introducing p2p pkg

I think it's time to move a lot of the peer-to-peer networking
but-not-ipfs-specific things into its own package: p2p.
This could in the future be split off into its own library.
The first thing to go is the peer.

peer/queue/queue_test.go

@@ -0,0 +1,140 @@
+package queue
+
+import (
+	"fmt"
+	"sync"
+	"testing"
+	"time"
+
+	peer "github.com/jbenet/go-ipfs/p2p/peer"
+	u "github.com/jbenet/go-ipfs/util"
+
+	context "github.com/jbenet/go-ipfs/Godeps/_workspace/src/code.google.com/p/go.net/context"
+)
+
+func TestQueue(t *testing.T) {
+
+	p1 := peer.ID("11140beec7b5ea3f0fdbc95d0dd47f3c5bc275da8a31") // these aren't valid, because need to hex-decode.
+	p2 := peer.ID("11140beec7b5ea3f0fdbc95d0dd47f3c5bc275da8a32") // these aren't valid, because need to hex-decode.
+	p3 := peer.ID("11140beec7b5ea3f0fdbc95d0dd47f3c5bc275da8a33") // these aren't valid, because need to hex-decode.
+	p4 := peer.ID("11140beec7b5ea3f0fdbc95d0dd47f3c5bc275da8a34") // these aren't valid, because need to hex-decode.
+	p5 := peer.ID("11140beec7b5ea3f0fdbc95d0dd47f3c5bc275da8a31") // these aren't valid, because need to hex-decode.
+	// but they work.
+
+	// these are the peer.IDs' XORKeySpace Key values:
+	// [228 47 151 130 156 102 222 232 218 31 132 94 170 208 80 253 120 103 55 35 91 237 48 157 81 245 57 247 66 150 9 40]
+	// [26 249 85 75 54 49 25 30 21 86 117 62 85 145 48 175 155 194 210 216 58 14 241 143 28 209 129 144 122 28 163 6]
+	// [78 135 26 216 178 181 224 181 234 117 2 248 152 115 255 103 244 34 4 152 193 88 9 225 8 127 216 158 226 8 236 246]
+	// [125 135 124 6 226 160 101 94 192 57 39 12 18 79 121 140 190 154 147 55 44 83 101 151 63 255 94 179 51 203 241 51]
+
+	pq := NewXORDistancePQ(u.Key("11140beec7b5ea3f0fdbc95d0dd47f3c5bc275da8a31"))
+	pq.Enqueue(p3)
+	pq.Enqueue(p1)
+	pq.Enqueue(p2)
+	pq.Enqueue(p4)
+	pq.Enqueue(p5)
+	pq.Enqueue(p1)
+
+	// should come out as: p1, p4, p3, p2
+
+	if d := pq.Dequeue(); d != p1 && d != p5 {
+		t.Error("ordering failed")
+	}
+
+	if d := pq.Dequeue(); d != p1 && d != p5 {
+		t.Error("ordering failed")
+	}
+
+	if d := pq.Dequeue(); d != p1 && d != p5 {
+		t.Error("ordering failed")
+	}
+
+	if pq.Dequeue() != p4 {
+		t.Error("ordering failed")
+	}
+
+	if pq.Dequeue() != p3 {
+		t.Error("ordering failed")
+	}
+
+	if pq.Dequeue() != p2 {
+		t.Error("ordering failed")
+	}
+
+}
+
+func newPeerTime(t time.Time) peer.ID {
+	s := fmt.Sprintf("hmmm time: %v", t)
+	h := u.Hash([]byte(s))
+	return peer.ID(h)
+}
+
+func TestSyncQueue(t *testing.T) {
+	tickT := time.Microsecond * 50
+	max := 5000
+	consumerN := 10
+	countsIn := make([]int, consumerN*2)
+	countsOut := make([]int, consumerN)
+
+	if testing.Short() {
+		max = 1000
+	}
+
+	ctx := context.Background()
+	pq := NewXORDistancePQ(u.Key("11140beec7b5ea3f0fdbc95d0dd47f3c5bc275da8a31"))
+	cq := NewChanQueue(ctx, pq)
+	wg := sync.WaitGroup{}
+
+	produce := func(p int) {
+		defer wg.Done()
+
+		tick := time.Tick(tickT)
+		for i := 0; i < max; i++ {
+			select {
+			case tim := <-tick:
+				countsIn[p]++
+				cq.EnqChan <- newPeerTime(tim)
+			case <-ctx.Done():
+				return
+			}
+		}
+	}
+
+	consume := func(c int) {
+		defer wg.Done()
+
+		for {
+			select {
+			case <-cq.DeqChan:
+				countsOut[c]++
+				if countsOut[c] >= max*2 {
+					return
+				}
+			case <-ctx.Done():
+				return
+			}
+		}
+	}
+
+	// make n * 2 producers and n consumers
+	for i := 0; i < consumerN; i++ {
+		wg.Add(3)
+		go produce(i)
+		go produce(consumerN + i)
+		go consume(i)
+	}
+
+	wg.Wait()
+
+	sum := func(ns []int) int {
+		total := 0
+		for _, n := range ns {
+			total += n
+		}
+		return total
+	}
+
+	if sum(countsIn) != sum(countsOut) {
+		t.Errorf("didnt get all of them out: %d/%d", sum(countsOut), sum(countsIn))
+	}
+}