Accounting metrics reporter (#18136)

p2p/protocols/reporter.go

@@ -0,0 +1,147 @@
+// Copyright 2018 The go-ethereum Authors
+// This file is part of the go-ethereum 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.
+//
+// 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 protocols
+
+import (
+	"encoding/binary"
+	"time"
+
+	"github.com/ethereum/go-ethereum/log"
+	"github.com/ethereum/go-ethereum/metrics"
+
+	"github.com/syndtr/goleveldb/leveldb"
+)
+
+//AccountMetrics abstracts away the metrics DB and
+//the reporter to persist metrics
+type AccountingMetrics struct {
+	reporter *reporter
+}
+
+//Close will be called when the node is being shutdown
+//for a graceful cleanup
+func (am *AccountingMetrics) Close() {
+	close(am.reporter.quit)
+	am.reporter.db.Close()
+}
+
+//reporter is an internal structure used to write p2p accounting related
+//metrics to a LevelDB. It will periodically write the accrued metrics to the DB.
+type reporter struct {
+	reg      metrics.Registry //the registry for these metrics (independent of other metrics)
+	interval time.Duration    //duration at which the reporter will persist metrics
+	db       *leveldb.DB      //the actual DB
+	quit     chan struct{}    //quit the reporter loop
+}
+
+//NewMetricsDB creates a new LevelDB instance used to persist metrics defined
+//inside p2p/protocols/accounting.go
+func NewAccountingMetrics(r metrics.Registry, d time.Duration, path string) *AccountingMetrics {
+	var val = make([]byte, 8)
+	var err error
+
+	//Create the LevelDB
+	db, err := leveldb.OpenFile(path, nil)
+	if err != nil {
+		log.Error(err.Error())
+		return nil
+	}
+
+	//Check for all defined metrics that there is a value in the DB
+	//If there is, assign it to the metric. This means that the node
+	//has been running before and that metrics have been persisted.
+	metricsMap := map[string]metrics.Counter{
+		"account.balance.credit": mBalanceCredit,
+		"account.balance.debit":  mBalanceDebit,
+		"account.bytes.credit":   mBytesCredit,
+		"account.bytes.debit":    mBytesDebit,
+		"account.msg.credit":     mMsgCredit,
+		"account.msg.debit":      mMsgDebit,
+		"account.peerdrops":      mPeerDrops,
+		"account.selfdrops":      mSelfDrops,
+	}
+	//iterate the map and get the values
+	for key, metric := range metricsMap {
+		val, err = db.Get([]byte(key), nil)
+		//until the first time a value is being written,
+		//this will return an error.
+		//it could be beneficial though to log errors later,
+		//but that would require a different logic
+		if err == nil {
+			metric.Inc(int64(binary.BigEndian.Uint64(val)))
+		}
+	}
+
+	//create the reporter
+	rep := &reporter{
+		reg:      r,
+		interval: d,
+		db:       db,
+		quit:     make(chan struct{}),
+	}
+
+	//run the go routine
+	go rep.run()
+
+	m := &AccountingMetrics{
+		reporter: rep,
+	}
+
+	return m
+}
+
+//run is the goroutine which periodically sends the metrics to the configured LevelDB
+func (r *reporter) run() {
+	intervalTicker := time.NewTicker(r.interval)
+
+	for {
+		select {
+		case <-intervalTicker.C:
+			//at each tick send the metrics
+			if err := r.save(); err != nil {
+				log.Error("unable to send metrics to LevelDB", "err", err)
+				//If there is an error in writing, exit the routine; we assume here that the error is
+				//severe and don't attempt to write again.
+				//Also, this should prevent leaking when the node is stopped
+				return
+			}
+		case <-r.quit:
+			//graceful shutdown
+			return
+		}
+	}
+}
+
+//send the metrics to the DB
+func (r *reporter) save() error {
+	//create a LevelDB Batch
+	batch := leveldb.Batch{}
+	//for each metric in the registry (which is independent)...
+	r.reg.Each(func(name string, i interface{}) {
+		metric, ok := i.(metrics.Counter)
+		if ok {
+			//assuming every metric here to be a Counter (separate registry)
+			//...create a snapshot...
+			ms := metric.Snapshot()
+			byteVal := make([]byte, 8)
+			binary.BigEndian.PutUint64(byteVal, uint64(ms.Count()))
+			//...and save the value to the DB
+			batch.Put([]byte(name), byteVal)
+		}
+	})
+	return r.db.Write(&batch, nil)
+}