refactor: remove WantManager

bitswap.go

@@ -22,7 +22,6 @@ import (
 	bssim "github.com/ipfs/go-bitswap/internal/sessioninterestmanager"
 	bssm "github.com/ipfs/go-bitswap/internal/sessionmanager"
 	bsspm "github.com/ipfs/go-bitswap/internal/sessionpeermanager"
-	bswm "github.com/ipfs/go-bitswap/internal/wantmanager"
 	bsmsg "github.com/ipfs/go-bitswap/message"
 	bsnet "github.com/ipfs/go-bitswap/network"
 	blocks "github.com/ipfs/go-block-format"
@@ -123,13 +122,13 @@ func New(parent context.Context, network bsnet.BitSwapNetwork,
 		return nil
 	})
 
-	var wm *bswm.WantManager
 	// onDontHaveTimeout is called when a want-block is sent to a peer that
 	// has an old version of Bitswap that doesn't support DONT_HAVE messages,
 	// or when no response is received within a timeout.
+	var sm *bssm.SessionManager
 	onDontHaveTimeout := func(p peer.ID, dontHaves []cid.Cid) {
-		// Simulate a DONT_HAVE message arriving to the WantManager
-		wm.ReceiveFrom(ctx, p, nil, nil, dontHaves)
+		// Simulate a message arriving with DONT_HAVEs
+		sm.ReceiveFrom(ctx, p, nil, nil, dontHaves)
 	}
 	peerQueueFactory := func(ctx context.Context, p peer.ID) bspm.PeerQueue {
 		return bsmq.New(ctx, p, network, onDontHaveTimeout)
@@ -138,25 +137,23 @@ func New(parent context.Context, network bsnet.BitSwapNetwork,
 	sim := bssim.New()
 	bpm := bsbpm.New()
 	pm := bspm.New(ctx, peerQueueFactory, network.Self())
-	wm = bswm.New(ctx, pm, sim, bpm)
 	pqm := bspqm.New(ctx, network)
 
-	sessionFactory := func(ctx context.Context, id uint64, spm bssession.SessionPeerManager,
+	sessionFactory := func(sessctx context.Context, id uint64, spm bssession.SessionPeerManager,
 		sim *bssim.SessionInterestManager,
 		pm bssession.PeerManager,
 		bpm *bsbpm.BlockPresenceManager,
 		notif notifications.PubSub,
 		provSearchDelay time.Duration,
 		rebroadcastDelay delay.D,
 		self peer.ID) bssm.Session {
-		return bssession.New(ctx, id, wm, spm, pqm, sim, pm, bpm, notif, provSearchDelay, rebroadcastDelay, self)
+		return bssession.New(ctx, sessctx, id, spm, pqm, sim, pm, bpm, notif, provSearchDelay, rebroadcastDelay, self)
 	}
 	sessionPeerManagerFactory := func(ctx context.Context, id uint64) bssession.SessionPeerManager {
 		return bsspm.New(id, network.ConnectionManager())
 	}
 	notif := notifications.New()
-	sm := bssm.New(ctx, sessionFactory, sim, sessionPeerManagerFactory, bpm, pm, notif, network.Self())
-	wm.SetSessionManager(sm)
+	sm = bssm.New(ctx, sessionFactory, sim, sessionPeerManagerFactory, bpm, pm, notif, network.Self())
 	engine := decision.NewEngine(ctx, bstore, network.ConnectionManager(), network.Self())
 
 	bs := &Bitswap{
@@ -166,7 +163,6 @@ func New(parent context.Context, network bsnet.BitSwapNetwork,
 		process:          px,
 		newBlocks:        make(chan cid.Cid, HasBlockBufferSize),
 		provideKeys:      make(chan cid.Cid, provideKeysBufferSize),
-		wm:               wm,
 		pm:               pm,
 		pqm:              pqm,
 		sm:               sm,
@@ -207,9 +203,6 @@ func New(parent context.Context, network bsnet.BitSwapNetwork,
 
 // Bitswap instances implement the bitswap protocol.
 type Bitswap struct {
-	// the wantlist tracks global wants for bitswap
-	wm *bswm.WantManager
-
 	pm *bspm.PeerManager
 
 	// the provider query manager manages requests to find providers
@@ -357,7 +350,7 @@ func (bs *Bitswap) receiveBlocksFrom(ctx context.Context, from peer.ID, blks []b
 
 	// Send all block keys (including duplicates) to any sessions that want them.
 	// (The duplicates are needed by sessions for accounting purposes)
-	bs.wm.ReceiveFrom(ctx, from, allKs, haves, dontHaves)
+	bs.sm.ReceiveFrom(ctx, from, allKs, haves, dontHaves)
 
 	// Send wanted blocks to decision engine
 	bs.engine.ReceiveFrom(from, wanted, haves)
@@ -480,14 +473,14 @@ func (bs *Bitswap) blockstoreHas(blks []blocks.Block) []bool {
 // PeerConnected is called by the network interface
 // when a peer initiates a new connection to bitswap.
 func (bs *Bitswap) PeerConnected(p peer.ID) {
-	bs.wm.Connected(p)
+	bs.pm.Connected(p)
 	bs.engine.PeerConnected(p)
 }
 
 // PeerDisconnected is called by the network interface when a peer
 // closes a connection
 func (bs *Bitswap) PeerDisconnected(p peer.ID) {
-	bs.wm.Disconnected(p)
+	bs.pm.Disconnected(p)
 	bs.engine.PeerDisconnected(p)
 }
 

docs/go-bitswap.puml

@@ -11,13 +11,6 @@ node "Sending Blocks" {
   [Engine] --> [TaskWorker (workers.go)]
 }
 
-node "Requesting Blocks" {
-  [Bitswap] --* [WantManager]
-  [WantManager] --> [BlockPresenceManager]
-  [WantManager] --> [PeerManager]
-  [PeerManager] --* [MessageQueue]
-}
-
 node "Providing" {
   [Bitswap] --* [Provide Collector (workers.go)]
   [Provide Collector (workers.go)] --* [Provide Worker (workers.go)]
@@ -31,14 +24,19 @@ node "Sessions (smart requests)" {
   [Bitswap] --* [SessionManager]
   [SessionManager] --> [SessionInterestManager]
   [SessionManager] --o [Session]
+  [SessionManager] --> [BlockPresenceManager]
   [Session] --* [sessionWantSender]
   [Session] --* [SessionPeerManager]
-  [Session] --> [WantManager]
   [Session] --> [ProvideQueryManager]
   [Session] --* [sessionWants]
   [Session] --> [SessionInterestManager]
   [sessionWantSender] --> [BlockPresenceManager]
+}
+
+node "Requesting Blocks" {  
+  [SessionManager] --> [PeerManager]
   [sessionWantSender] --> [PeerManager]
+  [PeerManager] --* [MessageQueue]
 }
 
 node "Network" {

docs/how-bitswap-works.md

@@ -74,8 +74,8 @@ When a message is received, Bitswap
   So that the Engine can send responses to the wants
 - Informs the Engine of any received blocks
   So that the Engine can send the received blocks to any peers that want them
-- Informs the WantManager of received blocks, HAVEs and DONT_HAVEs
-  So that the WantManager can inform interested sessions
+- Informs the SessionManager of received blocks, HAVEs and DONT_HAVEs
+  So that the SessionManager can inform interested sessions
 
 When the client makes an API call, Bitswap creates a new Session and calls the corresponding method (eg `GetBlocks()`).
 
@@ -101,9 +101,10 @@ The PeerTaskQueue prioritizes tasks such that the peers with the least amount of
 
 ### Requesting Blocks
 
-When the WantManager is informed of a new message, it
-- informs the SessionManager
-  The SessionManager informs the Sessions that are interested in the received blocks and wants
+When the SessionManager is informed of a new message, it
+- informs the BlockPresenceManager
+  The BlockPresenceManager keeps track of which peers have sent HAVES and DONT_HAVEs for each block
+- informs the Sessions that are interested in the received blocks and wants
 - informs the PeerManager of received blocks
   The PeerManager checks if any wants were send to a peer for the received blocks. If so it sends a `CANCEL` message to those peers.
 
@@ -114,7 +115,7 @@ The Session starts in "discovery" mode. This means it doesn't have any peers yet
 When the client initially requests blocks from a Session, the Session
 - informs the SessionInterestManager that it is interested in the want
 - informs the sessionWantManager of the want
-- tells the WantManager to broadcast a `want-have` to all connected peers so as to discover which peers have the block
+- tells the PeerManager to broadcast a `want-have` to all connected peers so as to discover which peers have the block
 - queries the ProviderQueryManager to discover which peers have the block
 
 When the session receives a message with `HAVE` or a `block`, it informs the SessionPeerManager. The SessionPeerManager keeps track of all peers in the session.

internal/session/session.go

@@ -25,17 +25,6 @@ const (
 	broadcastLiveWantsLimit = 64
 )
 
-// WantManager is an interface that can be used to request blocks
-// from given peers.
-type WantManager interface {
-	// BroadcastWantHaves sends want-haves to all connected peers (used for
-	// session discovery)
-	BroadcastWantHaves(context.Context, uint64, []cid.Cid)
-	// RemoveSession removes the session from the WantManager (when the
-	// session shuts down)
-	RemoveSession(context.Context, uint64)
-}
-
 // PeerManager keeps track of which sessions are interested in which peers
 // and takes care of sending wants for the sessions
 type PeerManager interface {
@@ -47,6 +36,11 @@ type PeerManager interface {
 	UnregisterSession(uint64)
 	// SendWants tells the PeerManager to send wants to the given peer
 	SendWants(ctx context.Context, peerId peer.ID, wantBlocks []cid.Cid, wantHaves []cid.Cid)
+	// BroadcastWantHaves sends want-haves to all connected peers (used for
+	// session discovery)
+	BroadcastWantHaves(context.Context, []cid.Cid)
+	// SendCancels tells the PeerManager to send cancels to all peers
+	SendCancels(context.Context, []cid.Cid)
 }
 
 // SessionPeerManager keeps track of peers in the session
@@ -97,8 +91,10 @@ type op struct {
 // info to, and who to request blocks from.
 type Session struct {
 	// dependencies
-	ctx            context.Context
-	wm             WantManager
+	bsctx          context.Context // context for bitswap
+	ctx            context.Context // context for session
+	pm             PeerManager
+	bpm            *bsbpm.BlockPresenceManager
 	sprm           SessionPeerManager
 	providerFinder ProviderFinder
 	sim            *bssim.SessionInterestManager
@@ -129,9 +125,10 @@ type Session struct {
 
 // New creates a new bitswap session whose lifetime is bounded by the
 // given context.
-func New(ctx context.Context,
+func New(
+	bsctx context.Context, // context for bitswap
+	ctx context.Context, // context for this session
 	id uint64,
-	wm WantManager,
 	sprm SessionPeerManager,
 	providerFinder ProviderFinder,
 	sim *bssim.SessionInterestManager,
@@ -144,8 +141,10 @@ func New(ctx context.Context,
 	s := &Session{
 		sw:                  newSessionWants(broadcastLiveWantsLimit),
 		tickDelayReqs:       make(chan time.Duration),
+		bsctx:               bsctx,
 		ctx:                 ctx,
-		wm:                  wm,
+		pm:                  pm,
+		bpm:                 bpm,
 		sprm:                sprm,
 		providerFinder:      providerFinder,
 		sim:                 sim,
@@ -301,13 +300,13 @@ func (s *Session) run(ctx context.Context) {
 				s.sw.WantsSent(oper.keys)
 			case opBroadcast:
 				// Broadcast want-haves to all peers
-				s.broadcastWantHaves(ctx, oper.keys)
+				s.broadcast(ctx, oper.keys)
 			default:
 				panic("unhandled operation")
 			}
 		case <-s.idleTick.C:
 			// The session hasn't received blocks for a while, broadcast
-			s.broadcastWantHaves(ctx, nil)
+			s.broadcast(ctx, nil)
 		case <-s.periodicSearchTimer.C:
 			// Periodically search for a random live want
 			s.handlePeriodicSearch(ctx)
@@ -325,23 +324,23 @@ func (s *Session) run(ctx context.Context) {
 // Called when the session hasn't received any blocks for some time, or when
 // all peers in the session have sent DONT_HAVE for a particular set of CIDs.
 // Send want-haves to all connected peers, and search for new peers with the CID.
-func (s *Session) broadcastWantHaves(ctx context.Context, wants []cid.Cid) {
+func (s *Session) broadcast(ctx context.Context, wants []cid.Cid) {
 	// If this broadcast is because of an idle timeout (we haven't received
 	// any blocks for a while) then broadcast all pending wants
 	if wants == nil {
 		wants = s.sw.PrepareBroadcast()
 	}
 
 	// Broadcast a want-have for the live wants to everyone we're connected to
-	s.wm.BroadcastWantHaves(ctx, s.id, wants)
+	s.broadcastWantHaves(ctx, wants)
 
 	// do not find providers on consecutive ticks
 	// -- just rely on periodic search widening
 	if len(wants) > 0 && (s.consecutiveTicks == 0) {
 		// Search for providers who have the first want in the list.
 		// Typically if the provider has the first block they will have
 		// the rest of the blocks also.
-		log.Debugf("Ses%d: FindMorePeers with want %s (1st of %d wants)", s.id, wants[0], len(wants))
+		log.Debugw("FindMorePeers", "session", s.id, "cid", wants[0], "pending", len(wants))
 		s.findMorePeers(ctx, wants[0])
 	}
 	s.resetIdleTick()
@@ -364,7 +363,7 @@ func (s *Session) handlePeriodicSearch(ctx context.Context) {
 	// for new providers for blocks.
 	s.findMorePeers(ctx, randomWant)
 
-	s.wm.BroadcastWantHaves(ctx, s.id, []cid.Cid{randomWant})
+	s.broadcastWantHaves(ctx, []cid.Cid{randomWant})
 
 	s.periodicSearchTimer.Reset(s.periodicSearchDelay.NextWaitTime())
 }
@@ -390,8 +389,19 @@ func (s *Session) handleShutdown() {
 	// Shut down the sessionWantSender (blocks until sessionWantSender stops
 	// sending)
 	s.sws.Shutdown()
-	// Remove the session from the want manager
-	s.wm.RemoveSession(s.ctx, s.id)
+
+	// Remove session's interest in the given blocks.
+	cancelKs := s.sim.RemoveSessionInterest(s.id)
+
+	// Free up block presence tracking for keys that no session is interested
+	// in anymore
+	s.bpm.RemoveKeys(cancelKs)
+
+	// Send CANCEL to all peers for blocks that no session is interested in
+	// anymore.
+	// Note: use bitswap context because session context has already been
+	// cancelled.
+	s.pm.SendCancels(s.bsctx, cancelKs)
 }
 
 // handleReceive is called when the session receives blocks from a peer
@@ -439,11 +449,17 @@ func (s *Session) wantBlocks(ctx context.Context, newks []cid.Cid) {
 	// No peers discovered yet, broadcast some want-haves
 	ks := s.sw.GetNextWants()
 	if len(ks) > 0 {
-		log.Infof("Ses%d: No peers - broadcasting %d want HAVE requests\n", s.id, len(ks))
-		s.wm.BroadcastWantHaves(ctx, s.id, ks)
+		log.Infow("No peers - broadcasting", "session", s.id, "want-count", len(ks))
+		s.broadcastWantHaves(ctx, ks)
 	}
 }
 
+// Send want-haves to all connected peers
+func (s *Session) broadcastWantHaves(ctx context.Context, wants []cid.Cid) {
+	log.Debugw("broadcastWantHaves", "session", s.id, "cids", wants)
+	s.pm.BroadcastWantHaves(ctx, wants)
+}
+
 // The session will broadcast if it has outstanding wants and doesn't receive
 // any blocks for some time.
 // The length of time is calculated