1 files changed, 168 insertions, 0 deletions
diff --git a/worker.go b/worker.go
new file mode 100644
index 00000000..8960b3fa
--- /dev/null
+++ b/worker.go
@@ -0,0 +1,168 @@
+package roadrunner
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"github.com/spiral/goridge"
+	"io"
+	"os/exec"
+	"strconv"
+	"strings"
+	"sync"
+	"sync/atomic"
+	"time"
+)
+
+// Worker - supervised process with api over goridge.Relay.
+type Worker struct {
+	// State current worker state.
+	State State
+
+	// Last time worker State has changed
+	Last time.Time
+
+	// NumExecutions how many times worker have been invoked.
+	NumExecutions uint64
+
+	// Pid contains process ID and empty until worker is started.
+	Pid *int
+
+	cmd *exec.Cmd     // underlying command process
+	err *bytes.Buffer // aggregates stderr
+	rl  goridge.Relay // communication bus with underlying process
+	mu  sync.RWMutex  // ensures than only one execution can be run at once
+}
+
+// NewWorker creates new worker
+func NewWorker(cmd *exec.Cmd) (*Worker, error) {
+	w := &Worker{
+		cmd:   cmd,
+		err:   bytes.NewBuffer(nil),
+		State: StateInactive,
+	}
+
+	if w.cmd.Process != nil {
+		return nil, fmt.Errorf("can't attach to running process")
+	}
+
+	return w, nil
+}
+
+// String returns worker description.
+func (w *Worker) String() string {
+	state := w.State.String()
+
+	if w.Pid != nil {
+		state = state + ", pid:" + strconv.Itoa(*w.Pid)
+	}
+
+	return fmt.Sprintf("(`%s` [%s], execs: %v)", strings.Join(w.cmd.Args, " "), state, w.NumExecutions)
+}
+
+// Start underlying process or return error
+func (w *Worker) Start() error {
+	stderr, err := w.cmd.StderrPipe()
+	if err != nil {
+		w.setState(StateError)
+		return err
+	}
+
+	// copying all process errors into buffer space
+	go io.Copy(w.err, stderr)
+
+	if err := w.cmd.Start(); err != nil {
+		w.setState(StateError)
+		return w.mockError(err)
+	}
+
+	w.setState(StateReady)
+
+	return nil
+}
+
+// Execute command and return result and result context.
+func (w *Worker) Execute(body []byte, ctx interface{}) (resp []byte, rCtx []byte, err error) {
+	w.mu.Lock()
+	defer w.mu.Unlock()
+
+	if w.State != StateReady {
+		return nil, nil, fmt.Errorf("worker must be in state `waiting` (`%s` given)", w.State)
+	}
+
+	w.setState(StateReady)
+	atomic.AddUint64(&w.NumExecutions, 1)
+
+	if ctx != nil {
+		if data, err := json.Marshal(ctx); err == nil {
+			w.rl.Send(data, goridge.PayloadControl)
+		} else {
+			return nil, nil, fmt.Errorf("invalid context: %s", err)
+		}
+	} else {
+		w.rl.Send(nil, goridge.PayloadControl|goridge.PayloadEmpty)
+	}
+
+	w.rl.Send(body, 0)
+
+	rCtx, p, err := w.rl.Receive()
+
+	if !p.HasFlag(goridge.PayloadControl) {
+		return nil, nil, w.mockError(fmt.Errorf("invalid response (check script integrity)"))
+	}
+
+	if p.HasFlag(goridge.PayloadError) {
+		w.setState(StateReady)
+		return nil, nil, JobError(rCtx)
+	}
+
+	if resp, p, err = w.rl.Receive(); err != nil {
+		w.setState(StateError)
+		return nil, nil, w.mockError(fmt.Errorf("worker error: %s", err))
+	}
+
+	w.setState(StateReady)
+	return resp, rCtx, nil
+}
+
+// Stop underlying process or return error.
+func (w *Worker) Stop() {
+	w.mu.Lock()
+	defer w.mu.Unlock()
+
+	w.setState(StateInactive)
+
+	go func() {
+		sendCommand(w.rl, &TerminateCommand{Terminate: true})
+	}()
+
+	w.cmd.Wait()
+	w.rl.Close()
+
+	w.setState(StateStopped)
+}
+
+// attach payload/control relay to the worker.
+func (w *Worker) attach(rl goridge.Relay) {
+	w.mu.Lock()
+	defer w.mu.Unlock()
+
+	w.rl = rl
+	w.setState(StateBooting)
+}
+
+// sets worker State and it's context (non blocking!).
+func (w *Worker) setState(state State) {
+	// safer?
+	w.State = state
+	w.Last = time.Now()
+}
+
+// mockError attaches worker specific error (from stderr) to parent error
+func (w *Worker) mockError(err error) WorkerError {
+	if w.err.Len() != 0 {
+		return WorkerError(w.err.String())
+	}
+
+	return WorkerError(err.Error())
+}