Gossip communication layer

This commit adds the gossip communication layer

Change-Id: I371445a5b84ef0c0e0764050bf0901db2b246df8
Signed-off-by: Yacov Manevich <yacovm@il.ibm.com>

gossip/comm/conn.go

@@ -0,0 +1,330 @@
+/*
+Copyright IBM Corp. 2016 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 comm
+
+import (
+	"fmt"
+	"sync"
+	"sync/atomic"
+
+	"github.com/hyperledger/fabric/gossip/proto"
+	"github.com/hyperledger/fabric/gossip/util"
+	"google.golang.org/grpc"
+)
+
+type handler func(*proto.GossipMessage)
+
+type connFactory interface {
+	createConnection(endpoint string, pkiID PKIidType) (*connection, error)
+}
+
+type connectionStore struct {
+	logger           *util.Logger             // logger
+	selfPKIid        PKIidType                // pkiID of this peer
+	isClosing        bool                     // whether this connection store is shutting down
+	connFactory      connFactory              // creates a connection to remote peer
+	sync.RWMutex                              // synchronize access to shared variables
+	pki2Conn         map[string]*connection   // mapping between pkiID to connections
+	destinationLocks map[string]*sync.RWMutex //mapping between pkiIDs and locks,
+	// used to prevent concurrent connection establishment to the same remote endpoint
+}
+
+func newConnStore(connFactory connFactory, pkiID PKIidType, logger *util.Logger) *connectionStore {
+	return &connectionStore{
+		connFactory:      connFactory,
+		isClosing:        false,
+		pki2Conn:         make(map[string]*connection),
+		selfPKIid:        pkiID,
+		destinationLocks: make(map[string]*sync.RWMutex),
+		logger:           logger,
+	}
+}
+
+func (cs *connectionStore) getConnection(peer *RemotePeer) (*connection, error) {
+	cs.RLock()
+	isClosing := cs.isClosing
+	cs.RUnlock()
+
+	if isClosing {
+		return nil, fmt.Errorf("Shutting down")
+	}
+
+	pkiID := peer.PKIID
+	endpoint := peer.Endpoint
+
+	cs.Lock()
+	destinationLock, hasConnected := cs.destinationLocks[string(pkiID)]
+	if !hasConnected {
+		destinationLock = &sync.RWMutex{}
+		cs.destinationLocks[string(pkiID)] = destinationLock
+	}
+	cs.Unlock()
+
+	destinationLock.Lock()
+
+	cs.RLock()
+	conn, exists := cs.pki2Conn[string(pkiID)]
+	if exists {
+		cs.RUnlock()
+		destinationLock.Unlock()
+		return conn, nil
+	}
+	cs.RUnlock()
+
+	createdConnection, err := cs.connFactory.createConnection(endpoint, pkiID)
+
+	destinationLock.Unlock()
+
+	cs.Lock()
+	delete(cs.destinationLocks, string(pkiID))
+	defer cs.Unlock()
+
+	// check again, maybe someone connected to us during the connection creation?
+	conn, exists = cs.pki2Conn[string(pkiID)]
+
+	if exists {
+		if createdConnection != nil {
+			createdConnection.close()
+		}
+		return conn, nil
+	}
+
+	// no one connected to us AND we failed connecting!
+	if err != nil {
+		return nil, err
+	}
+
+	// at this point in the code, we created a connection to a remote peer
+	conn = createdConnection
+	cs.pki2Conn[string(createdConnection.pkiID)] = conn
+
+	go conn.serviceInput()
+
+	return conn, nil
+}
+
+func (cs *connectionStore) connNum() int {
+	cs.RLock()
+	defer cs.RUnlock()
+	return len(cs.pki2Conn)
+}
+
+func (cs *connectionStore) closeConn(peer *RemotePeer) {
+	cs.Lock()
+	defer cs.Unlock()
+
+	if conn, exists := cs.pki2Conn[string(peer.PKIID)]; exists {
+		conn.close()
+		delete(cs.pki2Conn, string(conn.pkiID))
+	}
+}
+
+func (cs *connectionStore) shutdown() {
+	cs.Lock()
+	cs.isClosing = true
+	pkiIds2conn := cs.pki2Conn
+	cs.Unlock()
+
+	wg := sync.WaitGroup{}
+	for _, conn := range pkiIds2conn {
+		wg.Add(1)
+		go func(conn *connection) {
+			cs.closeByPKIid(conn.pkiID)
+			wg.Done()
+		}(conn)
+	}
+	wg.Wait()
+}
+
+func (cs *connectionStore) onConnected(serverStream proto.Gossip_GossipStreamServer, pkiID PKIidType) *connection {
+	cs.Lock()
+	defer cs.Unlock()
+
+	if c, exists := cs.pki2Conn[string(pkiID)]; exists {
+		c.close()
+	}
+
+	return cs.registerConn(pkiID, serverStream)
+}
+
+func (cs *connectionStore) registerConn(pkiID PKIidType, serverStream proto.Gossip_GossipStreamServer) *connection {
+	conn := newConnection(nil, nil, nil, serverStream)
+	conn.pkiID = pkiID
+	conn.logger = cs.logger
+	cs.pki2Conn[string(pkiID)] = conn
+	return conn
+}
+
+func (cs *connectionStore) closeByPKIid(pkiID PKIidType) {
+	cs.Lock()
+	defer cs.Unlock()
+	if conn, exists := cs.pki2Conn[string(pkiID)]; exists {
+		conn.close()
+		delete(cs.pki2Conn, string(pkiID))
+	}
+}
+
+func newConnection(cl proto.GossipClient, c *grpc.ClientConn, cs proto.Gossip_GossipStreamClient, ss proto.Gossip_GossipStreamServer) *connection {
+	connection := &connection{
+		cl:           cl,
+		conn:         c,
+		clientStream: cs,
+		serverStream: ss,
+		stopFlag:     int32(0),
+		stopChan:     make(chan struct{}, 1),
+	}
+
+	return connection
+}
+
+type connection struct {
+	logger       *util.Logger                    // logger
+	pkiID        PKIidType                       // pkiID of the remote endpoint
+	handler      handler                         // function to invoke upon a message reception
+	conn         *grpc.ClientConn                // gRPC connection to remote endpoint
+	cl           proto.GossipClient              // gRPC stub of remote endpoint
+	clientStream proto.Gossip_GossipStreamClient // client-side stream to remote endpoint
+	serverStream proto.Gossip_GossipStreamServer // server-side stream to remote endpoint
+	stopFlag     int32                           // indicates whether this connection is in process of stopping
+	stopChan     chan struct{}                   // a method to stop the server-side gRPC call from a different go-routine
+	sync.RWMutex                                 // synchronizes access to shared variables
+}
+
+func (conn *connection) close() {
+	if conn.toDie() {
+		return
+	}
+
+	amIFirst := atomic.CompareAndSwapInt32(&conn.stopFlag, int32(0), int32(1))
+	if !amIFirst {
+		return
+	}
+
+	conn.stopChan <- struct{}{}
+
+	conn.Lock()
+
+	if conn.clientStream != nil {
+		conn.clientStream.CloseSend()
+	}
+	if conn.conn != nil {
+		conn.conn.Close()
+	}
+
+	conn.Unlock()
+
+}
+
+func (conn *connection) toDie() bool {
+	return atomic.LoadInt32(&(conn.stopFlag)) == int32(1)
+}
+
+func (conn *connection) send(msg *proto.GossipMessage) error {
+	conn.Lock()
+	defer conn.Unlock()
+
+	if conn.toDie() {
+		return fmt.Errorf("Connection aborted")
+	}
+
+	if conn.clientStream != nil {
+		return conn.clientStream.Send(msg)
+	}
+
+	if conn.serverStream != nil {
+		return conn.serverStream.Send(msg)
+	}
+
+	return fmt.Errorf("Both streams are nil")
+}
+
+func (conn *connection) serviceInput() error {
+	errChan := make(chan error, 1)
+	msgChan := make(chan *proto.GossipMessage, defRecvBuffSize)
+	defer close(msgChan)
+
+	// Call stream.Recv() asynchronously in readFromStream(),
+	// and wait for either the Recv() call to end,
+	// or a signal to close the connection, which exits
+	// the method and makes the Recv() call to fail in the
+	// readFromStream() method
+	go conn.readFromStream(errChan, msgChan)
+
+	for !conn.toDie() {
+		select {
+		case stop := <-conn.stopChan:
+			conn.logger.Warning("Closing reading from stream")
+			conn.stopChan <- stop
+			return nil
+		case err := <-errChan:
+			return err
+		case msg := <-msgChan:
+			conn.handler(msg)
+		}
+	}
+	return nil
+}
+
+func (conn *connection) readFromStream(errChan chan error, msgChan chan *proto.GossipMessage) {
+	defer func() {
+		recover()
+	}() // msgChan might be closed
+	for !conn.toDie() {
+		stream := conn.getStream()
+		if stream == nil {
+			conn.logger.Error(conn.pkiID, "Stream is nil, aborting!")
+			errChan <- fmt.Errorf("Stream is nil")
+			return
+		}
+		msg, err := stream.Recv()
+		if conn.toDie() {
+			conn.logger.Warning(conn.pkiID, "canceling read because closing")
+			return
+		}
+		if err != nil {
+			errChan <- err
+			conn.logger.Warning(conn.pkiID, "Got error, aborting:", err)
+			return
+		}
+		msgChan <- msg
+	}
+}
+
+func (conn *connection) getStream() stream {
+	conn.Lock()
+	defer conn.Unlock()
+
+	if conn.clientStream != nil && conn.serverStream != nil {
+		e := "Both client and server stream are not nil, something went wrong"
+		conn.logger.Error(e)
+	}
+
+	if conn.clientStream != nil {
+		return conn.clientStream
+	}
+
+	if conn.serverStream != nil {
+		return conn.serverStream
+	}
+
+	return nil
+}
+
+type msgSending struct {
+	msg   *proto.GossipMessage
+	onErr func(error)
+}