From 6a1b36bd46e818e2f595c8a087375a63e1299c73 Mon Sep 17 00:00:00 2001
From: Armon Dadgar <armon.dadgar@gmail.com>
Date: Thu, 19 Dec 2013 15:08:55 -0800
Subject: [PATCH] Testing Client RPC to server

---
 consul/client.go          | 20 ++++++++++++++++++++
 consul/client_test.go     | 40 +++++++++++++++++++++++++++++++++++++++
 consul/structs/structs.go |  5 +++--
 3 files changed, 63 insertions(+), 2 deletions(-)

diff --git a/consul/client.go b/consul/client.go
index c7b73948c5..e67fdb3557 100644
--- a/consul/client.go
+++ b/consul/client.go
@@ -2,8 +2,10 @@ package consul
 
 import (
 	"fmt"
+	"github.com/hashicorp/consul/consul/structs"
 	"github.com/hashicorp/serf/serf"
 	"log"
+	"math/rand"
 	"net"
 	"os"
 	"path/filepath"
@@ -218,3 +220,21 @@ func (c *Client) nodeFail(me serf.MemberEvent) {
 		c.consulLock.Unlock()
 	}
 }
+
+// RPC is used to forward an RPC call to a consul server, or fail if no servers
+func (c *Client) RPC(method string, args interface{}, reply interface{}) error {
+	// Bail if we can't find any servers
+	c.consulLock.RLock()
+	if len(c.consuls) == 0 {
+		c.consulLock.RUnlock()
+		return structs.ErrNoServers
+	}
+
+	// Select a random addr
+	offset := rand.Int31() % int32(len(c.consuls))
+	server := c.consuls[offset]
+	c.consulLock.RUnlock()
+
+	// Forward to remote Consul
+	return c.connPool.RPC(server, method, args, reply)
+}
diff --git a/consul/client_test.go b/consul/client_test.go
index 58f7d2551a..0a535ed124 100644
--- a/consul/client_test.go
+++ b/consul/client_test.go
@@ -2,6 +2,7 @@ package consul
 
 import (
 	"fmt"
+	"github.com/hashicorp/consul/consul/structs"
 	"os"
 	"testing"
 	"time"
@@ -75,3 +76,42 @@ func TestClient_JoinLAN(t *testing.T) {
 		t.Fatalf("expected consul server")
 	}
 }
+
+func TestClient_RPC(t *testing.T) {
+	dir1, s1 := testServer(t)
+	defer os.RemoveAll(dir1)
+	defer s1.Shutdown()
+
+	dir2, c1 := testClient(t)
+	defer os.RemoveAll(dir2)
+	defer c1.Shutdown()
+
+	// Try an RPC
+	var out struct{}
+	if err := c1.RPC("Status.Ping", struct{}{}, &out); err != structs.ErrNoServers {
+		t.Fatalf("err: %v", err)
+	}
+
+	// Try to join
+	addr := fmt.Sprintf("127.0.0.1:%d",
+		s1.config.SerfLANConfig.MemberlistConfig.Port)
+	if err := c1.JoinLAN(addr); err != nil {
+		t.Fatalf("err: %v", err)
+	}
+
+	// Check the members
+	if len(s1.LANMembers()) != 2 {
+		t.Fatalf("bad len")
+	}
+
+	if len(c1.LANMembers()) != 2 {
+		t.Fatalf("bad len")
+	}
+
+	time.Sleep(10 * time.Millisecond)
+
+	// RPC shoudl succeed
+	if err := c1.RPC("Status.Ping", struct{}{}, &out); err != nil {
+		t.Fatalf("err: %v", err)
+	}
+}
diff --git a/consul/structs/structs.go b/consul/structs/structs.go
index 7839be2310..98bed54dca 100644
--- a/consul/structs/structs.go
+++ b/consul/structs/structs.go
@@ -7,8 +7,9 @@ import (
 )
 
 var (
-	ErrNoLeader = fmt.Errorf("No cluster leader")
-	ErrNoDCPath = fmt.Errorf("No path to datacenter")
+	ErrNoLeader  = fmt.Errorf("No cluster leader")
+	ErrNoDCPath  = fmt.Errorf("No path to datacenter")
+	ErrNoServers = fmt.Errorf("No known Consul servers")
 )
 
 type MessageType uint8