downloader: added missing blocks catchup functionality

When a parent is missing in the block list an attempt should be made to
fetch the missing parent and grandparents.

eth/downloader/downloader_test.go

@@ -14,7 +14,7 @@ import (
 
 var knownHash = common.Hash{1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}
 
-func createHashes(amount int) (hashes []common.Hash) {
+func createHashes(start, amount int) (hashes []common.Hash) {
 	hashes = make([]common.Hash, amount+1)
 	hashes[len(hashes)-1] = knownHash
 
@@ -49,7 +49,7 @@ type downloadTester struct {
 
 func newTester(t *testing.T, hashes []common.Hash, blocks map[common.Hash]*types.Block) *downloadTester {
 	tester := &downloadTester{t: t, hashes: hashes, blocks: blocks, done: make(chan bool)}
-	downloader := New(tester.hasBlock, tester.insertChain)
+	downloader := New(tester.hasBlock, tester.insertChain, func() *big.Int { return new(big.Int) })
 	tester.downloader = downloader
 
 	return tester
@@ -84,7 +84,7 @@ func (dl *downloadTester) getBlocks(id string) func([]common.Hash) error {
 			blocks[i] = dl.blocks[hash]
 		}
 
-		go dl.downloader.DeliverBlocks(id, blocks)
+		go dl.downloader.DeliverChunk(id, blocks)
 
 		return nil
 	}
@@ -109,11 +109,11 @@ func TestDownload(t *testing.T) {
 	glog.SetV(logger.Detail)
 	glog.SetToStderr(true)
 
-	hashes := createHashes(1000)
+	hashes := createHashes(0, 1000)
 	blocks := createBlocksFromHashes(hashes)
 	tester := newTester(t, hashes, blocks)
 
-	tester.newPeer("peer1", big.NewInt(10000), hashes[len(hashes)-1])
+	tester.newPeer("peer1", big.NewInt(10000), hashes[0])
 	tester.newPeer("peer2", big.NewInt(0), common.Hash{})
 	tester.badBlocksPeer("peer3", big.NewInt(0), common.Hash{})
 	tester.badBlocksPeer("peer4", big.NewInt(0), common.Hash{})
@@ -126,3 +126,30 @@ success:
 		t.Error("timout")
 	}
 }
+
+func TestMissing(t *testing.T) {
+	t.Skip()
+
+	glog.SetV(logger.Detail)
+	glog.SetToStderr(true)
+
+	hashes := createHashes(0, 1000)
+	extraHashes := createHashes(1001, 1003)
+	blocks := createBlocksFromHashes(append(extraHashes, hashes...))
+	tester := newTester(t, hashes, blocks)
+
+	tester.newPeer("peer1", big.NewInt(10000), hashes[len(hashes)-1])
+
+	hashes = append(extraHashes, hashes[:len(hashes)-1]...)
+	tester.newPeer("peer2", big.NewInt(0), common.Hash{})
+
+success1:
+	select {
+	case <-tester.done:
+		break success1
+	case <-time.After(10 * time.Second): // XXX this could actually fail on a slow computer
+		t.Error("timout")
+	}
+
+	tester.downloader.AddBlock("peer2", blocks[hashes[len(hashes)-1]], big.NewInt(10001))
+}

eth/downloader/peer.go

@@ -13,9 +13,51 @@ const (
 	idleState    = 4
 )
 
+type hashFetcherFn func(common.Hash) error
+type blockFetcherFn func([]common.Hash) error
+
+// XXX make threadsafe!!!!
+type peers map[string]*peer
+
+func (p peers) get(state int) []*peer {
+	var peers []*peer
+	for _, peer := range p {
+		peer.mu.RLock()
+		if peer.state == state {
+			peers = append(peers, peer)
+		}
+		peer.mu.RUnlock()
+	}
+
+	return peers
+}
+
+func (p peers) setState(id string, state int) {
+	if peer, exist := p[id]; exist {
+		peer.mu.Lock()
+		defer peer.mu.Unlock()
+		peer.state = state
+	}
+}
+
+func (p peers) getPeer(id string) *peer {
+	return p[id]
+}
+
+func (p peers) bestPeer() *peer {
+	var peer *peer
+	for _, cp := range p {
+		if peer == nil || cp.td.Cmp(peer.td) > 0 {
+			peer = cp
+		}
+	}
+	return peer
+}
+
 // peer represents an active peer
 type peer struct {
-	state int
+	state int // Peer state (working, idle)
+	rep   int // TODO peer reputation
 
 	mu         sync.RWMutex
 	id         string

eth/downloader/queue.go

@@ -2,9 +2,11 @@ package downloader
 
 import (
 	"math"
+	"math/big"
 	"sync"
 	"time"
 
+	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/core/types"
 	"gopkg.in/fatih/set.v0"
 )
@@ -12,6 +14,8 @@ import (
 // queue represents hashes that are either need fetching or are being fetched
 type queue struct {
 	hashPool    *set.Set
+	fetchPool   *set.Set
+	blockHashes *set.Set
 
 	mu       sync.Mutex
 	fetching map[string]*chunk
@@ -21,6 +25,8 @@ type queue struct {
 func newqueue() *queue {
 	return &queue{
 		hashPool:    set.New(),
+		fetchPool:   set.New(),
+		blockHashes: set.New(),
 		fetching:    make(map[string]*chunk),
 	}
 }
@@ -50,6 +56,8 @@ func (c *queue) get(p *peer, max int) *chunk {
 	})
 	// remove the fetchable hashes from hash pool
 	c.hashPool.Separate(hashes)
+	c.fetchPool.Merge(hashes)
+
 	// Create a new chunk for the seperated hashes. The time is being used
 	// to reset the chunk (timeout)
 	chunk := &chunk{hashes, time.Now()}
@@ -60,6 +68,22 @@ func (c *queue) get(p *peer, max int) *chunk {
 	return chunk
 }
 
+func (c *queue) has(hash common.Hash) bool {
+	return c.hashPool.Has(hash) || c.fetchPool.Has(hash)
+}
+
+func (c *queue) addBlock(id string, block *types.Block, td *big.Int) {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+
+	// when adding a block make sure it doesn't already exist
+	if !c.blockHashes.Has(block.Hash()) {
+		c.hashPool.Remove(block.Hash())
+		c.blocks = append(c.blocks, block)
+	}
+}
+
+// deliver delivers a chunk to the queue that was requested of the peer
 func (c *queue) deliver(id string, blocks []*types.Block) {
 	c.mu.Lock()
 	defer c.mu.Unlock()
@@ -70,15 +94,19 @@ func (c *queue) deliver(id string, blocks []*types.Block) {
 		delete(c.fetching, id)
 
 		// seperate the blocks and the hashes
-		chunk.seperate(blocks)
+		blockHashes := chunk.fetchedHashes(blocks)
+		// merge block hashes
+		c.blockHashes.Merge(blockHashes)
 		// Add the blocks
 		c.blocks = append(c.blocks, blocks...)
 
 		// Add back whatever couldn't be delivered
 		c.hashPool.Merge(chunk.hashes)
+		c.fetchPool.Separate(chunk.hashes)
 	}
 }
 
+// puts puts sets of hashes on to the queue for fetching
 func (c *queue) put(hashes *set.Set) {
 	c.mu.Lock()
 	defer c.mu.Unlock()
@@ -91,8 +119,12 @@ type chunk struct {
 	itime  time.Time
 }
 
-func (ch *chunk) seperate(blocks []*types.Block) {
+func (ch *chunk) fetchedHashes(blocks []*types.Block) *set.Set {
+	fhashes := set.New()
 	for _, block := range blocks {
-		ch.hashes.Remove(block.Hash())
+		fhashes.Add(block.Hash())
 	}
+	ch.hashes.Separate(fhashes)
+
+	return fhashes
 }