From ab4e3de1856c249664a56e52779e57635c50af78 Mon Sep 17 00:00:00 2001
From: Armon Dadgar <armon.dadgar@gmail.com>
Date: Tue, 10 Jun 2014 19:12:26 -0700
Subject: [PATCH] consul: Avoid network for server RPC. Fixes #148.

---
 consul/server.go | 49 +++++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 46 insertions(+), 3 deletions(-)

diff --git a/consul/server.go b/consul/server.go
index 0a29504c3de8..b1a744f4c716 100644
--- a/consul/server.go
+++ b/consul/server.go
@@ -2,6 +2,7 @@ package consul
 
 import (
 	"crypto/tls"
+	"errors"
 	"fmt"
 	"github.com/hashicorp/raft"
 	"github.com/hashicorp/raft-mdb"
@@ -11,6 +12,7 @@ import (
 	"net/rpc"
 	"os"
 	"path/filepath"
+	"reflect"
 	"runtime"
 	"strconv"
 	"sync"
@@ -489,11 +491,52 @@ func (s *Server) IsLeader() bool {
 	return s.raft.State() == raft.Leader
 }
 
+// inmemCodec is used to do an RPC call without going over a network
+type inmemCodec struct {
+	method string
+	args   interface{}
+	reply  interface{}
+	err    error
+}
+
+func (i *inmemCodec) ReadRequestHeader(req *rpc.Request) error {
+	req.ServiceMethod = i.method
+	return nil
+}
+
+func (i *inmemCodec) ReadRequestBody(args interface{}) error {
+	sourceValue := reflect.Indirect(reflect.Indirect(reflect.ValueOf(i.args)))
+	dst := reflect.Indirect(reflect.Indirect(reflect.ValueOf(args)))
+	dst.Set(sourceValue)
+	return nil
+}
+
+func (i *inmemCodec) WriteResponse(resp *rpc.Response, reply interface{}) error {
+	if resp.Error != "" {
+		i.err = errors.New(resp.Error)
+		return nil
+	}
+	sourceValue := reflect.Indirect(reflect.Indirect(reflect.ValueOf(reply)))
+	dst := reflect.Indirect(reflect.Indirect(reflect.ValueOf(i.reply)))
+	dst.Set(sourceValue)
+	return nil
+}
+
+func (i *inmemCodec) Close() error {
+	return nil
+}
+
 // RPC is used to make a local RPC call
 func (s *Server) RPC(method string, args interface{}, reply interface{}) error {
-	addr := s.rpcListener.Addr()
-	version := int(s.config.ProtocolVersion)
-	return s.connPool.RPC(addr, version, method, args, reply)
+	codec := &inmemCodec{
+		method: method,
+		args:   args,
+		reply:  reply,
+	}
+	if err := s.rpcServer.ServeRequest(codec); err != nil {
+		return err
+	}
+	return codec.err
 }
 
 // Stats is used to return statistics for debugging and insight