cli: get rid of exit channel

It wasn't a reliable way to determine if the command was "done". We need to wait
for run, post-run, etc. to finish first.

* Fixes #143

This commit:

1. Removes the exit channel from the CLI response emitter.
2. Adds a `Status()` function to the `cli.ResponseEmitter` as a replacement
   for (1).
3. Renames `Exit(code)` to `SetStatus(code)`. This new function doesn't
   immediately _do_ anything other than set the status.
4. Make sure to wait for _everything_ to finish before returning from `cli.Run`.

cli/responseemitter.go

@@ -14,21 +14,15 @@ import (
 
 var _ ResponseEmitter = &responseEmitter{}
 
-func NewResponseEmitter(stdout, stderr io.Writer, req *cmds.Request) (cmds.ResponseEmitter, <-chan int, error) {
-	ch := make(chan int)
+func NewResponseEmitter(stdout, stderr io.Writer, req *cmds.Request) (ResponseEmitter, error) {
 	encType, enc, err := cmds.GetEncoder(req, stdout, cmds.TextNewline)
-	if err != nil {
-		close(ch)
-		return nil, ch, err
-	}
 
 	return &responseEmitter{
 		stdout:  stdout,
 		stderr:  stderr,
 		encType: encType,
 		enc:     enc,
-		ch:      ch,
-	}, ch, err
+	}, err
 }
 
 // ResponseEmitter extends cmds.ResponseEmitter to give better control over the command line
@@ -37,7 +31,12 @@ type ResponseEmitter interface {
 
 	Stdout() io.Writer
 	Stderr() io.Writer
-	Exit(int)
+
+	// SetStatus sets the exit status for this command.
+	SetStatus(int)
+
+	// Status returns the exit status for the command.
+	Status() int
 }
 
 type responseEmitter struct {
@@ -50,8 +49,6 @@ type responseEmitter struct {
 	encType cmds.EncodingType
 	exit    int
 	closed  bool
-
-	ch chan<- int
 }
 
 func (re *responseEmitter) Type() cmds.PostRunType {
@@ -62,36 +59,6 @@ func (re *responseEmitter) SetLength(l uint64) {
 	re.length = l
 }
 
-func (re *responseEmitter) CloseWithError(err error) error {
-	var msg string
-	switch err {
-	case nil:
-		return re.Close()
-	case context.Canceled:
-		msg = "canceled"
-	case context.DeadlineExceeded:
-		msg = "timed out"
-	default:
-		msg = err.Error()
-	}
-
-	re.l.Lock()
-	defer re.l.Unlock()
-
-	if re.closed {
-		return cmds.ErrClosingClosedEmitter
-	}
-
-	re.exit = 1 // TODO we could let err carry an exit code
-
-	_, err = fmt.Fprintln(re.stderr, "Error:", msg)
-	if err != nil {
-		return err
-	}
-
-	return re.close()
-}
-
 func (re *responseEmitter) isClosed() bool {
 	re.l.Lock()
 	defer re.l.Unlock()
@@ -100,24 +67,39 @@ func (re *responseEmitter) isClosed() bool {
 }
 
 func (re *responseEmitter) Close() error {
+	return re.CloseWithError(nil)
+}
+
+func (re *responseEmitter) CloseWithError(err error) error {
 	re.l.Lock()
 	defer re.l.Unlock()
 
-	return re.close()
-}
-
-func (re *responseEmitter) close() error {
 	if re.closed {
 		return cmds.ErrClosingClosedEmitter
 	}
+	re.closed = true
+
+	var msg string
+	if err != nil {
+		if re.exit == 0 {
+			// Default "error" exit code.
+			re.exit = 1
+		}
+		switch err {
+		case context.Canceled:
+			msg = "canceled"
+		case context.DeadlineExceeded:
+			msg = "timed out"
+		default:
+			msg = err.Error()
+		}
 
-	re.ch <- re.exit
-	close(re.ch)
+		fmt.Fprintln(re.stderr, "Error:", msg)
+	}
 
 	defer func() {
 		re.stdout = nil
 		re.stderr = nil
-		re.closed = true
 	}()
 
 	// ignore error if the operating system doesn't support syncing std{out,err}
@@ -131,23 +113,19 @@ func (re *responseEmitter) close() error {
 		return false
 	}
 
+	var errStderr, errStdout error
 	if f, ok := re.stderr.(*os.File); ok {
-		err := f.Sync()
-		if err != nil {
-			if !ignoreError(err) {
-				return err
-			}
-		}
+		errStderr = f.Sync()
 	}
 	if f, ok := re.stdout.(*os.File); ok {
-		err := f.Sync()
-		if err != nil {
-			if !ignoreError(err) {
-				return err
-			}
-		}
+		errStdout = f.Sync()
+	}
+	if errStderr != nil && !ignoreError(errStderr) {
+		return errStderr
+	}
+	if errStdout != nil && !ignoreError(errStdout) {
+		return errStdout
 	}
-
 	return nil
 }
 
@@ -220,11 +198,16 @@ func (re *responseEmitter) Stdout() io.Writer {
 	return re.stdout
 }
 
-// Exit sends code to the channel that was returned by NewResponseEmitter, so main() can pass it to os.Exit()
-func (re *responseEmitter) Exit(code int) {
-	defer re.Close()
-
+// SetStatus sets the exit status of the command.
+func (re *responseEmitter) SetStatus(code int) {
 	re.l.Lock()
 	defer re.l.Unlock()
 	re.exit = code
 }
+
+// Status _returns_ the exit status of the command.
+func (re *responseEmitter) Status() int {
+	re.l.Lock()
+	defer re.l.Unlock()
+	return re.exit
+}

cli/responseemitter_test.go

@@ -23,17 +23,17 @@ type tcCloseWithError struct {
 
 func (tc tcCloseWithError) Run(t *testing.T) {
 	req := &cmds.Request{}
-	cmdsre, exitCh, err := NewResponseEmitter(tc.stdout, tc.stderr, req)
+	cmdsre, err := NewResponseEmitter(tc.stdout, tc.stderr, req)
 	if err != nil {
 		t.Fatal(err)
 	}
 
 	re := cmdsre.(ResponseEmitter)
 
-	go tc.f(re, t)
+	tc.f(re, t)
 
-	if exitCode := <-exitCh; exitCode != tc.exExit {
-		t.Fatalf("expected exit code %d, got %d", tc.exExit, exitCode)
+	if re.Status() != tc.exExit {
+		t.Fatalf("expected exit code %d, got %d", tc.exExit, re.Status())
 	}
 
 	if tc.stdout.String() != tc.exStdout {

cli/run.go

@@ -120,11 +120,6 @@ func Run(ctx context.Context, root *cmds.Command,
 		return err
 	}
 
-	var (
-		re     cmds.ResponseEmitter
-		exitCh <-chan int
-	)
-
 	encTypeStr, _ := req.Options[cmds.EncLong].(string)
 	encType := cmds.EncodingType(encTypeStr)
 
@@ -133,23 +128,17 @@ func Run(ctx context.Context, root *cmds.Command,
 		req.Options[cmds.EncLong] = cmds.JSON
 	}
 
-	// first if condition checks the command's encoder map, second checks global encoder map (cmd vs. cmds)
-	re, exitCh, err = NewResponseEmitter(stdout, stderr, req)
+	re, err := NewResponseEmitter(stdout, stderr, req)
 	if err != nil {
 		printErr(err)
 		return err
 	}
 
-	errCh := make(chan error, 1)
-	go func() {
-		err := exctr.Execute(req, re, env)
-		if err != nil {
-			errCh <- err
-		}
-	}()
-
-	select {
-	case err := <-errCh:
+	// Execute the command.
+	err = exctr.Execute(req, re, env)
+	// If we get an error here, don't bother reading the status from the
+	// response emitter. It may not even be closed.
+	if err != nil {
 		printErr(err)
 
 		if kiterr, ok := err.(*cmdkit.Error); ok {
@@ -160,12 +149,10 @@ func Run(ctx context.Context, root *cmds.Command,
 		}
 
 		return err
-
-	case code := <-exitCh:
-		if code != 0 {
-			return ExitError(code)
-		}
 	}
 
+	if code := re.Status(); code != 0 {
+		return ExitError(code)
+	}
 	return nil
 }

cli/run_test.go

@@ -0,0 +1,64 @@
+package cli
+
+import (
+	"context"
+	"os"
+	"testing"
+	"time"
+
+	"github.com/ipfs/go-ipfs-cmds"
+)
+
+var root = &cmds.Command{
+	Subcommands: map[string]*cmds.Command{
+		"test": &cmds.Command{
+			Run: func(req *cmds.Request, re cmds.ResponseEmitter, e cmds.Environment) error {
+				err := cmds.EmitOnce(re, 42)
+
+				time.Sleep(2 * time.Second)
+
+				e.(env).ch <- struct{}{}
+				return err
+			},
+		},
+	},
+}
+
+type env struct {
+	ch chan struct{}
+}
+
+func (e env) Context() context.Context {
+	return context.Background()
+}
+
+func TestRunWaits(t *testing.T) {
+	flag := make(chan struct{}, 1)
+
+	devnull, err := os.OpenFile(os.DevNull, os.O_RDWR, 0600)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer devnull.Close()
+
+	err = Run(
+		context.Background(),
+		root,
+		[]string{"test", "test"},
+		devnull, devnull, devnull,
+		func(ctx context.Context, req *cmds.Request) (cmds.Environment, error) {
+			return env{flag}, nil
+		},
+		func(req *cmds.Request, env interface{}) (cmds.Executor, error) {
+			return cmds.NewExecutor(req.Root), nil
+		},
+	)
+	if err != nil {
+		t.Fatal(err)
+	}
+	select {
+	case <-flag:
+	default:
+		t.Fatal("expected flag to be raised")
+	}
+}

cli/single_test.go

@@ -16,7 +16,7 @@ func TestSingle(t *testing.T) {
 
 	var bufout, buferr bytes.Buffer
 
-	re, exitCh, err := NewResponseEmitter(&bufout, &buferr, req)
+	re, err := NewResponseEmitter(&bufout, &buferr, req)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -40,7 +40,9 @@ func TestSingle(t *testing.T) {
 		wait <- struct{}{}
 	}()
 
-	exitCode := <-exitCh
+	<-wait
+
+	exitCode := re.Status()
 	if exitCode != 0 {
 		t.Errorf("expected exit code 0, got: %v", exitCode)
 	}
@@ -50,5 +52,4 @@ func TestSingle(t *testing.T) {
 		t.Fatalf("expected %#v, got %#v", "test\n", str)
 	}
 
-	<-wait
 }

examples/adder/cmd.go

@@ -184,16 +184,14 @@ var RootCmd = &cmds.Command{
 			PostRun: cmds.PostRunMap{
 				cmds.CLI: func(res cmds.Response, re cmds.ResponseEmitter) error {
 					clire := re.(cli.ResponseEmitter)
-
-					defer re.Close()
 					defer fmt.Println()
 
 					// length of line at last iteration
 					var lastLen int
 
 					var exit int
 					defer func() {
-						clire.Exit(exit)
+						clire.SetStatus(exit)
 					}()
 
 					for {