Test: fix flakey session peer manager tests

sessionpeermanager/sessionpeermanager.go

@@ -277,27 +277,38 @@ type getPeersMessage struct {
 	resp chan<- []bssd.OptimizedPeer
 }
 
+// Get all optimized peers in order followed by randomly ordered unoptimized
+// peers, with a limit of maxOptimizedPeers
 func (prm *getPeersMessage) handle(spm *SessionPeerManager) {
 	randomOrder := rand.Perm(len(spm.unoptimizedPeersArr))
+
+	// Number of peers to get in total: unoptimized + optimized
+	// limited by maxOptimizedPeers
 	maxPeers := len(spm.unoptimizedPeersArr) + len(spm.optimizedPeersArr)
 	if maxPeers > maxOptimizedPeers {
 		maxPeers = maxOptimizedPeers
 	}
+
+	// The best peer latency is the first optimized peer's latency.
+	// If we haven't recorded any peer's latency, use 0.
 	var bestPeerLatency float64
 	if len(spm.optimizedPeersArr) > 0 {
 		bestPeerLatency = float64(spm.activePeers[spm.optimizedPeersArr[0]].latency)
 	} else {
 		bestPeerLatency = 0
 	}
+
 	optimizedPeers := make([]bssd.OptimizedPeer, 0, maxPeers)
 	for i := 0; i < maxPeers; i++ {
+		// First add optimized peers in order
 		if i < len(spm.optimizedPeersArr) {
 			p := spm.optimizedPeersArr[i]
 			optimizedPeers = append(optimizedPeers, bssd.OptimizedPeer{
 				Peer:               p,
 				OptimizationRating: bestPeerLatency / float64(spm.activePeers[p].latency),
 			})
 		} else {
+			// Then add unoptimized peers in random order
 			p := spm.unoptimizedPeersArr[randomOrder[i-len(spm.optimizedPeersArr)]]
 			optimizedPeers = append(optimizedPeers, bssd.OptimizedPeer{Peer: p, OptimizationRating: 0.0})
 		}

sessionpeermanager/sessionpeermanager_test.go

@@ -2,6 +2,7 @@ package sessionpeermanager
 
 import (
 	"context"
+	"fmt"
 	"math/rand"
 	"sync"
 	"testing"
@@ -148,9 +149,10 @@ func TestRecordingReceivedBlocks(t *testing.T) {
 
 func TestOrderingPeers(t *testing.T) {
 	ctx := context.Background()
-	ctx, cancel := context.WithTimeout(ctx, 30*time.Millisecond)
+	ctx, cancel := context.WithTimeout(ctx, 60*time.Millisecond)
 	defer cancel()
-	peers := testutil.GeneratePeers(100)
+	peerCount := 100
+	peers := testutil.GeneratePeers(peerCount)
 	completed := make(chan struct{})
 	fpt := &fakePeerTagger{}
 	fppf := &fakePeerProviderFinder{peers, completed}
@@ -165,28 +167,32 @@ func TestOrderingPeers(t *testing.T) {
 	case <-ctx.Done():
 		t.Fatal("Did not finish finding providers")
 	}
-	time.Sleep(2 * time.Millisecond)
+	time.Sleep(5 * time.Millisecond)
 
 	// record broadcast
 	sessionPeerManager.RecordPeerRequests(nil, c)
 
 	// record receives
-	peer1 := peers[rand.Intn(100)]
-	peer2 := peers[rand.Intn(100)]
-	peer3 := peers[rand.Intn(100)]
-	time.Sleep(1 * time.Millisecond)
-	sessionPeerManager.RecordPeerResponse(peer1, []cid.Cid{c[0]})
+	randi := rand.Perm(peerCount)
+	peer1 := peers[randi[0]]
+	peer2 := peers[randi[1]]
+	peer3 := peers[randi[2]]
 	time.Sleep(5 * time.Millisecond)
+	sessionPeerManager.RecordPeerResponse(peer1, []cid.Cid{c[0]})
+	time.Sleep(25 * time.Millisecond)
 	sessionPeerManager.RecordPeerResponse(peer2, []cid.Cid{c[0]})
-	time.Sleep(1 * time.Millisecond)
+	time.Sleep(5 * time.Millisecond)
 	sessionPeerManager.RecordPeerResponse(peer3, []cid.Cid{c[0]})
 
 	sessionPeers := sessionPeerManager.GetOptimizedPeers()
 	if len(sessionPeers) != maxOptimizedPeers {
-		t.Fatal("Should not return more than the max of optimized peers")
+		t.Fatal(fmt.Sprintf("Should not return more (%d) than the max of optimized peers (%d)", len(sessionPeers), maxOptimizedPeers))
 	}
 
 	// should prioritize peers which are fastest
+	// peer1: ~5ms
+	// peer2: 5 + 25 = ~30ms
+	// peer3: 5 + 25 + 5 = ~35ms
 	if (sessionPeers[0].Peer != peer1) || (sessionPeers[1].Peer != peer2) || (sessionPeers[2].Peer != peer3) {
 		t.Fatal("Did not prioritize peers that received blocks")
 	}
@@ -202,7 +208,7 @@ func TestOrderingPeers(t *testing.T) {
 		t.Fatal("Did not assign rating to other optimized peers correctly")
 	}
 
-	// should other peers rating of zero
+	// should give other non-optimized peers rating of zero
 	for i := 3; i < maxOptimizedPeers; i++ {
 		if sessionPeers[i].OptimizationRating != 0.0 {
 			t.Fatal("Did not assign rating to unoptimized peer correctly")
@@ -220,13 +226,16 @@ func TestOrderingPeers(t *testing.T) {
 	// call again
 	nextSessionPeers := sessionPeerManager.GetOptimizedPeers()
 	if len(nextSessionPeers) != maxOptimizedPeers {
-		t.Fatal("Should not return more than the max of optimized peers")
+		t.Fatal(fmt.Sprintf("Should not return more (%d) than the max of optimized peers (%d)", len(nextSessionPeers), maxOptimizedPeers))
 	}
 
 	// should sort by average latency
+	// peer1: ~5ms
+	// peer3: (~35ms + ~5ms) / 2 = ~20ms
+	// peer2: ~30ms
 	if (nextSessionPeers[0].Peer != peer1) || (nextSessionPeers[1].Peer != peer3) ||
 		(nextSessionPeers[2].Peer != peer2) {
-		t.Fatal("Did not dedup peers which received multiple blocks")
+		t.Fatal("Did not correctly update order of peers sorted by average latency")
 	}
 
 	// should randomize other peers
@@ -358,7 +367,7 @@ func TestTimeoutsAndCancels(t *testing.T) {
 
 func TestUntaggingPeers(t *testing.T) {
 	ctx := context.Background()
-	ctx, cancel := context.WithTimeout(ctx, 10*time.Millisecond)
+	ctx, cancel := context.WithTimeout(ctx, 30*time.Millisecond)
 	defer cancel()
 	peers := testutil.GeneratePeers(5)
 	completed := make(chan struct{})
@@ -375,7 +384,7 @@ func TestUntaggingPeers(t *testing.T) {
 	case <-ctx.Done():
 		t.Fatal("Did not finish finding providers")
 	}
-	time.Sleep(2 * time.Millisecond)
+	time.Sleep(15 * time.Millisecond)
 
 	if fpt.count() != len(peers) {
 		t.Fatal("Peers were not tagged!")