Merge pull request #776 from weaveworks/tracer

Tracer!

probe/process/tree.go

@@ -7,6 +7,7 @@ import (
 // Tree represents all processes on the machine.
 type Tree interface {
 	GetParent(pid int) (int, error)
+	GetChildren(pid int) ([]int, error)
 }
 
 type tree struct {
@@ -32,3 +33,30 @@ func (pt *tree) GetParent(pid int) (int, error) {
 
 	return proc.PPID, nil
 }
+
+// GetChildren
+func (pt *tree) GetChildren(pid int) ([]int, error) {
+	_, ok := pt.processes[pid]
+	if !ok {
+		return []int{}, fmt.Errorf("PID %d not found", pid)
+	}
+
+	var isChild func(id int) bool
+	isChild = func(id int) bool {
+		p, ok := pt.processes[id]
+		if !ok || p.PPID == 0 {
+			return false
+		} else if p.PPID == pid {
+			return true
+		}
+		return isChild(p.PPID)
+	}
+
+	children := []int{pid}
+	for id := range pt.processes {
+		if isChild(id) {
+			children = append(children, id)
+		}
+	}
+	return children, nil
+}