[cpu][darwin] Remove calls to sysctl binary in cpu/cpu_darwin.go #639

Empirical benchmark (calling to cpu.Info):

Lomanics-iMac:~ lomanic$ time ./cpu_info
info 0: {"cpu":0,"vendorId":"GenuineIntel","family":"6","model":"30","stepping":5,"physicalId":"","coreId":"","cores":2,"modelName":"Intel(R) Core(TM) i5-6440HQ CPU @ 2.60GHz","mhz":2590,"cacheSize":256,"flags":["syscall","xd","em64t","lahf","lzcnt","prefetchw","rdtscp","tsci","fpu","vme","de","pse","tsc","msr","pae","mce","cx8","apic","sep","mtrr","pge","mca","cmov","pat","pse36","clfsh","mmx","fxsr","sse","sse2","htt","sse3","ssse3","cx16","sse4.1","sse4.2","popcnt","vmm"],"microcode":""}

real    0m0.049s
user    0m0.023s
sys     0m0.041s
Lomanics-iMac:~ lomanic$ time ./cpu_info.fixed
info 0: {"cpu":0,"vendorId":"GenuineIntel","family":"6","model":"30","stepping":5,"physicalId":"","coreId":"","cores":2,"modelName":"Intel(R) Core(TM) i5-6440HQ CPU @ 2.60GHz","mhz":2590,"cacheSize":256,"flags":["fpu","vme","de","pse","tsc","msr","pae","mce","cx8","apic","sep","mtrr","pge","mca","cmov","pat","pse36","clfsh","mmx","fxsr","sse","sse2","htt","sse3","ssse3","cx16","sse4.1","sse4.2","popcnt","vmm","syscall","xd","em64t","lahf","lzcnt","prefetchw","rdtscp","tsci"],"microcode":""}

real    0m0.010s
user    0m0.004s
sys     0m0.006s

cpu/cpu_darwin.go

@@ -4,9 +4,10 @@ package cpu
 
 import (
 	"context"
-	"os/exec"
 	"strconv"
 	"strings"
+
+	"golang.org/x/sys/unix"
 )
 
 // sys/resource.h
@@ -41,75 +42,46 @@ func Info() ([]InfoStat, error) {
 
 func InfoWithContext(ctx context.Context) ([]InfoStat, error) {
 	var ret []InfoStat
-	sysctl, err := exec.LookPath("/usr/sbin/sysctl")
-	if err != nil {
-		return ret, err
-	}
-	out, err := invoke.CommandWithContext(ctx, sysctl, "machdep.cpu")
-	if err != nil {
-		return ret, err
-	}
 
 	c := InfoStat{}
-	for _, line := range strings.Split(string(out), "\n") {
-		values := strings.Fields(line)
-		if len(values) < 1 {
-			continue
+	c.ModelName, _ = unix.Sysctl("machdep.cpu.brand_string")
+	family, _ := unix.SysctlUint32("machdep.cpu.family")
+	c.Family = strconv.FormatUint(uint64(family), 10)
+	model, _ := unix.SysctlUint32("machdep.cpu.model")
+	c.Model = strconv.FormatUint(uint64(model), 10)
+	stepping, _ := unix.SysctlUint32("machdep.cpu.stepping")
+	c.Stepping = int32(stepping)
+	features, err := unix.Sysctl("machdep.cpu.features")
+	if err == nil {
+		for _, v := range strings.Fields(features) {
+			c.Flags = append(c.Flags, strings.ToLower(v))
 		}
-
-		t, err := strconv.ParseInt(values[1], 10, 64)
-		// err is not checked here because some value is string.
-		if strings.HasPrefix(line, "machdep.cpu.brand_string") {
-			c.ModelName = strings.Join(values[1:], " ")
-		} else if strings.HasPrefix(line, "machdep.cpu.family") {
-			c.Family = values[1]
-		} else if strings.HasPrefix(line, "machdep.cpu.model") {
-			c.Model = values[1]
-		} else if strings.HasPrefix(line, "machdep.cpu.stepping") {
-			if err != nil {
-				return ret, err
-			}
-			c.Stepping = int32(t)
-		} else if strings.HasPrefix(line, "machdep.cpu.features") {
-			for _, v := range values[1:] {
-				c.Flags = append(c.Flags, strings.ToLower(v))
-			}
-		} else if strings.HasPrefix(line, "machdep.cpu.leaf7_features") {
-			for _, v := range values[1:] {
-				c.Flags = append(c.Flags, strings.ToLower(v))
-			}
-		} else if strings.HasPrefix(line, "machdep.cpu.extfeatures") {
-			for _, v := range values[1:] {
-				c.Flags = append(c.Flags, strings.ToLower(v))
-			}
-		} else if strings.HasPrefix(line, "machdep.cpu.core_count") {
-			if err != nil {
-				return ret, err
-			}
-			c.Cores = int32(t)
-		} else if strings.HasPrefix(line, "machdep.cpu.cache.size") {
-			if err != nil {
-				return ret, err
-			}
-			c.CacheSize = int32(t)
-		} else if strings.HasPrefix(line, "machdep.cpu.vendor") {
-			c.VendorID = values[1]
+	}
+	leaf7Features, err := unix.Sysctl("machdep.cpu.leaf7_features")
+	if err == nil {
+		for _, v := range strings.Fields(leaf7Features) {
+			c.Flags = append(c.Flags, strings.ToLower(v))
+		}
+	}
+	extfeatures, err := unix.Sysctl("machdep.cpu.extfeatures")
+	if err == nil {
+		for _, v := range strings.Fields(extfeatures) {
+			c.Flags = append(c.Flags, strings.ToLower(v))
 		}
 	}
+	cores, _ := unix.SysctlUint32("machdep.cpu.core_count")
+	c.Cores = int32(cores)
+	cacheSize, _ := unix.SysctlUint32("machdep.cpu.cache.size")
+	c.CacheSize = int32(cacheSize)
+	c.VendorID, _ = unix.Sysctl("machdep.cpu.vendor")
 
 	// Use the rated frequency of the CPU. This is a static value and does not
 	// account for low power or Turbo Boost modes.
-	out, err = invoke.CommandWithContext(ctx, sysctl, "hw.cpufrequency")
-	if err != nil {
-		return ret, err
-	}
-
-	values := strings.Fields(string(out))
-	hz, err := strconv.ParseFloat(values[1], 64)
+	cpuFrequency, err := unix.SysctlUint64("hw.cpufrequency")
 	if err != nil {
 		return ret, err
 	}
-	c.Mhz = hz / 1000000.0
+	c.Mhz = float64(cpuFrequency) / 1000000.0
 
 	return append(ret, c), nil
 }