p2p/protocols: added cleanup for DB and comments

p2p/protocols/accounting.go

@@ -109,8 +109,14 @@ func NewAccounting(balance Balance, po Prices) *Accounting {
 	return ah
 }
 
+//SetupAccountingMetrics creates a separate registry for p2p accounting metrics;
+//this registry should be independent of any other metrics as it persists at different endpoints.
+//It also instantiates the given metrics and starts the persisting go-routine which
+//at the passed interval writes the metrics to a LevelDB
 func SetupAccountingMetrics(reportInterval time.Duration, path string) *leveldb.DB {
+	//create an empty registry
 	registry := metrics.NewRegistry()
+	//instantiate the metrics
 	mBalanceCredit = metrics.NewRegisteredCounterForced("account.balance.credit", registry)
 	mBalanceDebit = metrics.NewRegisteredCounterForced("account.balance.debit", registry)
 	mBytesCredit = metrics.NewRegisteredCounterForced("account.bytes.credit", registry)
@@ -119,7 +125,7 @@ func SetupAccountingMetrics(reportInterval time.Duration, path string) *leveldb.
 	mMsgDebit = metrics.NewRegisteredCounterForced("account.msg.debit", registry)
 	mPeerDrops = metrics.NewRegisteredCounterForced("account.peerdrops", registry)
 	mSelfDrops = metrics.NewRegisteredCounterForced("account.selfdrops", registry)
-
+	//create the DB and start persisting
 	return NewMetricsDB(registry, reportInterval, path)
 }
 

p2p/protocols/reporter.go

@@ -26,22 +26,30 @@ import (
 	"github.com/syndtr/goleveldb/leveldb"
 )
 
+//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
+	reg      metrics.Registry //the registry for these metrics (independent of other metrics)
-	interval time.Duration
+	interval time.Duration    //duration at which the reporter will persist metrics
-	db       *leveldb.DB
+	db       *leveldb.DB      //the actual DB
 }
 
+//NewMetricsDB creates a new LevelDB instance used to persist metrics defined
+//inside p2p/protocols/accounting.go
 func NewMetricsDB(r metrics.Registry, d time.Duration, path string) *leveldb.DB {
 	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.
 	val, err = db.Get([]byte("account.balance.credit"), nil)
 	if err == nil {
 		mBalanceCredit.Inc(int64(binary.BigEndian.Uint64(val)))
@@ -75,40 +83,52 @@ func NewMetricsDB(r metrics.Registry, d time.Duration, path string) *leveldb.DB
 		mSelfDrops.Inc(int64(binary.BigEndian.Uint64(val)))
 	}
 
+	//create the reporter
 	reg := &reporter{
 		reg:      r,
 		interval: d,
 		db:       db,
 	}
 
+	//run the go routine
 	go reg.run()
 
 	return db
 
 }
 
+//run is the go routine which periodically sends the metrics to the configued LevelDB
 func (r *reporter) run() {
 	intervalTicker := time.NewTicker(r.interval)
 
 	for _ = range intervalTicker.C {
+		//at each tick send the metrics
 		if err := r.send(); err != nil {
 			log.Error("unable to send metrics to LevelDB. err=%v", "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
 		}
 	}
 }
 
+//send the metrics to the DB
 func (r *reporter) send() error {
 	var err error
+	//for each metric in the registry (which is independent)...
 	r.reg.Each(func(name string, i interface{}) {
 		switch metric := i.(type) {
+		//assuming every metric here to be a Counter (separate registry)
 		case metrics.Counter:
+			//...create a snapshot...
 			ms := metric.Snapshot()
 			byteVal := make([]byte, 8)
 			binary.BigEndian.PutUint64(byteVal, uint64(ms.Count()))
+			//...and save the value to the DB
 			err = r.db.Put([]byte(name), byteVal, nil)
+		default:
 		}
 	})
-
 	return err
 }

p2p/protocols/reporter_test.go

@@ -17,38 +17,53 @@
 package protocols
 
 import (
+	"io/ioutil"
 	"os"
+	"path/filepath"
 	"testing"
 	"time"
 
 	"github.com/ethereum/go-ethereum/log"
 )
 
+//TestReporter tests that the metrics being collected for p2p accounting
+//are being persisted and available after restart of a node.
+//It simulates restarting by just recreating the DB as if the node had restarted.
 func TestReporter(t *testing.T) {
-	dir := os.TempDir()
+	//create a test directory
+	dir, err := ioutil.TempDir("", "reporter-test")
+	if err != nil {
+		t.Fatal(err)
+	}
 	defer os.RemoveAll(dir)
 
+	//setup the metrics
 	log.Debug("Setting up metrics first time")
 	reportInterval := 100 * time.Millisecond
-	db := SetupAccountingMetrics(reportInterval, dir+"/test.db")
+	db := SetupAccountingMetrics(reportInterval, filepath.Join(dir, "test.db"))
 	log.Debug("Done.")
 
+	//do some metrics
 	mBalanceCredit.Inc(12)
 	mBytesCredit.Inc(34)
 	mMsgDebit.Inc(9)
 
-	//give the reporter time to write to DB
+	//give the reporter time to write the metrics to DB
 	time.Sleep(500 * time.Millisecond)
 
+	//set the metrics to nil - this effectively simulates the node having shut down...
 	mBalanceCredit = nil
 	mBytesCredit = nil
 	mMsgDebit = nil
+	//close the DB also, or we can't create a new one
 	db.Close()
 
+	//setup the metrics again
 	log.Debug("Setting up metrics second time")
-	SetupAccountingMetrics(reportInterval, dir+"/test.db")
+	SetupAccountingMetrics(reportInterval, filepath.Join(dir, "test.db"))
 	log.Debug("Done.")
 
+	//now check the metrics, they should have the same value as before "shutdown"
 	if mBalanceCredit.Count() != 12 {
 		t.Fatalf("Expected counter to be %d, but is %d", 12, mBalanceCredit.Count())
 	}

swarm/swap/swap.go

@@ -91,3 +91,8 @@ func (s *Swap) loadState(peer *protocols.Peer) (err error) {
 	}
 	return
 }
+
+//Clean up Swap
+func (swap *Swap) Close() {
+	swap.stateStore.Close()
+}

swarm/swarm.go

@@ -1,4 +1,4 @@
-// Copyright 2016 The go-ethereum Authors
+// 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
@@ -53,6 +53,7 @@ import (
 	"github.com/ethereum/go-ethereum/swarm/storage/mock"
 	"github.com/ethereum/go-ethereum/swarm/swap"
 	"github.com/ethereum/go-ethereum/swarm/tracing"
+	"github.com/syndtr/goleveldb/leveldb"
 )
 
 var (
@@ -66,20 +67,22 @@ var (
 
 // the swarm stack
 type Swarm struct {
-	config      *api.Config        // swarm configuration
+	config       *api.Config        // swarm configuration
-	api         *api.API           // high level api layer (fs/manifest)
+	api          *api.API           // high level api layer (fs/manifest)
-	dns         api.Resolver       // DNS registrar
+	dns          api.Resolver       // DNS registrar
-	fileStore   *storage.FileStore // distributed preimage archive, the local API to the storage with document level storage/retrieval support
+	fileStore    *storage.FileStore // distributed preimage archive, the local API to the storage with document level storage/retrieval support
-	streamer    *stream.Registry
+	streamer     *stream.Registry
-	bzz         *network.Bzz       // the logistic manager
+	bzz          *network.Bzz       // the logistic manager
-	backend     chequebook.Backend // simple blockchain Backend
+	backend      chequebook.Backend // simple blockchain Backend
-	privateKey  *ecdsa.PrivateKey
+	privateKey   *ecdsa.PrivateKey
-	corsString  string
+	corsString   string
-	swapEnabled bool
+	swapEnabled  bool
-	netStore    *storage.NetStore
+	netStore     *storage.NetStore
-	sfs         *fuse.SwarmFS // need this to cleanup all the active mounts on node exit
+	sfs          *fuse.SwarmFS // need this to cleanup all the active mounts on node exit
-	ps          *pss.Pss
+	ps           *pss.Pss
-	swap        *swap.Swap
+	swap         *swap.Swap
+	stateStore   *state.DBStore
+	metricsStore *leveldb.DB
 
 	tracerClose io.Closer
 }
@@ -179,7 +182,7 @@ func NewSwarm(config *api.Config, mockStore *mock.NodeStore) (self *Swarm, err e
 			return nil, err
 		}
 		self.swap = swap.New(balancesStore)
-		protocols.SetupAccountingMetrics(10 *time.Second, filepath.Join(config.Path, "metrics.db"))
+		self.metricsStore = protocols.SetupAccountingMetrics(10*time.Second, filepath.Join(config.Path, "metrics.db"))
 	}
 
 	var nodeID enode.ID
@@ -447,6 +450,15 @@ func (self *Swarm) Stop() error {
 		ch.Stop()
 		ch.Save()
 	}
+	if self.swap != nil {
+		self.swap.Close()
+	}
+	if self.metricsStore != nil {
+		self.metricsStore.Close()
+	}
+	if self.stateStore != nil {
+		self.stateStore.Close()
+	}
 
 	if self.netStore != nil {
 		self.netStore.Close()