PYTHON-2715 Use hello command for monitoring when supported (#654)

(cherry picked from commit b991185)

Author: prashantmital

pymongo/ismaster.py

@@ -193,3 +193,7 @@ def awaitable(self):
     @property
     def service_id(self):
         return self._doc.get('serviceId')
+
+    @property
+    def hello_ok(self):
+        return self._doc.get('helloOk', False)

pymongo/pool.py

@@ -539,6 +539,7 @@ def __init__(self, sock, pool, address, id):
         self.max_message_size = MAX_MESSAGE_SIZE
         self.max_write_batch_size = MAX_WRITE_BATCH_SIZE
         self.supports_sessions = False
+        self.hello_ok = None
         self.is_mongos = False
         self.op_msg_enabled = False
         self.listeners = pool.opts.event_listeners
@@ -586,10 +587,10 @@ def unpin(self):
             self.close_socket(ConnectionClosedReason.STALE)
 
     def hello_cmd(self):
-        if self.opts.server_api:
+        if self.opts.server_api or self.hello_ok:
             return SON([(HelloCompat.CMD, 1)])
         else:
-            return SON([(HelloCompat.LEGACY_CMD, 1)])
+            return SON([(HelloCompat.LEGACY_CMD, 1), ('helloOk', True)])
 
     def ismaster(self, all_credentials=None):
         return self._ismaster(None, None, None, all_credentials)
@@ -641,6 +642,7 @@ def _ismaster(self, cluster_time, topology_version,
         self.max_write_batch_size = ismaster.max_write_batch_size
         self.supports_sessions = (
             ismaster.logical_session_timeout_minutes is not None)
+        self.hello_ok = ismaster.hello_ok
         self.is_mongos = ismaster.server_type == SERVER_TYPE.Mongos
         if performing_handshake and self.compression_settings:
             ctx = self.compression_settings.get_compression_context(

test/discovery_and_monitoring/errors/error_handling_handshake.json

@@ -9,7 +9,8 @@
           "a:27017",
           {
             "ok": 1,
-            "ismaster": true,
+            "helloOk": true,
+            "isWritablePrimary": true,
             "hosts": [
               "a:27017"
             ],

test/discovery_and_monitoring/errors/non-stale-network-error.json

@@ -9,7 +9,8 @@
           "a:27017",
           {
             "ok": 1,
-            "ismaster": true,
+            "helloOk": true,
+            "isWritablePrimary": true,
             "hosts": [
               "a:27017"
             ],

test/discovery_and_monitoring/errors/non-stale-network-timeout-error.json

@@ -9,7 +9,8 @@
           "a:27017",
           {
             "ok": 1,
-            "ismaster": true,
+            "helloOk": true,
+            "isWritablePrimary": true,
             "hosts": [
               "a:27017"
             ],

test/discovery_and_monitoring/errors/non-stale-topologyVersion-greater-InterruptedAtShutdown.json

@@ -9,7 +9,8 @@
           "a:27017",
           {
             "ok": 1,
-            "ismaster": true,
+            "helloOk": true,
+            "isWritablePrimary": true,
             "hosts": [
               "a:27017"
             ],

test/discovery_and_monitoring/errors/non-stale-topologyVersion-greater-InterruptedDueToReplStateChange.json

@@ -9,7 +9,8 @@
           "a:27017",
           {
             "ok": 1,
-            "ismaster": true,
+            "helloOk": true,
+            "isWritablePrimary": true,
             "hosts": [
               "a:27017"
             ],

test/discovery_and_monitoring/errors/non-stale-topologyVersion-greater-LegacyNotPrimary.json

@@ -9,7 +9,8 @@
           "a:27017",
           {
             "ok": 1,
-            "ismaster": true,
+            "helloOk": true,
+            "isWritablePrimary": true,
             "hosts": [
               "a:27017"
             ],

test/discovery_and_monitoring/errors/non-stale-topologyVersion-greater-NotMasterNoSlaveOk.json renamed to test/discovery_and_monitoring/errors/non-stale-topologyVersion-greater-NotPrimaryNoSecondaryOk.json

@@ -1,5 +1,5 @@
 {
-  "description": "Non-stale topologyVersion greater NotMasterNoSlaveOk error",
+  "description": "Non-stale topologyVersion greater NotPrimaryNoSecondaryOk error",
   "uri": "mongodb://a/?replicaSet=rs",
   "phases": [
     {
@@ -9,7 +9,8 @@
           "a:27017",
           {
             "ok": 1,
-            "ismaster": true,
+            "helloOk": true,
+            "isWritablePrimary": true,
             "hosts": [
               "a:27017"
             ],
@@ -51,7 +52,7 @@
       }
     },
     {
-      "description": "Non-stale topologyVersion greater NotMasterNoSlaveOk error marks server Unknown",
+      "description": "Non-stale topologyVersion greater NotPrimaryNoSecondaryOk error marks server Unknown",
       "applicationErrors": [
         {
           "address": "a:27017",
@@ -60,7 +61,7 @@
           "type": "command",
           "response": {
             "ok": 0,
-            "errmsg": "NotMasterNoSlaveOk",
+            "errmsg": "NotPrimaryNoSecondaryOk",
             "code": 13435,
             "topologyVersion": {
               "processId": {

test/discovery_and_monitoring/errors/non-stale-topologyVersion-greater-NotMasterOrSecondary.json renamed to test/discovery_and_monitoring/errors/non-stale-topologyVersion-greater-NotPrimaryOrSecondary.json

@@ -1,5 +1,5 @@
 {
-  "description": "Non-stale topologyVersion greater NotMasterOrSecondary error",
+  "description": "Non-stale topologyVersion greater NotPrimaryOrSecondary error",
   "uri": "mongodb://a/?replicaSet=rs",
   "phases": [
     {
@@ -9,7 +9,8 @@
           "a:27017",
           {
             "ok": 1,
-            "ismaster": true,
+            "helloOk": true,
+            "isWritablePrimary": true,
             "hosts": [
               "a:27017"
             ],
@@ -51,7 +52,7 @@
       }
     },
     {
-      "description": "Non-stale topologyVersion greater NotMasterOrSecondary error marks server Unknown",
+      "description": "Non-stale topologyVersion greater NotPrimaryOrSecondary error marks server Unknown",
       "applicationErrors": [
         {
           "address": "a:27017",
@@ -60,7 +61,7 @@
           "type": "command",
           "response": {
             "ok": 0,
-            "errmsg": "NotMasterOrSecondary",
+            "errmsg": "NotPrimaryOrSecondary",
             "code": 13436,
             "topologyVersion": {
               "processId": {