Stop old dialers when we get a new proxy config

dialer/dialer.go

@@ -11,28 +11,37 @@ import (
 	"io"
 	"net"
 	"runtime/debug"
+	"sync/atomic"
 	"time"
 
 	"github.com/getlantern/golog"
 )
 
 var log = golog.LoggerFor("dialer")
 
+var currentDialer atomic.Value
+
 // New creates a new dialer that first tries to connect as quickly as possilbe while also
 // optimizing for the fastest dialer.
 func New(opts *Options) Dialer {
-	return NewTwoPhaseDialer(opts, func(opts *Options, existing Dialer) Dialer {
+	if currentDialer.Load() != nil {
+		log.Debug("Closing existing dialer")
+		currentDialer.Load().(Dialer).Close()
+	}
+	d := NewTwoPhaseDialer(opts, func(opts *Options, existing Dialer) Dialer {
 		bandit, err := NewBandit(opts)
 		if err != nil {
 			log.Errorf("Unable to create bandit: %v", err)
 			return existing
 		}
 		return bandit
 	})
+	currentDialer.Store(d)
+	return d
 }
 
 // NoDialer returns a dialer that does nothing. This is useful during startup
-// until a real dialer is available.
+// when we don't yet have proxies to dial through.
 func NoDialer() Dialer {
 	return &noDialer{}
 }
@@ -48,6 +57,11 @@ func (d *noDialer) DialContext(ctx context.Context, network, addr string) (net.C
 	return nil, errors.New("no dialer available")
 }
 
+func (d *noDialer) Close() {}
+
+// Make sure noDialer implements Dialer
+var _ Dialer = (*noDialer)(nil)
+
 const (
 	// NetworkConnect is a pseudo network name to instruct the dialer to establish
 	// a CONNECT tunnel to the proxy.
@@ -90,6 +104,9 @@ type Dialer interface {
 
 	// DialContext dials out to the domain or IP address representing a destination site.
 	DialContext(ctx context.Context, network, addr string) (net.Conn, error)
+
+	// Close closes the dialer and cleans up any resources
+	Close()
 }
 
 // hasSucceedingDialer checks whether or not any of the given dialers is able to successfully dial our proxies

dialer/fastconnect.go

@@ -29,8 +29,14 @@ type fastConnectDialer struct {
 
 	next func(*Options, Dialer) Dialer
 	opts *Options
+
+	// Create a channel for stopping connections to dialers
+	stopCh chan struct{}
 }
 
+// Make sure fastConnectDialer implements Dialer
+var _ Dialer = (*fastConnectDialer)(nil)
+
 func newFastConnectDialer(opts *Options, next func(opts *Options, existing Dialer) Dialer) *fastConnectDialer {
 	if opts.OnError == nil {
 		opts.OnError = func(error, bool) {}
@@ -45,6 +51,7 @@ func newFastConnectDialer(opts *Options, next func(opts *Options, existing Diale
 		opts:      opts,
 		next:      next,
 		topDialer: protectedDialer{},
+		stopCh:    make(chan struct{}, 10),
 	}
 }
 
@@ -76,6 +83,13 @@ func (fcd *fastConnectDialer) DialContext(ctx context.Context, network, addr str
 	return conn, err
 }
 
+func (fcd *fastConnectDialer) Close() {
+	// We don't call Stop on the Dialers themselves here because they are likely
+	// in use by other Dialers, such as the BanditDialer.
+	// Stop all dialing
+	fcd.stopCh <- struct{}{}
+}
+
 func (fcd *fastConnectDialer) onConnected(pd ProxyDialer, connectTime time.Duration) {
 	log.Debugf("Connected to %v", pd.Name())
 
@@ -99,13 +113,20 @@ func (fcd *fastConnectDialer) connectAll(dialers []ProxyDialer) {
 		return
 	}
 	log.Debugf("Dialing all dialers in parallel %#v", dialers)
-	// Loop until we're connected
-	for len(fcd.connected.dialers) < 2 {
-		fcd.parallelDial(dialers)
-		// Add jitter to avoid thundering herd
-		time.Sleep(time.Duration(rand.Intn(4000)) * time.Millisecond)
+	for {
+		// Loop until we're connected
+		if len(fcd.connected.dialers) < 2 {
+			fcd.parallelDial(dialers)
+		} else {
+			break
+		}
+		select {
+		case <-fcd.stopCh:
+			log.Debug("Stopping parallel dialing")
+			return
+		case <-time.After(time.Duration(rand.Intn(4000)) * time.Millisecond):
+		}
 	}
-
 	// At this point, we've tried all of the dialers, and they've all either
 	// succeeded or failed.
 

dialer/two_phase_dialer.go

@@ -16,6 +16,9 @@ type twoPhaseDialer struct {
 	activeDialer activeDialer
 }
 
+// Make sure twoPhaseDialer implements Dialer
+var _ Dialer = (*twoPhaseDialer)(nil)
+
 // NewTwoPhaseDialer creates a new dialer for checking proxy connectivity.
 func NewTwoPhaseDialer(opts *Options, next func(opts *Options, existing Dialer) Dialer) Dialer {
 	log.Debugf("Creating new two phase dialer with %d dialers", len(opts.Dialers))
@@ -45,6 +48,14 @@ func (ccd *twoPhaseDialer) DialContext(ctx context.Context, network string, addr
 	return td.DialContext(ctx, network, addr)
 }
 
+// Close implements Dialer.
+func (ccd *twoPhaseDialer) Close() {
+	td := ccd.activeDialer.get()
+	if td != nil {
+		td.Close()
+	}
+}
+
 // protectedDialer protects a dialer.Dialer with a RWMutex. We can't use an atomic.Value here
 // because Dialer is an interface.
 type activeDialer struct {