FAB-1849 LeaderElectionAdapter implementation

Implements adapter that connect between gossip discovery and communication
and leader election algorithm implementation

Change-Id: I60dc6a0a5d7d36f7e689a2b896371d11e588f46d
Signed-off-by: Gennady Laventman <gennady@il.ibm.com>

gossip/election/adapter.go

@@ -0,0 +1,223 @@
+/*
+Copyright IBM Corp. 2017 All Rights Reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+		 http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package election
+
+import (
+	"bytes"
+	"strconv"
+	"sync"
+	"time"
+
+	"github.com/hyperledger/fabric/gossip/api"
+	"github.com/hyperledger/fabric/gossip/comm"
+	"github.com/hyperledger/fabric/gossip/common"
+	"github.com/hyperledger/fabric/gossip/discovery"
+	"github.com/hyperledger/fabric/gossip/proto"
+	"github.com/op/go-logging"
+)
+
+type msgImpl struct {
+	msg *proto.GossipMessage
+}
+
+func (mi *msgImpl) SenderID() string {
+	return string(mi.msg.GetLeadershipMsg().GetMembership().PkiID)
+}
+
+func (mi *msgImpl) IsProposal() bool {
+	return !mi.IsDeclaration()
+}
+
+func (mi *msgImpl) IsDeclaration() bool {
+	isDeclaration, _ := strconv.ParseBool(string(mi.msg.GetLeadershipMsg().GetMembership().Metadata))
+	return isDeclaration
+}
+
+type peerImpl struct {
+	member *discovery.NetworkMember
+}
+
+func (pi *peerImpl) ID() string {
+	return string(pi.member.PKIid)
+}
+
+type gossip interface {
+	// Peers returns the NetworkMembers considered alive
+	Peers() []discovery.NetworkMember
+
+	// Accept returns a dedicated read-only channel for messages sent by other nodes that match a certain predicate.
+	// If passThrough is false, the messages are processed by the gossip layer beforehand.
+	// If passThrough is true, the gossip layer doesn't intervene and the messages
+	// can be used to send a reply back to the sender
+	Accept(acceptor common.MessageAcceptor, passThrough bool) (<-chan *proto.GossipMessage, <-chan comm.ReceivedMessage)
+
+	// Gossip sends a message to other peers to the network
+	Gossip(msg *proto.GossipMessage)
+}
+
+// MsgCrypto used to sign messages and verify received messages signatures
+type MsgCrypto interface {
+	// Sign signs a message, returns a signed message on success
+	// or an error on failure
+	Sign(msg []byte) ([]byte, error)
+
+	// Verify verifies a signed message
+	Verify(vkID, signature, message []byte) error
+
+	// Get returns the identity of a given pkiID, or error if such an identity
+	// isn't found
+	Get(pkiID common.PKIidType) (api.PeerIdentityType, error)
+}
+
+type adapterImpl struct {
+	gossip gossip
+	self   *discovery.NetworkMember
+
+	incTime uint64
+	seqNum  uint64
+
+	mcs MsgCrypto
+
+	channel common.ChainID
+
+	logger *logging.Logger
+
+	doneCh   chan struct{}
+	stopOnce *sync.Once
+}
+
+// NewAdapter creates new leader election adapter
+func NewAdapter(gossip gossip, self *discovery.NetworkMember, mcs MsgCrypto, channel common.ChainID) LeaderElectionAdapter {
+	return &adapterImpl{
+		gossip: gossip,
+		self:   self,
+
+		incTime: uint64(time.Now().UnixNano()),
+		seqNum:  uint64(0),
+
+		mcs: mcs,
+
+		channel: channel,
+
+		logger: logging.MustGetLogger("LeaderElectionAdapter"),
+
+		doneCh:   make(chan struct{}),
+		stopOnce: &sync.Once{},
+	}
+}
+
+func (ai *adapterImpl) Gossip(msg Msg) {
+	ai.gossip.Gossip(msg.(*msgImpl).msg)
+}
+
+func (ai *adapterImpl) Accept() <-chan Msg {
+	adapterCh, _ := ai.gossip.Accept(func(message interface{}) bool {
+		// Get only leadership org and channel messages
+		validMsg := message.(*proto.GossipMessage).Tag == proto.GossipMessage_CHAN_AND_ORG &&
+			message.(*proto.GossipMessage).IsLeadershipMsg() &&
+			bytes.Equal(message.(*proto.GossipMessage).Channel, ai.channel)
+		if validMsg {
+			leadershipMsg := message.(*proto.GossipMessage).GetLeadershipMsg()
+
+			verifier := func(identity []byte, signature, message []byte) error {
+				return ai.mcs.Verify(identity, signature, message)
+			}
+			identity, err := ai.mcs.Get(leadershipMsg.GetMembership().PkiID)
+			if err != nil {
+				ai.logger.Error("Failed verify, can't get identity", leadershipMsg, ":", err)
+				return false
+			}
+
+			if err := message.(*proto.GossipMessage).Verify(identity, verifier); err != nil {
+				ai.logger.Error("Failed verify", leadershipMsg, ":", err)
+				return false
+			}
+			return true
+		}
+		return false
+	}, false)
+
+	msgCh := make(chan Msg)
+
+	go func(inCh <-chan *proto.GossipMessage, outCh chan Msg, stopCh chan struct{}) {
+		for {
+			select {
+			case <-stopCh:
+				return
+			case gossipMsg, ok := <-inCh:
+				if ok {
+					outCh <- &msgImpl{gossipMsg}
+				} else {
+					return
+				}
+			}
+		}
+	}(adapterCh, msgCh, ai.doneCh)
+	return msgCh
+}
+
+func (ai *adapterImpl) CreateMessage(isDeclaration bool) Msg {
+	ai.seqNum++
+	seqNum := ai.seqNum
+
+	metadata := []byte{}
+	metadata = strconv.AppendBool(metadata, isDeclaration)
+
+	leadershipMsg := &proto.LeadershipMessage{
+		Membership: &proto.Member{
+			PkiID:    ai.self.PKIid,
+			Endpoint: ai.self.Endpoint,
+			Metadata: metadata,
+		},
+		Timestamp: &proto.PeerTime{
+			IncNumber: ai.incTime,
+			SeqNum:    seqNum,
+		},
+	}
+
+	msg := &proto.GossipMessage{
+		Nonce:   0,
+		Tag:     proto.GossipMessage_CHAN_AND_ORG,
+		Content: &proto.GossipMessage_LeadershipMsg{LeadershipMsg: leadershipMsg},
+		Channel: ai.channel,
+	}
+
+	signer := func(msg []byte) ([]byte, error) {
+		return ai.mcs.Sign(msg)
+	}
+
+	msg.Sign(signer)
+	return &msgImpl{msg}
+}
+
+func (ai *adapterImpl) Peers() []Peer {
+	peers := ai.gossip.Peers()
+
+	var res []Peer
+	for _, peer := range peers {
+		res = append(res, &peerImpl{&peer})
+	}
+
+	return res
+}
+
+func (ai *adapterImpl) Stop() {
+	stopFunc := func() {
+		close(ai.doneCh)
+	}
+	ai.stopOnce.Do(stopFunc)
+}