From 9d7ae40003e0620d74be6e85680e1aad92f6fa17 Mon Sep 17 00:00:00 2001
From: Brian Tiger Chow <brian.holderchow@gmail.com>
Date: Sun, 21 Sep 2014 23:34:42 -0700
Subject: [PATCH] feat(bitswap) expose ability to toggle "niceness"

true -> always send to peer

false -> use ledger-based strategy described in IPFS paper draft 3
---
 core/core.go                               |  3 ++-
 exchange/bitswap/bitswap.go                |  4 ++--
 exchange/bitswap/bitswap_test.go           |  3 ++-
 exchange/bitswap/strategy/math.go          |  3 +++
 exchange/bitswap/strategy/strategy.go      | 13 +++++++++++--
 exchange/bitswap/strategy/strategy_test.go |  2 +-
 6 files changed, 21 insertions(+), 7 deletions(-)

diff --git a/core/core.go b/core/core.go
index 423dffe81..d925405dd 100644
--- a/core/core.go
+++ b/core/core.go
@@ -118,7 +118,8 @@ func NewIpfsNode(cfg *config.Config, online bool) (*IpfsNode, error) {
 		// TODO(brian): perform this inside NewDHT factory method
 		dhtService.Handler = route // wire the handler to the service.
 
-		exchangeSession = bitswap.NetMessageSession(ctx, local, exchangeService, route, d)
+		const alwaysSendToPeer = true // use YesManStrategy
+		exchangeSession = bitswap.NetMessageSession(ctx, local, exchangeService, route, d, alwaysSendToPeer)
 
 		// TODO(brian): pass a context to initConnections
 		go initConnections(ctx, cfg, peerstore, route)
diff --git a/exchange/bitswap/bitswap.go b/exchange/bitswap/bitswap.go
index fcc558a2c..4f5bb45e7 100644
--- a/exchange/bitswap/bitswap.go
+++ b/exchange/bitswap/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(),
diff --git a/exchange/bitswap/bitswap_test.go b/exchange/bitswap/bitswap_test.go
index 2173fb57f..107180af7 100644
--- a/exchange/bitswap/bitswap_test.go
+++ b/exchange/bitswap/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(),
diff --git a/exchange/bitswap/strategy/math.go b/exchange/bitswap/strategy/math.go
index 21b1ff163..c5339e5b3 100644
--- a/exchange/bitswap/strategy/math.go
+++ b/exchange/bitswap/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())
 }
diff --git a/exchange/bitswap/strategy/strategy.go b/exchange/bitswap/strategy/strategy.go
index dc7a8e1b3..1cd4a021f 100644
--- a/exchange/bitswap/strategy/strategy.go
+++ b/exchange/bitswap/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,
 	}
 }
 
diff --git a/exchange/bitswap/strategy/strategy_test.go b/exchange/bitswap/strategy/strategy_test.go
index e90bcd4ec..21f293c1c 100644
--- a/exchange/bitswap/strategy/strategy_test.go
+++ b/exchange/bitswap/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),
 	}
 }