1 files changed, 97 insertions, 0 deletions
diff --git a/eth/downloader/peer.go b/eth/downloader/peer.go
new file mode 100644
index 000000000..f66e5afd8
--- /dev/null
+++ b/eth/downloader/peer.go
@@ -0,0 +1,97 @@
+package downloader
+
+import (
+	"errors"
+	"math/big"
+	"sync"
+
+	"github.com/ethereum/go-ethereum/common"
+)
+
+const (
+	workingState = 2
+	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 // Peer state (working, idle)
+	rep   int // TODO peer reputation
+
+	mu         sync.RWMutex
+	id         string
+	td         *big.Int
+	recentHash common.Hash
+
+	getHashes hashFetcherFn
+	getBlocks blockFetcherFn
+}
+
+// create a new peer
+func newPeer(id string, td *big.Int, hash common.Hash, getHashes hashFetcherFn, getBlocks blockFetcherFn) *peer {
+	return &peer{id: id, td: td, recentHash: hash, getHashes: getHashes, getBlocks: getBlocks, state: idleState}
+}
+
+// fetch a chunk using the peer
+func (p *peer) fetch(chunk *chunk) error {
+	p.mu.Lock()
+	defer p.mu.Unlock()
+
+	if p.state == workingState {
+		return errors.New("peer already fetching chunk")
+	}
+
+	// set working state
+	p.state = workingState
+	// convert the set to a fetchable slice
+	hashes, i := make([]common.Hash, chunk.hashes.Size()), 0
+	chunk.hashes.Each(func(v interface{}) bool {
+		hashes[i] = v.(common.Hash)
+		i++
+		return true
+	})
+	p.getBlocks(hashes)
+
+	return nil
+}