turn process monitoring events into structured objects

internal/psscanner/proclist.go

@@ -25,7 +25,7 @@ var cmdLineReader = func(pid int) ([]byte, error) {
 
 type procList map[int]string
 
-func (pl procList) refresh(eventCh chan string) error {
+func (pl procList) refresh(eventCh chan PSEvent) error {
 	pids, err := getPIDs()
 	if err != nil {
 		return err
@@ -74,16 +74,16 @@ func file2Pid(f os.FileInfo) (int, error) {
 	return pid, nil
 }
 
-func (pl procList) addPid(pid int, eventCh chan string) {
+func (pl procList) addPid(pid int, eventCh chan PSEvent) {
 	cmd, err := getCmd(pid)
 	if err != nil {
 		cmd = "???" // process probably terminated
 	}
 	uid, err := getUID(pid)
 	if err != nil {
-		uid = "???"
+		uid = -1
 	}
-	eventCh <- fmt.Sprintf("UID=%-4s PID=%-6d | %s", uid, pid, cmd)
+	eventCh <- PSEvent{UID: uid, PID: pid, CMD: cmd}
 	pl[pid] = cmd
 }
 
@@ -100,18 +100,26 @@ func getCmd(pid int) (string, error) {
 	return string(cmd), nil
 }
 
-func getUID(pid int) (string, error) {
+func getUID(pid int) (int, error) {
 	stat, err := procStatusReader(pid)
 	if err != nil {
-		return "", err
+		return -1, err
 	}
+
 	lines := strings.Split(string(stat), "\n")
 	if len(lines) < 9 {
-		return "", fmt.Errorf("no uid information")
+		return -1, fmt.Errorf("no uid information")
 	}
+
 	uidL := strings.Split(lines[8], "\t")
 	if len(uidL) < 2 {
-		return "", fmt.Errorf("uid line read incomplete")
+		return -1, fmt.Errorf("uid line read incomplete")
 	}
-	return uidL[1], nil
+
+	uid, err := strconv.Atoi(uidL[1])
+	if err != nil {
+		return -1, fmt.Errorf("converting %s to int: %v", uidL[1], err)
+	}
+
+	return uid, nil
 }

internal/psscanner/proclist_test.go

@@ -136,14 +136,14 @@ func TestGetUID(t *testing.T) {
 		pid     int
 		stat    []byte
 		statErr error
-		uid     string
+		uid     int
 		err     string
 	}{
-		{pid: 7, stat: completeStatus, statErr: nil, uid: "0", err: ""},                                         // can read normal stat
-		{pid: 7, stat: uidLineBroken, statErr: nil, uid: "", err: "uid line read incomplete"},                   // errors on incomplete Uid line
-		{pid: 7, stat: notEnoughLines, statErr: nil, uid: "", err: "no uid information"},                        // errors for insufficient lines
-		{pid: 7, stat: []byte(""), statErr: nil, uid: "", err: "no uid information"},                            // errors for insufficient lines
-		{pid: 7, stat: []byte(""), statErr: errors.New("file-system-error"), uid: "", err: "file-system-error"}, // returns file system errors
+		{pid: 7, stat: completeStatus, statErr: nil, uid: 0, err: ""},                                           // can read normal stat
+		{pid: 7, stat: uidLineBroken, statErr: nil, uid: -1, err: "uid line read incomplete"},                   // errors on incomplete Uid line
+		{pid: 7, stat: notEnoughLines, statErr: nil, uid: -1, err: "no uid information"},                        // errors for insufficient lines
+		{pid: 7, stat: []byte(""), statErr: nil, uid: -1, err: "no uid information"},                            // errors for insufficient lines
+		{pid: 7, stat: []byte(""), statErr: errors.New("file-system-error"), uid: -1, err: "file-system-error"}, // returns file system errors
 	}
 
 	for _, tt := range tests {
@@ -151,7 +151,7 @@ func TestGetUID(t *testing.T) {
 		uid, err := getUID(tt.pid)
 		if uid != tt.uid {
 			fmt.Printf("STAT: %s", tt.stat)
-			t.Errorf("Wrong uid returned: got %s but want %s", uid, tt.uid)
+			t.Errorf("Wrong uid returned: got %d but want %d", uid, tt.uid)
 		}
 		if (err != nil || tt.err != "") && fmt.Sprintf("%v", err) != tt.err {
 			t.Errorf("Wrong error returned: got %v but want %s", err, tt.err)
@@ -174,18 +174,18 @@ func mockProcStatusReader(stat []byte, err error) (restore func()) {
 
 func TestRefresh(t *testing.T) {
 	tests := []struct {
-		eventCh   chan string
+		eventCh   chan PSEvent
 		pl        procList
 		newPids   []int
 		pidsAfter []int
 		events    []string
 	}{
-		{eventCh: make(chan string), pl: procList{}, newPids: []int{1, 2, 3}, pidsAfter: []int{3, 2, 1}, events: []string{
+		{eventCh: make(chan PSEvent), pl: procList{}, newPids: []int{1, 2, 3}, pidsAfter: []int{3, 2, 1}, events: []string{
 			"UID=???  PID=3      | the-command",
 			"UID=???  PID=2      | the-command",
 			"UID=???  PID=1      | the-command",
 		}},
-		{eventCh: make(chan string), pl: procList{1: "pid-found-before"}, newPids: []int{1, 2, 3}, pidsAfter: []int{1, 3, 2}, events: []string{
+		{eventCh: make(chan PSEvent), pl: procList{1: "pid-found-before"}, newPids: []int{1, 2, 3}, pidsAfter: []int{1, 3, 2}, events: []string{
 			"UID=???  PID=3      | the-command",
 			"UID=???  PID=2      | the-command",
 		}}, // no events emitted for PIDs already known
@@ -200,7 +200,7 @@ func TestRefresh(t *testing.T) {
 		done := make(chan struct{})
 		go func() {
 			for e := range tt.eventCh {
-				events = append(events, e)
+				events = append(events, e.String())
 			}
 			done <- struct{}{}
 		}()

internal/psscanner/psscanner.go

@@ -1,13 +1,33 @@
 package psscanner
 
+import (
+	"fmt"
+	"strconv"
+)
+
 type PSScanner struct{}
 
+type PSEvent struct {
+	UID int
+	PID int
+	CMD string
+}
+
+func (evt PSEvent) String() string {
+	uid := strconv.Itoa(evt.UID)
+	if evt.UID == -1 {
+		uid = "???"
+	}
+
+	return fmt.Sprintf("UID=%-4s PID=%-6d | %s", uid, evt.PID, evt.CMD)
+}
+
 func NewPSScanner() *PSScanner {
 	return &PSScanner{}
 }
 
-func (p *PSScanner) Run(triggerCh chan struct{}) (chan string, chan error) {
-	eventCh := make(chan string, 100)
+func (p *PSScanner) Run(triggerCh chan struct{}) (chan PSEvent, chan error) {
+	eventCh := make(chan PSEvent, 100)
 	errCh := make(chan error)
 	pl := make(procList)
 

internal/psscanner/psscanner_test.go

@@ -48,7 +48,7 @@ func TestRun(t *testing.T) {
 			case <-time.After(timeout):
 				t.Errorf("did not receive event in time")
 			case e := <-eventCh:
-				if e != tt.events[i] {
+				if e.String() != tt.events[i] {
 					t.Errorf("Wrong event received: got '%s' but wanted '%s'", e, tt.events[i])
 				}
 			case err := <-errCh: