SERVER-48776 remove config term/version check in quorum checker

(cherry picked from commit 1c3532ee1941e37f934f6c14bdc7786619d6b258)

3 files changed, 13 insertions, 144 deletions

diff --git a/src/mongo/db/repl/check_quorum_for_config_change.cpp b/src/mongo/db/repl/check_quorum_for_config_change.cpp
index 40ae42d86f4..327e44e75cc 100644
--- a/src/mongo/db/repl/check_quorum_for_config_change.cpp
+++ b/src/mongo/db/repl/check_quorum_for_config_change.cpp
@@ -225,25 +225,6 @@ void QuorumChecker::_tabulateHeartbeatResponse(const RemoteCommandRequest& reque
         return;
     }
 
-    if (!hbResp.getReplicaSetName().empty()) {
-        if (hbResp.getConfigVersionAndTerm() >= _rsConfig->getConfigVersionAndTerm()) {
-            static constexpr char message[] =
-                "Our config (term, version) is no larger than that of the request target";
-            _vetoStatus = {ErrorCodes::NewReplicaSetConfigurationIncompatible,
-                           str::stream() << message << ", rsConfig: "
-                                         << _rsConfig->getConfigVersionAndTerm().toString()
-                                         << ", requestTarget: " << request.target.toString()
-                                         << ", requestTargetConfig: "
-                                         << hbResp.getConfigVersionAndTerm().toString()};
-            LOGV2_WARNING(23725,
-                          message,
-                          "rsConfig"_attr = _rsConfig->getConfigVersionAndTerm(),
-                          "requestTarget"_attr = request.target.toString(),
-                          "requestTargetConfig"_attr = hbResp.getConfigVersionAndTerm());
-            return;
-        }
-    }
-
     if (_rsConfig->hasReplicaSetId()) {
         StatusWith<rpc::ReplSetMetadata> replMetadata =
             rpc::ReplSetMetadata::readFromMetadata(response.data);
diff --git a/src/mongo/db/repl/check_quorum_for_config_change_test.cpp b/src/mongo/db/repl/check_quorum_for_config_change_test.cpp
index 4d8032a22ad..05c0679edae 100644
--- a/src/mongo/db/repl/check_quorum_for_config_change_test.cpp
+++ b/src/mongo/db/repl/check_quorum_for_config_change_test.cpp
@@ -482,124 +482,12 @@ TEST_F(CheckQuorumForInitiate, QuorumCheckFailedDueToSetIdMismatch) {
     ASSERT_NOT_REASON_CONTAINS(status, "h5:1");
 }
 
-TEST_F(CheckQuorumForInitiate, QuorumCheckFailedDueToInitializedNode) {
-    // In this test, "we" are host "h3:1".  All nodes respond
-    // successfully to their heartbeat requests, but quorum check fails because
-    // "h5" declares that it is already initialized.
-
-    const ReplSetConfig rsConfig =
-        assertMakeRSConfig(BSON("_id"
-                                << "rs0"
-                                << "version" << 1 << "protocolVersion" << 1 << "members"
-                                << BSON_ARRAY(BSON("_id" << 1 << "host"
-                                                         << "h1:1")
-                                              << BSON("_id" << 2 << "host"
-                                                            << "h2:1")
-                                              << BSON("_id" << 3 << "host"
-                                                            << "h3:1")
-                                              << BSON("_id" << 4 << "host"
-                                                            << "h4:1")
-                                              << BSON("_id" << 5 << "host"
-                                                            << "h5:1"))));
-    const int myConfigIndex = 2;
-    const BSONObj hbRequest = makeHeartbeatRequest(rsConfig, myConfigIndex);
-
-    startQuorumCheck(rsConfig, myConfigIndex);
-    const Date_t startDate = getNet()->now();
-    const int numCommandsExpected = rsConfig.getNumMembers() - 1;
-    stdx::unordered_set<HostAndPort> seenHosts;
-    getNet()->enterNetwork();
-    for (int i = 0; i < numCommandsExpected; ++i) {
-        const NetworkInterfaceMock::NetworkOperationIterator noi = getNet()->getNextReadyRequest();
-        const RemoteCommandRequest& request = noi->getRequest();
-        ASSERT_EQUALS("admin", request.dbname);
-        ASSERT_BSONOBJ_EQ(hbRequest, request.cmdObj);
-        ASSERT(seenHosts.insert(request.target).second)
-            << "Already saw " << request.target.toString();
-        if (request.target == HostAndPort("h5", 1)) {
-            long long configVersion = 1;
-            getNet()->scheduleResponse(
-                noi,
-                startDate + Milliseconds(10),
-                makeHeartbeatResponse(rsConfig, Milliseconds(8), configVersion));
-        } else {
-            getNet()->scheduleResponse(noi,
-                                       startDate + Milliseconds(10),
-                                       makeHeartbeatResponse(rsConfig, Milliseconds(8)));
-        }
-    }
-    getNet()->runUntil(startDate + Milliseconds(10));
-    getNet()->exitNetwork();
-    Status status = waitForQuorumCheck();
-    ASSERT_EQUALS(ErrorCodes::NewReplicaSetConfigurationIncompatible, status);
-    ASSERT_STRING_SEARCH_REGEX(status.reason(), "Our config .* is no larger");
-    ASSERT_NOT_REASON_CONTAINS(status, "h1:1");
-    ASSERT_NOT_REASON_CONTAINS(status, "h2:1");
-    ASSERT_NOT_REASON_CONTAINS(status, "h3:1");
-    ASSERT_NOT_REASON_CONTAINS(status, "h4:1");
-    ASSERT_REASON_CONTAINS(status, "h5:1");
-}
-
-TEST_F(CheckQuorumForInitiate, QuorumCheckFailedDueToInitializedNodeOnlyOneRespondent) {
-    // In this test, "we" are host "h3:1".  Only node "h5" responds before the test completes,
-    // and quorum check fails because "h5" declares that it is already initialized.
-    //
-    // Compare to QuorumCheckFailedDueToInitializedNode, above.
-
-    const ReplSetConfig rsConfig =
-        assertMakeRSConfig(BSON("_id"
-                                << "rs0"
-                                << "version" << 1 << "protocolVersion" << 1 << "members"
-                                << BSON_ARRAY(BSON("_id" << 1 << "host"
-                                                         << "h1:1")
-                                              << BSON("_id" << 2 << "host"
-                                                            << "h2:1")
-                                              << BSON("_id" << 3 << "host"
-                                                            << "h3:1")
-                                              << BSON("_id" << 4 << "host"
-                                                            << "h4:1")
-                                              << BSON("_id" << 5 << "host"
-                                                            << "h5:1"))));
-    const int myConfigIndex = 2;
-    const BSONObj hbRequest = makeHeartbeatRequest(rsConfig, myConfigIndex);
-
-    startQuorumCheck(rsConfig, myConfigIndex);
-    const Date_t startDate = getNet()->now();
-    const int numCommandsExpected = rsConfig.getNumMembers() - 1;
-    stdx::unordered_set<HostAndPort> seenHosts;
-    getNet()->enterNetwork();
-    for (int i = 0; i < numCommandsExpected; ++i) {
-        const NetworkInterfaceMock::NetworkOperationIterator noi = getNet()->getNextReadyRequest();
-        const RemoteCommandRequest& request = noi->getRequest();
-        ASSERT_EQUALS("admin", request.dbname);
-        ASSERT_BSONOBJ_EQ(hbRequest, request.cmdObj);
-        ASSERT(seenHosts.insert(request.target).second)
-            << "Already saw " << request.target.toString();
-        if (request.target == HostAndPort("h5", 1)) {
-            long long configVersion = 1;
-            getNet()->scheduleResponse(
-                noi,
-                startDate + Milliseconds(10),
-                makeHeartbeatResponse(rsConfig, Milliseconds(8), configVersion));
-        } else {
-            getNet()->blackHole(noi);
-        }
-    }
-    getNet()->runUntil(startDate + Milliseconds(10));
-    getNet()->exitNetwork();
-    Status status = waitForQuorumCheck();
-    ASSERT_EQUALS(ErrorCodes::NewReplicaSetConfigurationIncompatible, status);
-    ASSERT_STRING_SEARCH_REGEX(status.reason(), "Our config .* is no larger");
-    ASSERT_NOT_REASON_CONTAINS(status, "h1:1");
-    ASSERT_NOT_REASON_CONTAINS(status, "h2:1");
-    ASSERT_NOT_REASON_CONTAINS(status, "h3:1");
-    ASSERT_NOT_REASON_CONTAINS(status, "h4:1");
-    ASSERT_REASON_CONTAINS(status, "h5:1");
-}
-
-TEST_F(CheckQuorumForReconfig, QuorumCheckVetoedDueToHigherConfigVersion) {
+TEST_F(CheckQuorumForReconfig, QuorumCheckSucceedsWhenOtherNodesHaveHigherVersion) {
     // In this test, "we" are host "h3:1".  The request to "h2" does not arrive before the end
     // of the test, and the request to "h1" comes back indicating a higher config version.
+    //
+    // Since The quorum checker does not compare config versions or terms of remotes nodes,
+    // this test should always succeed.
 
     const ReplSetConfig rsConfig =
         assertMakeRSConfig(BSON("_id"
@@ -639,11 +527,7 @@ TEST_F(CheckQuorumForReconfig, QuorumCheckVetoedDueToHigherConfigVersion) {
     getNet()->runUntil(startDate + Milliseconds(10));
     getNet()->exitNetwork();
     Status status = waitForQuorumCheck();
-    ASSERT_EQUALS(ErrorCodes::NewReplicaSetConfigurationIncompatible, status);
-    ASSERT_STRING_SEARCH_REGEX(status.reason(), "Our config .* is no larger");
-    ASSERT_REASON_CONTAINS(status, "h1:1");
-    ASSERT_NOT_REASON_CONTAINS(status, "h2:1");
-    ASSERT_NOT_REASON_CONTAINS(status, "h3:1");
+    ASSERT_OK(status);
 }
 
 TEST_F(CheckQuorumForReconfig, QuorumCheckVetoedDueToIncompatibleSetName) {
diff --git a/src/mongo/db/repl/replication_coordinator_impl_reconfig_test.cpp b/src/mongo/db/repl/replication_coordinator_impl_reconfig_test.cpp
index 6f0a0efacc7..45037075cd4 100644
--- a/src/mongo/db/repl/replication_coordinator_impl_reconfig_test.cpp
+++ b/src/mongo/db/repl/replication_coordinator_impl_reconfig_test.cpp
@@ -329,7 +329,7 @@ void doReplSetReconfig(ReplicationCoordinatorImpl* replCoord,
     *status = replCoord->processReplSetReconfig(opCtx, args, &garbage);
 }
 
-TEST_F(ReplCoordTest, QuorumCheckFailsWhenOtherNodesHaveHigherTerm) {
+TEST_F(ReplCoordTest, QuorumCheckSucceedsWhenOtherNodesHaveHigherTerm) {
     // Initiate a config without a term to avoid stepup auto-reconfig.
     auto configObj =
         configWithMembers(2, -1, BSON_ARRAY(member(1, "node1:12345") << member(2, "node2:12345")));
@@ -356,7 +356,9 @@ TEST_F(ReplCoordTest, QuorumCheckFailsWhenOtherNodesHaveHigherTerm) {
     repl::ReplSetHeartbeatResponse hbResp;
     hbResp.setSetName("mySet");
     hbResp.setState(MemberState::RS_SECONDARY);
-    // The config version from the remote is lower, but its term is higher.
+    // The config version from the remote is lower, but its term is higher. The quorum checker
+    // does not compare config versions or terms of remotes nodes, so this should always
+    // succeed.
     hbResp.setConfigVersion(2);
     hbResp.setConfigTerm(getReplCoord()->getTerm() + 1);
     hbResp.setAppliedOpTimeAndWallTime({opTime, net->now()});
@@ -365,7 +367,7 @@ TEST_F(ReplCoordTest, QuorumCheckFailsWhenOtherNodesHaveHigherTerm) {
     net->runReadyNetworkOperations();
     net->exitNetwork();
     reconfigThread.join();
-    ASSERT_EQUALS(ErrorCodes::NewReplicaSetConfigurationIncompatible, status);
+    ASSERT_OK(status);
 }
 
 TEST_F(ReplCoordTest, QuorumCheckSucceedsWhenOtherNodesHaveLowerTerm) {
@@ -395,7 +397,9 @@ TEST_F(ReplCoordTest, QuorumCheckSucceedsWhenOtherNodesHaveLowerTerm) {
     repl::ReplSetHeartbeatResponse hbResp;
     hbResp.setSetName("mySet");
     hbResp.setState(MemberState::RS_SECONDARY);
-    // The config version from the remote is higher, but its term is lower.
+    // The config version from the remote is higher, but its term is lower. The quorum checker
+    // does not compare config versions or terms of remotes nodes, so this should always
+    // succeed.
     hbResp.setConfigVersion(4);
     hbResp.setConfigTerm(getReplCoord()->getTerm() - 1);
     hbResp.setAppliedOpTimeAndWallTime({opTime, net->now()});