Merge pull request #942 from jimmidyson/net-stats-from-proc

Drop regexp for net stats parsing

container/libcontainer/helpers.go

@@ -18,6 +18,7 @@ import (
 	"bufio"
 	"fmt"
 	"io/ioutil"
+	"os"
 	"path"
 	"regexp"
 	"strconv"
@@ -135,7 +136,6 @@ func networkStatsFromProc(rootFs string, pid int) ([]info.InterfaceStats, error)
 
 var (
 	ignoredDevicePrefixes = []string{"lo", "veth", "docker"}
-	netStatLineRE         = regexp.MustCompile("[  ]*(.+):([  ]+[0-9]+){16}")
 )
 
 func isIgnoredDevice(ifName string) bool {
@@ -147,6 +147,8 @@ func isIgnoredDevice(ifName string) bool {
 	return false
 }
 
+const netstatsLine = `%s %d %d %d %d %d %d %d %d %d %d %d %d %d %d %d %d`
+
 func scanInterfaceStats(netStatsFile string) ([]info.InterfaceStats, error) {
 	var (
 		bkt uint64
@@ -154,34 +156,26 @@ func scanInterfaceStats(netStatsFile string) ([]info.InterfaceStats, error) {
 
 	stats := []info.InterfaceStats{}
 
-	data, err := ioutil.ReadFile(netStatsFile)
+	file, err := os.Open(netStatsFile)
 	if err != nil {
 		return stats, fmt.Errorf("failure opening %s: %v", netStatsFile, err)
 	}
+	defer file.Close()
 
-	reader := strings.NewReader(string(data))
-	scanner := bufio.NewScanner(reader)
-
-	scanner.Split(bufio.ScanLines)
+	scanner := bufio.NewScanner(file)
 
 	for scanner.Scan() {
 		line := scanner.Text()
-		if netStatLineRE.MatchString(line) {
-			line = strings.Replace(line, ":", "", -1)
+		line = strings.Replace(line, ":", "", -1)
 
-			i := info.InterfaceStats{}
+		i := info.InterfaceStats{}
 
-			_, err := fmt.Sscanf(line, "%s %d %d %d %d %d %d %d %d %d %d %d %d %d %d %d %d",
-				&i.Name, &i.RxBytes, &i.RxPackets, &i.RxErrors, &i.RxDropped, &bkt, &bkt, &bkt,
-				&bkt, &i.TxBytes, &i.TxPackets, &i.TxErrors, &i.TxDropped, &bkt, &bkt, &bkt, &bkt)
+		_, err := fmt.Sscanf(line, netstatsLine,
+			&i.Name, &i.RxBytes, &i.RxPackets, &i.RxErrors, &i.RxDropped, &bkt, &bkt, &bkt,
+			&bkt, &i.TxBytes, &i.TxPackets, &i.TxErrors, &i.TxDropped, &bkt, &bkt, &bkt, &bkt)
 
-			if err != nil {
-				return stats, fmt.Errorf("failure opening %s: %v", netStatsFile, err)
-			}
-
-			if !isIgnoredDevice(i.Name) {
-				stats = append(stats, i)
-			}
+		if err == nil && !isIgnoredDevice(i.Name) {
+			stats = append(stats, i)
 		}
 	}
 

container/libcontainer/helpers_test.go

@@ -0,0 +1,63 @@
+// Copyright 2014 Google Inc. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package libcontainer
+
+import (
+	"testing"
+
+	info "github.com/google/cadvisor/info/v1"
+)
+
+func TestScanInterfaceStats(t *testing.T) {
+	stats, err := scanInterfaceStats("testdata/procnetdev")
+	if err != nil {
+		t.Error(err)
+	}
+
+	var netdevstats = []info.InterfaceStats{
+		{
+			Name:      "wlp4s0",
+			RxBytes:   1,
+			RxPackets: 2,
+			RxErrors:  3,
+			RxDropped: 4,
+			TxBytes:   9,
+			TxPackets: 10,
+			TxErrors:  11,
+			TxDropped: 12,
+		},
+		{
+			Name:      "em1",
+			RxBytes:   315849,
+			RxPackets: 1172,
+			RxErrors:  0,
+			RxDropped: 0,
+			TxBytes:   315850,
+			TxPackets: 1173,
+			TxErrors:  0,
+			TxDropped: 0,
+		},
+	}
+
+	if len(stats) != len(netdevstats) {
+		t.Errorf("Expected 2 net stats, got %d", len(stats))
+	}
+
+	for i, v := range netdevstats {
+		if v != stats[i] {
+			t.Errorf("Expected %#v, got %#v", v, stats[i])
+		}
+	}
+}

container/libcontainer/testdata/procnetdev

@@ -0,0 +1,6 @@
+Inter-|   Receive                                                |  Transmit
+ face |bytes    packets errs drop fifo frame compressed multicast|bytes    packets errs drop fifo colls carrier compressed
+wlp4s0:       1       2    3    4    5     6          7         8        9       10    11    12    13     14       15          0
+docker0:       0       0    0    0    0     0          0         0        0       0    0    0    0     0       0          0
+    lo:  0    0    0    0    0     0          0         0   0    0    0    0    0     0       0          0
+   em1:  315849    1172    0    0    0     0          0         0   315850    1173    0    0    0     0       0          0