eth, eth/downloader: remove duplicate consts, bump hash fetch to 2K

eth/downloader/downloader.go

@@ -15,8 +15,10 @@ import (
 )
 
 const (
-	maxHashFetch     = 512              // Amount of hashes to be fetched per chunk
-	maxBlockFetch    = 128              // Amount of blocks to be fetched per chunk
+	MinHashFetch  = 512  // Minimum amount of hashes to not consider a peer stalling
+	MaxHashFetch  = 2048 // Amount of hashes to be fetched per retrieval request
+	MaxBlockFetch = 128  // Amount of blocks to be fetched per retrieval request
+
 	peerCountTimeout = 12 * time.Second // Amount of time it takes for the peer handler to ignore minDesiredPeerCount
 	hashTTL          = 5 * time.Second  // Time it takes for a hash request to time out
 )
@@ -290,7 +292,7 @@ func (d *Downloader) fetchHashes(p *peer, h common.Hash) error {
 			}
 			if !done {
 				// Check that the peer is not stalling the sync
-				if len(inserts) < maxHashFetch {
+				if len(inserts) < MinHashFetch {
 					return ErrStallingPeer
 				}
 				// Try and fetch a random block to verify the hash batch
@@ -451,7 +453,7 @@ out:
 					}
 					// Get a possible chunk. If nil is returned no chunk
 					// could be returned due to no hashes available.
-					request := d.queue.Reserve(peer, maxBlockFetch)
+					request := d.queue.Reserve(peer, MaxBlockFetch)
 					if request == nil {
 						continue
 					}

eth/downloader/downloader_test.go

@@ -135,7 +135,7 @@ func (dl *downloadTester) getBlock(hash common.Hash) *types.Block {
 
 // getHashes retrieves a batch of hashes for reconstructing the chain.
 func (dl *downloadTester) getHashes(head common.Hash) error {
-	limit := maxHashFetch
+	limit := MaxHashFetch
 	if dl.maxHashFetch > 0 {
 		limit = dl.maxHashFetch
 	}

eth/downloader/queue.go

@@ -17,7 +17,7 @@ import (
 )
 
 const (
-	blockCacheLimit = 1024 // Maximum number of blocks to cache before throttling the download
+	blockCacheLimit = 8 * MaxBlockFetch // Maximum number of blocks to cache before throttling the download
 )
 
 // fetchRequest is a currently running block retrieval operation.

eth/handler.go

@@ -206,8 +206,8 @@ func (self *ProtocolManager) handleMsg(p *peer) error {
 			return errResp(ErrDecode, "->msg %v: %v", msg, err)
 		}
 
-		if request.Amount > maxHashes {
-			request.Amount = maxHashes
+		if request.Amount > downloader.MaxHashFetch {
+			request.Amount = downloader.MaxHashFetch
 		}
 
 		hashes := self.chainman.GetBlockHashesFromHash(request.Hash, request.Amount)
@@ -254,7 +254,7 @@ func (self *ProtocolManager) handleMsg(p *peer) error {
 			if block != nil {
 				blocks = append(blocks, block)
 			}
-			if i == maxBlocks {
+			if i == downloader.MaxBlockFetch {
 				break
 			}
 		}

eth/peer.go

@@ -8,6 +8,7 @@ import (
 
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/core/types"
+	"github.com/ethereum/go-ethereum/eth/downloader"
 	"github.com/ethereum/go-ethereum/logger"
 	"github.com/ethereum/go-ethereum/logger/glog"
 	"github.com/ethereum/go-ethereum/p2p"
@@ -100,8 +101,8 @@ func (p *peer) sendTransaction(tx *types.Transaction) error {
 }
 
 func (p *peer) requestHashes(from common.Hash) error {
-	glog.V(logger.Debug).Infof("[%s] fetching hashes (%d) %x...\n", p.id, maxHashes, from[:4])
-	return p2p.Send(p.rw, GetBlockHashesMsg, getBlockHashesMsgData{from, maxHashes})
+	glog.V(logger.Debug).Infof("[%s] fetching hashes (%d) %x...\n", p.id, downloader.MaxHashFetch, from[:4])
+	return p2p.Send(p.rw, GetBlockHashesMsg, getBlockHashesMsgData{from, downloader.MaxHashFetch})
 }
 
 func (p *peer) requestBlocks(hashes []common.Hash) error {

eth/protocol.go

@@ -12,8 +12,6 @@ const (
 	NetworkId          = 0
 	ProtocolLength     = uint64(8)
 	ProtocolMaxMsgSize = 10 * 1024 * 1024
-	maxHashes          = 512
-	maxBlocks          = 128
 )
 
 // eth protocol message codes