simplification of Fetchers (#1344)

storage/request.go

@@ -0,0 +1,58 @@
+// Copyright 2018 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+package storage
+
+import (
+	"sync"
+	"time"
+
+	"github.com/ethersphere/swarm/network/timeouts"
+
+	"github.com/ethereum/go-ethereum/p2p/enode"
+)
+
+// Request encapsulates all the necessary arguments when making a request to NetStore.
+// These could have also been added as part of the interface of NetStore.Get, but a request struct seemed
+// like a better option
+type Request struct {
+	Addr        Address  // chunk address
+	Origin      enode.ID // who is sending us that request? we compare Origin to the suggested peer from RequestFromPeers
+	PeersToSkip sync.Map // peers not to request chunk from
+}
+
+// NewRequest returns a new instance of Request based on chunk address skip check and
+// a map of peers to skip.
+func NewRequest(addr Address) *Request {
+	return &Request{
+		Addr: addr,
+	}
+}
+
+// SkipPeer returns if the peer with nodeID should not be requested to deliver a chunk.
+// Peers to skip are kept per Request and for a time period of FailedPeerSkipDelay.
+func (r *Request) SkipPeer(nodeID string) bool {
+	val, ok := r.PeersToSkip.Load(nodeID)
+	if !ok {
+		return false
+	}
+	t, ok := val.(time.Time)
+	if ok && time.Now().After(t.Add(timeouts.FailedPeerSkipDelay)) {
+		r.PeersToSkip.Delete(nodeID)
+		return false
+	}
+	return true
+}