Disable FailFast on client.IsServing()

User of the client should associate a proper timeout with the context
instead.

Signed-off-by: Kenfe-Mickael Laventure <mickael.laventure@gmail.com>

dialer.go

@@ -0,0 +1,52 @@
+package containerd
+
+import (
+	"net"
+	"strings"
+	"time"
+
+	"github.com/pkg/errors"
+)
+
+type dialResult struct {
+	c   net.Conn
+	err error
+}
+
+func Dialer(address string, timeout time.Duration) (net.Conn, error) {
+	var (
+		stopC = make(chan struct{})
+		synC  = make(chan *dialResult)
+	)
+	address = strings.TrimPrefix(address, "unix://")
+	go func() {
+		defer close(synC)
+		for {
+			select {
+			case <-stopC:
+				return
+			default:
+				c, err := dialer(address, timeout)
+				if isNoent(err) {
+					<-time.After(10 * time.Millisecond)
+					continue
+				}
+				synC <- &dialResult{c, err}
+				return
+			}
+		}
+	}()
+	select {
+	case dr := <-synC:
+		return dr.c, dr.err
+	case <-time.After(timeout):
+		close(stopC)
+		go func() {
+			dr := <-synC
+			if dr != nil {
+				dr.c.Close()
+			}
+		}()
+		return nil, errors.Errorf("dial %s: no such file or directory", address)
+	}
+}