do not send cancel message to peer that sent block

CHANGELOG.md

@@ -19,6 +19,7 @@ The following emojis are used to highlight certain changes:
 - `gateway` Support for custom DNSLink / DoH resolvers on `localhost` to simplify integration with non-ICANN DNS systems [#645](https://github.com/ipfs/boxo/pull/645)
 
 ### Changed
+- Do not send CANCEL to peer that block was received from, as this is redundant. [#784](https://github.com/ipfs/boxo/pull/784)
 
 - `gateway` The default DNSLink resolver for `.eth` TLD changed to `https://dns.eth.limo/dns-query` [#781](https://github.com/ipfs/boxo/pull/781)
 - `gateway` The default DNSLink resolver for `.crypto` TLD changed to `https://resolver.unstoppable.io/dns-query` [#782](https://github.com/ipfs/boxo/pull/782)

bitswap/client/internal/peermanager/peermanager.go

@@ -156,12 +156,12 @@ func (pm *PeerManager) SendWants(ctx context.Context, p peer.ID, wantBlocks []ci
 
 // SendCancels sends cancels for the given keys to all peers who had previously
 // received a want for those keys.
-func (pm *PeerManager) SendCancels(ctx context.Context, cancelKs []cid.Cid) {
+func (pm *PeerManager) SendCancels(ctx context.Context, cancelKs []cid.Cid, excludePeer peer.ID) {
 	pm.pqLk.Lock()
 	defer pm.pqLk.Unlock()
 
 	// Send a CANCEL to each peer that has been sent a want-block or want-have
-	pm.pwm.sendCancels(cancelKs)
+	pm.pwm.sendCancels(cancelKs, excludePeer)
 }
 
 // CurrentWants returns the list of pending wants (both want-haves and want-blocks).

bitswap/client/internal/peermanager/peermanager_test.go

@@ -239,7 +239,7 @@ func TestSendCancels(t *testing.T) {
 	collectMessages(msgs, 2*time.Millisecond)
 
 	// Send cancels for 1 want-block and 1 want-have
-	peerManager.SendCancels(ctx, []cid.Cid{cids[0], cids[2]})
+	peerManager.SendCancels(ctx, []cid.Cid{cids[0], cids[2]}, "")
 	collected := collectMessages(msgs, 2*time.Millisecond)
 
 	if _, ok := collected[peer2]; ok {
@@ -250,7 +250,7 @@ func TestSendCancels(t *testing.T) {
 	}
 
 	// Send cancels for all cids
-	peerManager.SendCancels(ctx, cids)
+	peerManager.SendCancels(ctx, cids, "")
 	collected = collectMessages(msgs, 2*time.Millisecond)
 
 	if _, ok := collected[peer2]; ok {
@@ -261,6 +261,49 @@ func TestSendCancels(t *testing.T) {
 	}
 }
 
+func TestSendCancelsExclude(t *testing.T) {
+	ctx, cancel := context.WithTimeout(context.Background(), time.Second)
+	defer cancel()
+	msgs := make(chan msg, 16)
+	peerQueueFactory := makePeerQueueFactory(msgs)
+	tp := random.Peers(3)
+	self, peer1, peer2 := tp[0], tp[1], tp[2]
+	peerManager := New(ctx, peerQueueFactory, self)
+	cids := random.Cids(4)
+
+	// Connect to peer1 and peer2
+	peerManager.Connected(peer1)
+	peerManager.Connected(peer2)
+
+	// Send 2 want-blocks and 1 want-have to peer1
+	peerManager.SendWants(ctx, peer1, []cid.Cid{cids[0], cids[1]}, []cid.Cid{cids[2]})
+
+	// Clear messages
+	collectMessages(msgs, 2*time.Millisecond)
+
+	// Send cancels for 1 want-block and 1 want-have
+	peerManager.SendCancels(ctx, []cid.Cid{cids[0], cids[2]}, peer1)
+	collected := collectMessages(msgs, 2*time.Millisecond)
+
+	if _, ok := collected[peer2]; ok {
+		t.Fatal("Expected no cancels to be sent to peer that was not sent messages")
+	}
+	if len(collected[peer1].cancels) != 0 {
+		t.Fatal("Expected no cancels to be sent to excluded peer")
+	}
+
+	// Send cancels for all cids
+	peerManager.SendCancels(ctx, cids, "")
+	collected = collectMessages(msgs, 2*time.Millisecond)
+
+	if _, ok := collected[peer2]; ok {
+		t.Fatal("Expected no cancels to be sent to peer that was not sent messages")
+	}
+	if len(collected[peer1].cancels) != 3 {
+		t.Fatal("Expected cancel to be sent for want-blocks")
+	}
+}
+
 func (s *sess) ID() uint64 {
 	return s.id
 }
@@ -376,7 +419,7 @@ func BenchmarkPeerManager(b *testing.B) {
 			limit := len(wanted) / 10
 			cancel := wanted[:limit]
 			wanted = wanted[limit:]
-			peerManager.SendCancels(ctx, cancel)
+			peerManager.SendCancels(ctx, cancel, "")
 		}
 	}
 }

bitswap/client/internal/peermanager/peerwantmanager.go

@@ -233,7 +233,7 @@ func (pwm *peerWantManager) sendWants(p peer.ID, wantBlocks []cid.Cid, wantHaves
 
 // sendCancels sends a cancel to each peer to which a corresponding want was
 // sent
-func (pwm *peerWantManager) sendCancels(cancelKs []cid.Cid) {
+func (pwm *peerWantManager) sendCancels(cancelKs []cid.Cid, excludePeer peer.ID) {
 	if len(cancelKs) == 0 {
 		return
 	}
@@ -298,6 +298,7 @@ func (pwm *peerWantManager) sendCancels(cancelKs []cid.Cid) {
 				cancelPeers[p] = struct{}{}
 			}
 		}
+		delete(cancelPeers, excludePeer)
 		for p := range cancelPeers {
 			pws, ok := pwm.peerWants[p]
 			if !ok {

bitswap/client/internal/peermanager/peerwantmanager_test.go

@@ -245,7 +245,7 @@ func TestPWMSendCancels(t *testing.T) {
 
 	// Cancel 1 want-block and 1 want-have that were sent to p0
 	clearSent(peerQueues)
-	pwm.sendCancels([]cid.Cid{wb1[0], wh1[0]})
+	pwm.sendCancels([]cid.Cid{wb1[0], wh1[0]}, "")
 	// Should cancel the want-block and want-have
 	require.Empty(t, pq1.cancels, "Expected no cancels sent to p1")
 	require.ElementsMatch(t, pq0.cancels, []cid.Cid{wb1[0], wh1[0]}, "Expected 2 cids to be cancelled")
@@ -255,7 +255,7 @@ func TestPWMSendCancels(t *testing.T) {
 	// Cancel everything
 	clearSent(peerQueues)
 	allCids := append(allwb, allwh...)
-	pwm.sendCancels(allCids)
+	pwm.sendCancels(allCids, "")
 	// Should cancel the remaining want-blocks and want-haves for p0
 	require.ElementsMatch(t, pq0.cancels, []cid.Cid{wb1[1], wh1[1]}, "Expected un-cancelled cids to be cancelled")
 
@@ -312,7 +312,7 @@ func TestStats(t *testing.T) {
 	// Cancel 1 want-block that was sent to p0
 	// and 1 want-block that was not sent
 	cids5 := random.Cids(1)
-	pwm.sendCancels(append(cids5, cids[0]))
+	pwm.sendCancels(append(cids5, cids[0]), "")
 
 	require.Equal(t, 7, g.count, "Expected 7 wants")
 	require.Equal(t, 3, wbg.count, "Expected 3 want-blocks")
@@ -332,7 +332,7 @@ func TestStats(t *testing.T) {
 	require.Zero(t, wbg.count, "Expected 0 want-blocks")
 
 	// Cancel one remaining broadcast want-have
-	pwm.sendCancels(cids2[:1])
+	pwm.sendCancels(cids2[:1], "")
 	require.Equal(t, 2, g.count, "Expected 2 wants")
 	require.Zero(t, wbg.count, "Expected 0 want-blocks")
 }
@@ -362,7 +362,7 @@ func TestStatsOverlappingWantBlockWantHave(t *testing.T) {
 	require.Equal(t, 4, wbg.count, "Expected 4 want-blocks")
 
 	// Cancel 1 of each group of cids
-	pwm.sendCancels([]cid.Cid{cids[0], cids2[0]})
+	pwm.sendCancels([]cid.Cid{cids[0], cids2[0]}, "")
 
 	require.Equal(t, 2, g.count, "Expected 2 wants")
 	require.Equal(t, 2, wbg.count, "Expected 2 want-blocks")

bitswap/client/internal/session/session.go

@@ -43,7 +43,7 @@ type PeerManager interface {
 	// session discovery)
 	BroadcastWantHaves(context.Context, []cid.Cid)
 	// SendCancels tells the PeerManager to send cancels to all peers
-	SendCancels(context.Context, []cid.Cid)
+	SendCancels(context.Context, []cid.Cid, peer.ID)
 }
 
 // SessionManager manages all the sessions

bitswap/client/internal/session/session_test.go

@@ -151,7 +151,7 @@ func (pm *fakePeerManager) BroadcastWantHaves(ctx context.Context, cids []cid.Ci
 	case <-ctx.Done():
 	}
 }
-func (pm *fakePeerManager) SendCancels(ctx context.Context, cancels []cid.Cid) {}
+func (pm *fakePeerManager) SendCancels(ctx context.Context, cancels []cid.Cid, excludePeer peer.ID) {}
 
 func TestSessionGetBlocks(t *testing.T) {
 	ctx, cancel := context.WithTimeout(context.Background(), 100*time.Millisecond)

bitswap/client/internal/session/sessionwantsender_test.go

@@ -78,9 +78,9 @@ func (pm *mockPeerManager) has(p peer.ID, sid uint64) bool {
 	return false
 }
 
-func (*mockPeerManager) UnregisterSession(uint64)                      {}
-func (*mockPeerManager) BroadcastWantHaves(context.Context, []cid.Cid) {}
-func (*mockPeerManager) SendCancels(context.Context, []cid.Cid)        {}
+func (*mockPeerManager) UnregisterSession(uint64)                        {}
+func (*mockPeerManager) BroadcastWantHaves(context.Context, []cid.Cid)   {}
+func (*mockPeerManager) SendCancels(context.Context, []cid.Cid, peer.ID) {}
 
 func (pm *mockPeerManager) SendWants(ctx context.Context, p peer.ID, wantBlocks []cid.Cid, wantHaves []cid.Cid) bool {
 	pm.lk.Lock()

bitswap/client/internal/sessionmanager/sessionmanager.go

@@ -173,7 +173,7 @@ func (sm *SessionManager) ReceiveFrom(ctx context.Context, p peer.ID, blks []cid
 	}
 
 	// Send CANCEL to all peers with want-have / want-block
-	sm.peerManager.SendCancels(ctx, blks)
+	sm.peerManager.SendCancels(ctx, blks, p)
 }
 
 // CancelSessionWants is called when a session cancels wants because a call to
@@ -193,5 +193,5 @@ func (sm *SessionManager) cancelWants(wants []cid.Cid) {
 	// Send CANCEL to all peers for blocks that no session is interested in
 	// anymore.
 	// Note: use bitswap context because session context may already be Done.
-	sm.peerManager.SendCancels(sm.ctx, wants)
+	sm.peerManager.SendCancels(sm.ctx, wants, "")
 }

bitswap/client/internal/sessionmanager/sessionmanager_test.go

@@ -70,7 +70,7 @@ func (*fakePeerManager) RegisterSession(peer.ID, bspm.Session)
 func (*fakePeerManager) UnregisterSession(uint64)                                      {}
 func (*fakePeerManager) SendWants(context.Context, peer.ID, []cid.Cid, []cid.Cid) bool { return true }
 func (*fakePeerManager) BroadcastWantHaves(context.Context, []cid.Cid)                 {}
-func (fpm *fakePeerManager) SendCancels(ctx context.Context, cancels []cid.Cid) {
+func (fpm *fakePeerManager) SendCancels(ctx context.Context, cancels []cid.Cid, excludePeer peer.ID) {
 	fpm.lk.Lock()
 	defer fpm.lk.Unlock()
 	fpm.cancels = append(fpm.cancels, cancels...)