store: add Timeout option

Signed-off-by: Vasiliy Tolstov <v.tolstov@unistack.org>

store/options.go

@@ -34,6 +34,8 @@ type Options struct {
 	Addrs []string
 	// Wrappers store wrapper that called before actual functions
 	// Wrappers []Wrapper
+	// Timeout specifies timeout duration for all operations
+	Timeout time.Duration
 }
 
 // NewOptions creates options struct
@@ -110,6 +112,13 @@ func Tracer(t tracer.Tracer) Option {
 	}
 }
 
+// Timeout sets the timeout
+func Timeout(td time.Duration) Option {
+	return func(o *Options) {
+		o.Timeout = td
+	}
+}
+
 // Addrs contains the addresses or other connection information of the backing storage.
 // For example, an etcd implementation would contain the nodes of the cluster.
 // A SQL implementation could contain one or more connection strings.