Fix races with DialQueue variables

dial_queue.go

@@ -9,7 +9,7 @@ import (
 	queue "github.com/libp2p/go-libp2p-peerstore/queue"
 )
 
-var (
+const (
 	// DialQueueMinParallelism is the minimum number of worker dial goroutines that will be alive at any time.
 	DialQueueMinParallelism = 6
 	// DialQueueMaxParallelism is the maximum number of worker dial goroutines that can be alive at any time.
@@ -25,8 +25,10 @@ type dialQueue struct {
 	ctx    context.Context
 	dialFn func(context.Context, peer.ID) error
 
-	nWorkers      int
-	scalingFactor float64
+	nWorkers          int
+	scalingFactor     float64
+	scalingMutePeriod time.Duration
+	maxIdle           time.Duration
 
 	in  *queue.ChanQueue
 	out *queue.ChanQueue
@@ -61,12 +63,16 @@ type waitingCh struct {
 // Dialler throttling (e.g. FD limit exceeded) is a concern, as we can easily spin up more workers to compensate, and
 // end up adding fuel to the fire. Since we have no deterministic way to detect this for now, we hard-limit concurrency
 // to DialQueueMaxParallelism.
-func newDialQueue(ctx context.Context, target string, in *queue.ChanQueue, dialFn func(context.Context, peer.ID) error) *dialQueue {
+func newDialQueue(ctx context.Context, target string, in *queue.ChanQueue, dialFn func(context.Context, peer.ID) error,
+	maxIdle, scalingMutePeriod time.Duration,
+) *dialQueue {
 	sq := &dialQueue{
-		ctx:           ctx,
-		dialFn:        dialFn,
-		nWorkers:      DialQueueMinParallelism,
-		scalingFactor: 1.5,
+		ctx:               ctx,
+		dialFn:            dialFn,
+		nWorkers:          DialQueueMinParallelism,
+		scalingFactor:     1.5,
+		scalingMutePeriod: scalingMutePeriod,
+		maxIdle:           maxIdle,
 
 		in:  in,
 		out: queue.NewChanQueue(ctx, queue.NewXORDistancePQ(target)),
@@ -145,13 +151,13 @@ func (dq *dialQueue) control() {
 				dialled = nil
 			}
 		case <-dq.growCh:
-			if time.Since(lastScalingEvt) < DialQueueScalingMutePeriod {
+			if time.Since(lastScalingEvt) < dq.scalingMutePeriod {
 				continue
 			}
 			dq.grow()
 			lastScalingEvt = time.Now()
 		case <-dq.shrinkCh:
-			if time.Since(lastScalingEvt) < DialQueueScalingMutePeriod {
+			if time.Since(lastScalingEvt) < dq.scalingMutePeriod {
 				continue
 			}
 			dq.shrink()
@@ -259,7 +265,7 @@ func (dq *dialQueue) worker() {
 		case <-idleTimer.C:
 		default:
 		}
-		idleTimer.Reset(DialQueueMaxIdle)
+		idleTimer.Reset(dq.maxIdle)
 
 		select {
 		case <-dq.dieCh:

dial_queue_test.go

@@ -2,7 +2,6 @@ package dht
 
 import (
 	"context"
-	"fmt"
 	"sync"
 	"sync/atomic"
 	"testing"
@@ -12,12 +11,7 @@ import (
 	queue "github.com/libp2p/go-libp2p-peerstore/queue"
 )
 
-func init() {
-	DialQueueScalingMutePeriod = 0
-}
-
 func TestDialQueueGrowsOnSlowDials(t *testing.T) {
-	DialQueueMaxIdle = 10 * time.Minute
 
 	in := queue.NewChanQueue(context.Background(), queue.NewXORDistancePQ("test"))
 	hang := make(chan struct{})
@@ -35,7 +29,7 @@ func TestDialQueueGrowsOnSlowDials(t *testing.T) {
 	}
 
 	// remove the mute period to grow faster.
-	dq := newDialQueue(context.Background(), "test", in, dialFn)
+	dq := newDialQueue(context.Background(), "test", in, dialFn, 10*time.Minute, 0)
 
 	for i := 0; i < 4; i++ {
 		_ = dq.Consume()
@@ -55,7 +49,6 @@ func TestDialQueueGrowsOnSlowDials(t *testing.T) {
 
 func TestDialQueueShrinksWithNoConsumers(t *testing.T) {
 	// reduce interference from the other shrink path.
-	DialQueueMaxIdle = 10 * time.Minute
 
 	in := queue.NewChanQueue(context.Background(), queue.NewXORDistancePQ("test"))
 	hang := make(chan struct{})
@@ -68,12 +61,7 @@ func TestDialQueueShrinksWithNoConsumers(t *testing.T) {
 		return nil
 	}
 
-	dq := newDialQueue(context.Background(), "test", in, dialFn)
-
-	defer func() {
-		recover()
-		fmt.Println(dq.nWorkers)
-	}()
+	dq := newDialQueue(context.Background(), "test", in, dialFn, 10*time.Minute, 0)
 
 	// acquire 3 consumers, everytime we acquire a consumer, we will grow the pool because no dial job is completed
 	// and immediately returnable.
@@ -117,8 +105,6 @@ func TestDialQueueShrinksWithNoConsumers(t *testing.T) {
 
 // Inactivity = workers are idle because the DHT query is progressing slow and is producing too few peers to dial.
 func TestDialQueueShrinksWithWhenIdle(t *testing.T) {
-	DialQueueMaxIdle = 1 * time.Second
-
 	in := queue.NewChanQueue(context.Background(), queue.NewXORDistancePQ("test"))
 	hang := make(chan struct{})
 
@@ -135,7 +121,7 @@ func TestDialQueueShrinksWithWhenIdle(t *testing.T) {
 		in.EnqChan <- peer.ID(i)
 	}
 
-	dq := newDialQueue(context.Background(), "test", in, dialFn)
+	dq := newDialQueue(context.Background(), "test", in, dialFn, time.Second, 0)
 
 	// keep up to speed with backlog by releasing the dial function every time we acquire a channel.
 	for i := 0; i < 13; i++ {
@@ -161,8 +147,6 @@ func TestDialQueueShrinksWithWhenIdle(t *testing.T) {
 }
 
 func TestDialQueueMutePeriodHonored(t *testing.T) {
-	DialQueueScalingMutePeriod = 2 * time.Second
-
 	in := queue.NewChanQueue(context.Background(), queue.NewXORDistancePQ("test"))
 	hang := make(chan struct{})
 	var wg sync.WaitGroup
@@ -178,7 +162,7 @@ func TestDialQueueMutePeriodHonored(t *testing.T) {
 		in.EnqChan <- peer.ID(i)
 	}
 
-	dq := newDialQueue(context.Background(), "test", in, dialFn)
+	dq := newDialQueue(context.Background(), "test", in, dialFn, DialQueueMaxIdle, 2*time.Second)
 
 	// pick up three consumers.
 	for i := 0; i < 3; i++ {

query.go

@@ -103,7 +103,7 @@ func newQueryRunner(q *dhtQuery) *dhtQueryRunner {
 		peersToQuery:   peersToQuery,
 		proc:           proc,
 	}
-	r.peersDialed = newDialQueue(ctx, q.key, peersToQuery, r.dialPeer)
+	r.peersDialed = newDialQueue(ctx, q.key, peersToQuery, r.dialPeer, DialQueueMaxIdle, DialQueueScalingMutePeriod)
 	return r
 }