Discovery: speed up lookup tests

This speeds up the discover package test suite from 60-80 sec to 20-40 sec.

* disable lookup.slowdown() in tests
* dgramPipe: refactor to use a channel
* log ListenV4 err

The improvements can be compared using:
go test -count 1 ./p2p/discover
go test ./p2p/discover -test.run TestUDPv4_Lookup -blockprofile b.dat
go tool pprof -tree b.txt

p2p/discover/lookup.go

@@ -35,6 +35,7 @@ type lookup struct {
 	result      nodesByDistance
 	replyBuffer []*node
 	queries     int
+	noSlowdown  bool
 }
 
 type queryFunc func(*node) ([]*node, error)
@@ -50,6 +51,8 @@ func newLookup(ctx context.Context, tab *Table, target enode.ID, q queryFunc) *l
 		cancelCh:  ctx.Done(),
 		queries:   -1,
 	}
+	it.noSlowdown = isDisabledLookupSlowdown(ctx)
+
 	// Don't query further if we hit ourself.
 	// Unlikely to happen often in practice.
 	it.asked[tab.self().ID()] = true
@@ -129,7 +132,18 @@ func (it *lookup) startQueries() bool {
 	return it.queries > 0
 }
 
+func disableLookupSlowdown(ctx context.Context) context.Context {
+	return context.WithValue(ctx, "p2p.discover.lookup.noSlowdown", true)
+}
+
+func isDisabledLookupSlowdown(ctx context.Context) bool {
+	return ctx.Value("p2p.discover.lookup.noSlowdown") != nil
+}
+
 func (it *lookup) slowdown() {
+	if it.noSlowdown {
+		return
+	}
 	sleep := time.NewTimer(1 * time.Second)
 	defer sleep.Stop()
 	select {

p2p/discover/v4_udp_test.go

@@ -29,7 +29,6 @@ import (
 	"net"
 	"reflect"
 	"runtime"
-	"sync"
 	"testing"
 	"time"
 
@@ -77,10 +76,14 @@ func newUDPTest(t *testing.T) *udpTest {
 	}
 	ln := enode.NewLocalNode(test.db, test.localkey)
 	ctx := context.Background()
-	test.udp, _ = ListenV4(ctx, test.pipe, ln, Config{
+	ctx = disableLookupSlowdown(ctx)
+	test.udp, err = ListenV4(ctx, test.pipe, ln, Config{
 		PrivateKey: test.localkey,
 		Log:        testlog.Logger(t, log.LvlError),
 	})
+	if err != nil {
+		panic(err)
+	}
 	test.table = test.udp.tab
 	// Wait for initial refresh so the table doesn't send unexpected findnode.
 	<-test.table.initDone
@@ -589,6 +592,7 @@ func startLocalhostV4(t *testing.T, cfg Config) *UDPv4 {
 	ln.SetStaticIP(realaddr.IP)
 	ln.SetFallbackUDP(realaddr.Port)
 	ctx := context.Background()
+	ctx = disableLookupSlowdown(ctx)
 	udp, err := ListenV4(ctx, socket, ln, cfg)
 	if err != nil {
 		t.Fatal(err)
@@ -598,11 +602,8 @@ func startLocalhostV4(t *testing.T, cfg Config) *UDPv4 {
 
 // dgramPipe is a fake UDP socket. It queues all sent datagrams.
 type dgramPipe struct {
-	mu      *sync.Mutex
-	cond    *sync.Cond
-	closing chan struct{}
-	closed  bool
-	queue   []dgram
+	queue  chan dgram
+	closed chan struct{}
 }
 
 type dgram struct {
@@ -611,42 +612,34 @@ type dgram struct {
 }
 
 func newpipe() *dgramPipe {
-	mu := new(sync.Mutex)
 	return &dgramPipe{
-		closing: make(chan struct{}),
-		cond:    &sync.Cond{L: mu},
-		mu:      mu,
+		make(chan dgram, 1000),
+		make(chan struct{}),
 	}
 }
 
 // WriteToUDP queues a datagram.
 func (c *dgramPipe) WriteToUDP(b []byte, to *net.UDPAddr) (n int, err error) {
 	msg := make([]byte, len(b))
 	copy(msg, b)
-	c.mu.Lock()
-	defer c.mu.Unlock()
-	if c.closed {
-		return 0, errors.New("closed")
-	}
-	c.queue = append(c.queue, dgram{*to, b})
-	c.cond.Signal()
+
+	n = 0
+	err = errors.New("closed")
+	defer recover()
+
+	c.queue <- dgram{*to, b}
 	return len(b), nil
 }
 
 // ReadFromUDP just hangs until the pipe is closed.
 func (c *dgramPipe) ReadFromUDP(b []byte) (n int, addr *net.UDPAddr, err error) {
-	<-c.closing
+	<-c.closed
 	return 0, nil, io.EOF
 }
 
 func (c *dgramPipe) Close() error {
-	c.mu.Lock()
-	defer c.mu.Unlock()
-	if !c.closed {
-		close(c.closing)
-		c.closed = true
-	}
-	c.cond.Broadcast()
+	close(c.queue)
+	close(c.closed)
 	return nil
 }
 
@@ -655,29 +648,16 @@ func (c *dgramPipe) LocalAddr() net.Addr {
 }
 
 func (c *dgramPipe) receive() (dgram, error) {
-	c.mu.Lock()
-	defer c.mu.Unlock()
-
-	var timedOut bool
-	timer := time.AfterFunc(3*time.Second, func() {
-		c.mu.Lock()
-		timedOut = true
-		c.mu.Unlock()
-		c.cond.Broadcast()
-	})
-	defer timer.Stop()
+	ctx, cancel := context.WithTimeout(context.Background(), 3*time.Second)
+	defer cancel()
 
-	for len(c.queue) == 0 && !c.closed && !timedOut {
-		c.cond.Wait()
-	}
-	if c.closed {
+	select {
+	case p, isOpen := <-c.queue:
+		if isOpen {
+			return p, nil
+		}
 		return dgram{}, errClosed
-	}
-	if timedOut {
+	case <-ctx.Done():
 		return dgram{}, errTimeout
 	}
-	p := c.queue[0]
-	copy(c.queue, c.queue[1:])
-	c.queue = c.queue[:len(c.queue)-1]
-	return p, nil
 }

p2p/discover/v5_udp_test.go

@@ -104,6 +104,7 @@ func startLocalhostV5(t *testing.T, cfg Config) *UDPv5 {
 	ln.SetStaticIP(realaddr.IP)
 	ln.Set(enr.UDP(realaddr.Port))
 	ctx := context.Background()
+	ctx = disableLookupSlowdown(ctx)
 	udp, err := ListenV5(ctx, socket, ln, cfg)
 	if err != nil {
 		t.Fatal(err)
@@ -729,6 +730,7 @@ func newUDPV5Test(t *testing.T) *udpV5Test {
 	ln.SetStaticIP(net.IP{10, 0, 0, 1})
 	ln.Set(enr.UDP(30303))
 	ctx := context.Background()
+	ctx = disableLookupSlowdown(ctx)
 	test.udp, err = ListenV5(ctx, test.pipe, ln, Config{
 		PrivateKey:   test.localkey,
 		Log:          testlog.Logger(t, log.LvlError),