SERVER-27230 Always emit string status fields in replica set status

(cherry picked from commit d01dde5b3cca80a5db8c07c6d3f029c60f3b332e)

2 files changed, 192 insertions, 9 deletions

diff --git a/src/mongo/db/repl/topology_coordinator_impl.cpp b/src/mongo/db/repl/topology_coordinator_impl.cpp
index f5302008206..a416dbcad49 100644
--- a/src/mongo/db/repl/topology_coordinator_impl.cpp
+++ b/src/mongo/db/repl/topology_coordinator_impl.cpp
@@ -1622,9 +1622,10 @@ void TopologyCoordinatorImpl::prepareStatusResponse(const ReplSetStatusArgs& rsS
         if (_maintenanceModeCalls) {
             response->append("maintenanceMode", _maintenanceModeCalls);
         }
-        std::string s = _getHbmsg(now);
-        if (!s.empty())
-            response->append("infoMessage", s);
+        response->append("lastHeartbeatMessage", "");
+        response->append("syncingTo", "");
+
+        response->append("infoMessage", _getHbmsg(now));
         *result = Status(ErrorCodes::InvalidReplicaSetConfig,
                          "Our replica set config is invalid or we are not a member of it");
         return;
@@ -1650,15 +1651,15 @@ void TopologyCoordinatorImpl::prepareStatusResponse(const ReplSetStatusArgs& rsS
 
             if (!_syncSource.empty() && !_iAmPrimary()) {
                 bb.append("syncingTo", _syncSource.toString());
+            } else {
+                bb.append("syncingTo", "");
             }
 
             if (_maintenanceModeCalls) {
                 bb.append("maintenanceMode", _maintenanceModeCalls);
             }
 
-            std::string s = _getHbmsg(now);
-            if (!s.empty())
-                bb.append("infoMessage", s);
+            bb.append("infoMessage", _getHbmsg(now));
 
             if (myState.primary()) {
                 bb.append("electionTime", _electionTime);
@@ -1667,6 +1668,7 @@ void TopologyCoordinatorImpl::prepareStatusResponse(const ReplSetStatusArgs& rsS
             }
             bb.appendIntOrLL("configVersion", _rsConfig.getConfigVersion());
             bb.append("self", true);
+            bb.append("lastHeartbeatMessage", "");
             membersOut.push_back(bb.obj());
         } else {
             // add non-self member
@@ -1706,9 +1708,7 @@ void TopologyCoordinatorImpl::prepareStatusResponse(const ReplSetStatusArgs& rsS
             Milliseconds ping = _getPing(itConfig.getHostAndPort());
             if (ping != UninitializedPing) {
                 bb.append("pingMs", durationCount<Milliseconds>(ping));
-                std::string s = it->getLastHeartbeatMsg();
-                if (!s.empty())
-                    bb.append("lastHeartbeatMessage", s);
+                bb.append("lastHeartbeatMessage", it->getLastHeartbeatMsg());
             }
             if (it->hasAuthIssue()) {
                 bb.append("authenticated", false);
@@ -1716,8 +1716,12 @@ void TopologyCoordinatorImpl::prepareStatusResponse(const ReplSetStatusArgs& rsS
             const HostAndPort& syncSource = it->getSyncSource();
             if (!syncSource.empty() && !state.primary()) {
                 bb.append("syncingTo", syncSource.toString());
+            } else {
+                bb.append("syncingTo", "");
             }
 
+            bb.append("infoMessage", "");
+
             if (state == MemberState::RS_PRIMARY) {
                 bb.append("electionTime", it->getElectionTime());
                 bb.appendDate(
@@ -1740,6 +1744,8 @@ void TopologyCoordinatorImpl::prepareStatusResponse(const ReplSetStatusArgs& rsS
     // Add sync source info
     if (!_syncSource.empty() && !myState.primary() && !myState.removed()) {
         response->append("syncingTo", _syncSource.toString());
+    } else {
+        response->append("syncingTo", "");
     }
 
     if (_rsConfig.isConfigServer()) {
diff --git a/src/mongo/db/repl/topology_coordinator_impl_v1_test.cpp b/src/mongo/db/repl/topology_coordinator_impl_v1_test.cpp
index 8f60269cd71..264aba8a357 100644
--- a/src/mongo/db/repl/topology_coordinator_impl_v1_test.cpp
+++ b/src/mongo/db/repl/topology_coordinator_impl_v1_test.cpp
@@ -3988,6 +3988,183 @@ TEST_F(HeartbeatResponseTestV1, UpdateHeartbeatDataTermPreventsPriorityTakeover)
     ASSERT_EQUALS(2, getCurrentPrimaryIndex());
 }
 
+TEST_F(TopoCoordTest,
+       StatusResponseAlwaysIncludesStringStatusFieldsForReplicaSetMembersNoHeartbeats) {
+
+    Date_t heartbeatTime = Date_t::fromMillisSinceEpoch(5000);
+    Seconds uptimeSecs(10);
+    Date_t curTime = heartbeatTime + uptimeSecs;
+    OpTime oplogProgress(Timestamp(3, 4), 0);
+
+    ASSERT_TRUE(TopologyCoordinator::Role::follower == getTopoCoord().getRole());
+    ASSERT_EQUALS(MemberState::RS_STARTUP, getTopoCoord().getMemberState().s);
+    updateConfig(BSON("_id"
+                      << "rs0"
+                      << "version"
+                      << 5
+                      << "members"
+                      << BSON_ARRAY(BSON("_id" << 0 << "host"
+                                               << "host0:27017")
+                                    << BSON("_id" << 1 << "host"
+                                                  << "host1:27017"))
+                      << "protocolVersion"
+                      << 1),
+                 0);
+    {
+        BSONObjBuilder statusBuilder;
+        Status resultStatus(ErrorCodes::InternalError, "prepareStatusResponse didn't set result");
+        getTopoCoord().prepareStatusResponse(
+            TopologyCoordinator::ReplSetStatusArgs{
+                curTime,
+                static_cast<unsigned>(durationCount<Seconds>(uptimeSecs)),
+                oplogProgress,
+                oplogProgress,
+                oplogProgress,
+                OpTime(),
+                BSONObj()},
+            &statusBuilder,
+            &resultStatus);
+
+        ASSERT_OK(resultStatus);
+        BSONObj rsStatus = statusBuilder.obj();
+        BSONObj member0Status = rsStatus["members"].Array()[0].Obj();
+        BSONObj member1Status = rsStatus["members"].Array()[1].Obj();
+
+        // These fields should all be empty, since this node has not received heartbeats and has
+        // no sync source yet.
+        ASSERT_EQUALS("", rsStatus["syncingTo"].String());
+        ASSERT_EQUALS("", member0Status["syncingTo"].String());
+        ASSERT_EQUALS("", member0Status["lastHeartbeatMessage"].String());
+        ASSERT_EQUALS("", member0Status["infoMessage"].String());
+        ASSERT_EQUALS("", member1Status["syncingTo"].String());
+        ASSERT_EQUALS("", member1Status["lastHeartbeatMessage"].String());
+        ASSERT_EQUALS("", member1Status["infoMessage"].String());
+    }
+}
+
+TEST_F(TopoCoordTest,
+       StatusResponseAlwaysIncludesStringStatusFieldsForReplicaSetMembersWithHeartbeats) {
+
+    Date_t heartbeatTime = Date_t::fromMillisSinceEpoch(5000);
+    Seconds uptimeSecs(10);
+    Date_t curTime = heartbeatTime + uptimeSecs;
+    OpTime oplogProgress(Timestamp(3, 4), 0);
+
+    ASSERT_TRUE(TopologyCoordinator::Role::follower == getTopoCoord().getRole());
+    ASSERT_EQUALS(MemberState::RS_STARTUP, getTopoCoord().getMemberState().s);
+    updateConfig(BSON("_id"
+                      << "rs0"
+                      << "version"
+                      << 5
+                      << "members"
+                      << BSON_ARRAY(BSON("_id" << 0 << "host"
+                                               << "host0:27017")
+                                    << BSON("_id" << 1 << "host"
+                                                  << "host1:27017"))
+                      << "protocolVersion"
+                      << 1),
+                 0);
+
+    ASSERT(getTopoCoord().getSyncSourceAddress().empty());
+
+    // Receive heartbeats and choose a sync source.
+    setSelfMemberState(MemberState::RS_SECONDARY);
+
+    OpTime election = OpTime();
+
+    // Record two rounds of pings so the node can pick a sync source.
+    receiveUpHeartbeat(HostAndPort("host1"),
+                       "rs0",
+                       MemberState::RS_PRIMARY,
+                       election,
+                       oplogProgress,
+                       oplogProgress);
+    receiveUpHeartbeat(HostAndPort("host1"),
+                       "rs0",
+                       MemberState::RS_PRIMARY,
+                       election,
+                       oplogProgress,
+                       oplogProgress);
+
+    getTopoCoord().chooseNewSyncSource(
+        now(), OpTime(), TopologyCoordinator::ChainingPreference::kUseConfiguration);
+    ASSERT_EQUALS(HostAndPort("host1"), getTopoCoord().getSyncSourceAddress());
+
+    {
+        BSONObjBuilder statusBuilder;
+        Status resultStatus(ErrorCodes::InternalError, "prepareStatusResponse didn't set result");
+        getTopoCoord().prepareStatusResponse(
+            TopologyCoordinator::ReplSetStatusArgs{
+                curTime,
+                static_cast<unsigned>(durationCount<Seconds>(uptimeSecs)),
+                oplogProgress,
+                oplogProgress,
+                oplogProgress,
+                OpTime(),
+                BSONObj()},
+            &statusBuilder,
+            &resultStatus);
+
+        ASSERT_OK(resultStatus);
+        BSONObj rsStatus = statusBuilder.obj();
+        BSONObj member0Status = rsStatus["members"].Array()[0].Obj();
+        BSONObj member1Status = rsStatus["members"].Array()[1].Obj();
+
+        // Node 0 (self) has received heartbeats and has a sync source.
+        ASSERT_EQUALS("host1:27017", rsStatus["syncingTo"].String());
+        ASSERT_EQUALS("host1:27017", member0Status["syncingTo"].String());
+        ASSERT_EQUALS("syncing from: host1:27017", member0Status["infoMessage"].String());
+        ASSERT_EQUALS("", member0Status["lastHeartbeatMessage"].String());
+        ASSERT_EQUALS("", member1Status["syncingTo"].String());
+        ASSERT_EQUALS("", member1Status["infoMessage"].String());
+        ASSERT_EQUALS("", member1Status["lastHeartbeatMessage"].String());
+    }
+}
+
+TEST_F(TopoCoordTest, StatusResponseAlwaysIncludesStringStatusFieldsForNonMembers) {
+    Date_t heartbeatTime = Date_t::fromMillisSinceEpoch(5000);
+    Seconds uptimeSecs(10);
+    Date_t curTime = heartbeatTime + uptimeSecs;
+    OpTime oplogProgress(Timestamp(3, 4), 0);
+
+    ASSERT_TRUE(TopologyCoordinator::Role::follower == getTopoCoord().getRole());
+    ASSERT_EQUALS(MemberState::RS_STARTUP, getTopoCoord().getMemberState().s);
+    updateConfig(BSON("_id"
+                      << "rs0"
+                      << "version"
+                      << 5
+                      << "members"
+                      << BSON_ARRAY(BSON("_id" << 0 << "host"
+                                               << "host0:27017"))
+                      << "protocolVersion"
+                      << 1),
+                 -1);  // This node is no longer part of this replica set.
+
+    BSONObjBuilder statusBuilder;
+    Status resultStatus(ErrorCodes::InternalError, "prepareStatusResponse didn't set result");
+    getTopoCoord().prepareStatusResponse(
+        TopologyCoordinator::ReplSetStatusArgs{
+            curTime,
+            static_cast<unsigned>(durationCount<Seconds>(uptimeSecs)),
+            oplogProgress,
+            oplogProgress,
+            oplogProgress,
+            OpTime(),
+            BSONObj()},
+        &statusBuilder,
+        &resultStatus);
+
+    ASSERT_NOT_OK(resultStatus);
+    ASSERT_EQUALS(ErrorCodes::InvalidReplicaSetConfig, resultStatus);
+
+    BSONObj rsStatus = statusBuilder.obj();
+
+    // These fields should all be empty, since this node is not a member of a replica set.
+    ASSERT_EQUALS("", rsStatus["lastHeartbeatMessage"].String());
+    ASSERT_EQUALS("", rsStatus["syncingTo"].String());
+    ASSERT_EQUALS("", rsStatus["infoMessage"].String());
+}
+
 TEST_F(HeartbeatResponseTestV1,
        ScheduleElectionIfAMajorityOfVotersIsVisibleEvenThoughATrueMajorityIsNot) {
     updateConfig(BSON("_id"