feature(worker): move command execution logic to a runner object

worker/runner.go

@@ -0,0 +1,112 @@
+package worker
+
+import (
+	"errors"
+	"os"
+	"os/exec"
+	"strings"
+	"syscall"
+	"time"
+
+	"golang.org/x/sys/unix"
+)
+
+// runner is to run os commands giving command line, env and log file
+// it's an alternative to python-sh or go-sh
+// TODO: cgroup excution
+
+type cmdJob struct {
+	cmd        *exec.Cmd
+	workingDir string
+	env        map[string]string
+	logFile    *os.File
+	finished   chan struct{}
+}
+
+func newCmdJob(cmdAndArgs []string, workingDir string, env map[string]string) *cmdJob {
+	var cmd *exec.Cmd
+	if len(cmdAndArgs) == 1 {
+		cmd = exec.Command(cmdAndArgs[0])
+	} else if len(cmdAndArgs) > 1 {
+		c := cmdAndArgs[0]
+		args := cmdAndArgs[1:]
+		cmd = exec.Command(c, args...)
+	} else if len(cmdAndArgs) == 0 {
+		panic("Command length should be at least 1!")
+	}
+
+	cmd.Dir = workingDir
+	cmd.Env = newEnviron(env, true)
+
+	return &cmdJob{
+		cmd:        cmd,
+		workingDir: workingDir,
+		env:        env,
+	}
+}
+
+// start job and wait
+func (c *cmdJob) Run() error {
+	err := c.cmd.Start()
+	if err != nil {
+		return err
+	}
+	return c.Wait()
+}
+
+func (c *cmdJob) Start() error {
+	c.finished = make(chan struct{}, 1)
+	return c.cmd.Start()
+}
+
+func (c *cmdJob) Wait() error {
+	err := c.cmd.Wait()
+	c.finished <- struct{}{}
+	return err
+}
+
+func (c *cmdJob) SetLogFile(logFile *os.File) {
+	c.cmd.Stdout = logFile
+	c.cmd.Stderr = logFile
+}
+
+func (c *cmdJob) Terminate() error {
+	if c.cmd == nil {
+		return errors.New("Command not initialized")
+	}
+	if c.cmd.Process == nil {
+		return errors.New("No Process Running")
+	}
+	err := unix.Kill(c.cmd.Process.Pid, syscall.SIGTERM)
+	if err != nil {
+		return err
+	}
+
+	select {
+	case <-time.After(2 * time.Second):
+		unix.Kill(c.cmd.Process.Pid, syscall.SIGKILL)
+		return errors.New("SIGTERM failed to kill the job")
+	case <-c.finished:
+		return nil
+	}
+}
+
+// Copied from go-sh
+func newEnviron(env map[string]string, inherit bool) []string { //map[string]string {
+	environ := make([]string, 0, len(env))
+	if inherit {
+		for _, line := range os.Environ() {
+			// if os environment and env collapses,
+			// omit the os one
+			k := strings.Split(line, "=")[0]
+			if _, ok := env[k]; ok {
+				continue
+			}
+			environ = append(environ, line)
+		}
+	}
+	for k, v := range env {
+		environ = append(environ, k+"="+v)
+	}
+	return environ
+}