coder · spikecurtis · Nov 7, 2024 · Oct 28, 2024
diff --git a/tailnet/controllers.go b/tailnet/controllers.go
@@ -4,6 +4,7 @@ import (
 	"context"
 	"fmt"
 	"io"
+	"math"
 	"strings"
 	"sync"
 	"time"
@@ -16,6 +17,7 @@ import (
 
 	"cdr.dev/slog"
 	"github.com/coder/coder/v2/tailnet/proto"
+	"github.com/coder/quartz"
 )
 
 // A Controller connects to the tailnet control plane, and then uses the control protocols to
@@ -523,3 +525,142 @@ func sendTelemetry(
 	}
 	return false
 }
+
+type basicResumeTokenController struct {
+	logger slog.Logger
+
+	sync.Mutex
+	token     *proto.RefreshResumeTokenResponse
+	refresher *basicResumeTokenRefresher
+
+	// for testing
+	clock quartz.Clock
+}
+
+func (b *basicResumeTokenController) New(client ResumeTokenClient) CloserWaiter {
+	b.Lock()
+	defer b.Unlock()
+	if b.refresher != nil {
+		cErr := b.refresher.Close(context.Background())
+		if cErr != nil {
+			b.logger.Debug(context.Background(), "closed previous refresher", slog.Error(cErr))
+		}
+	}
+	b.refresher = newBasicResumeTokenRefresher(b.logger, b.clock, b, client)
+	return b.refresher
+}
+
+func (b *basicResumeTokenController) Token() (string, bool) {
+	b.Lock()
+	defer b.Unlock()
+	if b.token == nil {
+		return "", false
+	}
+	if b.token.ExpiresAt.AsTime().Before(b.clock.Now()) {
+		return "", false
+	}
+	return b.token.Token, true
+}
+
+func NewBasicResumeTokenController(logger slog.Logger, clock quartz.Clock) ResumeTokenController {
+	return &basicResumeTokenController{
+		logger: logger,
+		clock:  clock,
+	}
+}
+
+type basicResumeTokenRefresher struct {
+	logger slog.Logger
+	ctx    context.Context
+	cancel context.CancelFunc
+	ctrl   *basicResumeTokenController
+	client ResumeTokenClient
+	errCh  chan error
+
+	sync.Mutex
+	closed bool
+	timer  *quartz.Timer
+}
+
+func (r *basicResumeTokenRefresher) Close(_ context.Context) error {
+	r.cancel()
+	r.Lock()
+	defer r.Unlock()
+	if r.closed {
+		return nil
+	}
+	r.closed = true
+	r.timer.Stop()
+	select {
+	case r.errCh <- nil:
+	default: // already have an error
+	}
+	return nil
+}
+
+func (r *basicResumeTokenRefresher) Wait() <-chan error {
+	return r.errCh
+}
+
+const never time.Duration = math.MaxInt64
+
+func newBasicResumeTokenRefresher(
+	logger slog.Logger, clock quartz.Clock,
+	ctrl *basicResumeTokenController, client ResumeTokenClient,
+) *basicResumeTokenRefresher {
+	r := &basicResumeTokenRefresher{
+		logger: logger,
+		ctrl:   ctrl,
+		client: client,
+		errCh:  make(chan error, 1),
+	}
+	r.ctx, r.cancel = context.WithCancel(context.Background())
+	r.timer = clock.AfterFunc(never, r.refresh)
+	go r.refresh()
+	return r
+}
+
+func (r *basicResumeTokenRefresher) refresh() {
+	if r.ctx.Err() != nil {
+		return // context done, no need to refresh
+	}
+	res, err := r.client.RefreshResumeToken(r.ctx, &proto.RefreshResumeTokenRequest{})
+	if xerrors.Is(err, context.Canceled) || xerrors.Is(err, context.DeadlineExceeded) {
+		// these can only come from being closed, no need to log
+		select {
+		case r.errCh <- nil:
+		default: // already have an error
+		}
+		return
+	}
+	if err != nil {
+		r.logger.Error(r.ctx, "error refreshing coordinator resume token", slog.Error(err))
+		select {
+		case r.errCh <- err:
+		default: // already have an error
+		}
+		return
+	}
+	r.logger.Debug(r.ctx, "refreshed coordinator resume token",
+		slog.F("expires_at", res.GetExpiresAt()),
+		slog.F("refresh_in", res.GetRefreshIn()),
+	)
+	r.ctrl.Lock()
+	if r.ctrl.refresher == r { // don't overwrite if we're not the current refresher
+		r.ctrl.token = res
+	} else {
+		r.logger.Debug(context.Background(), "not writing token because we have a new client")
+	}
+	r.ctrl.Unlock()
+	dur := res.RefreshIn.AsDuration()
+	if dur <= 0 {
+		// A sensible delay to refresh again.
+		dur = 30 * time.Minute
+	}
+	r.Lock()
+	defer r.Unlock()
+	if r.closed {
+		return
+	}
+	r.timer.Reset(dur, "basicResumeTokenRefresher", "refresh")
+}
diff --git a/tailnet/controllers_test.go b/tailnet/controllers_test.go
@@ -13,6 +13,8 @@ import (
 	"github.com/stretchr/testify/require"
 	"go.uber.org/mock/gomock"
 	"golang.org/x/xerrors"
+	"google.golang.org/protobuf/types/known/durationpb"
+	"google.golang.org/protobuf/types/known/timestamppb"
 	"storj.io/drpc"
 	"storj.io/drpc/drpcerr"
 	"tailscale.com/tailcfg"
@@ -24,6 +26,7 @@ import (
 	"github.com/coder/coder/v2/tailnet/proto"
 	"github.com/coder/coder/v2/tailnet/tailnettest"
 	"github.com/coder/coder/v2/testutil"
+	"github.com/coder/quartz"
 )
 
 func TestInMemoryCoordination(t *testing.T) {
@@ -507,3 +510,171 @@ type fakeTelemetryCall struct {
 	req   *proto.TelemetryRequest
 	errCh chan error
 }
+
+func TestBasicResumeTokenController_Mainline(t *testing.T) {
+	t.Parallel()
+	ctx := testutil.Context(t, testutil.WaitShort)
+	logger := slogtest.Make(t, nil).Leveled(slog.LevelDebug)
+	fr := newFakeResumeTokenClient(ctx)
+	mClock := quartz.NewMock(t)
+	trp := mClock.Trap().TimerReset("basicResumeTokenRefresher", "refresh")
+	defer trp.Close()
+
+	uut := tailnet.NewBasicResumeTokenController(logger, mClock)
+	_, ok := uut.Token()
+	require.False(t, ok)
+
+	cwCh := make(chan tailnet.CloserWaiter, 1)
+	go func() {
+		cwCh <- uut.New(fr)
+	}()
+	call := testutil.RequireRecvCtx(ctx, t, fr.calls)
+	testutil.RequireSendCtx(ctx, t, call.resp, &proto.RefreshResumeTokenResponse{
+		Token:     "test token 1",
+		RefreshIn: durationpb.New(100 * time.Second),
+		ExpiresAt: timestamppb.New(mClock.Now().Add(200 * time.Second)),
+	})
+	trp.MustWait(ctx).Release() // initial refresh done
+	token, ok := uut.Token()
+	require.True(t, ok)
+	require.Equal(t, "test token 1", token)
+	cw := testutil.RequireRecvCtx(ctx, t, cwCh)
+
+	w := mClock.Advance(100 * time.Second)
+	call = testutil.RequireRecvCtx(ctx, t, fr.calls)
+	testutil.RequireSendCtx(ctx, t, call.resp, &proto.RefreshResumeTokenResponse{
+		Token:     "test token 2",
+		RefreshIn: durationpb.New(50 * time.Second),
+		ExpiresAt: timestamppb.New(mClock.Now().Add(200 * time.Second)),
+	})
+	resetCall := trp.MustWait(ctx)
+	require.Equal(t, resetCall.Duration, 50*time.Second)
+	resetCall.Release()
+	w.MustWait(ctx)
+	token, ok = uut.Token()
+	require.True(t, ok)
+	require.Equal(t, "test token 2", token)
+
+	err := cw.Close(ctx)
+	require.NoError(t, err)
+	err = testutil.RequireRecvCtx(ctx, t, cw.Wait())
+	require.NoError(t, err)
+
+	token, ok = uut.Token()
+	require.True(t, ok)
+	require.Equal(t, "test token 2", token)
+
+	mClock.Advance(201 * time.Second).MustWait(ctx)
+	_, ok = uut.Token()
+	require.False(t, ok)
+}
+
+func TestBasicResumeTokenController_NewWhileRefreshing(t *testing.T) {
+	t.Parallel()
+	ctx := testutil.Context(t, testutil.WaitShort)
+	logger := slogtest.Make(t, nil).Leveled(slog.LevelDebug)
+	mClock := quartz.NewMock(t)
+	trp := mClock.Trap().TimerReset("basicResumeTokenRefresher", "refresh")
+	defer trp.Close()
+
+	uut := tailnet.NewBasicResumeTokenController(logger, mClock)
+	_, ok := uut.Token()
+	require.False(t, ok)
+
+	fr1 := newFakeResumeTokenClient(ctx)
+	cwCh1 := make(chan tailnet.CloserWaiter, 1)
+	go func() {
+		cwCh1 <- uut.New(fr1)
+	}()
+	call1 := testutil.RequireRecvCtx(ctx, t, fr1.calls)
+
+	fr2 := newFakeResumeTokenClient(ctx)
+	cwCh2 := make(chan tailnet.CloserWaiter, 1)
+	go func() {
+		cwCh2 <- uut.New(fr2)
+	}()
+	call2 := testutil.RequireRecvCtx(ctx, t, fr2.calls)
+
+	testutil.RequireSendCtx(ctx, t, call2.resp, &proto.RefreshResumeTokenResponse{
+		Token:     "test token 2.0",
+		RefreshIn: durationpb.New(102 * time.Second),
+		ExpiresAt: timestamppb.New(mClock.Now().Add(200 * time.Second)),
+	})
+
+	cw2 := testutil.RequireRecvCtx(ctx, t, cwCh2) // this ensures Close was called on 1
+
+	testutil.RequireSendCtx(ctx, t, call1.resp, &proto.RefreshResumeTokenResponse{
+		Token:     "test token 1",
+		RefreshIn: durationpb.New(101 * time.Second),
+		ExpiresAt: timestamppb.New(mClock.Now().Add(200 * time.Second)),
+	})
+
+	trp.MustWait(ctx).Release()
+
+	token, ok := uut.Token()
+	require.True(t, ok)
+	require.Equal(t, "test token 2.0", token)
+
+	// refresher 1 should already be closed.
+	cw1 := testutil.RequireRecvCtx(ctx, t, cwCh1)
+	err := testutil.RequireRecvCtx(ctx, t, cw1.Wait())
+	require.NoError(t, err)
+
+	w := mClock.Advance(102 * time.Second)
+	call := testutil.RequireRecvCtx(ctx, t, fr2.calls)
+	testutil.RequireSendCtx(ctx, t, call.resp, &proto.RefreshResumeTokenResponse{
+		Token:     "test token 2.1",
+		RefreshIn: durationpb.New(50 * time.Second),
+		ExpiresAt: timestamppb.New(mClock.Now().Add(200 * time.Second)),
+	})
+	resetCall := trp.MustWait(ctx)
+	require.Equal(t, resetCall.Duration, 50*time.Second)
+	resetCall.Release()
+	w.MustWait(ctx)
+	token, ok = uut.Token()
+	require.True(t, ok)
+	require.Equal(t, "test token 2.1", token)
+
+	err = cw2.Close(ctx)
+	require.NoError(t, err)
+	err = testutil.RequireRecvCtx(ctx, t, cw2.Wait())
+	require.NoError(t, err)
+}
+
+func newFakeResumeTokenClient(ctx context.Context) *fakeResumeTokenClient {
+	return &fakeResumeTokenClient{
+		ctx:   ctx,
+		calls: make(chan *fakeResumeTokenCall),
+	}
+}
+
+type fakeResumeTokenClient struct {
+	ctx   context.Context
+	calls chan *fakeResumeTokenCall
+}
+
+func (f *fakeResumeTokenClient) RefreshResumeToken(_ context.Context, _ *proto.RefreshResumeTokenRequest) (*proto.RefreshResumeTokenResponse, error) {
+	call := &fakeResumeTokenCall{
+		resp:  make(chan *proto.RefreshResumeTokenResponse),
+		errCh: make(chan error),
+	}
+	select {
+	case <-f.ctx.Done():
+		return nil, f.ctx.Err()
+	case f.calls <- call:
+		// OK
+	}
+	select {
+	case <-f.ctx.Done():
+		return nil, f.ctx.Err()
+	case err := <-call.errCh:
+		return nil, err
+	case resp := <-call.resp:
+		return resp, nil
+	}
+}
+
+type fakeResumeTokenCall struct {
+	resp  chan *proto.RefreshResumeTokenResponse
+	errCh chan error
+}