Cross platform support for the 'processes' plugin

closes #798

plugins/inputs/system/processes.go

@@ -1,61 +1,216 @@
+// +build !windows
+
 package system
 
 import (
+	"bytes"
 	"fmt"
+	"io/ioutil"
 	"log"
+	"os"
+	"os/exec"
+	"path"
+	"runtime"
+	"strconv"
 
 	"github.com/influxdata/telegraf"
 	"github.com/influxdata/telegraf/plugins/inputs"
-	"github.com/shirou/gopsutil/process"
 )
 
 type Processes struct {
+	execPS       func() ([]byte, error)
+	readProcFile func(statFile string) ([]byte, error)
+
+	forcePS   bool
+	forceProc bool
 }
 
-func (_ *Processes) Description() string {
-	return "Get the number of processes and group them by status (Linux only)"
+func (p *Processes) Description() string {
+	return "Get the number of processes and group them by status"
 }
 
-func (_ *Processes) SampleConfig() string { return "" }
+func (p *Processes) SampleConfig() string { return "" }
 
-func (s *Processes) Gather(acc telegraf.Accumulator) error {
-	pids, err := process.Pids()
-	if err != nil {
-		return fmt.Errorf("error getting pids list: %s", err)
+func (p *Processes) Gather(acc telegraf.Accumulator) error {
+	// Get an empty map of metric fields
+	fields := getEmptyFields()
+
+	// Decide if we will use 'ps' to get stats (use procfs otherwise)
+	usePS := true
+	if runtime.GOOS == "linux" {
+		usePS = false
 	}
-	// TODO handle other OS (Windows/BSD/Solaris/OSX)
-	fields := map[string]interface{}{
-		"paging":   uint64(0),
-		"blocked":  uint64(0),
-		"zombie":   uint64(0),
-		"stopped":  uint64(0),
-		"running":  uint64(0),
-		"sleeping": uint64(0),
+	if p.forcePS {
+		usePS = true
+	} else if p.forceProc {
+		usePS = false
 	}
-	for _, pid := range pids {
-		process, err := process.NewProcess(pid)
-		if err != nil {
-			log.Printf("Can not get process %d status: %s", pid, err)
-			continue
+
+	// Gather stats from 'ps' or procfs
+	if usePS {
+		if err := p.gatherFromPS(fields); err != nil {
+			return err
 		}
-		status, err := process.Status()
-		if err != nil {
-			log.Printf("Can not get process %d status: %s\n", pid, err)
-			continue
+	} else {
+		if err := p.gatherFromProc(fields); err != nil {
+			return err
 		}
-		_, exists := fields[status]
-		if !exists {
-			log.Printf("Status '%s' for process with pid: %d\n", status, pid)
-			continue
-		}
-		fields[status] = fields[status].(uint64) + uint64(1)
 	}
 
 	acc.AddFields("processes", fields, nil)
 	return nil
 }
+
+// Gets empty fields of metrics based on the OS
+func getEmptyFields() map[string]interface{} {
+	fields := map[string]interface{}{
+		"blocked":  int64(0),
+		"zombie":   int64(0),
+		"stopped":  int64(0),
+		"running":  int64(0),
+		"sleeping": int64(0),
+		"total":    int64(0),
+	}
+	switch runtime.GOOS {
+	case "freebsd":
+		fields["idle"] = int64(0)
+		fields["wait"] = int64(0)
+	case "darwin":
+		fields["idle"] = int64(0)
+	case "openbsd":
+		fields["idle"] = int64(0)
+	case "linux":
+		fields["paging"] = int64(0)
+		fields["total_threads"] = int64(0)
+	}
+	return fields
+}
+
+// exec `ps` to get all process states
+func (p *Processes) gatherFromPS(fields map[string]interface{}) error {
+	out, err := p.execPS()
+	if err != nil {
+		return err
+	}
+
+	for i, status := range bytes.Fields(out) {
+		if i == 0 && string(status) == "STAT" {
+			// This is a header, skip it
+			continue
+		}
+		switch status[0] {
+		case 'W':
+			fields["wait"] = fields["wait"].(int64) + int64(1)
+		case 'U', 'D', 'L':
+			// Also known as uninterruptible sleep or disk sleep
+			fields["blocked"] = fields["blocked"].(int64) + int64(1)
+		case 'Z':
+			fields["zombie"] = fields["zombie"].(int64) + int64(1)
+		case 'T':
+			fields["stopped"] = fields["stopped"].(int64) + int64(1)
+		case 'R':
+			fields["running"] = fields["running"].(int64) + int64(1)
+		case 'S':
+			fields["sleeping"] = fields["sleeping"].(int64) + int64(1)
+		case 'I':
+			fields["idle"] = fields["idle"].(int64) + int64(1)
+		default:
+			log.Printf("processes: Unknown state [ %s ] from ps",
+				string(status[0]))
+		}
+		fields["total"] = fields["total"].(int64) + int64(1)
+	}
+	return nil
+}
+
+// get process states from /proc/(pid)/stat files
+func (p *Processes) gatherFromProc(fields map[string]interface{}) error {
+	files, err := ioutil.ReadDir("/proc")
+	if err != nil {
+		return err
+	}
+
+	for _, file := range files {
+		if !file.IsDir() {
+			continue
+		}
+
+		statFile := path.Join("/proc", file.Name(), "stat")
+		data, err := p.readProcFile(statFile)
+		if err != nil {
+			return err
+		}
+		if data == nil {
+			continue
+		}
+
+		stats := bytes.Fields(data)
+		if len(stats) < 3 {
+			return fmt.Errorf("Something is terribly wrong with %s", statFile)
+		}
+		switch stats[2][0] {
+		case 'R':
+			fields["running"] = fields["running"].(int64) + int64(1)
+		case 'S':
+			fields["sleeping"] = fields["sleeping"].(int64) + int64(1)
+		case 'D':
+			fields["blocked"] = fields["blocked"].(int64) + int64(1)
+		case 'Z':
+			fields["zombies"] = fields["zombies"].(int64) + int64(1)
+		case 'T', 't':
+			fields["stopped"] = fields["stopped"].(int64) + int64(1)
+		case 'W':
+			fields["paging"] = fields["paging"].(int64) + int64(1)
+		default:
+			log.Printf("processes: Unknown state [ %s ] in file %s",
+				string(stats[2][0]), statFile)
+		}
+		fields["total"] = fields["total"].(int64) + int64(1)
+
+		threads, err := strconv.Atoi(string(stats[19]))
+		if err != nil {
+			log.Printf("processes: Error parsing thread count: %s", err)
+			continue
+		}
+		fields["total_threads"] = fields["total_threads"].(int64) + int64(threads)
+	}
+	return nil
+}
+
+func readProcFile(statFile string) ([]byte, error) {
+	if _, err := os.Stat(statFile); os.IsNotExist(err) {
+		return nil, nil
+	} else if err != nil {
+		return nil, err
+	}
+
+	data, err := ioutil.ReadFile(statFile)
+	if err != nil {
+		return nil, err
+	}
+
+	return data, nil
+}
+
+func execPS() ([]byte, error) {
+	bin, err := exec.LookPath("ps")
+	if err != nil {
+		return nil, err
+	}
+
+	out, err := exec.Command(bin, "axo", "state").Output()
+	if err != nil {
+		return nil, err
+	}
+
+	return out, err
+}
+
 func init() {
 	inputs.Add("processes", func() telegraf.Input {
-		return &Processes{}
+		return &Processes{
+			execPS:       execPS,
+			readProcFile: readProcFile,
+		}
 	})
 }