object layer initialization using distributed locking (#2397)

* vendorized latest minio/dsync

* wip - object layer initialization using distributed locking

vendor/github.com/minio/dsync/dmutex.go

@@ -21,7 +21,6 @@ import (
 	"math"
 	"math/rand"
 	"net/rpc"
-	"strings"
 	"sync"
 	"time"
 )
@@ -52,7 +51,7 @@ func connectLazy(dm *DMutex) {
 	for i := range dm.clnts {
 		if dm.clnts[i] == nil {
 			// pass in unique path (as required by server.HandleHTTP()
-			dm.clnts[i], _ = rpc.DialHTTPPath("tcp", nodes[i], rpcPath+"-"+strings.Split(nodes[i], ":")[1])
+			dm.clnts[i], _ = rpc.DialHTTPPath("tcp", nodes[i], rpcPaths[i])
 		}
 	}
 }

vendor/github.com/minio/dsync/dsync.go

@@ -28,7 +28,7 @@ const DefaultPath = "/rpc/dsync"
 
 var n int
 var nodes []string
-var rpcPath string
+var rpcPaths []string
 
 func closeClients(clients []*rpc.Client) {
 	for _, clnt := range clients {
@@ -36,8 +36,8 @@ func closeClients(clients []*rpc.Client) {
 	}
 }
 
-// Same as SetNodes, but takes a path argument different from the package-level default.
-func SetNodesWithPath(nodeList []string, path string) (err error) {
+// Same as SetNodes, but takes a slice of rpc paths as argument different from the package-level default.
+func SetNodesWithPath(nodeList []string, paths []string) (err error) {
 
 	// Validate if number of nodes is within allowable range.
 	if n != 0 {
@@ -50,7 +50,8 @@ func SetNodesWithPath(nodeList []string, path string) (err error) {
 
 	nodes = make([]string, len(nodeList))
 	copy(nodes, nodeList[:])
-	rpcPath = path
+	rpcPaths = make([]string, len(paths))
+	copy(rpcPaths, paths[:])
 	n = len(nodes)
 	return nil
 }

vendor/vendor.json

@@ -98,10 +98,10 @@
 			"revisionTime": "2015-11-18T20:00:48-08:00"
 		},
 		{
-			"checksumSHA1": "KCM0UiuvLA5fPiX5I83/HTklxlI=",
+			"checksumSHA1": "r1Vf/vQTkMsZrDVORBGAAIlOMP4=",
 			"path": "github.com/minio/dsync",
-			"revision": "c10eebd6b637bb834d502a6574c53e0ea6c64997",
-			"revisionTime": "2016-08-05T20:56:13Z"
+			"revision": "6bfa8c0c1c37959c1bda15bfdae228a986d3cca8",
+			"revisionTime": "2016-08-07T19:01:27Z"
 		},
 		{
 			"path": "github.com/minio/go-homedir",