consul: Basic RPC framework

consul/config.go

@@ -9,9 +9,10 @@ import (
 )
 
 const (
-	DefaultRaftAddr    = "0.0.0.0:8300"
-	DefaultLANSerfPort = 8301
-	DefaultWANSerfPort = 8302
+	DefaultRPCAddr     = "0.0.0.0:8300"
+	DefaultRaftAddr    = "0.0.0.0:8301"
+	DefaultLANSerfPort = 8302
+	DefaultWANSerfPort = 8303
 )
 
 // Config is used to configure the server
@@ -31,6 +32,10 @@ type Config struct {
 	// RaftConfig is the configuration used for Raft in the local DC
 	RaftConfig *raft.Config
 
+	// RPCAddr is the RPC address used by Consul. This should be reachable
+	// by the WAN and LAN
+	RPCAddr string
+
 	// SerfLocalConfig is the configuration for the local serf
 	SerfLocalConfig *serf.Config
 
@@ -53,6 +58,7 @@ func DefaultConfig() *Config {
 		Datacenter:       "dc1",
 		NodeName:         hostname,
 		RaftBindAddr:     DefaultRaftAddr,
+		RPCAddr:          DefaultRPCAddr,
 		RaftConfig:       raft.DefaultConfig(),
 		SerfLocalConfig:  serf.DefaultConfig(),
 		SerfRemoteConfig: serf.DefaultConfig(),

consul/server.go

@@ -4,7 +4,10 @@ import (
 	"fmt"
 	"github.com/hashicorp/raft"
 	"github.com/hashicorp/serf/serf"
+	"github.com/ugorji/go/codec"
 	"log"
+	"net"
+	"net/rpc"
 	"os"
 	"path/filepath"
 	"sync"
@@ -43,6 +46,14 @@ type Server struct {
 	raftStore     *raft.SQLiteStore
 	raftTransport *raft.NetworkTransport
 
+	// rpcClients is used to track active clients
+	rpcClients    map[net.Conn]struct{}
+	rpcClientLock sync.Mutex
+
+	// rpcListener is used to listen for incoming connections
+	rpcListener net.Listener
+	rpcServer   *rpc.Server
+
 	// serfLAN is the Serf cluster maintained inside the DC
 	// which contains all the DC nodes
 	serfLAN *serf.Serf
@@ -78,6 +89,8 @@ func NewServer(config *Config) (*Server, error) {
 		eventChLAN: make(chan serf.Event, 256),
 		eventChWAN: make(chan serf.Event, 256),
 		logger:     logger,
+		rpcClients: make(map[net.Conn]struct{}),
+		rpcServer:  rpc.NewServer(),
 		shutdownCh: make(chan struct{}),
 	}
 
@@ -182,6 +195,17 @@ func (s *Server) setupRaft() error {
 	return nil
 }
 
+// setupRPC is used to setup the RPC listener
+func (s *Server) setupRPC() error {
+	list, err := net.Listen("tcp", s.config.RPCAddr)
+	if err != nil {
+		return err
+	}
+	s.rpcListener = list
+	go s.listen()
+	return nil
+}
+
 // Shutdown is used to shutdown the server
 func (s *Server) Shutdown() error {
 	s.logger.Printf("[INFO] Shutting down Consul server")
@@ -213,6 +237,19 @@ func (s *Server) Shutdown() error {
 		s.raftStore = nil
 		s.raftTransport = nil
 	}
+
+	if s.rpcListener != nil {
+		s.rpcListener.Close()
+		s.rpcListener = nil
+	}
+
+	// Close all the RPC connections
+	s.rpcClientLock.Lock()
+	for conn := range s.rpcClients {
+		conn.Close()
+	}
+	s.rpcClientLock.Unlock()
+
 	return nil
 }
 
@@ -239,3 +276,43 @@ func (s *Server) wanEventHandler() {
 		}
 	}
 }
+
+// listen is used to listen for incoming RPC connections
+func (s *Server) listen() {
+	for {
+		// Accept a connection
+		conn, err := s.rpcListener.Accept()
+		if err != nil {
+			if s.shutdown {
+				return
+			}
+			s.logger.Printf("[ERR] Failed to accept RPC conn: %v", err)
+			continue
+		}
+
+		// Track this client
+		s.rpcClientLock.Lock()
+		s.rpcClients[conn] = struct{}{}
+		s.rpcClientLock.Unlock()
+
+		go s.handleConn(conn)
+	}
+}
+
+// handleConn is used to service a single RPC connection
+func (s *Server) handleConn(conn net.Conn) {
+	defer func() {
+		conn.Close()
+		s.rpcClientLock.Lock()
+		delete(s.rpcClients, conn)
+		s.rpcClientLock.Unlock()
+	}()
+
+	rpcCodec := codec.GoRpc.ServerCodec(conn, &codec.MsgpackHandle{})
+	for !s.shutdown {
+		if err := s.rpcServer.ServeRequest(rpcCodec); err != nil {
+			s.logger.Printf("[ERR] RPC error: %v (%v)", err, conn)
+			return
+		}
+	}
+}