network: add block queue

This one will replace blockCache in Blockchain itself as it can and should be
external from it. The idea is that we only feed successive blocks into the
Blockchain and it only stores valid proper Blockchain and nothing else.

pkg/network/blockqueue_test.go

@@ -0,0 +1,71 @@
+package network
+
+import (
+	"testing"
+	"time"
+
+	"github.com/CityOfZion/neo-go/pkg/core"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestBlockQueue(t *testing.T) {
+	chain := &testChain{}
+	// notice, it's not yet running
+	bq := newBlockQueue(0, chain)
+	blocks := make([]*core.Block, 11)
+	for i := 1; i < 11; i++ {
+		blocks[i] = &core.Block{BlockBase: core.BlockBase{Index: uint32(i)}}
+	}
+	// not the ones expected currently
+	for i := 3; i < 5; i++ {
+		assert.NoError(t, bq.putBlock(blocks[i]))
+	}
+	// nothing should be put into the blockchain
+	assert.Equal(t, uint32(0), chain.BlockHeight())
+	assert.Equal(t, 2, bq.length())
+	// now added expected ones (with duplicates)
+	for i := 1; i < 5; i++ {
+		assert.NoError(t, bq.putBlock(blocks[i]))
+	}
+	// but they're still not put into the blockchain, because bq isn't running
+	assert.Equal(t, uint32(0), chain.BlockHeight())
+	assert.Equal(t, 4, bq.length())
+	go bq.run()
+	// run() is asynchronous, so we need some kind of timeout anyway and this is the simplest one
+	for i := 0; i < 5; i++ {
+		if chain.BlockHeight() != 4 {
+			time.Sleep(time.Second)
+		}
+	}
+	assert.Equal(t, 0, bq.length())
+	assert.Equal(t, uint32(4), chain.BlockHeight())
+	// put some old blocks
+	for i := 1; i < 5; i++ {
+		assert.NoError(t, bq.putBlock(blocks[i]))
+	}
+	assert.Equal(t, 0, bq.length())
+	assert.Equal(t, uint32(4), chain.BlockHeight())
+	// unexpected blocks with run() active
+	assert.NoError(t, bq.putBlock(blocks[8]))
+	assert.Equal(t, 1, bq.length())
+	assert.Equal(t, uint32(4), chain.BlockHeight())
+	assert.NoError(t, bq.putBlock(blocks[7]))
+	assert.Equal(t, 2, bq.length())
+	assert.Equal(t, uint32(4), chain.BlockHeight())
+	// sparse put
+	assert.NoError(t, bq.putBlock(blocks[10]))
+	assert.Equal(t, 3, bq.length())
+	assert.Equal(t, uint32(4), chain.BlockHeight())
+	assert.NoError(t, bq.putBlock(blocks[6]))
+	assert.NoError(t, bq.putBlock(blocks[5]))
+	// run() is asynchronous, so we need some kind of timeout anyway and this is the simplest one
+	for i := 0; i < 5; i++ {
+		if chain.BlockHeight() != 8 {
+			time.Sleep(time.Second)
+		}
+	}
+	assert.Equal(t, 1, bq.length())
+	assert.Equal(t, uint32(8), chain.BlockHeight())
+	bq.discard()
+	assert.Equal(t, 0, bq.length())
+}