diff --git a/blocks/blockstore/blockstore.go b/blocks/blockstore/blockstore.go
index d4849cb43bd..e203ffc502d 100644
--- a/blocks/blockstore/blockstore.go
+++ b/blocks/blockstore/blockstore.go
@@ -6,14 +6,16 @@ import (
 	"errors"
 
 	ds "github.com/jbenet/go-ipfs/Godeps/_workspace/src/github.com/jbenet/go-datastore"
-
 	mh "github.com/jbenet/go-ipfs/Godeps/_workspace/src/github.com/jbenet/go-multihash"
+
 	blocks "github.com/jbenet/go-ipfs/blocks"
 	u "github.com/jbenet/go-ipfs/util"
 )
 
 var ValueTypeMismatch = errors.New("The retrieved value is not a Block")
 
+var ErrNotFound = errors.New("blockstore: block not found")
+
 // Blockstore wraps a ThreadSafeDatastore
 type Blockstore interface {
 	DeleteBlock(u.Key) error
@@ -34,6 +36,9 @@ type blockstore struct {
 
 func (bs *blockstore) Get(k u.Key) (*blocks.Block, error) {
 	maybeData, err := bs.datastore.Get(k.DsKey())
+	if err == ds.ErrNotFound {
+		return nil, ErrNotFound
+	}
 	if err != nil {
 		return nil, err
 	}
diff --git a/blockservice/blockservice.go b/blockservice/blockservice.go
index f44eaa0f5a4..9014cab461e 100644
--- a/blockservice/blockservice.go
+++ b/blockservice/blockservice.go
@@ -8,8 +8,6 @@ import (
 	"fmt"
 
 	context "github.com/jbenet/go-ipfs/Godeps/_workspace/src/code.google.com/p/go.net/context"
-	ds "github.com/jbenet/go-ipfs/Godeps/_workspace/src/github.com/jbenet/go-datastore"
-
 	blocks "github.com/jbenet/go-ipfs/blocks"
 	"github.com/jbenet/go-ipfs/blocks/blockstore"
 	exchange "github.com/jbenet/go-ipfs/exchange"
@@ -67,7 +65,7 @@ func (s *BlockService) GetBlock(ctx context.Context, k u.Key) (*blocks.Block, er
 		return block, nil
 		// TODO be careful checking ErrNotFound. If the underlying
 		// implementation changes, this will break.
-	} else if err == ds.ErrNotFound && s.Exchange != nil {
+	} else if err == blockstore.ErrNotFound && s.Exchange != nil {
 		log.Debug("Blockservice: Searching bitswap.")
 		blk, err := s.Exchange.GetBlock(ctx, k)
 		if err != nil {
diff --git a/epictest/addcat_test.go b/epictest/addcat_test.go
index a69660cf4fd..09ba58f7948 100644
--- a/epictest/addcat_test.go
+++ b/epictest/addcat_test.go
@@ -26,10 +26,6 @@ import (
 const kSeed = 1
 
 func Test100MBInstantaneous(t *testing.T) {
-	t.Log("a sanity check")
-
-	t.Parallel()
-
 	conf := Config{
 		NetworkLatency:    0,
 		RoutingLatency:    0,
@@ -41,10 +37,7 @@ func Test100MBInstantaneous(t *testing.T) {
 
 func TestDegenerateSlowBlockstore(t *testing.T) {
 	SkipUnlessEpic(t)
-	t.Parallel()
-
 	conf := Config{BlockstoreLatency: 50 * time.Millisecond}
-
 	if err := AddCatPowers(conf, 128); err != nil {
 		t.Fatal(err)
 	}
@@ -52,10 +45,7 @@ func TestDegenerateSlowBlockstore(t *testing.T) {
 
 func TestDegenerateSlowNetwork(t *testing.T) {
 	SkipUnlessEpic(t)
-	t.Parallel()
-
 	conf := Config{NetworkLatency: 400 * time.Millisecond}
-
 	if err := AddCatPowers(conf, 128); err != nil {
 		t.Fatal(err)
 	}
@@ -63,10 +53,7 @@ func TestDegenerateSlowNetwork(t *testing.T) {
 
 func TestDegenerateSlowRouting(t *testing.T) {
 	SkipUnlessEpic(t)
-	t.Parallel()
-
 	conf := Config{RoutingLatency: 400 * time.Millisecond}
-
 	if err := AddCatPowers(conf, 128); err != nil {
 		t.Fatal(err)
 	}
@@ -74,10 +61,7 @@ func TestDegenerateSlowRouting(t *testing.T) {
 
 func Test100MBMacbookCoastToCoast(t *testing.T) {
 	SkipUnlessEpic(t)
-	t.Parallel()
-
 	conf := Config{}.Network_NYtoSF().Blockstore_SlowSSD2014().Routing_Slow()
-
 	if err := AddCatBytes(RandomBytes(100*1024*1024), conf); err != nil {
 		t.Fatal(err)
 	}
diff --git a/exchange/bitswap/bitswap.go b/exchange/bitswap/bitswap.go
index 64f29352819..912ed1210c6 100644
--- a/exchange/bitswap/bitswap.go
+++ b/exchange/bitswap/bitswap.go
@@ -3,36 +3,46 @@
 package bitswap
 
 import (
+	"math"
 	"sync"
 	"time"
 
 	context "github.com/jbenet/go-ipfs/Godeps/_workspace/src/code.google.com/p/go.net/context"
-
 	blocks "github.com/jbenet/go-ipfs/blocks"
 	blockstore "github.com/jbenet/go-ipfs/blocks/blockstore"
 	exchange "github.com/jbenet/go-ipfs/exchange"
+	decision "github.com/jbenet/go-ipfs/exchange/bitswap/decision"
 	bsmsg "github.com/jbenet/go-ipfs/exchange/bitswap/message"
 	bsnet "github.com/jbenet/go-ipfs/exchange/bitswap/network"
 	notifications "github.com/jbenet/go-ipfs/exchange/bitswap/notifications"
-	strategy "github.com/jbenet/go-ipfs/exchange/bitswap/strategy"
+	wantlist "github.com/jbenet/go-ipfs/exchange/bitswap/wantlist"
 	peer "github.com/jbenet/go-ipfs/peer"
 	u "github.com/jbenet/go-ipfs/util"
 	eventlog "github.com/jbenet/go-ipfs/util/eventlog"
+	pset "github.com/jbenet/go-ipfs/util/peerset"
 )
 
 var log = eventlog.Logger("bitswap")
 
-// Number of providers to request for sending a wantlist to
-// TODO: if a 'non-nice' strategy is implemented, consider increasing this value
-const maxProvidersPerRequest = 3
+const (
+	// Number of providers to request for sending a wantlist to
+	// TODO: if a 'non-nice' strategy is implemented, consider increasing this value
+	maxProvidersPerRequest = 3
+	providerRequestTimeout = time.Second * 10
+	hasBlockTimeout        = time.Second * 15
+	sizeBatchRequestChan   = 32
+	// kMaxPriority is the max priority as defined by the bitswap protocol
+	kMaxPriority = math.MaxInt32
+)
 
-const providerRequestTimeout = time.Second * 10
-const hasBlockTimeout = time.Second * 15
+var (
+	rebroadcastDelay = time.Second * 10
+)
 
-// New initializes a BitSwap instance that communicates over the
-// provided BitSwapNetwork. This function registers the returned instance as
-// the network delegate.
-// Runs until context is cancelled
+// New initializes a BitSwap instance that communicates over the provided
+// BitSwapNetwork. This function registers the returned instance as the network
+// delegate.
+// Runs until context is cancelled.
 func New(parent context.Context, p peer.Peer, network bsnet.BitSwapNetwork, routing bsnet.Routing,
 	bstore blockstore.Blockstore, nice bool) exchange.Interface {
 
@@ -41,6 +51,7 @@ func New(parent context.Context, p peer.Peer, network bsnet.BitSwapNetwork, rout
 	notif := notifications.New()
 	go func() {
 		<-ctx.Done()
+		cancelFunc()
 		notif.Shutdown()
 	}()
 
@@ -48,14 +59,15 @@ func New(parent context.Context, p peer.Peer, network bsnet.BitSwapNetwork, rout
 		blockstore:    bstore,
 		cancelFunc:    cancelFunc,
 		notifications: notif,
-		strategy:      strategy.New(nice),
+		engine:        decision.NewEngine(ctx, bstore),
 		routing:       routing,
 		sender:        network,
-		wantlist:      u.NewKeySet(),
-		batchRequests: make(chan []u.Key, 32),
+		wantlist:      wantlist.NewThreadSafe(),
+		batchRequests: make(chan []u.Key, sizeBatchRequestChan),
 	}
 	network.SetDelegate(bs)
-	go bs.loop(ctx)
+	go bs.clientWorker(ctx)
+	go bs.taskWorker(ctx)
 
 	return bs
 }
@@ -80,12 +92,9 @@ type bitswap struct {
 	// have more than a single block in the set
 	batchRequests chan []u.Key
 
-	// strategy listens to network traffic and makes decisions about how to
-	// interact with partners.
-	// TODO(brian): save the strategy's state to the datastore
-	strategy strategy.Strategy
+	engine *decision.Engine
 
-	wantlist u.KeySet
+	wantlist *wantlist.ThreadSafe
 
 	// cancelFunc signals cancellation to the bitswap event loop
 	cancelFunc func()
@@ -153,12 +162,7 @@ func (bs *bitswap) HasBlock(ctx context.Context, blk *blocks.Block) error {
 	}
 	bs.wantlist.Remove(blk.Key())
 	bs.notifications.Publish(blk)
-	child, _ := context.WithTimeout(ctx, hasBlockTimeout)
-	if err := bs.sendToPeersThatWant(child, blk); err != nil {
-		return err
-	}
-	child, _ = context.WithTimeout(ctx, hasBlockTimeout)
-	return bs.routing.Provide(child, blk.Key())
+	return bs.routing.Provide(ctx, blk.Key())
 }
 
 func (bs *bitswap) sendWantListTo(ctx context.Context, peers <-chan peer.Peer) error {
@@ -166,13 +170,15 @@ func (bs *bitswap) sendWantListTo(ctx context.Context, peers <-chan peer.Peer) e
 		panic("Cant send wantlist to nil peerchan")
 	}
 	message := bsmsg.New()
-	for _, wanted := range bs.wantlist.Keys() {
-		message.AddWanted(wanted)
+	for _, wanted := range bs.wantlist.Entries() {
+		message.AddEntry(wanted.Key, wanted.Priority)
 	}
+	wg := sync.WaitGroup{}
 	for peerToQuery := range peers {
-		log.Debug("sending query to: %s", peerToQuery)
 		log.Event(ctx, "PeerToQuery", peerToQuery)
+		wg.Add(1)
 		go func(p peer.Peer) {
+			defer wg.Done()
 
 			log.Event(ctx, "DialPeer", p)
 			err := bs.sender.DialPeer(ctx, p)
@@ -189,57 +195,76 @@ func (bs *bitswap) sendWantListTo(ctx context.Context, peers <-chan peer.Peer) e
 			// FIXME ensure accounting is handled correctly when
 			// communication fails. May require slightly different API to
 			// get better guarantees. May need shared sequence numbers.
-			bs.strategy.MessageSent(p, message)
+			bs.engine.MessageSent(p, message)
 		}(peerToQuery)
 	}
+	wg.Wait()
 	return nil
 }
 
-func (bs *bitswap) sendWantlistToProviders(ctx context.Context, ks []u.Key) {
+func (bs *bitswap) sendWantlistToProviders(ctx context.Context, wantlist *wantlist.ThreadSafe) {
+	ctx, cancel := context.WithCancel(ctx)
+	defer cancel()
+
+	message := bsmsg.New()
+	message.SetFull(true)
+	for _, e := range bs.wantlist.Entries() {
+		message.AddEntry(e.Key, e.Priority)
+	}
+
+	ps := pset.New()
+
+	// Get providers for all entries in wantlist (could take a while)
 	wg := sync.WaitGroup{}
-	for _, k := range ks {
+	for _, e := range wantlist.Entries() {
 		wg.Add(1)
 		go func(k u.Key) {
+			defer wg.Done()
 			child, _ := context.WithTimeout(ctx, providerRequestTimeout)
 			providers := bs.routing.FindProvidersAsync(child, k, maxProvidersPerRequest)
 
-			err := bs.sendWantListTo(ctx, providers)
-			if err != nil {
-				log.Errorf("error sending wantlist: %s", err)
+			for prov := range providers {
+				if ps.TryAdd(prov) { //Do once per peer
+					bs.send(ctx, prov, message)
+				}
 			}
-			wg.Done()
-		}(k)
+		}(e.Key)
 	}
 	wg.Wait()
 }
 
+func (bs *bitswap) taskWorker(ctx context.Context) {
+	for {
+		select {
+		case <-ctx.Done():
+			return
+		case envelope := <-bs.engine.Outbox():
+			bs.send(ctx, envelope.Peer, envelope.Message)
+		}
+	}
+}
+
 // TODO ensure only one active request per key
-func (bs *bitswap) loop(parent context.Context) {
+func (bs *bitswap) clientWorker(parent context.Context) {
 
 	ctx, cancel := context.WithCancel(parent)
 
-	broadcastSignal := time.NewTicker(bs.strategy.GetRebroadcastDelay())
-	defer func() {
-		cancel() // signal to derived async functions
-		broadcastSignal.Stop()
-	}()
+	broadcastSignal := time.After(rebroadcastDelay)
+	defer cancel()
 
 	for {
 		select {
-		case <-broadcastSignal.C:
+		case <-broadcastSignal:
 			// Resend unfulfilled wantlist keys
-			bs.sendWantlistToProviders(ctx, bs.wantlist.Keys())
+			bs.sendWantlistToProviders(ctx, bs.wantlist)
+			broadcastSignal = time.After(rebroadcastDelay)
 		case ks := <-bs.batchRequests:
-			// TODO: implement batching on len(ks) > X for some X
-			//		i.e. if given 20 keys, fetch first five, then next
-			//		five, and so on, so we are more likely to be able to
-			//		effectively stream the data
 			if len(ks) == 0 {
 				log.Warning("Received batch request for zero blocks")
 				continue
 			}
-			for _, k := range ks {
-				bs.wantlist.Add(k)
+			for i, k := range ks {
+				bs.wantlist.Add(k, kMaxPriority-i)
 			}
 			// NB: send want list to providers for the first peer in this list.
 			//		the assumption is made that the providers of the first key in
@@ -277,45 +302,45 @@ func (bs *bitswap) ReceiveMessage(ctx context.Context, p peer.Peer, incoming bsm
 		return nil, nil
 	}
 
-	// Record message bytes in ledger
-	// TODO: this is bad, and could be easily abused.
-	// Should only track *useful* messages in ledger
 	// This call records changes to wantlists, blocks received,
 	// and number of bytes transfered.
-	bs.strategy.MessageReceived(p, incoming)
+	bs.engine.MessageReceived(p, incoming)
+	// TODO: this is bad, and could be easily abused.
+	// Should only track *useful* messages in ledger
 
 	for _, block := range incoming.Blocks() {
-		if err := bs.HasBlock(ctx, block); err != nil {
+		hasBlockCtx, _ := context.WithTimeout(ctx, hasBlockTimeout)
+		if err := bs.HasBlock(hasBlockCtx, block); err != nil {
 			log.Error(err)
 		}
 	}
-
-	for _, key := range incoming.Wantlist() {
-		if bs.strategy.ShouldSendBlockToPeer(key, p) {
-			if block, errBlockNotFound := bs.blockstore.Get(key); errBlockNotFound != nil {
-				continue
-			} else {
-				// Create a separate message to send this block in
-				blkmsg := bsmsg.New()
-
-				// TODO: only send this the first time
-				//		no sense in sending our wantlist to the
-				//		same peer multiple times
-				for _, k := range bs.wantlist.Keys() {
-					blkmsg.AddWanted(k)
-				}
-
-				blkmsg.AddBlock(block)
-				bs.send(ctx, p, blkmsg)
-				bs.strategy.BlockSentToPeer(block.Key(), p)
-			}
-		}
+	var keys []u.Key
+	for _, block := range incoming.Blocks() {
+		keys = append(keys, block.Key())
 	}
+	bs.cancelBlocks(ctx, keys)
 
 	// TODO: consider changing this function to not return anything
 	return nil, nil
 }
 
+func (bs *bitswap) cancelBlocks(ctx context.Context, bkeys []u.Key) {
+	if len(bkeys) < 1 {
+		return
+	}
+	message := bsmsg.New()
+	message.SetFull(false)
+	for _, k := range bkeys {
+		message.Cancel(k)
+	}
+	for _, p := range bs.engine.Peers() {
+		err := bs.send(ctx, p, message)
+		if err != nil {
+			log.Errorf("Error sending message: %s", err)
+		}
+	}
+}
+
 func (bs *bitswap) ReceiveError(err error) {
 	log.Errorf("Bitswap ReceiveError: %s", err)
 	// TODO log the network error
@@ -328,25 +353,7 @@ func (bs *bitswap) send(ctx context.Context, p peer.Peer, m bsmsg.BitSwapMessage
 	if err := bs.sender.SendMessage(ctx, p, m); err != nil {
 		return err
 	}
-	return bs.strategy.MessageSent(p, m)
-}
-
-func (bs *bitswap) sendToPeersThatWant(ctx context.Context, block *blocks.Block) error {
-	for _, p := range bs.strategy.Peers() {
-		if bs.strategy.BlockIsWantedByPeer(block.Key(), p) {
-			if bs.strategy.ShouldSendBlockToPeer(block.Key(), p) {
-				message := bsmsg.New()
-				message.AddBlock(block)
-				for _, wanted := range bs.wantlist.Keys() {
-					message.AddWanted(wanted)
-				}
-				if err := bs.send(ctx, p, message); err != nil {
-					return err
-				}
-			}
-		}
-	}
-	return nil
+	return bs.engine.MessageSent(p, m)
 }
 
 func (bs *bitswap) Close() error {
diff --git a/exchange/bitswap/bitswap_test.go b/exchange/bitswap/bitswap_test.go
index d58ff596a1e..2c04b05082e 100644
--- a/exchange/bitswap/bitswap_test.go
+++ b/exchange/bitswap/bitswap_test.go
@@ -11,6 +11,7 @@ import (
 	blocksutil "github.com/jbenet/go-ipfs/blocks/blocksutil"
 	tn "github.com/jbenet/go-ipfs/exchange/bitswap/testnet"
 	mockrouting "github.com/jbenet/go-ipfs/routing/mock"
+	u "github.com/jbenet/go-ipfs/util"
 	delay "github.com/jbenet/go-ipfs/util/delay"
 	testutil "github.com/jbenet/go-ipfs/util/testutil"
 )
@@ -25,6 +26,7 @@ func TestClose(t *testing.T) {
 	vnet := tn.VirtualNetwork(delay.Fixed(kNetworkDelay))
 	rout := mockrouting.NewServer()
 	sesgen := NewSessionGenerator(vnet, rout)
+	defer sesgen.Close()
 	bgen := blocksutil.NewBlockGenerator()
 
 	block := bgen.Next()
@@ -39,6 +41,7 @@ func TestGetBlockTimeout(t *testing.T) {
 	net := tn.VirtualNetwork(delay.Fixed(kNetworkDelay))
 	rs := mockrouting.NewServer()
 	g := NewSessionGenerator(net, rs)
+	defer g.Close()
 
 	self := g.Next()
 
@@ -56,11 +59,13 @@ func TestProviderForKeyButNetworkCannotFind(t *testing.T) {
 	net := tn.VirtualNetwork(delay.Fixed(kNetworkDelay))
 	rs := mockrouting.NewServer()
 	g := NewSessionGenerator(net, rs)
+	defer g.Close()
 
 	block := blocks.NewBlock([]byte("block"))
 	rs.Client(testutil.NewPeerWithIDString("testing")).Provide(context.Background(), block.Key()) // but not on network
 
 	solo := g.Next()
+	defer solo.Exchange.Close()
 
 	ctx, _ := context.WithTimeout(context.Background(), time.Nanosecond)
 	_, err := solo.Exchange.GetBlock(ctx, block.Key())
@@ -78,8 +83,10 @@ func TestGetBlockFromPeerAfterPeerAnnounces(t *testing.T) {
 	rs := mockrouting.NewServer()
 	block := blocks.NewBlock([]byte("block"))
 	g := NewSessionGenerator(net, rs)
+	defer g.Close()
 
 	hasBlock := g.Next()
+	defer hasBlock.Exchange.Close()
 
 	if err := hasBlock.Blockstore().Put(block); err != nil {
 		t.Fatal(err)
@@ -89,6 +96,7 @@ func TestGetBlockFromPeerAfterPeerAnnounces(t *testing.T) {
 	}
 
 	wantsBlock := g.Next()
+	defer wantsBlock.Exchange.Close()
 
 	ctx, _ := context.WithTimeout(context.Background(), time.Second)
 	received, err := wantsBlock.Exchange.GetBlock(ctx, block.Key())
@@ -107,7 +115,7 @@ func TestLargeSwarm(t *testing.T) {
 		t.SkipNow()
 	}
 	t.Parallel()
-	numInstances := 5
+	numInstances := 500
 	numBlocks := 2
 	PerformDistributionTest(t, numInstances, numBlocks)
 }
@@ -129,6 +137,7 @@ func PerformDistributionTest(t *testing.T, numInstances, numBlocks int) {
 	net := tn.VirtualNetwork(delay.Fixed(kNetworkDelay))
 	rs := mockrouting.NewServer()
 	sg := NewSessionGenerator(net, rs)
+	defer sg.Close()
 	bg := blocksutil.NewBlockGenerator()
 
 	t.Log("Test a few nodes trying to get one file with a lot of blocks")
@@ -138,24 +147,29 @@ func PerformDistributionTest(t *testing.T, numInstances, numBlocks int) {
 
 	t.Log("Give the blocks to the first instance")
 
+	var blkeys []u.Key
 	first := instances[0]
 	for _, b := range blocks {
 		first.Blockstore().Put(b)
+		blkeys = append(blkeys, b.Key())
 		first.Exchange.HasBlock(context.Background(), b)
 		rs.Client(first.Peer).Provide(context.Background(), b.Key())
 	}
 
 	t.Log("Distribute!")
 
-	var wg sync.WaitGroup
-
+	wg := sync.WaitGroup{}
 	for _, inst := range instances {
-		for _, b := range blocks {
-			wg.Add(1)
-			// NB: executing getOrFail concurrently puts tremendous pressure on
-			// the goroutine scheduler
-			getOrFail(inst, b, t, &wg)
-		}
+		wg.Add(1)
+		go func(inst Instance) {
+			defer wg.Done()
+			outch, err := inst.Exchange.GetBlocks(context.TODO(), blkeys)
+			if err != nil {
+				t.Fatal(err)
+			}
+			for _ = range outch {
+			}
+		}(inst)
 	}
 	wg.Wait()
 
@@ -189,60 +203,75 @@ func TestSendToWantingPeer(t *testing.T) {
 	net := tn.VirtualNetwork(delay.Fixed(kNetworkDelay))
 	rs := mockrouting.NewServer()
 	sg := NewSessionGenerator(net, rs)
+	defer sg.Close()
 	bg := blocksutil.NewBlockGenerator()
 
-	me := sg.Next()
-	w := sg.Next()
-	o := sg.Next()
+	oldVal := rebroadcastDelay
+	rebroadcastDelay = time.Second / 2
+	defer func() { rebroadcastDelay = oldVal }()
 
-	t.Logf("Session %v\n", me.Peer)
-	t.Logf("Session %v\n", w.Peer)
-	t.Logf("Session %v\n", o.Peer)
+	peerA := sg.Next()
+	peerB := sg.Next()
 
-	alpha := bg.Next()
+	t.Logf("Session %v\n", peerA.Peer)
+	t.Logf("Session %v\n", peerB.Peer)
 
-	const timeout = 100 * time.Millisecond // FIXME don't depend on time
+	timeout := time.Second
+	waitTime := time.Second * 5
 
-	t.Logf("Peer %v attempts to get %v. NB: not available\n", w.Peer, alpha.Key())
-	ctx, _ := context.WithTimeout(context.Background(), timeout)
-	_, err := w.Exchange.GetBlock(ctx, alpha.Key())
-	if err == nil {
-		t.Fatalf("Expected %v to NOT be available", alpha.Key())
+	alpha := bg.Next()
+	// peerA requests and waits for block alpha
+	ctx, _ := context.WithTimeout(context.TODO(), waitTime)
+	alphaPromise, err := peerA.Exchange.GetBlocks(ctx, []u.Key{alpha.Key()})
+	if err != nil {
+		t.Fatal(err)
 	}
 
-	beta := bg.Next()
-	t.Logf("Peer %v announes availability  of %v\n", w.Peer, beta.Key())
-	ctx, _ = context.WithTimeout(context.Background(), timeout)
-	if err := w.Blockstore().Put(beta); err != nil {
+	// peerB announces to the network that he has block alpha
+	ctx, _ = context.WithTimeout(context.TODO(), timeout)
+	err = peerB.Exchange.HasBlock(ctx, alpha)
+	if err != nil {
 		t.Fatal(err)
 	}
-	w.Exchange.HasBlock(ctx, beta)
 
-	t.Logf("%v gets %v from %v and discovers it wants %v\n", me.Peer, beta.Key(), w.Peer, alpha.Key())
-	ctx, _ = context.WithTimeout(context.Background(), timeout)
-	if _, err := me.Exchange.GetBlock(ctx, beta.Key()); err != nil {
-		t.Fatal(err)
+	// At some point, peerA should get alpha (or timeout)
+	blkrecvd, ok := <-alphaPromise
+	if !ok {
+		t.Fatal("context timed out and broke promise channel!")
 	}
 
-	t.Logf("%v announces availability of %v\n", o.Peer, alpha.Key())
-	ctx, _ = context.WithTimeout(context.Background(), timeout)
-	if err := o.Blockstore().Put(alpha); err != nil {
-		t.Fatal(err)
+	if blkrecvd.Key() != alpha.Key() {
+		t.Fatal("Wrong block!")
 	}
-	o.Exchange.HasBlock(ctx, alpha)
 
-	t.Logf("%v requests %v\n", me.Peer, alpha.Key())
-	ctx, _ = context.WithTimeout(context.Background(), timeout)
-	if _, err := me.Exchange.GetBlock(ctx, alpha.Key()); err != nil {
+}
+
+func TestBasicBitswap(t *testing.T) {
+	net := tn.VirtualNetwork(delay.Fixed(kNetworkDelay))
+	rs := mockrouting.NewServer()
+	sg := NewSessionGenerator(net, rs)
+	bg := blocksutil.NewBlockGenerator()
+
+	t.Log("Test a few nodes trying to get one file with a lot of blocks")
+
+	instances := sg.Instances(2)
+	blocks := bg.Blocks(1)
+	err := instances[0].Exchange.HasBlock(context.TODO(), blocks[0])
+	if err != nil {
 		t.Fatal(err)
 	}
 
-	t.Logf("%v should now have %v\n", w.Peer, alpha.Key())
-	block, err := w.Blockstore().Get(alpha.Key())
+	ctx, _ := context.WithTimeout(context.TODO(), time.Second*5)
+	blk, err := instances[1].Exchange.GetBlock(ctx, blocks[0].Key())
 	if err != nil {
-		t.Fatalf("Should not have received an error: %s", err)
+		t.Fatal(err)
 	}
-	if block.Key() != alpha.Key() {
-		t.Fatal("Expected to receive alpha from me")
+
+	t.Log(blk)
+	for _, inst := range instances {
+		err := inst.Exchange.Close()
+		if err != nil {
+			t.Fatal(err)
+		}
 	}
 }
diff --git a/exchange/bitswap/decision/engine.go b/exchange/bitswap/decision/engine.go
new file mode 100644
index 00000000000..ea453943731
--- /dev/null
+++ b/exchange/bitswap/decision/engine.go
@@ -0,0 +1,224 @@
+package decision
+
+import (
+	"sync"
+
+	context "github.com/jbenet/go-ipfs/Godeps/_workspace/src/code.google.com/p/go.net/context"
+	bstore "github.com/jbenet/go-ipfs/blocks/blockstore"
+	bsmsg "github.com/jbenet/go-ipfs/exchange/bitswap/message"
+	wl "github.com/jbenet/go-ipfs/exchange/bitswap/wantlist"
+	peer "github.com/jbenet/go-ipfs/peer"
+	u "github.com/jbenet/go-ipfs/util"
+)
+
+// TODO consider taking responsibility for other types of requests. For
+// example, there could be a |cancelQueue| for all of the cancellation
+// messages that need to go out. There could also be a |wantlistQueue| for
+// the local peer's wantlists. Alternatively, these could all be bundled
+// into a single, intelligent global queue that efficiently
+// batches/combines and takes all of these into consideration.
+//
+// Right now, messages go onto the network for four reasons:
+// 1. an initial `sendwantlist` message to a provider of the first key in a request
+// 2. a periodic full sweep of `sendwantlist` messages to all providers
+// 3. upon receipt of blocks, a `cancel` message to all peers
+// 4. draining the priority queue of `blockrequests` from peers
+//
+// Presently, only `blockrequests` are handled by the decision engine.
+// However, there is an opportunity to give it more responsibility! If the
+// decision engine is given responsibility for all of the others, it can
+// intelligently decide how to combine requests efficiently.
+//
+// Some examples of what would be possible:
+//
+// * when sending out the wantlists, include `cancel` requests
+// * when handling `blockrequests`, include `sendwantlist` and `cancel` as appropriate
+// * when handling `cancel`, if we recently received a wanted block from a
+// 	 peer, include a partial wantlist that contains a few other high priority
+//   blocks
+//
+// In a sense, if we treat the decision engine as a black box, it could do
+// whatever it sees fit to produce desired outcomes (get wanted keys
+// quickly, maintain good relationships with peers, etc).
+
+var log = u.Logger("engine")
+
+const (
+	sizeOutboxChan = 4
+)
+
+// Envelope contains a message for a Peer
+type Envelope struct {
+	// Peer is the intended recipient
+	Peer peer.Peer
+	// Message is the payload
+	Message bsmsg.BitSwapMessage
+}
+
+type Engine struct {
+	// peerRequestQueue is a priority queue of requests received from peers.
+	// Requests are popped from the queue, packaged up, and placed in the
+	// outbox.
+	peerRequestQueue *taskQueue
+
+	// FIXME it's a bit odd for the client and the worker to both share memory
+	// (both modify the peerRequestQueue) and also to communicate over the
+	// workSignal channel. consider sending requests over the channel and
+	// allowing the worker to have exclusive access to the peerRequestQueue. In
+	// that case, no lock would be required.
+	workSignal chan struct{}
+
+	// outbox contains outgoing messages to peers
+	outbox chan Envelope
+
+	bs bstore.Blockstore
+
+	lock sync.RWMutex // protects the fields immediatly below
+	// ledgerMap lists Ledgers by their Partner key.
+	ledgerMap map[u.Key]*ledger
+}
+
+func NewEngine(ctx context.Context, bs bstore.Blockstore) *Engine {
+	e := &Engine{
+		ledgerMap:        make(map[u.Key]*ledger),
+		bs:               bs,
+		peerRequestQueue: newTaskQueue(),
+		outbox:           make(chan Envelope, sizeOutboxChan),
+		workSignal:       make(chan struct{}),
+	}
+	go e.taskWorker(ctx)
+	return e
+}
+
+func (e *Engine) taskWorker(ctx context.Context) {
+	for {
+		nextTask := e.peerRequestQueue.Pop()
+		if nextTask == nil {
+			// No tasks in the list?
+			// Wait until there are!
+			select {
+			case <-ctx.Done():
+				return
+			case <-e.workSignal:
+			}
+			continue
+		}
+		block, err := e.bs.Get(nextTask.Entry.Key)
+		if err != nil {
+			log.Warning("engine: task exists to send block, but block is not in blockstore")
+			continue
+		}
+		// construct message here so we can make decisions about any additional
+		// information we may want to include at this time.
+		m := bsmsg.New()
+		m.AddBlock(block)
+		// TODO: maybe add keys from our wantlist?
+		select {
+		case <-ctx.Done():
+			return
+		case e.outbox <- Envelope{Peer: nextTask.Target, Message: m}:
+		}
+	}
+}
+
+func (e *Engine) Outbox() <-chan Envelope {
+	return e.outbox
+}
+
+// Returns a slice of Peers with whom the local node has active sessions
+func (e *Engine) Peers() []peer.Peer {
+	e.lock.RLock()
+	defer e.lock.RUnlock()
+
+	response := make([]peer.Peer, 0)
+	for _, ledger := range e.ledgerMap {
+		response = append(response, ledger.Partner)
+	}
+	return response
+}
+
+// MessageReceived performs book-keeping. Returns error if passed invalid
+// arguments.
+func (e *Engine) MessageReceived(p peer.Peer, m bsmsg.BitSwapMessage) error {
+	newWorkExists := false
+	defer func() {
+		if newWorkExists {
+			// Signal task generation to restart (if stopped!)
+			select {
+			case e.workSignal <- struct{}{}:
+			default:
+			}
+		}
+	}()
+	e.lock.Lock()
+	defer e.lock.Unlock()
+
+	l := e.findOrCreate(p)
+	if m.Full() {
+		l.wantList = wl.New()
+	}
+	for _, entry := range m.Wantlist() {
+		if entry.Cancel {
+			l.CancelWant(entry.Key)
+			e.peerRequestQueue.Remove(entry.Key, p)
+		} else {
+			l.Wants(entry.Key, entry.Priority)
+			if exists, err := e.bs.Has(entry.Key); err == nil && exists {
+				newWorkExists = true
+				e.peerRequestQueue.Push(entry.Entry, p)
+			}
+		}
+	}
+
+	for _, block := range m.Blocks() {
+		// FIXME extract blocks.NumBytes(block) or block.NumBytes() method
+		l.ReceivedBytes(len(block.Data))
+		for _, l := range e.ledgerMap {
+			if l.WantListContains(block.Key()) {
+				newWorkExists = true
+				e.peerRequestQueue.Push(wl.Entry{block.Key(), 1}, l.Partner)
+			}
+		}
+	}
+	return nil
+}
+
+// TODO add contents of m.WantList() to my local wantlist? NB: could introduce
+// race conditions where I send a message, but MessageSent gets handled after
+// MessageReceived. The information in the local wantlist could become
+// inconsistent. Would need to ensure that Sends and acknowledgement of the
+// send happen atomically
+
+func (e *Engine) MessageSent(p peer.Peer, m bsmsg.BitSwapMessage) error {
+	e.lock.Lock()
+	defer e.lock.Unlock()
+
+	l := e.findOrCreate(p)
+	for _, block := range m.Blocks() {
+		l.SentBytes(len(block.Data))
+		l.wantList.Remove(block.Key())
+		e.peerRequestQueue.Remove(block.Key(), p)
+	}
+
+	return nil
+}
+
+func (e *Engine) numBytesSentTo(p peer.Peer) uint64 {
+	// NB not threadsafe
+	return e.findOrCreate(p).Accounting.BytesSent
+}
+
+func (e *Engine) numBytesReceivedFrom(p peer.Peer) uint64 {
+	// NB not threadsafe
+	return e.findOrCreate(p).Accounting.BytesRecv
+}
+
+// ledger lazily instantiates a ledger
+func (e *Engine) findOrCreate(p peer.Peer) *ledger {
+	l, ok := e.ledgerMap[p.Key()]
+	if !ok {
+		l = newLedger(p)
+		e.ledgerMap[p.Key()] = l
+	}
+	return l
+}
diff --git a/exchange/bitswap/decision/engine_test.go b/exchange/bitswap/decision/engine_test.go
new file mode 100644
index 00000000000..14893757303
--- /dev/null
+++ b/exchange/bitswap/decision/engine_test.go
@@ -0,0 +1,93 @@
+package decision
+
+import (
+	"strings"
+	"testing"
+
+	context "github.com/jbenet/go-ipfs/Godeps/_workspace/src/code.google.com/p/go.net/context"
+	ds "github.com/jbenet/go-ipfs/Godeps/_workspace/src/github.com/jbenet/go-datastore"
+	sync "github.com/jbenet/go-ipfs/Godeps/_workspace/src/github.com/jbenet/go-datastore/sync"
+	blocks "github.com/jbenet/go-ipfs/blocks"
+	blockstore "github.com/jbenet/go-ipfs/blocks/blockstore"
+	message "github.com/jbenet/go-ipfs/exchange/bitswap/message"
+	peer "github.com/jbenet/go-ipfs/peer"
+	testutil "github.com/jbenet/go-ipfs/util/testutil"
+)
+
+type peerAndEngine struct {
+	peer.Peer
+	Engine *Engine
+}
+
+func newPeerAndLedgermanager(idStr string) peerAndEngine {
+	return peerAndEngine{
+		Peer: testutil.NewPeerWithIDString(idStr),
+		//Strategy: New(true),
+		Engine: NewEngine(context.TODO(),
+			blockstore.NewBlockstore(sync.MutexWrap(ds.NewMapDatastore()))),
+	}
+}
+
+func TestConsistentAccounting(t *testing.T) {
+	sender := newPeerAndLedgermanager("Ernie")
+	receiver := newPeerAndLedgermanager("Bert")
+
+	// Send messages from Ernie to Bert
+	for i := 0; i < 1000; i++ {
+
+		m := message.New()
+		content := []string{"this", "is", "message", "i"}
+		m.AddBlock(blocks.NewBlock([]byte(strings.Join(content, " "))))
+
+		sender.Engine.MessageSent(receiver.Peer, m)
+		receiver.Engine.MessageReceived(sender.Peer, m)
+	}
+
+	// Ensure sender records the change
+	if sender.Engine.numBytesSentTo(receiver.Peer) == 0 {
+		t.Fatal("Sent bytes were not recorded")
+	}
+
+	// Ensure sender and receiver have the same values
+	if sender.Engine.numBytesSentTo(receiver.Peer) != receiver.Engine.numBytesReceivedFrom(sender.Peer) {
+		t.Fatal("Inconsistent book-keeping. Strategies don't agree")
+	}
+
+	// Ensure sender didn't record receving anything. And that the receiver
+	// didn't record sending anything
+	if receiver.Engine.numBytesSentTo(sender.Peer) != 0 || sender.Engine.numBytesReceivedFrom(receiver.Peer) != 0 {
+		t.Fatal("Bert didn't send bytes to Ernie")
+	}
+}
+
+func TestPeerIsAddedToPeersWhenMessageReceivedOrSent(t *testing.T) {
+
+	sanfrancisco := newPeerAndLedgermanager("sf")
+	seattle := newPeerAndLedgermanager("sea")
+
+	m := message.New()
+
+	sanfrancisco.Engine.MessageSent(seattle.Peer, m)
+	seattle.Engine.MessageReceived(sanfrancisco.Peer, m)
+
+	if seattle.Peer.Key() == sanfrancisco.Peer.Key() {
+		t.Fatal("Sanity Check: Peers have same Key!")
+	}
+
+	if !peerIsPartner(seattle.Peer, sanfrancisco.Engine) {
+		t.Fatal("Peer wasn't added as a Partner")
+	}
+
+	if !peerIsPartner(sanfrancisco.Peer, seattle.Engine) {
+		t.Fatal("Peer wasn't added as a Partner")
+	}
+}
+
+func peerIsPartner(p peer.Peer, e *Engine) bool {
+	for _, partner := range e.Peers() {
+		if partner.Key() == p.Key() {
+			return true
+		}
+	}
+	return false
+}
diff --git a/exchange/bitswap/strategy/ledger.go b/exchange/bitswap/decision/ledger.go
similarity index 74%
rename from exchange/bitswap/strategy/ledger.go
rename to exchange/bitswap/decision/ledger.go
index 84e92d0356e..eea87af1fcf 100644
--- a/exchange/bitswap/strategy/ledger.go
+++ b/exchange/bitswap/decision/ledger.go
@@ -1,8 +1,9 @@
-package strategy
+package decision
 
 import (
 	"time"
 
+	wl "github.com/jbenet/go-ipfs/exchange/bitswap/wantlist"
 	peer "github.com/jbenet/go-ipfs/peer"
 	u "github.com/jbenet/go-ipfs/util"
 )
@@ -11,10 +12,9 @@ import (
 // access/lookups.
 type keySet map[u.Key]struct{}
 
-func newLedger(p peer.Peer, strategy strategyFunc) *ledger {
+func newLedger(p peer.Peer) *ledger {
 	return &ledger{
-		wantList:   keySet{},
-		Strategy:   strategy,
+		wantList:   wl.New(),
 		Partner:    p,
 		sentToPeer: make(map[u.Key]time.Time),
 	}
@@ -39,17 +39,20 @@ type ledger struct {
 	exchangeCount uint64
 
 	// wantList is a (bounded, small) set of keys that Partner desires.
-	wantList keySet
+	wantList *wl.Wantlist
 
 	// sentToPeer is a set of keys to ensure we dont send duplicate blocks
 	// to a given peer
 	sentToPeer map[u.Key]time.Time
+}
 
-	Strategy strategyFunc
+type debtRatio struct {
+	BytesSent uint64
+	BytesRecv uint64
 }
 
-func (l *ledger) ShouldSend() bool {
-	return l.Strategy(l)
+func (dr *debtRatio) Value() float64 {
+	return float64(dr.BytesSent) / float64(dr.BytesRecv+1)
 }
 
 func (l *ledger) SentBytes(n int) {
@@ -65,14 +68,17 @@ func (l *ledger) ReceivedBytes(n int) {
 }
 
 // TODO: this needs to be different. We need timeouts.
-func (l *ledger) Wants(k u.Key) {
+func (l *ledger) Wants(k u.Key, priority int) {
 	log.Debugf("peer %s wants %s", l.Partner, k)
-	l.wantList[k] = struct{}{}
+	l.wantList.Add(k, priority)
+}
+
+func (l *ledger) CancelWant(k u.Key) {
+	l.wantList.Remove(k)
 }
 
 func (l *ledger) WantListContains(k u.Key) bool {
-	_, ok := l.wantList[k]
-	return ok
+	return l.wantList.Contains(k)
 }
 
 func (l *ledger) ExchangeCount() uint64 {
diff --git a/exchange/bitswap/decision/taskqueue.go b/exchange/bitswap/decision/taskqueue.go
new file mode 100644
index 00000000000..a76c56e9ba3
--- /dev/null
+++ b/exchange/bitswap/decision/taskqueue.go
@@ -0,0 +1,84 @@
+package decision
+
+import (
+	"sync"
+
+	wantlist "github.com/jbenet/go-ipfs/exchange/bitswap/wantlist"
+	peer "github.com/jbenet/go-ipfs/peer"
+	u "github.com/jbenet/go-ipfs/util"
+)
+
+// TODO: at some point, the strategy needs to plug in here
+// to help decide how to sort tasks (on add) and how to select
+// tasks (on getnext). For now, we are assuming a dumb/nice strategy.
+type taskQueue struct {
+	// TODO: make this into a priority queue
+	lock    sync.Mutex
+	tasks   []*task
+	taskmap map[string]*task
+}
+
+func newTaskQueue() *taskQueue {
+	return &taskQueue{
+		taskmap: make(map[string]*task),
+	}
+}
+
+type task struct {
+	Entry  wantlist.Entry
+	Target peer.Peer
+	Trash  bool
+}
+
+// Push currently adds a new task to the end of the list
+func (tl *taskQueue) Push(entry wantlist.Entry, to peer.Peer) {
+	tl.lock.Lock()
+	defer tl.lock.Unlock()
+	if task, ok := tl.taskmap[taskKey(to, entry.Key)]; ok {
+		// TODO: when priority queue is implemented,
+		//       rearrange this task
+		task.Entry.Priority = entry.Priority
+		return
+	}
+	task := &task{
+		Entry:  entry,
+		Target: to,
+	}
+	tl.tasks = append(tl.tasks, task)
+	tl.taskmap[taskKey(to, entry.Key)] = task
+}
+
+// Pop 'pops' the next task to be performed. Returns nil no task exists.
+func (tl *taskQueue) Pop() *task {
+	tl.lock.Lock()
+	defer tl.lock.Unlock()
+	var out *task
+	for len(tl.tasks) > 0 {
+		// TODO: instead of zero, use exponential distribution
+		//       it will help reduce the chance of receiving
+		//		 the same block from multiple peers
+		out = tl.tasks[0]
+		tl.tasks = tl.tasks[1:]
+		delete(tl.taskmap, taskKey(out.Target, out.Entry.Key))
+		if out.Trash {
+			continue // discarding tasks that have been removed
+		}
+		break // and return |out|
+	}
+	return out
+}
+
+// Remove lazily removes a task from the queue
+func (tl *taskQueue) Remove(k u.Key, p peer.Peer) {
+	tl.lock.Lock()
+	t, ok := tl.taskmap[taskKey(p, k)]
+	if ok {
+		t.Trash = true
+	}
+	tl.lock.Unlock()
+}
+
+// taskKey returns a key that uniquely identifies a task.
+func taskKey(p peer.Peer, k u.Key) string {
+	return string(p.Key() + k)
+}
diff --git a/exchange/bitswap/message/internal/pb/message.pb.go b/exchange/bitswap/message/internal/pb/message.pb.go
index f6f8a9bbc35..4ddfc56f756 100644
--- a/exchange/bitswap/message/internal/pb/message.pb.go
+++ b/exchange/bitswap/message/internal/pb/message.pb.go
@@ -21,16 +21,16 @@ var _ = proto.Marshal
 var _ = math.Inf
 
 type Message struct {
-	Wantlist         []string `protobuf:"bytes,1,rep,name=wantlist" json:"wantlist,omitempty"`
-	Blocks           [][]byte `protobuf:"bytes,2,rep,name=blocks" json:"blocks,omitempty"`
-	XXX_unrecognized []byte   `json:"-"`
+	Wantlist         *Message_Wantlist `protobuf:"bytes,1,opt,name=wantlist" json:"wantlist,omitempty"`
+	Blocks           [][]byte          `protobuf:"bytes,2,rep,name=blocks" json:"blocks,omitempty"`
+	XXX_unrecognized []byte            `json:"-"`
 }
 
 func (m *Message) Reset()         { *m = Message{} }
 func (m *Message) String() string { return proto.CompactTextString(m) }
 func (*Message) ProtoMessage()    {}
 
-func (m *Message) GetWantlist() []string {
+func (m *Message) GetWantlist() *Message_Wantlist {
 	if m != nil {
 		return m.Wantlist
 	}
@@ -44,5 +44,61 @@ func (m *Message) GetBlocks() [][]byte {
 	return nil
 }
 
+type Message_Wantlist struct {
+	Entries          []*Message_Wantlist_Entry `protobuf:"bytes,1,rep,name=entries" json:"entries,omitempty"`
+	Full             *bool                     `protobuf:"varint,2,opt,name=full" json:"full,omitempty"`
+	XXX_unrecognized []byte                    `json:"-"`
+}
+
+func (m *Message_Wantlist) Reset()         { *m = Message_Wantlist{} }
+func (m *Message_Wantlist) String() string { return proto.CompactTextString(m) }
+func (*Message_Wantlist) ProtoMessage()    {}
+
+func (m *Message_Wantlist) GetEntries() []*Message_Wantlist_Entry {
+	if m != nil {
+		return m.Entries
+	}
+	return nil
+}
+
+func (m *Message_Wantlist) GetFull() bool {
+	if m != nil && m.Full != nil {
+		return *m.Full
+	}
+	return false
+}
+
+type Message_Wantlist_Entry struct {
+	Block            *string `protobuf:"bytes,1,opt,name=block" json:"block,omitempty"`
+	Priority         *int32  `protobuf:"varint,2,opt,name=priority" json:"priority,omitempty"`
+	Cancel           *bool   `protobuf:"varint,3,opt,name=cancel" json:"cancel,omitempty"`
+	XXX_unrecognized []byte  `json:"-"`
+}
+
+func (m *Message_Wantlist_Entry) Reset()         { *m = Message_Wantlist_Entry{} }
+func (m *Message_Wantlist_Entry) String() string { return proto.CompactTextString(m) }
+func (*Message_Wantlist_Entry) ProtoMessage()    {}
+
+func (m *Message_Wantlist_Entry) GetBlock() string {
+	if m != nil && m.Block != nil {
+		return *m.Block
+	}
+	return ""
+}
+
+func (m *Message_Wantlist_Entry) GetPriority() int32 {
+	if m != nil && m.Priority != nil {
+		return *m.Priority
+	}
+	return 0
+}
+
+func (m *Message_Wantlist_Entry) GetCancel() bool {
+	if m != nil && m.Cancel != nil {
+		return *m.Cancel
+	}
+	return false
+}
+
 func init() {
 }
diff --git a/exchange/bitswap/message/internal/pb/message.proto b/exchange/bitswap/message/internal/pb/message.proto
index a8c6c72520b..7c44f3a6b59 100644
--- a/exchange/bitswap/message/internal/pb/message.proto
+++ b/exchange/bitswap/message/internal/pb/message.proto
@@ -1,6 +1,19 @@
 package bitswap.message.pb;
 
 message Message {
-	repeated string wantlist = 1;
-	repeated bytes blocks = 2;
+
+  message Wantlist {
+
+    message Entry {
+      optional string block = 1; // the block key
+      optional int32 priority = 2; // the priority (normalized). default to 1
+      optional bool cancel = 3;  // whether this revokes an entry
+    }
+
+    repeated Entry entries = 1; // a list of wantlist entries
+    optional bool full = 2;     // whether this is the full wantlist. default to false
+  }
+
+  optional Wantlist wantlist = 1;
+  repeated bytes blocks = 2;
 }
diff --git a/exchange/bitswap/message/message.go b/exchange/bitswap/message/message.go
index 62a39be91b0..7f7f1d08e35 100644
--- a/exchange/bitswap/message/message.go
+++ b/exchange/bitswap/message/message.go
@@ -5,10 +5,12 @@ import (
 
 	blocks "github.com/jbenet/go-ipfs/blocks"
 	pb "github.com/jbenet/go-ipfs/exchange/bitswap/message/internal/pb"
+	wantlist "github.com/jbenet/go-ipfs/exchange/bitswap/wantlist"
 	inet "github.com/jbenet/go-ipfs/net"
 	u "github.com/jbenet/go-ipfs/util"
 
 	ggio "github.com/jbenet/go-ipfs/Godeps/_workspace/src/code.google.com/p/gogoprotobuf/io"
+	proto "github.com/jbenet/go-ipfs/Godeps/_workspace/src/code.google.com/p/goprotobuf/proto"
 )
 
 // TODO move message.go into the bitswap package
@@ -17,21 +19,23 @@ import (
 type BitSwapMessage interface {
 	// Wantlist returns a slice of unique keys that represent data wanted by
 	// the sender.
-	Wantlist() []u.Key
+	Wantlist() []Entry
 
 	// Blocks returns a slice of unique blocks
 	Blocks() []*blocks.Block
 
-	// AddWanted adds the key to the Wantlist.
-	//
-	// Insertion order determines priority. That is, earlier insertions are
-	// deemed higher priority than keys inserted later.
-	//
-	// t = 0, msg.AddWanted(A)
-	// t = 1, msg.AddWanted(B)
-	//
-	// implies Priority(A) > Priority(B)
-	AddWanted(u.Key)
+	// AddEntry adds an entry to the Wantlist.
+	AddEntry(key u.Key, priority int)
+
+	Cancel(key u.Key)
+
+	// Sets whether or not the contained wantlist represents the entire wantlist
+	// true = full wantlist
+	// false = wantlist 'patch'
+	// default: true
+	SetFull(isFull bool)
+
+	Full() bool
 
 	AddBlock(*blocks.Block)
 	Exportable
@@ -43,23 +47,33 @@ type Exportable interface {
 }
 
 type impl struct {
-	existsInWantlist map[u.Key]struct{}      // map to detect duplicates
-	wantlist         []u.Key                 // slice to preserve ordering
-	blocks           map[u.Key]*blocks.Block // map to detect duplicates
+	full     bool
+	wantlist map[u.Key]Entry
+	blocks   map[u.Key]*blocks.Block // map to detect duplicates
 }
 
 func New() BitSwapMessage {
+	return newMsg()
+}
+
+func newMsg() *impl {
 	return &impl{
-		blocks:           make(map[u.Key]*blocks.Block),
-		existsInWantlist: make(map[u.Key]struct{}),
-		wantlist:         make([]u.Key, 0),
+		blocks:   make(map[u.Key]*blocks.Block),
+		wantlist: make(map[u.Key]Entry),
+		full:     true,
 	}
 }
 
+type Entry struct {
+	wantlist.Entry
+	Cancel bool
+}
+
 func newMessageFromProto(pbm pb.Message) BitSwapMessage {
-	m := New()
-	for _, s := range pbm.GetWantlist() {
-		m.AddWanted(u.Key(s))
+	m := newMsg()
+	m.SetFull(pbm.GetWantlist().GetFull())
+	for _, e := range pbm.GetWantlist().GetEntries() {
+		m.addEntry(u.Key(e.GetBlock()), int(e.GetPriority()), e.GetCancel())
 	}
 	for _, d := range pbm.GetBlocks() {
 		b := blocks.NewBlock(d)
@@ -68,8 +82,20 @@ func newMessageFromProto(pbm pb.Message) BitSwapMessage {
 	return m
 }
 
-func (m *impl) Wantlist() []u.Key {
-	return m.wantlist
+func (m *impl) SetFull(full bool) {
+	m.full = full
+}
+
+func (m *impl) Full() bool {
+	return m.full
+}
+
+func (m *impl) Wantlist() []Entry {
+	var out []Entry
+	for _, e := range m.wantlist {
+		out = append(out, e)
+	}
+	return out
 }
 
 func (m *impl) Blocks() []*blocks.Block {
@@ -80,13 +106,28 @@ func (m *impl) Blocks() []*blocks.Block {
 	return bs
 }
 
-func (m *impl) AddWanted(k u.Key) {
-	_, exists := m.existsInWantlist[k]
+func (m *impl) Cancel(k u.Key) {
+	m.addEntry(k, 0, true)
+}
+
+func (m *impl) AddEntry(k u.Key, priority int) {
+	m.addEntry(k, priority, false)
+}
+
+func (m *impl) addEntry(k u.Key, priority int, cancel bool) {
+	e, exists := m.wantlist[k]
 	if exists {
-		return
+		e.Priority = priority
+		e.Cancel = cancel
+	} else {
+		m.wantlist[k] = Entry{
+			Entry: wantlist.Entry{
+				Key:      k,
+				Priority: priority,
+			},
+			Cancel: cancel,
+		}
 	}
-	m.existsInWantlist[k] = struct{}{}
-	m.wantlist = append(m.wantlist, k)
 }
 
 func (m *impl) AddBlock(b *blocks.Block) {
@@ -106,14 +147,19 @@ func FromNet(r io.Reader) (BitSwapMessage, error) {
 }
 
 func (m *impl) ToProto() *pb.Message {
-	pb := new(pb.Message)
-	for _, k := range m.Wantlist() {
-		pb.Wantlist = append(pb.Wantlist, string(k))
+	pbm := new(pb.Message)
+	pbm.Wantlist = new(pb.Message_Wantlist)
+	for _, e := range m.wantlist {
+		pbm.Wantlist.Entries = append(pbm.Wantlist.Entries, &pb.Message_Wantlist_Entry{
+			Block:    proto.String(string(e.Key)),
+			Priority: proto.Int32(int32(e.Priority)),
+			Cancel:   &e.Cancel,
+		})
 	}
 	for _, b := range m.Blocks() {
-		pb.Blocks = append(pb.Blocks, b.Data)
+		pbm.Blocks = append(pbm.Blocks, b.Data)
 	}
-	return pb
+	return pbm
 }
 
 func (m *impl) ToNet(w io.Writer) error {
diff --git a/exchange/bitswap/message/message_test.go b/exchange/bitswap/message/message_test.go
index 681b60a6f30..a0df38c0b21 100644
--- a/exchange/bitswap/message/message_test.go
+++ b/exchange/bitswap/message/message_test.go
@@ -4,6 +4,8 @@ import (
 	"bytes"
 	"testing"
 
+	proto "github.com/jbenet/go-ipfs/Godeps/_workspace/src/code.google.com/p/goprotobuf/proto"
+
 	blocks "github.com/jbenet/go-ipfs/blocks"
 	pb "github.com/jbenet/go-ipfs/exchange/bitswap/message/internal/pb"
 	u "github.com/jbenet/go-ipfs/util"
@@ -12,22 +14,26 @@ import (
 func TestAppendWanted(t *testing.T) {
 	const str = "foo"
 	m := New()
-	m.AddWanted(u.Key(str))
+	m.AddEntry(u.Key(str), 1)
 
-	if !contains(m.ToProto().GetWantlist(), str) {
+	if !wantlistContains(m.ToProto().GetWantlist(), str) {
 		t.Fail()
 	}
+	m.ToProto().GetWantlist().GetEntries()
 }
 
 func TestNewMessageFromProto(t *testing.T) {
 	const str = "a_key"
 	protoMessage := new(pb.Message)
-	protoMessage.Wantlist = []string{string(str)}
-	if !contains(protoMessage.Wantlist, str) {
+	protoMessage.Wantlist = new(pb.Message_Wantlist)
+	protoMessage.Wantlist.Entries = []*pb.Message_Wantlist_Entry{
+		&pb.Message_Wantlist_Entry{Block: proto.String(str)},
+	}
+	if !wantlistContains(protoMessage.Wantlist, str) {
 		t.Fail()
 	}
 	m := newMessageFromProto(*protoMessage)
-	if !contains(m.ToProto().GetWantlist(), str) {
+	if !wantlistContains(m.ToProto().GetWantlist(), str) {
 		t.Fail()
 	}
 }
@@ -57,7 +63,7 @@ func TestWantlist(t *testing.T) {
 	keystrs := []string{"foo", "bar", "baz", "bat"}
 	m := New()
 	for _, s := range keystrs {
-		m.AddWanted(u.Key(s))
+		m.AddEntry(u.Key(s), 1)
 	}
 	exported := m.Wantlist()
 
@@ -65,12 +71,12 @@ func TestWantlist(t *testing.T) {
 		present := false
 		for _, s := range keystrs {
 
-			if s == string(k) {
+			if s == string(k.Key) {
 				present = true
 			}
 		}
 		if !present {
-			t.Logf("%v isn't in original list", string(k))
+			t.Logf("%v isn't in original list", k.Key)
 			t.Fail()
 		}
 	}
@@ -80,19 +86,19 @@ func TestCopyProtoByValue(t *testing.T) {
 	const str = "foo"
 	m := New()
 	protoBeforeAppend := m.ToProto()
-	m.AddWanted(u.Key(str))
-	if contains(protoBeforeAppend.GetWantlist(), str) {
+	m.AddEntry(u.Key(str), 1)
+	if wantlistContains(protoBeforeAppend.GetWantlist(), str) {
 		t.Fail()
 	}
 }
 
 func TestToNetFromNetPreservesWantList(t *testing.T) {
 	original := New()
-	original.AddWanted(u.Key("M"))
-	original.AddWanted(u.Key("B"))
-	original.AddWanted(u.Key("D"))
-	original.AddWanted(u.Key("T"))
-	original.AddWanted(u.Key("F"))
+	original.AddEntry(u.Key("M"), 1)
+	original.AddEntry(u.Key("B"), 1)
+	original.AddEntry(u.Key("D"), 1)
+	original.AddEntry(u.Key("T"), 1)
+	original.AddEntry(u.Key("F"), 1)
 
 	var buf bytes.Buffer
 	if err := original.ToNet(&buf); err != nil {
@@ -106,11 +112,11 @@ func TestToNetFromNetPreservesWantList(t *testing.T) {
 
 	keys := make(map[u.Key]bool)
 	for _, k := range copied.Wantlist() {
-		keys[k] = true
+		keys[k.Key] = true
 	}
 
 	for _, k := range original.Wantlist() {
-		if _, ok := keys[k]; !ok {
+		if _, ok := keys[k.Key]; !ok {
 			t.Fatalf("Key Missing: \"%v\"", k)
 		}
 	}
@@ -146,9 +152,18 @@ func TestToAndFromNetMessage(t *testing.T) {
 	}
 }
 
-func contains(s []string, x string) bool {
-	for _, a := range s {
-		if a == x {
+func wantlistContains(wantlist *pb.Message_Wantlist, x string) bool {
+	for _, e := range wantlist.GetEntries() {
+		if e.GetBlock() == x {
+			return true
+		}
+	}
+	return false
+}
+
+func contains(strs []string, x string) bool {
+	for _, s := range strs {
+		if s == x {
 			return true
 		}
 	}
@@ -159,8 +174,8 @@ func TestDuplicates(t *testing.T) {
 	b := blocks.NewBlock([]byte("foo"))
 	msg := New()
 
-	msg.AddWanted(b.Key())
-	msg.AddWanted(b.Key())
+	msg.AddEntry(b.Key(), 1)
+	msg.AddEntry(b.Key(), 1)
 	if len(msg.Wantlist()) != 1 {
 		t.Fatal("Duplicate in BitSwapMessage")
 	}
diff --git a/exchange/bitswap/strategy/interface.go b/exchange/bitswap/strategy/interface.go
deleted file mode 100644
index 58385f5b76c..00000000000
--- a/exchange/bitswap/strategy/interface.go
+++ /dev/null
@@ -1,40 +0,0 @@
-package strategy
-
-import (
-	"time"
-
-	bsmsg "github.com/jbenet/go-ipfs/exchange/bitswap/message"
-	peer "github.com/jbenet/go-ipfs/peer"
-	u "github.com/jbenet/go-ipfs/util"
-)
-
-type Strategy interface {
-	// Returns a slice of Peers with whom the local node has active sessions
-	Peers() []peer.Peer
-
-	// BlockIsWantedByPeer returns true if peer wants the block given by this
-	// key
-	BlockIsWantedByPeer(u.Key, peer.Peer) bool
-
-	// ShouldSendTo(Peer) decides whether to send data to this Peer
-	ShouldSendBlockToPeer(u.Key, peer.Peer) bool
-
-	// Seed initializes the decider to a deterministic state
-	Seed(int64)
-
-	// MessageReceived records receipt of message for accounting purposes
-	MessageReceived(peer.Peer, bsmsg.BitSwapMessage) error
-
-	// MessageSent records sending of message for accounting purposes
-	MessageSent(peer.Peer, bsmsg.BitSwapMessage) error
-
-	NumBytesSentTo(peer.Peer) uint64
-
-	NumBytesReceivedFrom(peer.Peer) uint64
-
-	BlockSentToPeer(u.Key, peer.Peer)
-
-	// Values determining bitswap behavioural patterns
-	GetBatchSize() int
-	GetRebroadcastDelay() time.Duration
-}
diff --git a/exchange/bitswap/strategy/ledger_test.go b/exchange/bitswap/strategy/ledger_test.go
deleted file mode 100644
index 4271d525c20..00000000000
--- a/exchange/bitswap/strategy/ledger_test.go
+++ /dev/null
@@ -1 +0,0 @@
-package strategy
diff --git a/exchange/bitswap/strategy/math.go b/exchange/bitswap/strategy/math.go
deleted file mode 100644
index c5339e5b357..00000000000
--- a/exchange/bitswap/strategy/math.go
+++ /dev/null
@@ -1,34 +0,0 @@
-package strategy
-
-import (
-	"math"
-	"math/rand"
-)
-
-type strategyFunc func(*ledger) bool
-
-// TODO avoid using rand.Float64 method. it uses a singleton lock and may cause
-// performance issues. Instead, instantiate a rand struct and use that to call
-// Float64()
-func standardStrategy(l *ledger) bool {
-	return rand.Float64() <= probabilitySend(l.Accounting.Value())
-}
-
-func yesManStrategy(l *ledger) bool {
-	return true
-}
-
-func probabilitySend(ratio float64) float64 {
-	x := 1 + math.Exp(6-3*ratio)
-	y := 1 / x
-	return 1 - y
-}
-
-type debtRatio struct {
-	BytesSent uint64
-	BytesRecv uint64
-}
-
-func (dr *debtRatio) Value() float64 {
-	return float64(dr.BytesSent) / float64(dr.BytesRecv+1)
-}
diff --git a/exchange/bitswap/strategy/math_test.go b/exchange/bitswap/strategy/math_test.go
deleted file mode 100644
index 58092bc09df..00000000000
--- a/exchange/bitswap/strategy/math_test.go
+++ /dev/null
@@ -1,17 +0,0 @@
-package strategy
-
-import (
-	"testing"
-)
-
-func TestProbabilitySendDecreasesAsRatioIncreases(t *testing.T) {
-	grateful := debtRatio{BytesSent: 0, BytesRecv: 10000}
-	pWhenGrateful := probabilitySend(grateful.Value())
-
-	abused := debtRatio{BytesSent: 10000, BytesRecv: 0}
-	pWhenAbused := probabilitySend(abused.Value())
-
-	if pWhenGrateful < pWhenAbused {
-		t.Fail()
-	}
-}
diff --git a/exchange/bitswap/strategy/strategy.go b/exchange/bitswap/strategy/strategy.go
deleted file mode 100644
index fe7414caa73..00000000000
--- a/exchange/bitswap/strategy/strategy.go
+++ /dev/null
@@ -1,169 +0,0 @@
-package strategy
-
-import (
-	"errors"
-	"sync"
-	"time"
-
-	bsmsg "github.com/jbenet/go-ipfs/exchange/bitswap/message"
-	peer "github.com/jbenet/go-ipfs/peer"
-	u "github.com/jbenet/go-ipfs/util"
-)
-
-const resendTimeoutPeriod = time.Minute
-
-var log = u.Logger("strategy")
-
-// TODO niceness should be on a per-peer basis. Use-case: Certain peers are
-// "trusted" and/or controlled by a single human user. The user may want for
-// these peers to exchange data freely
-func New(nice bool) Strategy {
-	var stratFunc strategyFunc
-	if nice {
-		stratFunc = yesManStrategy
-	} else {
-		stratFunc = standardStrategy
-	}
-	return &strategist{
-		ledgerMap:    ledgerMap{},
-		strategyFunc: stratFunc,
-	}
-}
-
-type strategist struct {
-	lock sync.RWMutex
-	ledgerMap
-	strategyFunc
-}
-
-// LedgerMap lists Ledgers by their Partner key.
-type ledgerMap map[peerKey]*ledger
-
-// FIXME share this externally
-type peerKey u.Key
-
-// Peers returns a list of peers
-func (s *strategist) Peers() []peer.Peer {
-	s.lock.RLock()
-	defer s.lock.RUnlock()
-
-	response := make([]peer.Peer, 0)
-	for _, ledger := range s.ledgerMap {
-		response = append(response, ledger.Partner)
-	}
-	return response
-}
-
-func (s *strategist) BlockIsWantedByPeer(k u.Key, p peer.Peer) bool {
-	s.lock.RLock()
-	defer s.lock.RUnlock()
-
-	ledger := s.ledger(p)
-	return ledger.WantListContains(k)
-}
-
-func (s *strategist) ShouldSendBlockToPeer(k u.Key, p peer.Peer) bool {
-	s.lock.RLock()
-	defer s.lock.RUnlock()
-
-	ledger := s.ledger(p)
-
-	// Dont resend blocks within a certain time period
-	t, ok := ledger.sentToPeer[k]
-	if ok && t.Add(resendTimeoutPeriod).After(time.Now()) {
-		return false
-	}
-
-	return ledger.ShouldSend()
-}
-
-func (s *strategist) BlockSentToPeer(k u.Key, p peer.Peer) {
-	s.lock.Lock()
-	defer s.lock.Unlock()
-
-	ledger := s.ledger(p)
-	ledger.sentToPeer[k] = time.Now()
-}
-
-func (s *strategist) Seed(int64) {
-	s.lock.Lock()
-	defer s.lock.Unlock()
-
-	// TODO
-}
-
-// MessageReceived performs book-keeping. Returns error if passed invalid
-// arguments.
-func (s *strategist) MessageReceived(p peer.Peer, m bsmsg.BitSwapMessage) error {
-	s.lock.Lock()
-	defer s.lock.Unlock()
-
-	// TODO find a more elegant way to handle this check
-	if p == nil {
-		return errors.New("Strategy received nil peer")
-	}
-	if m == nil {
-		return errors.New("Strategy received nil message")
-	}
-	l := s.ledger(p)
-	for _, key := range m.Wantlist() {
-		l.Wants(key)
-	}
-	for _, block := range m.Blocks() {
-		// FIXME extract blocks.NumBytes(block) or block.NumBytes() method
-		l.ReceivedBytes(len(block.Data))
-	}
-	return nil
-}
-
-// TODO add contents of m.WantList() to my local wantlist? NB: could introduce
-// race conditions where I send a message, but MessageSent gets handled after
-// MessageReceived. The information in the local wantlist could become
-// inconsistent. Would need to ensure that Sends and acknowledgement of the
-// send happen atomically
-
-func (s *strategist) MessageSent(p peer.Peer, m bsmsg.BitSwapMessage) error {
-	s.lock.Lock()
-	defer s.lock.Unlock()
-
-	l := s.ledger(p)
-	for _, block := range m.Blocks() {
-		l.SentBytes(len(block.Data))
-	}
-
-	// TODO remove these blocks from peer's want list
-
-	return nil
-}
-
-func (s *strategist) NumBytesSentTo(p peer.Peer) uint64 {
-	s.lock.RLock()
-	defer s.lock.RUnlock()
-
-	return s.ledger(p).Accounting.BytesSent
-}
-
-func (s *strategist) NumBytesReceivedFrom(p peer.Peer) uint64 {
-	s.lock.RLock()
-	defer s.lock.RUnlock()
-
-	return s.ledger(p).Accounting.BytesRecv
-}
-
-// ledger lazily instantiates a ledger
-func (s *strategist) ledger(p peer.Peer) *ledger {
-	l, ok := s.ledgerMap[peerKey(p.Key())]
-	if !ok {
-		l = newLedger(p, s.strategyFunc)
-		s.ledgerMap[peerKey(p.Key())] = l
-	}
-	return l
-}
-
-func (s *strategist) GetBatchSize() int {
-	return 10
-}
-
-func (s *strategist) GetRebroadcastDelay() time.Duration {
-	return time.Second * 5
-}
diff --git a/exchange/bitswap/strategy/strategy_test.go b/exchange/bitswap/strategy/strategy_test.go
deleted file mode 100644
index e063dff688e..00000000000
--- a/exchange/bitswap/strategy/strategy_test.go
+++ /dev/null
@@ -1,104 +0,0 @@
-package strategy
-
-import (
-	"strings"
-	"testing"
-
-	blocks "github.com/jbenet/go-ipfs/blocks"
-	message "github.com/jbenet/go-ipfs/exchange/bitswap/message"
-	peer "github.com/jbenet/go-ipfs/peer"
-	testutil "github.com/jbenet/go-ipfs/util/testutil"
-)
-
-type peerAndStrategist struct {
-	peer.Peer
-	Strategy
-}
-
-func newPeerAndStrategist(idStr string) peerAndStrategist {
-	return peerAndStrategist{
-		Peer:     testutil.NewPeerWithIDString(idStr),
-		Strategy: New(true),
-	}
-}
-
-func TestConsistentAccounting(t *testing.T) {
-	sender := newPeerAndStrategist("Ernie")
-	receiver := newPeerAndStrategist("Bert")
-
-	// Send messages from Ernie to Bert
-	for i := 0; i < 1000; i++ {
-
-		m := message.New()
-		content := []string{"this", "is", "message", "i"}
-		m.AddBlock(blocks.NewBlock([]byte(strings.Join(content, " "))))
-
-		sender.MessageSent(receiver.Peer, m)
-		receiver.MessageReceived(sender.Peer, m)
-	}
-
-	// Ensure sender records the change
-	if sender.NumBytesSentTo(receiver.Peer) == 0 {
-		t.Fatal("Sent bytes were not recorded")
-	}
-
-	// Ensure sender and receiver have the same values
-	if sender.NumBytesSentTo(receiver.Peer) != receiver.NumBytesReceivedFrom(sender.Peer) {
-		t.Fatal("Inconsistent book-keeping. Strategies don't agree")
-	}
-
-	// Ensure sender didn't record receving anything. And that the receiver
-	// didn't record sending anything
-	if receiver.NumBytesSentTo(sender.Peer) != 0 || sender.NumBytesReceivedFrom(receiver.Peer) != 0 {
-		t.Fatal("Bert didn't send bytes to Ernie")
-	}
-}
-
-func TestBlockRecordedAsWantedAfterMessageReceived(t *testing.T) {
-	beggar := newPeerAndStrategist("can't be chooser")
-	chooser := newPeerAndStrategist("chooses JIF")
-
-	block := blocks.NewBlock([]byte("data wanted by beggar"))
-
-	messageFromBeggarToChooser := message.New()
-	messageFromBeggarToChooser.AddWanted(block.Key())
-
-	chooser.MessageReceived(beggar.Peer, messageFromBeggarToChooser)
-	// for this test, doesn't matter if you record that beggar sent
-
-	if !chooser.BlockIsWantedByPeer(block.Key(), beggar.Peer) {
-		t.Fatal("chooser failed to record that beggar wants block")
-	}
-}
-
-func TestPeerIsAddedToPeersWhenMessageReceivedOrSent(t *testing.T) {
-
-	sanfrancisco := newPeerAndStrategist("sf")
-	seattle := newPeerAndStrategist("sea")
-
-	m := message.New()
-
-	sanfrancisco.MessageSent(seattle.Peer, m)
-	seattle.MessageReceived(sanfrancisco.Peer, m)
-
-	if seattle.Peer.Key() == sanfrancisco.Peer.Key() {
-		t.Fatal("Sanity Check: Peers have same Key!")
-	}
-
-	if !peerIsPartner(seattle.Peer, sanfrancisco.Strategy) {
-		t.Fatal("Peer wasn't added as a Partner")
-	}
-
-	if !peerIsPartner(sanfrancisco.Peer, seattle.Strategy) {
-		t.Fatal("Peer wasn't added as a Partner")
-	}
-}
-
-func peerIsPartner(p peer.Peer, s Strategy) bool {
-	for _, partner := range s.Peers() {
-		if partner.Key() == p.Key() {
-			return true
-		}
-	}
-	return false
-}
diff --git a/exchange/bitswap/wantlist/wantlist.go b/exchange/bitswap/wantlist/wantlist.go
new file mode 100644
index 00000000000..aa58ee155f5
--- /dev/null
+++ b/exchange/bitswap/wantlist/wantlist.go
@@ -0,0 +1,111 @@
+package wantlist
+
+import (
+	u "github.com/jbenet/go-ipfs/util"
+	"sort"
+	"sync"
+)
+
+type ThreadSafe struct {
+	lk sync.RWMutex
+	Wantlist
+}
+
+// not threadsafe
+type Wantlist struct {
+	set map[u.Key]Entry
+}
+
+type Entry struct {
+	// TODO consider making entries immutable so they can be shared safely and
+	// slices can be copied efficiently.
+	Key      u.Key
+	Priority int
+}
+
+type entrySlice []Entry
+
+func (es entrySlice) Len() int           { return len(es) }
+func (es entrySlice) Swap(i, j int)      { es[i], es[j] = es[j], es[i] }
+func (es entrySlice) Less(i, j int) bool { return es[i].Priority > es[j].Priority }
+
+func NewThreadSafe() *ThreadSafe {
+	return &ThreadSafe{
+		Wantlist: *New(),
+	}
+}
+
+func New() *Wantlist {
+	return &Wantlist{
+		set: make(map[u.Key]Entry),
+	}
+}
+
+func (w *ThreadSafe) Add(k u.Key, priority int) {
+	// TODO rm defer for perf
+	w.lk.Lock()
+	defer w.lk.Unlock()
+	w.Wantlist.Add(k, priority)
+}
+
+func (w *ThreadSafe) Remove(k u.Key) {
+	// TODO rm defer for perf
+	w.lk.Lock()
+	defer w.lk.Unlock()
+	w.Wantlist.Remove(k)
+}
+
+func (w *ThreadSafe) Contains(k u.Key) bool {
+	// TODO rm defer for perf
+	w.lk.RLock()
+	defer w.lk.RUnlock()
+	return w.Wantlist.Contains(k)
+}
+
+func (w *ThreadSafe) Entries() []Entry {
+	w.lk.RLock()
+	defer w.lk.RUnlock()
+	return w.Wantlist.Entries()
+}
+
+func (w *ThreadSafe) SortedEntries() []Entry {
+	w.lk.RLock()
+	defer w.lk.RUnlock()
+	return w.Wantlist.SortedEntries()
+}
+
+func (w *Wantlist) Add(k u.Key, priority int) {
+	if _, ok := w.set[k]; ok {
+		return
+	}
+	w.set[k] = Entry{
+		Key:      k,
+		Priority: priority,
+	}
+}
+
+func (w *Wantlist) Remove(k u.Key) {
+	delete(w.set, k)
+}
+
+func (w *Wantlist) Contains(k u.Key) bool {
+	_, ok := w.set[k]
+	return ok
+}
+
+func (w *Wantlist) Entries() []Entry {
+	var es entrySlice
+	for _, e := range w.set {
+		es = append(es, e)
+	}
+	return es
+}
+
+func (w *Wantlist) SortedEntries() []Entry {
+	var es entrySlice
+	for _, e := range w.set {
+		es = append(es, e)
+	}
+	sort.Sort(es)
+	return es
+}
diff --git a/merkledag/merkledag.go b/merkledag/merkledag.go
index d22e3a39698..3d8916b034f 100644
--- a/merkledag/merkledag.go
+++ b/merkledag/merkledag.go
@@ -2,6 +2,7 @@
 package merkledag
 
 import (
+	"bytes"
 	"fmt"
 	"sync"
 	"time"
@@ -294,8 +295,9 @@ func FetchGraph(ctx context.Context, root *Node, serv DAGService) chan struct{}
 // returns the indexes of any links pointing to it
 func FindLinks(n *Node, k u.Key) []int {
 	var out []int
+	keybytes := []byte(k)
 	for i, lnk := range n.Links {
-		if u.Key(lnk.Hash) == k {
+		if bytes.Equal([]byte(lnk.Hash), keybytes) {
 			out = append(out, i)
 		}
 	}
diff --git a/net/backpressure/backpressure.go b/net/backpressure/backpressure.go
new file mode 100644
index 00000000000..19950a72801
--- /dev/null
+++ b/net/backpressure/backpressure.go
@@ -0,0 +1 @@
+package backpressure_tests
diff --git a/routing/dht/dht.go b/routing/dht/dht.go
index 5a68bd75925..6e49c84cfda 100644
--- a/routing/dht/dht.go
+++ b/routing/dht/dht.go
@@ -120,15 +120,12 @@ func (dht *IpfsDHT) putProvider(ctx context.Context, p peer.Peer, key string) er
 	// add self as the provider
 	pmes.ProviderPeers = pb.PeersToPBPeers(dht.network, []peer.Peer{dht.self})
 
-	rpmes, err := dht.sendRequest(ctx, p, pmes)
+	err := dht.sendMessage(ctx, p, pmes)
 	if err != nil {
 		return err
 	}
 
 	log.Debugf("%s putProvider: %s for %s", dht.self, p, u.Key(key))
-	if rpmes.GetKey() != pmes.GetKey() {
-		return errors.New("provider not added correctly")
-	}
 
 	return nil
 }
diff --git a/routing/dht/dht_net.go b/routing/dht/dht_net.go
index d1898f15c37..6e46b4de63b 100644
--- a/routing/dht/dht_net.go
+++ b/routing/dht/dht_net.go
@@ -8,8 +8,8 @@ import (
 	peer "github.com/jbenet/go-ipfs/peer"
 	pb "github.com/jbenet/go-ipfs/routing/dht/pb"
 
-	ggio "github.com/jbenet/go-ipfs/Godeps/_workspace/src/code.google.com/p/gogoprotobuf/io"
 	context "github.com/jbenet/go-ipfs/Godeps/_workspace/src/code.google.com/p/go.net/context"
+	ggio "github.com/jbenet/go-ipfs/Godeps/_workspace/src/code.google.com/p/gogoprotobuf/io"
 )
 
 // handleNewStream implements the inet.StreamHandler
@@ -102,3 +102,24 @@ func (dht *IpfsDHT) sendRequest(ctx context.Context, p peer.Peer, pmes *pb.Messa
 	log.Event(ctx, "dhtReceivedMessage", dht.self, p, rpmes)
 	return rpmes, nil
 }
+
+// sendMessage sends out a message
+func (dht *IpfsDHT) sendMessage(ctx context.Context, p peer.Peer, pmes *pb.Message) error {
+
+	log.Debugf("%s dht starting stream", dht.self)
+	s, err := dht.network.NewStream(inet.ProtocolDHT, p)
+	if err != nil {
+		return err
+	}
+	defer s.Close()
+
+	w := ggio.NewDelimitedWriter(s)
+
+	log.Debugf("%s writing", dht.self)
+	if err := w.WriteMsg(pmes); err != nil {
+		return err
+	}
+	log.Event(ctx, "dhtSentMessage", dht.self, p, pmes)
+	log.Debugf("%s done", dht.self)
+	return nil
+}
diff --git a/routing/dht/routing.go b/routing/dht/routing.go
index 76260e71085..51f15ff21be 100644
--- a/routing/dht/routing.go
+++ b/routing/dht/routing.go
@@ -11,6 +11,7 @@ import (
 	pb "github.com/jbenet/go-ipfs/routing/dht/pb"
 	kb "github.com/jbenet/go-ipfs/routing/kbucket"
 	u "github.com/jbenet/go-ipfs/util"
+	pset "github.com/jbenet/go-ipfs/util/peerset"
 )
 
 // asyncQueryBuffer is the size of buffered channels in async queries. This
@@ -140,11 +141,11 @@ func (dht *IpfsDHT) FindProvidersAsync(ctx context.Context, key u.Key, count int
 func (dht *IpfsDHT) findProvidersAsyncRoutine(ctx context.Context, key u.Key, count int, peerOut chan peer.Peer) {
 	defer close(peerOut)
 
-	ps := newPeerSet()
+	ps := pset.NewLimited(count)
 	provs := dht.providers.GetProviders(ctx, key)
 	for _, p := range provs {
 		// NOTE: assuming that this list of peers is unique
-		if ps.AddIfSmallerThan(p, count) {
+		if ps.TryAdd(p) {
 			select {
 			case peerOut <- p:
 			case <-ctx.Done():
@@ -175,7 +176,7 @@ func (dht *IpfsDHT) findProvidersAsyncRoutine(ctx context.Context, key u.Key, co
 
 		// Add unique providers from request, up to 'count'
 		for _, prov := range provs {
-			if ps.AddIfSmallerThan(prov, count) {
+			if ps.TryAdd(prov) {
 				select {
 				case peerOut <- prov:
 				case <-ctx.Done():
@@ -207,7 +208,7 @@ func (dht *IpfsDHT) findProvidersAsyncRoutine(ctx context.Context, key u.Key, co
 	}
 }
 
-func (dht *IpfsDHT) addPeerListAsync(ctx context.Context, k u.Key, peers []*pb.Message_Peer, ps *peerSet, count int, out chan peer.Peer) {
+func (dht *IpfsDHT) addPeerListAsync(ctx context.Context, k u.Key, peers []*pb.Message_Peer, ps *pset.PeerSet, count int, out chan peer.Peer) {
 	var wg sync.WaitGroup
 	for _, pbp := range peers {
 		wg.Add(1)
@@ -225,7 +226,7 @@ func (dht *IpfsDHT) addPeerListAsync(ctx context.Context, k u.Key, peers []*pb.M
 			}
 
 			dht.providers.AddProvider(k, p)
-			if ps.AddIfSmallerThan(p, count) {
+			if ps.TryAdd(p) {
 				select {
 				case out <- p:
 				case <-ctx.Done():
diff --git a/routing/dht/util.go b/routing/dht/util.go
index 00ac38dbc7e..2b0c1e2a2a7 100644
--- a/routing/dht/util.go
+++ b/routing/dht/util.go
@@ -2,8 +2,6 @@ package dht
 
 import (
 	"sync"
-
-	peer "github.com/jbenet/go-ipfs/peer"
 )
 
 // Pool size is the number of nodes used for group find/set RPC calls
@@ -39,45 +37,3 @@ func (c *counter) Size() (s int) {
 	c.mut.Unlock()
 	return
 }
-
-// peerSet is a threadsafe set of peers
-type peerSet struct {
-	ps map[string]bool
-	lk sync.RWMutex
-}
-
-func newPeerSet() *peerSet {
-	ps := new(peerSet)
-	ps.ps = make(map[string]bool)
-	return ps
-}
-
-func (ps *peerSet) Add(p peer.Peer) {
-	ps.lk.Lock()
-	ps.ps[string(p.ID())] = true
-	ps.lk.Unlock()
-}
-
-func (ps *peerSet) Contains(p peer.Peer) bool {
-	ps.lk.RLock()
-	_, ok := ps.ps[string(p.ID())]
-	ps.lk.RUnlock()
-	return ok
-}
-
-func (ps *peerSet) Size() int {
-	ps.lk.RLock()
-	defer ps.lk.RUnlock()
-	return len(ps.ps)
-}
-
-func (ps *peerSet) AddIfSmallerThan(p peer.Peer, maxsize int) bool {
-	var success bool
-	ps.lk.Lock()
-	if _, ok := ps.ps[string(p.ID())]; !ok && len(ps.ps) < maxsize {
-		success = true
-		ps.ps[string(p.ID())] = true
-	}
-	ps.lk.Unlock()
-	return success
-}
diff --git a/routing/mock/mockrouting_test.go b/routing/mock/mockrouting_test.go
index 6700cd8eded..44b1b52bd64 100644
--- a/routing/mock/mockrouting_test.go
+++ b/routing/mock/mockrouting_test.go
@@ -36,6 +36,9 @@ func TestClientFindProviders(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
+
+	// This is bad... but simulating networks is hard
+	time.Sleep(time.Millisecond * 300)
 	max := 100
 
 	providersFromHashTable, err := rs.Client(peer).FindProviders(context.Background(), k)
@@ -160,6 +163,7 @@ func TestValidAfter(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
+	t.Log("providers", providers)
 	if len(providers) != 1 {
 		t.Fail()
 	}
diff --git a/util/peerset/peerset.go b/util/peerset/peerset.go
new file mode 100644
index 00000000000..5dcf266822c
--- /dev/null
+++ b/util/peerset/peerset.go
@@ -0,0 +1,61 @@
+package peerset
+
+import (
+	peer "github.com/jbenet/go-ipfs/peer"
+	"sync"
+)
+
+// PeerSet is a threadsafe set of peers
+type PeerSet struct {
+	ps   map[string]bool // FIXME can be map[string]struct{}
+	lk   sync.RWMutex
+	size int
+}
+
+func New() *PeerSet {
+	ps := new(PeerSet)
+	ps.ps = make(map[string]bool)
+	ps.size = -1
+	return ps
+}
+
+func NewLimited(size int) *PeerSet {
+	ps := new(PeerSet)
+	ps.ps = make(map[string]bool)
+	ps.size = size
+	return ps
+}
+
+func (ps *PeerSet) Add(p peer.Peer) {
+	ps.lk.Lock()
+	ps.ps[string(p.ID())] = true
+	ps.lk.Unlock()
+}
+
+func (ps *PeerSet) Contains(p peer.Peer) bool {
+	ps.lk.RLock()
+	_, ok := ps.ps[string(p.ID())]
+	ps.lk.RUnlock()
+	return ok
+}
+
+func (ps *PeerSet) Size() int {
+	ps.lk.RLock()
+	defer ps.lk.RUnlock()
+	return len(ps.ps)
+}
+
+// TryAdd Attempts to add the given peer into the set.
+// This operation can fail for one of two reasons:
+// 1) The given peer is already in the set
+// 2) The number of peers in the set is equal to size
+func (ps *PeerSet) TryAdd(p peer.Peer) bool {
+	var success bool
+	ps.lk.Lock()
+	if _, ok := ps.ps[string(p.ID())]; !ok && (len(ps.ps) < ps.size || ps.size == -1) {
+		success = true
+		ps.ps[string(p.ID())] = true
+	}
+	ps.lk.Unlock()
+	return success
+}