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// 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)
}
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