum/go-ethereum/metrics"
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)
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// Handler returns an HTTP handler which dump metrics in Prometheus format.
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func Handler(reg metrics.Registry) http.Handler {
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return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
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// Gather and pre-sort the metrics to avoid random listings
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var names []string
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reg.Each(func(name string, i interface{}) {
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names = append(names, name)
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})
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sort.Strings(names)
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// Aggregate all the metrics into a Prometheus collector
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c := newCollector()
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for _, name := range names {
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i := reg.Get(name)
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switch m := i.(type) {
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case metrics.Counter:
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c.addCounter(name, m.Snapshot())
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case metrics.CounterFloat64:
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c.addCounterFloat64(name, m.Snapshot())
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case metrics.Gauge:
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c.addGauge(name, m.Snapshot())
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case metrics.GaugeFloat64:
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c.addGaugeFloat64(name, m.Snapshot())
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case metrics.Histogram:
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c.addHistogram(name, m.Snapshot())
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case metrics.Meter:
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c.addMeter(name, m.Snapshot())
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case metrics.Timer:
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c.addTimer(name, m.Snapshot())
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case metrics.ResettingTimer:
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c.addResettingTimer(name, m.Snapshot())
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default:
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log.Warn("Unknown Prometheus metric type", "type", fmt.Sprintf("%T", i))
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}
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}
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w.Header().Add("Content-Type", "text/plain")
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w.Header().Add("Content-Length", fmt.Sprint(c.buff.Len()))
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w.Write(c.buff.Bytes())
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})
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}
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