Merge pull request #3 from struCoder/dev

feat(dev): add error and update readme

README.md

@@ -3,16 +3,19 @@ Cross-platform process cpu % and memory usage of a PID for golang
 
 Ideas from https://github.com/soyuka/pidusage but just use Golang
 
+[![Go Report Card](https://goreportcard.com/badge/github.com/struCoder/pidusage)](https://goreportcard.com/report/github.com/struCoder/pidusage)
+[![GoDoc](https://godoc.org/github.com/struCoder/pidusage?status.svg)](https://godoc.org/github.com/struCoder/pidusage)
+
 ## API
 
 ```golang
 import (
   "os"
-	"github.com/struCoder/pmgo/lib/utils"
+	"github.com/struCoder/pidusage"
 )
 
 func printStat() {
-	sysInfo := pidusage.GetStat(os.Process.Pid)
+	sysInfo, err := pidusage.GetStat(os.Process.Pid)
 }
 ```
 
@@ -21,7 +24,7 @@ func printStat() {
 A check on the `runtime.GOOS` is done to determine the method to use.
 
 ### Linux
-We use `/proc/{pid}/stat` in addition to the the `PAGE_SIZE` and the `CLK_TCK` direclty from `getconf()` command. Uptime comes from `proc/uptime` file because it's more accurate than the nodejs `os.uptime()`.
+We use `/proc/{pid}/stat` in addition to the the `PAGE_SIZE` and the `CLK_TCK` direclty from `getconf()` command. Uptime comes from `proc/uptime`
 
 Cpu usage is computed by following [those instructions](http://stackoverflow.com/questions/16726779/how-do-i-get-the-total-cpu-usage-of-an-application-from-proc-pid-stat/16736599#16736599). It keeps an history of the current processor time for the given pid so that the computed value gets more and more accurate. Don't forget to do `unmonitor(pid)` so that history gets cleared.
 Cpu usage does not check the child process tree!

pidusage.go

@@ -1,6 +1,7 @@
 package pidusage
 
 import (
+	"errors"
 	"io/ioutil"
 	"math"
 	"os/exec"
@@ -27,15 +28,15 @@ type Stat struct {
 	uptime float64
 }
 
-type fn func(int) *SysInfo
+type fn func(int) (*SysInfo, error)
 
 var fnMap map[string]fn
 var platform string
 var history map[int]Stat
 var eol string
 
-func wrapper(statType string) func(pid int) *SysInfo {
-	return func(pid int) *SysInfo {
+func wrapper(statType string) func(pid int) (*SysInfo, error) {
+	return func(pid int) (*SysInfo, error) {
 		return stat(pid, statType)
 	}
 }
@@ -67,7 +68,7 @@ func parseFloat(val string) float64 {
 	return floatVal
 }
 
-func stat(pid int, statType string) *SysInfo {
+func stat(pid int, statType string) (*SysInfo, error) {
 	sysInfo := &SysInfo{}
 	_history := history[pid]
 	if statType == "ps" {
@@ -77,6 +78,9 @@ func stat(pid int, statType string) *SysInfo {
 		}
 		stdout, _ := exec.Command("ps", args, strconv.Itoa(pid)).Output()
 		ret := formatStdOut(stdout, 1)
+		if len(ret) == 0 {
+			return sysInfo, errors.New("can not foud this pid: " + strconv.Itoa(pid))
+		}
 		sysInfo.CPU = parseFloat(ret[0])
 		sysInfo.Memory = parseFloat(ret[1]) * 1024
 	} else if statType == "proc" {
@@ -98,7 +102,11 @@ func stat(pid int, statType string) *SysInfo {
 		}
 
 		procStatFileBytes, err := ioutil.ReadFile(path.Join("/proc", strconv.Itoa(pid), "stat"))
-		infos := strings.Split(strings.SplitAfter(string(procStatFileBytes), ")")[1], " ")
+		splitAfter := strings.SplitAfter(string(procStatFileBytes), ")")
+		if len(splitAfter) == 0 {
+			return sysInfo, errors.New("can not foud this pid: " + strconv.Itoa(pid))
+		}
+		infos := strings.Split(splitAfter[1], " ")
 		stat := &Stat{
 			utime:  parseFloat(infos[12]),
 			stime:  parseFloat(infos[13]),
@@ -135,12 +143,12 @@ func stat(pid int, statType string) *SysInfo {
 		sysInfo.CPU = (total / seconds) * 100
 		sysInfo.Memory = stat.rss * pageSize
 	}
-	return sysInfo
+	return sysInfo, nil
 
 }
 
 // GetStat will return current system CPU and memory data
-func GetStat(pid int) *SysInfo {
-	sysInfo := fnMap[platform](pid)
-	return sysInfo
+func GetStat(pid int) (*SysInfo, error) {
+	sysInfo, err := fnMap[platform](pid)
+	return sysInfo, err
 }