Merge pull request #1569 from scop/perf/regex-compile

Avoid repeated regexp compilations

cpu/cpu_solaris.go

@@ -36,6 +36,8 @@ func Times(percpu bool) ([]TimesStat, error) {
 	return TimesWithContext(context.Background(), percpu)
 }
 
+var kstatSplit = regexp.MustCompile(`[:\s]+`)
+
 func TimesWithContext(ctx context.Context, percpu bool) ([]TimesStat, error) {
 	kstatSysOut, err := invoke.CommandWithContext(ctx, "kstat", "-p", "cpu_stat:*:*:/^idle$|^user$|^kernel$|^iowait$|^swap$/")
 	if err != nil {
@@ -47,9 +49,8 @@ func TimesWithContext(ctx context.Context, percpu bool) ([]TimesStat, error) {
 	kern := make(map[float64]float64)
 	iowt := make(map[float64]float64)
 	// swap := make(map[float64]float64)
-	re := regexp.MustCompile(`[:\s]+`)
 	for _, line := range strings.Split(string(kstatSysOut), "\n") {
-		fields := re.Split(line, -1)
+		fields := kstatSplit.Split(line, -1)
 		if fields[0] != "cpu_stat" {
 			continue
 		}

disk/disk_solaris.go

@@ -83,6 +83,8 @@ func PartitionsWithContext(ctx context.Context, all bool) ([]PartitionStat, erro
 	return ret, err
 }
 
+var kstatSplit = regexp.MustCompile(`[:\s]+`)
+
 func IOCountersWithContext(ctx context.Context, names ...string) (map[string]IOCountersStat, error) {
 	var issolaris bool
 	if runtime.GOOS == "illumos" {
@@ -107,7 +109,6 @@ func IOCountersWithContext(ctx context.Context, names ...string) (map[string]IOC
 	writesarr := make(map[string]uint64)
 	rtimearr := make(map[string]uint64)
 	wtimearr := make(map[string]uint64)
-	re := regexp.MustCompile(`[:\s]+`)
 
 	// in case the name is "/dev/sda1", then convert to "sda1"
 	for i, name := range names {
@@ -115,7 +116,7 @@ func IOCountersWithContext(ctx context.Context, names ...string) (map[string]IOC
 	}
 
 	for _, line := range lines {
-		fields := re.Split(line, -1)
+		fields := kstatSplit.Split(line, -1)
 		if len(fields) == 0 {
 			continue
 		}

host/host_linux.go

@@ -339,13 +339,15 @@ func getSlackwareVersion(contents []string) string {
 	return c
 }
 
+var redhatishReleaseMatch = regexp.MustCompile(`release (\w[\d.]*)`)
+
 func getRedhatishVersion(contents []string) string {
 	c := strings.ToLower(strings.Join(contents, ""))
 
 	if strings.Contains(c, "rawhide") {
 		return "rawhide"
 	}
-	if matches := regexp.MustCompile(`release (\w[\d.]*)`).FindStringSubmatch(c); matches != nil {
+	if matches := redhatishReleaseMatch.FindStringSubmatch(c); matches != nil {
 		return matches[1]
 	}
 	return ""
@@ -362,12 +364,17 @@ func getRedhatishPlatform(contents []string) string {
 	return f[0]
 }
 
+var (
+	suseVersionMatch    = regexp.MustCompile(`VERSION = ([\d.]+)`)
+	susePatchLevelMatch = regexp.MustCompile(`PATCHLEVEL = (\d+)`)
+)
+
 func getSuseVersion(contents []string) string {
 	version := ""
 	for _, line := range contents {
-		if matches := regexp.MustCompile(`VERSION = ([\d.]+)`).FindStringSubmatch(line); matches != nil {
+		if matches := suseVersionMatch.FindStringSubmatch(line); matches != nil {
 			version = matches[1]
-		} else if matches := regexp.MustCompile(`PATCHLEVEL = ([\d]+)`).FindStringSubmatch(line); matches != nil {
+		} else if matches = susePatchLevelMatch.FindStringSubmatch(line); matches != nil {
 			version = version + "." + matches[1]
 		}
 	}

net/net_solaris.go

@@ -23,6 +23,8 @@ func IOCounters(pernic bool) ([]IOCountersStat, error) {
 	return IOCountersWithContext(context.Background(), pernic)
 }
 
+var kstatSplit = regexp.MustCompile(`[:\s]+`)
+
 func IOCountersWithContext(ctx context.Context, pernic bool) ([]IOCountersStat, error) {
 	// collect all the net class's links with below statistics
 	filterstr := "/^(?!vnic)/::phys:/^rbytes64$|^ipackets64$|^idrops64$|^ierrors$|^obytes64$|^opackets64$|^odrops64$|^oerrors$/"
@@ -47,9 +49,8 @@ func IOCountersWithContext(ctx context.Context, pernic bool) ([]IOCountersStat,
 	odrops64arr := make(map[string]uint64)
 	oerrorsarr := make(map[string]uint64)
 
-	re := regexp.MustCompile(`[:\s]+`)
 	for _, line := range lines {
-		fields := re.Split(line, -1)
+		fields := kstatSplit.Split(line, -1)
 		interfaceName := fields[0]
 		instance := fields[1]
 		switch fields[3] {