From 852e14fbb85cc8e6ac5522d5eaeb1e61623f505d Mon Sep 17 00:00:00 2001
From: Matt Broadstone <mbroadst@mongodb.com>
Date: Wed, 17 Jul 2019 09:05:12 -0400
Subject: [PATCH] feat: add concept of `data-bearing` type to
 `ServerDescription`

---
 lib/core/sdam/server_description.js | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/lib/core/sdam/server_description.js b/lib/core/sdam/server_description.js
index 45310a4063..41a5cf5b72 100644
--- a/lib/core/sdam/server_description.js
+++ b/lib/core/sdam/server_description.js
@@ -19,6 +19,13 @@ const WRITABLE_SERVER_TYPES = new Set([
   ServerType.Mongos
 ]);
 
+const DATA_BEARING_SERVER_TYPES = new Set([
+  ServerType.RSPrimary,
+  ServerType.RSSecondary,
+  ServerType.Mongos,
+  ServerType.Standalone
+]);
+
 const ISMASTER_FIELDS = [
   'minWireVersion',
   'maxWireVersion',
@@ -99,6 +106,13 @@ class ServerDescription {
     return this.type === ServerType.RSSecondary || this.isWritable;
   }
 
+  /**
+   * @return {Boolean} Is this server data bearing
+   */
+  get isDataBearing() {
+    return DATA_BEARING_SERVER_TYPES.has(this.type);
+  }
+
   /**
    * @return {Boolean} Is this server available for writes
    */