File: pipe_factory.go

package roadrunner

import (
	"github.com/pkg/errors"
	"github.com/spiral/goridge"
	"io"
	"os/exec"
)

// PipeFactory connects to workers using standard
// streams (STDIN, STDOUT pipes).
type PipeFactory struct {
}

// NewPipeFactory returns new factory instance and starts
// listening
func NewPipeFactory() *PipeFactory {
	return &PipeFactory{}
}

// SpawnWorker creates new worker and connects it to goridge relay,
// method Wait() must be handled on level above.
func (f *PipeFactory) SpawnWorker(cmd *exec.Cmd) (w *Worker, err error) {
	if w, err = newWorker(cmd); err != nil {
		return nil, err
	}

	var (
		in  io.ReadCloser
		out io.WriteCloser
	)

	if in, err = cmd.StdoutPipe(); err != nil {
		return nil, err
	}

	if out, err = cmd.StdinPipe(); err != nil {
		return nil, err
	}

	w.rl = goridge.NewPipeRelay(in, out)

	if err := w.start(); err != nil {
		return nil, errors.Wrap(err, "process error")
	}

	if pid, err := fetchPID(w.rl); pid != *w.Pid {
		go func(w *Worker) { w.Kill() }(w)
		if wErr := w.Wait(); wErr != nil {
			err = errors.Wrap(wErr, err.Error())
		}

		return nil, errors.Wrap(err, "unable to connect to worker")
	}

	w.state.set(StateReady)
	return w, nil
}