feat(bitswap) expose ability to toggle "niceness"

true -> always send to peer

false -> use ledger-based strategy described in IPFS paper draft 3

bitswap.go

@@ -19,13 +19,13 @@ import (
 
 // NetMessageSession initializes a BitSwap session that communicates over the
 // provided NetMessage service
-func NetMessageSession(parent context.Context, p *peer.Peer, s bsnet.NetMessageService, directory bsnet.Routing, d ds.Datastore) exchange.Interface {
+func NetMessageSession(parent context.Context, p *peer.Peer, s bsnet.NetMessageService, directory bsnet.Routing, d ds.Datastore, nice bool) exchange.Interface {
 
 	networkAdapter := bsnet.NetMessageAdapter(s, nil)
 	bs := &bitswap{
 		blockstore:    blockstore.NewBlockstore(d),
 		notifications: notifications.New(),
-		strategy:      strategy.New(),
+		strategy:      strategy.New(nice),
 		routing:       directory,
 		sender:        networkAdapter,
 		wantlist:      u.NewKeySet(),

bitswap_test.go

@@ -283,10 +283,11 @@ func session(net tn.Network, rs tn.RoutingServer, id peer.ID) instance {
 	htc := rs.Client(p)
 
 	blockstore := bstore.NewBlockstore(ds.NewMapDatastore())
+	const alwaysSendToPeer = true
 	bs := &bitswap{
 		blockstore:    blockstore,
 		notifications: notifications.New(),
-		strategy:      strategy.New(),
+		strategy:      strategy.New(alwaysSendToPeer),
 		routing:       htc,
 		sender:        adapter,
 		wantlist:      util.NewKeySet(),

strategy/math.go

@@ -7,6 +7,9 @@ import (
 
 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())
 }

strategy/strategy.go

@@ -9,10 +9,19 @@ import (
 )
 
 // TODO declare thread-safe datastore
-func New() 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: yesManStrategy,
+		strategyFunc: stratFunc,
 	}
 }
 

strategy/strategy_test.go

@@ -17,7 +17,7 @@ type peerAndStrategist struct {
 func newPeerAndStrategist(idStr string) peerAndStrategist {
 	return peerAndStrategist{
 		Peer:     &peer.Peer{ID: peer.ID(idStr)},
-		Strategy: New(),
+		Strategy: New(true),
 	}
 }