debug: finish server when all session finished

Signed-off-by: Kohei Tokunaga <ktokunaga.mail@gmail.com>

controller/remote/controller.go

@@ -152,6 +152,16 @@ func serveCmd(dockerCli command.Cli) *cobra.Command {
 				return cbuild.RunBuild(ctx, dockerCli, *options, stdin, progress, true)
 			})
 			defer b.Close()
+			sessionsDoneCh := make(chan struct{})
+			go func() {
+				for {
+					if !b.isUsed() {
+						sessionsDoneCh <- struct{}{}
+						break
+					}
+					time.Sleep(10 * time.Second)
+				}
+			}()
 
 			// serve server
 			addr := filepath.Join(root, defaultSocketFilename)
@@ -187,6 +197,9 @@ func serveCmd(dockerCli command.Cli) *cobra.Command {
 			signal.Notify(sigCh, syscall.SIGINT)
 			signal.Notify(sigCh, syscall.SIGTERM)
 			select {
+			case <-sessionsDoneCh:
+				logrus.Infof("all sessions finished")
+				return nil
 			case err := <-errCh:
 				logrus.Errorf("got error %s, exiting", err)
 				return err

controller/remote/server.go

@@ -3,8 +3,6 @@ package remote
 import (
 	"context"
 	"io"
-	"sync"
-	"sync/atomic"
 	"time"
 
 	"github.com/docker/buildx/build"
@@ -23,54 +21,39 @@ type BuildFunc func(ctx context.Context, options *pb.BuildOptions, stdin io.Read
 
 func NewServer(buildFunc BuildFunc) *Server {
 	return &Server{
-		buildFunc: buildFunc,
+		sessions: newSessionManager(buildFunc),
 	}
 }
 
 type Server struct {
-	buildFunc BuildFunc
+	sessions *sessionManager
-	session   map[string]*session
-	sessionMu sync.Mutex
 }
 
-type session struct {
+func (m *Server) isUsed() bool {
-	buildOnGoing atomic.Bool
+	if m.sessions.sessionCreated() && len(m.sessions.list()) == 0 {
-	statusChan   chan *pb.StatusResponse
+		return false
-	cancelBuild  func()
+	}
-	buildOptions *pb.BuildOptions
+	return true
-	inputPipe    *io.PipeWriter
-
-	result *build.ResultHandle
-
-	processes *processes.Manager
-}
-
-func (s *session) cancelRunningProcesses() {
-	s.processes.CancelRunningProcesses()
 }
 
 func (m *Server) ListProcesses(ctx context.Context, req *pb.ListProcessesRequest) (res *pb.ListProcessesResponse, err error) {
-	m.sessionMu.Lock()
+	s := m.sessions.get(req.Ref)
-	defer m.sessionMu.Unlock()
+	if s == nil {
-	s, ok := m.session[req.Ref]
-	if !ok {
 		return nil, errors.Errorf("unknown ref %q", req.Ref)
 	}
 	res = new(pb.ListProcessesResponse)
-	for _, p := range s.processes.ListProcesses() {
+	for _, p := range s.listProcesses() {
 		res.Infos = append(res.Infos, p)
 	}
 	return res, nil
 }
 
 func (m *Server) DisconnectProcess(ctx context.Context, req *pb.DisconnectProcessRequest) (res *pb.DisconnectProcessResponse, err error) {
-	m.sessionMu.Lock()
+	s := m.sessions.get(req.Ref)
-	defer m.sessionMu.Unlock()
+	if s == nil {
-	s, ok := m.session[req.Ref]
-	if !ok {
 		return nil, errors.Errorf("unknown ref %q", req.Ref)
 	}
-	return res, s.processes.DeleteProcess(req.ProcessID)
+	return res, s.deleteProcess(req.ProcessID)
 }
 
 func (m *Server) Info(ctx context.Context, req *pb.InfoRequest) (res *pb.InfoResponse, err error) {
@@ -84,56 +67,20 @@ func (m *Server) Info(ctx context.Context, req *pb.InfoRequest) (res *pb.InfoRes
 }
 
 func (m *Server) List(ctx context.Context, req *pb.ListRequest) (res *pb.ListResponse, err error) {
-	keys := make(map[string]struct{})
-
-	m.sessionMu.Lock()
-	for k := range m.session {
-		keys[k] = struct{}{}
-	}
-	m.sessionMu.Unlock()
-
-	var keysL []string
-	for k := range keys {
-		keysL = append(keysL, k)
-	}
 	return &pb.ListResponse{
-		Keys: keysL,
+		Keys: m.sessions.list(),
 	}, nil
 }
 
 func (m *Server) Disconnect(ctx context.Context, req *pb.DisconnectRequest) (res *pb.DisconnectResponse, err error) {
-	key := req.Ref
+	if err := m.sessions.delete(req.Ref); err != nil {
-	if key == "" {
+		return nil, errors.Errorf("failed to delete session %q: %v", req.Ref, err)
-		return nil, errors.New("disconnect: empty key")
 	}
-
-	m.sessionMu.Lock()
-	if s, ok := m.session[key]; ok {
-		if s.cancelBuild != nil {
-			s.cancelBuild()
-		}
-		s.cancelRunningProcesses()
-		if s.result != nil {
-			s.result.Done()
-		}
-	}
-	delete(m.session, key)
-	m.sessionMu.Unlock()
-
 	return &pb.DisconnectResponse{}, nil
 }
 
 func (m *Server) Close() error {
-	m.sessionMu.Lock()
+	m.sessions.close()
-	for k := range m.session {
-		if s, ok := m.session[k]; ok {
-			if s.cancelBuild != nil {
-				s.cancelBuild()
-			}
-			s.cancelRunningProcesses()
-		}
-	}
-	m.sessionMu.Unlock()
 	return nil
 }
 
@@ -142,15 +89,11 @@ func (m *Server) Inspect(ctx context.Context, req *pb.InspectRequest) (*pb.Inspe
 	if ref == "" {
 		return nil, errors.New("inspect: empty key")
 	}
-	var bo *pb.BuildOptions
+	s := m.sessions.get(ref)
-	m.sessionMu.Lock()
+	if s == nil {
-	if s, ok := m.session[ref]; ok {
-		bo = s.buildOptions
-	} else {
-		m.sessionMu.Unlock()
 		return nil, errors.Errorf("inspect: unknown key %v", ref)
 	}
-	m.sessionMu.Unlock()
+	bo := s.getBuildOptions()
 	return &pb.InspectResponse{Options: bo}, nil
 }
 
@@ -160,77 +103,17 @@ func (m *Server) Build(ctx context.Context, req *pb.BuildRequest) (*pb.BuildResp
 		return nil, errors.New("build: empty key")
 	}
 
-	// Prepare status channel and session
+	s := m.sessions.get(ref)
-	m.sessionMu.Lock()
+	if s == nil {
-	if m.session == nil {
+		s = m.sessions.newSession(ref)
-		m.session = make(map[string]*session)
-	}
-	s, ok := m.session[ref]
-	if ok {
-		if !s.buildOnGoing.CompareAndSwap(false, true) {
-			m.sessionMu.Unlock()
-			return &pb.BuildResponse{}, errors.New("build ongoing")
-		}
-		s.cancelRunningProcesses()
-		s.result = nil
-	} else {
-		s = &session{}
-		s.buildOnGoing.Store(true)
-	}
-
-	s.processes = processes.NewManager()
-	statusChan := make(chan *pb.StatusResponse)
-	s.statusChan = statusChan
-	inR, inW := io.Pipe()
-	defer inR.Close()
-	s.inputPipe = inW
-	m.session[ref] = s
-	m.sessionMu.Unlock()
-	defer func() {
-		close(statusChan)
-		m.sessionMu.Lock()
-		s, ok := m.session[ref]
-		if ok {
-			s.statusChan = nil
-			s.buildOnGoing.Store(false)
-		}
-		m.sessionMu.Unlock()
-	}()
-
-	pw := pb.NewProgressWriter(statusChan)
-
-	// Build the specified request
-	ctx, cancel := context.WithCancel(ctx)
-	defer cancel()
-	resp, res, buildErr := m.buildFunc(ctx, req.Options, inR, pw)
-	m.sessionMu.Lock()
-	if s, ok := m.session[ref]; ok {
-		// NOTE: buildFunc can return *build.ResultHandle even on error (e.g. when it's implemented using (github.com/docker/buildx/controller/build).RunBuild).
-		if res != nil {
-			s.result = res
-			s.cancelBuild = cancel
-			s.buildOptions = req.Options
-			m.session[ref] = s
-			if buildErr != nil {
-				buildErr = controllererrors.WrapBuild(buildErr, ref)
-			}
-		}
-	} else {
-		m.sessionMu.Unlock()
-		return nil, errors.Errorf("build: unknown key %v", ref)
-	}
-	m.sessionMu.Unlock()
-
-	if buildErr != nil {
-		return nil, buildErr
 	}
-
+	resp, err := s.build(ctx, req.Options, func(err error) error { return controllererrors.WrapBuild(err, ref) })
 	if resp == nil {
 		resp = &client.SolveResponse{}
 	}
 	return &pb.BuildResponse{
 		ExporterResponse: resp.ExporterResponse,
-	}, nil
+	}, err
 }
 
 func (m *Server) Status(req *pb.StatusRequest, stream pb.Controller_StatusServer) error {
@@ -240,18 +123,15 @@ func (m *Server) Status(req *pb.StatusRequest, stream pb.Controller_StatusServer
 	}
 
 	// Wait and get status channel prepared by Build()
+	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
+	defer cancel()
 	var statusChan <-chan *pb.StatusResponse
-	for {
+	_, err := m.sessions.waitAndGet(ctx, ref, func(s *session) bool {
-		// TODO: timeout?
+		statusChan = s.getStatusChan()
-		m.sessionMu.Lock()
+		return statusChan != nil
-		if _, ok := m.session[ref]; !ok || m.session[ref].statusChan == nil {
+	})
-			m.sessionMu.Unlock()
+	if err != nil {
-			time.Sleep(time.Millisecond) // TODO: wait Build without busy loop and make it cancellable
+		return err
-			continue
-		}
-		statusChan = m.session[ref].statusChan
-		m.sessionMu.Unlock()
-		break
 	}
 
 	// forward status
@@ -286,23 +166,19 @@ func (m *Server) Input(stream pb.Controller_InputServer) (err error) {
 	}
 
 	// Wait and get input stream pipe prepared by Build()
+	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
+	defer cancel()
 	var inputPipeW *io.PipeWriter
-	for {
+	if _, err := m.sessions.waitAndGet(ctx, ref, func(s *session) bool {
-		// TODO: timeout?
+		inputPipeW = s.getInputWriter()
-		m.sessionMu.Lock()
+		return inputPipeW != nil
-		if _, ok := m.session[ref]; !ok || m.session[ref].inputPipe == nil {
+	}); err != nil {
-			m.sessionMu.Unlock()
+		return err
-			time.Sleep(time.Millisecond) // TODO: wait Build without busy loop and make it cancellable
-			continue
-		}
-		inputPipeW = m.session[ref].inputPipe
-		m.sessionMu.Unlock()
-		break
 	}
 
 	// Forward input stream
 	eg, ctx := errgroup.WithContext(context.TODO())
-	done := make(chan struct{})
+	doneCh := make(chan struct{})
 	msgCh := make(chan *pb.InputMessage)
 	eg.Go(func() error {
 		defer close(msgCh)
@@ -316,7 +192,7 @@ func (m *Server) Input(stream pb.Controller_InputServer) (err error) {
 			}
 			select {
 			case msgCh <- msg:
-			case <-done:
+			case <-doneCh:
 				return nil
 			case <-ctx.Done():
 				return nil
@@ -324,7 +200,7 @@ func (m *Server) Input(stream pb.Controller_InputServer) (err error) {
 		}
 	})
 	eg.Go(func() (retErr error) {
-		defer close(done)
+		defer close(doneCh)
 		defer func() {
 			if retErr != nil {
 				inputPipeW.CloseWithError(retErr)
@@ -378,26 +254,23 @@ func (m *Server) Invoke(srv pb.Controller_InvokeServer) error {
 			ref := initMessage.Ref
 			cfg := initMessage.InvokeConfig
 
-			m.sessionMu.Lock()
+			s := m.sessions.get(ref)
-			s, ok := m.session[ref]
+			if s == nil {
-			if !ok {
-				m.sessionMu.Unlock()
 				return errors.Errorf("invoke: unknown key %v", ref)
 			}
-			m.sessionMu.Unlock()
 
 			pid := initMessage.ProcessID
 			if pid == "" {
 				return errors.Errorf("invoke: specify process ID")
 			}
-			proc, ok := s.processes.Get(pid)
+			proc, ok := s.getProcess(pid)
 			if !ok {
 				// Start a new process.
 				if cfg == nil {
 					return errors.New("no container config is provided")
 				}
 				var err error
-				proc, err = s.processes.StartProcess(pid, s.result, cfg)
+				proc, err = s.startProcess(pid, cfg)
 				if err != nil {
 					return err
 				}

controller/remote/session.go

@@ -0,0 +1,217 @@
+package remote
+
+import (
+	"context"
+	"io"
+	"sync"
+	"sync/atomic"
+
+	"github.com/docker/buildx/build"
+	"github.com/docker/buildx/controller/pb"
+	"github.com/docker/buildx/controller/processes"
+	"github.com/moby/buildkit/client"
+	"github.com/pkg/errors"
+)
+
+type session struct {
+	manager *sessionManager
+
+	buildOnGoing atomic.Bool
+	statusChan   chan *pb.StatusResponse
+	cancelBuild  func()
+	buildOptions *pb.BuildOptions
+	inputPipe    *io.PipeWriter
+
+	result *build.ResultHandle
+
+	processes *processes.Manager
+
+	mu sync.Mutex
+}
+
+func (s *session) close() {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	s.processes.CancelRunningProcesses()
+	if s.cancelBuild != nil {
+		s.cancelBuild()
+	}
+	if s.result != nil {
+		s.result.Done()
+	}
+}
+
+func (s *session) getProcess(id string) (*processes.Process, bool) {
+	return s.processes.Get(id)
+}
+
+func (s *session) listProcesses() []*pb.ProcessInfo {
+	return s.processes.ListProcesses()
+}
+
+func (s *session) deleteProcess(id string) error {
+	return s.processes.DeleteProcess(id)
+}
+
+func (s *session) startProcess(id string, cfg *pb.InvokeConfig) (*processes.Process, error) {
+	res := s.result
+	return s.processes.StartProcess(id, res, cfg)
+}
+
+func (s *session) build(ctx context.Context, options *pb.BuildOptions, wrapBuildError func(error) error) (*client.SolveResponse, error) {
+	s.mu.Lock()
+	if !s.buildOnGoing.CompareAndSwap(false, true) {
+		s.mu.Unlock()
+		return nil, errors.New("build ongoing")
+	}
+	if s.processes != nil {
+		s.processes.CancelRunningProcesses()
+	}
+	s.processes = processes.NewManager()
+	s.result = nil
+	s.statusChan = make(chan *pb.StatusResponse)
+
+	inR, inW := io.Pipe()
+	s.inputPipe = inW
+
+	bCtx, cancel := context.WithCancel(ctx)
+
+	var doneOnce sync.Once
+	s.cancelBuild = func() {
+		doneOnce.Do(func() {
+			s.mu.Lock()
+			cancel()
+			close(s.statusChan)
+			s.statusChan = nil
+			s.buildOnGoing.Store(false)
+			s.mu.Unlock()
+		})
+	}
+	defer s.cancelBuild()
+	s.manager.updateCond.Broadcast()
+	s.mu.Unlock()
+
+	resp, res, buildErr := s.manager.buildFunc(bCtx, options, inR, pb.NewProgressWriter(s.statusChan))
+
+	s.mu.Lock()
+	// NOTE: buildFunc can return *build.ResultHandle even on error (e.g. when it's implemented using (github.com/docker/buildx/controller/build).RunBuild).
+	if res != nil {
+		s.result = res
+		s.buildOptions = options
+		s.manager.updateCond.Broadcast()
+		if buildErr != nil {
+			buildErr = wrapBuildError(buildErr)
+		}
+	}
+	s.mu.Unlock()
+
+	return resp, buildErr
+}
+
+func (s *session) getStatusChan() chan *pb.StatusResponse {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	return s.statusChan
+}
+
+func (s *session) getInputWriter() *io.PipeWriter {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	return s.inputPipe
+}
+
+func (s *session) getBuildOptions() *pb.BuildOptions {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	return s.buildOptions
+}
+
+func newSessionManager(buildFunc BuildFunc) *sessionManager {
+	var mu sync.Mutex
+	return &sessionManager{
+		updateCond:   sync.NewCond(&mu),
+		updateCondMu: &mu,
+		buildFunc:    buildFunc,
+	}
+}
+
+type sessionManager struct {
+	sessions  sync.Map
+	buildFunc BuildFunc
+
+	updateCond   *sync.Cond
+	updateCondMu *sync.Mutex
+
+	created atomic.Bool
+}
+
+func (m *sessionManager) newSession(ref string) *session {
+	s := &session{manager: m, processes: processes.NewManager()}
+	m.add(ref, s)
+	return s
+}
+
+func (m *sessionManager) add(id string, v *session) {
+	m.sessions.Store(id, v)
+	m.updateCond.Broadcast()
+	m.created.Store(true)
+}
+
+func (m *sessionManager) get(id string) *session {
+	v, ok := m.sessions.Load(id)
+	if !ok {
+		return nil
+	}
+	return v.(*session)
+}
+
+func (m *sessionManager) delete(id string) error {
+	v, ok := m.sessions.LoadAndDelete(id)
+	if !ok {
+		return errors.Errorf("unknown session %q", id)
+	}
+	v.(*session).close()
+	return nil
+}
+
+func (m *sessionManager) list() (res []string) {
+	m.sessions.Range(func(key, value any) bool {
+		res = append(res, key.(string))
+		return true
+	})
+	return
+}
+
+func (m *sessionManager) close() error {
+	m.sessions.Range(func(key, value any) bool {
+		value.(*session).close()
+		return true
+	})
+	return nil
+}
+
+func (m *sessionManager) waitAndGet(ctx context.Context, id string, f func(s *session) bool) (*session, error) {
+	go func() {
+		<-ctx.Done()
+		m.updateCond.Broadcast()
+	}()
+	for {
+		select {
+		case <-ctx.Done():
+			return nil, ctx.Err()
+		default:
+		}
+		s := m.get(id)
+		if s == nil || !f(s) {
+			m.updateCondMu.Lock()
+			m.updateCond.Wait()
+			m.updateCondMu.Unlock()
+			continue
+		}
+		return s, nil
+	}
+}
+
+func (m *sessionManager) sessionCreated() bool {
+	return m.created.Load()
+}