Datadir symlinks cache

cmd/opera/launcher/launcher.go

@@ -14,7 +14,6 @@ import (
 	"github.com/ethereum/go-ethereum/console/prompt"
 	"github.com/ethereum/go-ethereum/ethclient"
 	"github.com/ethereum/go-ethereum/log"
-	gmetrics "github.com/ethereum/go-ethereum/metrics"
 	"github.com/ethereum/go-ethereum/node"
 	"github.com/ethereum/go-ethereum/p2p/discover/discfilter"
 	"github.com/ethereum/go-ethereum/params"
@@ -301,9 +300,7 @@ func makeNode(ctx *cli.Context, cfg *config, genesisStore *genesisstore.Store) (
 		_ = genesisStore.Close()
 	}
 
-	if gmetrics.Enabled {
-		metrics.SetDataDir(cfg.Node.DataDir)
-	}
+	metrics.SetDataDir(cfg.Node.DataDir)
 	memorizeDBPreset(cfg)
 
 	// substitute default bootnodes if requested

cmd/opera/launcher/metrics/metrics.go

@@ -15,42 +15,40 @@ var once sync.Once
 
 func SetDataDir(datadir string) {
 	once.Do(func() {
-		go measureDbDir("db_size", datadir)
-	})
-}
 
-func measureDbDir(name, datadir string) {
-	var (
-		dbSize int64
-		gauge  metrics.Gauge
-		rescan = (len(datadir) > 0 && datadir != "inmemory")
-	)
-	for {
-		time.Sleep(10 * time.Second)
+		var dbSize int64
+		_ = metrics.NewRegisteredFunctionalGauge("db_size", nil, func() int64 {
+			return atomic.LoadInt64(&dbSize)
+		})
 
-		if rescan {
-			size := sizeOfDir(datadir, new(int))
-			atomic.StoreInt64(&dbSize, size)
+		if !metrics.Enabled {
+			return
 		}
 
-		if gauge == nil {
-			gauge = metrics.NewRegisteredFunctionalGauge(name, nil, func() int64 {
-				return atomic.LoadInt64(&dbSize)
-			})
+		if len(datadir) == 0 || datadir == "inmemory" {
+			return
 		}
 
-		if !rescan {
-			break
-		}
+		go measureDbDir(datadir, &dbSize)
+
+	})
+}
+
+func measureDbDir(datadir string, dbSize *int64) {
+	for {
+		time.Sleep(10 * time.Second)
+		size := sizeOfDir(datadir)
+		atomic.StoreInt64(dbSize, size)
 	}
 }
 
-func sizeOfDir(dir string, counter *int) (size int64) {
+var (
+	symlinksCache     = make(map[string]string, 10e6)
+	symlinksThrottler = &throttler{Period: 1000, Timeout: 100 * time.Millisecond}
+)
+
+func sizeOfDir(dir string) (size int64) {
 	err := filepath.Walk(dir, func(path string, info os.FileInfo, err error) error {
-		*counter++
-		if *counter % 100 == 0 {
-			time.Sleep(100 * time.Millisecond)
-		}
 		if err != nil {
 			log.Debug("datadir walk", "path", path, "err", err)
 			return filepath.SkipDir
@@ -60,9 +58,19 @@ func sizeOfDir(dir string, counter *int) (size int64) {
 			return nil
 		}
 
-		dst, err := filepath.EvalSymlinks(path)
-		if err == nil && dst != path {
-			size += sizeOfDir(dst, counter)
+		dst, cached := symlinksCache[path]
+		if !cached {
+			symlinksThrottler.Do()
+			var err error
+			dst, err = filepath.EvalSymlinks(path)
+			if err != nil || dst == path {
+				dst = ""
+			}
+			symlinksCache[path] = dst
+		}
+
+		if dst != "" {
+			size += sizeOfDir(dst)
 		} else {
 			size += info.Size()
 		}

cmd/opera/launcher/metrics/metrics_test.go

@@ -0,0 +1,21 @@
+package metrics
+
+import (
+	"testing"
+)
+
+func BenchmarkSizeOfDir(b *testing.B) {
+	var (
+		datadir = "~/.opera"
+		size    int64
+	)
+
+	symlinksThrottler = new(throttler) // disabled throttling
+	size = sizeOfDir(datadir)          // cache warming
+	b.ResetTimer()
+
+	for i := 0; i < (b.N * 10); i++ {
+		size = sizeOfDir(datadir)
+	}
+	b.Log(size)
+}

cmd/opera/launcher/metrics/throttler.go

@@ -0,0 +1,22 @@
+package metrics
+
+import (
+	"time"
+)
+
+type throttler struct {
+	Period  uint
+	Timeout time.Duration
+	count   uint
+}
+
+func (t *throttler) Do() {
+	if t.Period == 0 {
+		return
+	}
+
+	t.count++
+	if t.count%t.Period == 0 {
+		time.Sleep(t.Timeout)
+	}
+}