SERVER-46120 Make OplogQueryMetadata non-optional

23 files changed, 84 insertions, 269 deletions

diff --git a/src/mongo/db/repl/bgsync.cpp b/src/mongo/db/repl/bgsync.cpp
index 0d25c62ca9f..eed57307446 100644
--- a/src/mongo/db/repl/bgsync.cpp
+++ b/src/mongo/db/repl/bgsync.cpp
@@ -111,7 +111,7 @@ public:
         BackgroundSync* bgsync);
     bool shouldStopFetching(const HostAndPort& source,
                             const rpc::ReplSetMetadata& replMetadata,
-                            boost::optional<rpc::OplogQueryMetadata> oqMetadata) override;
+                            const rpc::OplogQueryMetadata& oqMetadata) override;
 
 private:
     BackgroundSync* _bgsync;
@@ -127,7 +127,7 @@ DataReplicatorExternalStateBackgroundSync::DataReplicatorExternalStateBackground
 bool DataReplicatorExternalStateBackgroundSync::shouldStopFetching(
     const HostAndPort& source,
     const rpc::ReplSetMetadata& replMetadata,
-    boost::optional<rpc::OplogQueryMetadata> oqMetadata) {
+    const rpc::OplogQueryMetadata& oqMetadata) {
     if (_bgsync->shouldStopFetching()) {
         return true;
     }
diff --git a/src/mongo/db/repl/data_replicator_external_state.h b/src/mongo/db/repl/data_replicator_external_state.h
index 51b7f65c20e..6215015be2c 100644
--- a/src/mongo/db/repl/data_replicator_external_state.h
+++ b/src/mongo/db/repl/data_replicator_external_state.h
@@ -94,12 +94,10 @@ public:
      * Evaluates quality of sync source. Accepts the current sync source; the last optime on this
      * sync source (from metadata); and whether this sync source has a sync source (also from
      * metadata).
-     *
-     * TODO (SERVER-27668): Make OplogQueryMetadata non-optional in mongodb 3.8.
      */
     virtual bool shouldStopFetching(const HostAndPort& source,
                                     const rpc::ReplSetMetadata& replMetadata,
-                                    boost::optional<rpc::OplogQueryMetadata> oqMetadata) = 0;
+                                    const rpc::OplogQueryMetadata& oqMetadata) = 0;
 
     /**
      * This function creates an oplog buffer of the type specified at server startup.
diff --git a/src/mongo/db/repl/data_replicator_external_state_impl.cpp b/src/mongo/db/repl/data_replicator_external_state_impl.cpp
index 4596bddc980..443cb43adbe 100644
--- a/src/mongo/db/repl/data_replicator_external_state_impl.cpp
+++ b/src/mongo/db/repl/data_replicator_external_state_impl.cpp
@@ -95,33 +95,19 @@ void DataReplicatorExternalStateImpl::processMetadata(const rpc::ReplSetMetadata
 bool DataReplicatorExternalStateImpl::shouldStopFetching(
     const HostAndPort& source,
     const rpc::ReplSetMetadata& replMetadata,
-    boost::optional<rpc::OplogQueryMetadata> oqMetadata) {
+    const rpc::OplogQueryMetadata& oqMetadata) {
     // Re-evaluate quality of sync target.
     if (_replicationCoordinator->shouldChangeSyncSource(source, replMetadata, oqMetadata)) {
-        // If OplogQueryMetadata was provided, its values were used to determine if we should
-        // change sync sources.
-        if (oqMetadata) {
-            LOGV2(21150,
-                  "Canceling oplog query due to OplogQueryMetadata. We have to choose a new "
-                  "sync source. Current source: {syncSource}, OpTime {lastAppliedOpTime}, "
-                  "its sync source index:{syncSourceIndex}",
-                  "Canceling oplog query due to OplogQueryMetadata. We have to choose a new "
-                  "sync source",
-                  "syncSource"_attr = source,
-                  "lastAppliedOpTime"_attr = oqMetadata->getLastOpApplied(),
-                  "syncSourceIndex"_attr = oqMetadata->getSyncSourceIndex());
-
-        } else {
-            LOGV2(21151,
-                  "Canceling oplog query due to ReplSetMetadata. We have to choose a new sync "
-                  "source. Current source: {syncSource}, OpTime {lastVisibleOpTime}, its "
-                  "sync source index:{syncSourceIndex}",
-                  "Canceling oplog query due to ReplSetMetadata. We have to choose a new sync "
-                  "source",
-                  "syncSource"_attr = source,
-                  "lastVisibleOpTime"_attr = replMetadata.getLastOpVisible(),
-                  "syncSourceIndex"_attr = replMetadata.getSyncSourceIndex());
-        }
+        LOGV2(21150,
+              "Canceling oplog query due to OplogQueryMetadata. We have to choose a new "
+              "sync source. Current source: {syncSource}, OpTime {lastAppliedOpTime}, "
+              "its sync source index:{syncSourceIndex}",
+              "Canceling oplog query due to OplogQueryMetadata. We have to choose a new "
+              "sync source",
+              "syncSource"_attr = source,
+              "lastAppliedOpTime"_attr = oqMetadata.getLastOpApplied(),
+              "syncSourceIndex"_attr = oqMetadata.getSyncSourceIndex());
+
         return true;
     }
     return false;
diff --git a/src/mongo/db/repl/data_replicator_external_state_impl.h b/src/mongo/db/repl/data_replicator_external_state_impl.h
index 4be02bc2b97..f866e9078f5 100644
--- a/src/mongo/db/repl/data_replicator_external_state_impl.h
+++ b/src/mongo/db/repl/data_replicator_external_state_impl.h
@@ -56,7 +56,7 @@ public:
 
     bool shouldStopFetching(const HostAndPort& source,
                             const rpc::ReplSetMetadata& replMetadata,
-                            boost::optional<rpc::OplogQueryMetadata> oqMetadata) override;
+                            const rpc::OplogQueryMetadata& oqMetadata) override;
 
     std::unique_ptr<OplogBuffer> makeInitialSyncOplogBuffer(OperationContext* opCtx) const override;
 
diff --git a/src/mongo/db/repl/data_replicator_external_state_initial_sync.cpp b/src/mongo/db/repl/data_replicator_external_state_initial_sync.cpp
index c6f573e5115..793f0cc5953 100644
--- a/src/mongo/db/repl/data_replicator_external_state_initial_sync.cpp
+++ b/src/mongo/db/repl/data_replicator_external_state_initial_sync.cpp
@@ -40,8 +40,9 @@ DataReplicatorExternalStateInitialSync::DataReplicatorExternalStateInitialSync(
     : DataReplicatorExternalStateImpl(replicationCoordinator, replicationCoordinatorExternalState) {
 }
 
-bool DataReplicatorExternalStateInitialSync::shouldStopFetching(
-    const HostAndPort&, const rpc::ReplSetMetadata&, boost::optional<rpc::OplogQueryMetadata>) {
+bool DataReplicatorExternalStateInitialSync::shouldStopFetching(const HostAndPort&,
+                                                                const rpc::ReplSetMetadata&,
+                                                                const rpc::OplogQueryMetadata&) {
 
     // Since initial sync does not allow for sync source changes, it should not check if there are
     // better sync sources. If there is a problem on the sync source, it will manifest itself in the
diff --git a/src/mongo/db/repl/data_replicator_external_state_initial_sync.h b/src/mongo/db/repl/data_replicator_external_state_initial_sync.h
index 038accdd4ff..d35757e60d0 100644
--- a/src/mongo/db/repl/data_replicator_external_state_initial_sync.h
+++ b/src/mongo/db/repl/data_replicator_external_state_initial_sync.h
@@ -46,7 +46,7 @@ public:
 
     bool shouldStopFetching(const HostAndPort& source,
                             const rpc::ReplSetMetadata& replMetadata,
-                            boost::optional<rpc::OplogQueryMetadata> oqMetadata) override;
+                            const rpc::OplogQueryMetadata& oqMetadata) override;
 };
 
 }  // namespace repl
diff --git a/src/mongo/db/repl/data_replicator_external_state_mock.cpp b/src/mongo/db/repl/data_replicator_external_state_mock.cpp
index 10b4ae6fd3d..3a7124f4a4c 100644
--- a/src/mongo/db/repl/data_replicator_external_state_mock.cpp
+++ b/src/mongo/db/repl/data_replicator_external_state_mock.cpp
@@ -92,18 +92,10 @@ void DataReplicatorExternalStateMock::processMetadata(const rpc::ReplSetMetadata
 bool DataReplicatorExternalStateMock::shouldStopFetching(
     const HostAndPort& source,
     const rpc::ReplSetMetadata& replMetadata,
-    boost::optional<rpc::OplogQueryMetadata> oqMetadata) {
+    const rpc::OplogQueryMetadata& oqMetadata) {
     lastSyncSourceChecked = source;
-
-    // If OplogQueryMetadata was provided, use its values, otherwise use the ones in
-    // ReplSetMetadata.
-    if (oqMetadata) {
-        syncSourceLastOpTime = oqMetadata->getLastOpApplied();
-        syncSourceHasSyncSource = oqMetadata->getSyncSourceIndex() != -1;
-    } else {
-        syncSourceLastOpTime = replMetadata.getLastOpVisible();
-        syncSourceHasSyncSource = replMetadata.getSyncSourceIndex() != -1;
-    }
+    syncSourceLastOpTime = oqMetadata.getLastOpApplied();
+    syncSourceHasSyncSource = oqMetadata.getSyncSourceIndex() != -1;
     return shouldStopFetchingResult;
 }
 
diff --git a/src/mongo/db/repl/data_replicator_external_state_mock.h b/src/mongo/db/repl/data_replicator_external_state_mock.h
index 7aee165ce85..55a353237e0 100644
--- a/src/mongo/db/repl/data_replicator_external_state_mock.h
+++ b/src/mongo/db/repl/data_replicator_external_state_mock.h
@@ -53,7 +53,7 @@ public:
 
     bool shouldStopFetching(const HostAndPort& source,
                             const rpc::ReplSetMetadata& replMetadata,
-                            boost::optional<rpc::OplogQueryMetadata> oqMetadata) override;
+                            const rpc::OplogQueryMetadata& oqMetadata) override;
 
     std::unique_ptr<OplogBuffer> makeInitialSyncOplogBuffer(OperationContext* opCtx) const override;
 
diff --git a/src/mongo/db/repl/initial_syncer_test.cpp b/src/mongo/db/repl/initial_syncer_test.cpp
index 6344cefc503..a22e52b30b3 100644
--- a/src/mongo/db/repl/initial_syncer_test.cpp
+++ b/src/mongo/db/repl/initial_syncer_test.cpp
@@ -158,7 +158,7 @@ public:
     }
     bool shouldChangeSyncSource(const HostAndPort& currentSource,
                                 const rpc::ReplSetMetadata& replMetadata,
-                                boost::optional<rpc::OplogQueryMetadata> oqMetadata) override {
+                                const rpc::OplogQueryMetadata& oqMetadata) override {
         return _syncSourceSelector->shouldChangeSyncSource(currentSource, replMetadata, oqMetadata);
     }
 
diff --git a/src/mongo/db/repl/oplog_fetcher.cpp b/src/mongo/db/repl/oplog_fetcher.cpp
index 58a874c3b1a..1aa4774f89d 100644
--- a/src/mongo/db/repl/oplog_fetcher.cpp
+++ b/src/mongo/db/repl/oplog_fetcher.cpp
@@ -129,22 +129,20 @@ Milliseconds calculateAwaitDataTimeout(const ReplSetConfig& config) {
  * oplog to be ahead of ours. If false, the sync source's oplog is allowed to be at the same point
  * as ours, but still cannot be behind ours.
  *
- * TODO (SERVER-27668): Make remoteLastOpApplied, and remoteRBID non-optional.
- *
  * Returns OplogStartMissing if we cannot find the optime of the last fetched operation in
  * the remote oplog.
  */
 Status checkRemoteOplogStart(const OplogFetcher::Documents& documents,
                              OpTime lastFetched,
-                             boost::optional<OpTime> remoteLastOpApplied,
+                             OpTime remoteLastOpApplied,
                              int requiredRBID,
-                             boost::optional<int> remoteRBID,
+                             int remoteRBID,
                              bool requireFresherSyncSource) {
     // Once we establish our cursor, we need to ensure that our upstream node hasn't rolled back
     // since that could cause it to not have our required minValid point. The cursor will be
     // killed if the upstream node rolls back so we don't need to keep checking once the cursor
     // is established.
-    if (remoteRBID && (*remoteRBID != requiredRBID)) {
+    if (remoteRBID != requiredRBID) {
         return Status(ErrorCodes::InvalidSyncSource,
                       "Upstream node rolled back after choosing it as a sync source. Choosing "
                       "new sync source.");
@@ -153,10 +151,10 @@ Status checkRemoteOplogStart(const OplogFetcher::Documents& documents,
     // Sometimes our remoteLastOpApplied may be stale; if we received a document with an
     // opTime later than remoteLastApplied, we can assume the remote is at least up to that
     // opTime.
-    if (remoteLastOpApplied && !documents.empty()) {
+    if (!documents.empty()) {
         const auto docOpTime = OpTime::parseFromOplogEntry(documents.back());
         if (docOpTime.isOK()) {
-            remoteLastOpApplied = std::max(*remoteLastOpApplied, docOpTime.getValue());
+            remoteLastOpApplied = std::max(remoteLastOpApplied, docOpTime.getValue());
         }
     }
 
@@ -164,10 +162,10 @@ Status checkRemoteOplogStart(const OplogFetcher::Documents& documents,
     // failed to detect the rollback if it occurred between sync source selection (when we check the
     // candidate is ahead of us) and sync source resolution (when we got 'requiredRBID'). If the
     // sync source is now behind us, choose a new sync source to prevent going into rollback.
-    if (remoteLastOpApplied && (*remoteLastOpApplied < lastFetched)) {
+    if (remoteLastOpApplied < lastFetched) {
         return Status(ErrorCodes::InvalidSyncSource,
                       str::stream()
-                          << "Sync source's last applied OpTime " << remoteLastOpApplied->toString()
+                          << "Sync source's last applied OpTime " << remoteLastOpApplied.toString()
                           << " is older than our last fetched OpTime " << lastFetched.toString()
                           << ". Choosing new sync source.");
     }
@@ -181,12 +179,12 @@ Status checkRemoteOplogStart(const OplogFetcher::Documents& documents,
     // problematic to check this condition for initial sync, since the 'lastFetched' OpTime will
     // almost always equal the 'remoteLastApplied', since we fetch the sync source's last applied
     // OpTime to determine where to start our OplogFetcher.
-    if (requireFresherSyncSource && remoteLastOpApplied && *remoteLastOpApplied <= lastFetched) {
+    if (requireFresherSyncSource && remoteLastOpApplied <= lastFetched) {
         return Status(ErrorCodes::InvalidSyncSource,
                       str::stream()
                           << "Sync source must be ahead of me. My last fetched oplog optime: "
                           << lastFetched.toString() << ", latest oplog optime of sync source: "
-                          << remoteLastOpApplied->toString());
+                          << remoteLastOpApplied.toString());
     }
 
     // At this point we know that our sync source has our minValid and is not behind us, so if our
@@ -215,31 +213,6 @@ Status checkRemoteOplogStart(const OplogFetcher::Documents& documents,
     }
     return Status::OK();
 }
-
-/**
- * Parses the cursor's metadata response for the OplogQueryMetadata. If there is an error it returns
- * it. If no OplogQueryMetadata is provided then it returns boost::none.
- *
- * OplogQueryMetadata is made optional for backwards compatibility.
- * TODO SERVER-27668: Make this non-optional. When this stops being optional we can remove the
- * duplicated fields in both metadata types and begin to always use OplogQueryMetadata's data.
- */
-StatusWith<boost::optional<rpc::OplogQueryMetadata>> parseOplogQueryMetadata(
-    const BSONObj& metadata) {
-    boost::optional<rpc::OplogQueryMetadata> oqMetadata = boost::none;
-
-    bool receivedOplogQueryMetadata = metadata.hasElement(rpc::kOplogQueryMetadataFieldName);
-    if (receivedOplogQueryMetadata) {
-        auto metadataResult = rpc::OplogQueryMetadata::readFromMetadata(metadata);
-        if (!metadataResult.isOK()) {
-            return metadataResult.getStatus();
-        }
-
-        oqMetadata = boost::make_optional(metadataResult.getValue());
-    }
-
-    return oqMetadata;
-}
 }  // namespace
 
 
@@ -770,7 +743,7 @@ Status OplogFetcher::_onSuccessfulBatch(const Documents& documents) {
         LOGV2_DEBUG(21271, 2, "Oplog fetcher read 0 operations from remote oplog");
     }
 
-    auto oqMetadataResult = parseOplogQueryMetadata(_metadataObj);
+    auto oqMetadataResult = rpc::OplogQueryMetadata::readFromMetadata(_metadataObj);
     if (!oqMetadataResult.isOK()) {
         LOGV2_ERROR(21278,
                     "invalid oplog query metadata from sync source {syncSource}: "
@@ -787,14 +760,11 @@ Status OplogFetcher::_onSuccessfulBatch(const Documents& documents) {
     auto lastFetched = _getLastOpTimeFetched();
 
     if (_firstBatch) {
-        auto remoteRBID = oqMetadata ? boost::make_optional(oqMetadata->getRBID()) : boost::none;
-        auto remoteLastApplied =
-            oqMetadata ? boost::make_optional(oqMetadata->getLastOpApplied()) : boost::none;
         auto status = checkRemoteOplogStart(documents,
                                             lastFetched,
-                                            remoteLastApplied,
+                                            oqMetadata.getLastOpApplied(),
                                             _requiredRBID,
-                                            remoteRBID,
+                                            oqMetadata.getRBID(),
                                             _requireFresherSyncSource);
         if (!status.isOK()) {
             // Stop oplog fetcher and execute rollback if necessary.
@@ -850,8 +820,7 @@ Status OplogFetcher::_onSuccessfulBatch(const Documents& documents) {
 
         // We will only ever have OplogQueryMetadata if we have ReplSetMetadata, so it is safe
         // to call processMetadata() in this if block.
-        invariant(oqMetadata);
-        _dataReplicatorExternalState->processMetadata(replSetMetadata, *oqMetadata);
+        _dataReplicatorExternalState->processMetadata(replSetMetadata, oqMetadata);
     }
 
     // Increment stats. We read all of the docs in the query.
@@ -873,17 +842,9 @@ Status OplogFetcher::_onSuccessfulBatch(const Documents& documents) {
         str::stream errMsg;
         errMsg << "sync source " << _source.toString();
         errMsg << " (config version: " << replSetMetadata.getConfigVersion();
-        // If OplogQueryMetadata was provided, its values were used to determine if we should
-        // stop fetching from this sync source.
-        if (oqMetadata) {
-            errMsg << "; last applied optime: " << oqMetadata->getLastOpApplied().toString();
-            errMsg << "; sync source index: " << oqMetadata->getSyncSourceIndex();
-            errMsg << "; primary index: " << oqMetadata->getPrimaryIndex();
-        } else {
-            errMsg << "; last visible optime: " << replSetMetadata.getLastOpVisible().toString();
-            errMsg << "; sync source index: " << replSetMetadata.getSyncSourceIndex();
-            errMsg << "; primary index: " << replSetMetadata.getPrimaryIndex();
-        }
+        errMsg << "; last applied optime: " << oqMetadata.getLastOpApplied().toString();
+        errMsg << "; sync source index: " << oqMetadata.getSyncSourceIndex();
+        errMsg << "; primary index: " << oqMetadata.getPrimaryIndex();
         errMsg << ") is no longer valid";
         return Status(ErrorCodes::InvalidSyncSource, errMsg);
     }
@@ -932,7 +893,7 @@ bool OplogFetcher::OplogFetcherRestartDecisionDefault::shouldContinue(OplogFetch
 
 void OplogFetcher::OplogFetcherRestartDecisionDefault::fetchSuccessful(OplogFetcher* fetcher) {
     _numRestarts = 0;
-};
+}
 
 OplogFetcher::OplogFetcherRestartDecision::~OplogFetcherRestartDecision(){};
 
diff --git a/src/mongo/db/repl/oplog_fetcher_test.cpp b/src/mongo/db/repl/oplog_fetcher_test.cpp
index 0191fc2ada0..2c80bbd5931 100644
--- a/src/mongo/db/repl/oplog_fetcher_test.cpp
+++ b/src/mongo/db/repl/oplog_fetcher_test.cpp
@@ -306,8 +306,8 @@ protected:
     /**
      * Tests checkSyncSource result handling.
      */
-    void testSyncSourceChecking(boost::optional<const rpc::ReplSetMetadata&> replMetadata,
-                                boost::optional<const rpc::OplogQueryMetadata&> oqMetadata);
+    void testSyncSourceChecking(const rpc::ReplSetMetadata& replMetadata,
+                                const rpc::OplogQueryMetadata& oqMetadata);
 
     void validateLastBatch(bool skipFirstDoc, OplogFetcher::Documents docs, OpTime lastFetched);
 
@@ -453,9 +453,8 @@ std::unique_ptr<ShutdownState> OplogFetcherTest::processSingleBatch(const Messag
     return shutdownState;
 }
 
-void OplogFetcherTest::testSyncSourceChecking(
-    boost::optional<const rpc::ReplSetMetadata&> replMetadata,
-    boost::optional<const rpc::OplogQueryMetadata&> oqMetadata) {
+void OplogFetcherTest::testSyncSourceChecking(const rpc::ReplSetMetadata& replMetadata,
+                                              const rpc::OplogQueryMetadata& oqMetadata) {
     auto firstEntry = makeNoopOplogEntry(lastFetched);
     auto secondEntry = makeNoopOplogEntry({{Seconds(456), 0}, lastFetched.getTerm()});
     auto thirdEntry = makeNoopOplogEntry({{Seconds(789), 0}, lastFetched.getTerm()});
@@ -824,14 +823,12 @@ TEST_F(OplogFetcherTest, InvalidOplogQueryMetadataInResponseStopsTheOplogFetcher
                   processSingleBatch(makeFirstBatch(cursorId, {entry}, metadataObj))->getStatus());
 }
 
-DEATH_TEST_REGEX_F(OplogFetcherTest,
-                   ValidMetadataInResponseWithoutOplogMetadataInvariants,
-                   "Invariant failure.*oqMetadata") {
+TEST_F(OplogFetcherTest, ValidMetadataInResponseWithoutOplogMetadataStopsTheOplogFetcher) {
     CursorId cursorId = 22LL;
     auto entry = makeNoopOplogEntry(lastFetched);
     auto metadataObj = makeOplogBatchMetadata(replSetMetadata, boost::none);
-
-    processSingleBatch(makeFirstBatch(cursorId, {entry}, metadataObj));
+    ASSERT_EQUALS(ErrorCodes::NoSuchKey,
+                  processSingleBatch(makeFirstBatch(cursorId, {entry}, metadataObj))->getStatus());
 }
 
 TEST_F(OplogFetcherTest, ValidMetadataWithInResponseShouldBeForwardedToProcessMetadataFn) {
@@ -936,17 +933,6 @@ TEST_F(OplogFetcherTest,
     ASSERT(dataReplicatorExternalState->metadataWasProcessed);
 }
 
-TEST_F(OplogFetcherTest,
-       MetadataWithoutOplogQueryMetadataIsNotProcessedOnBatchThatTriggersRollback) {
-    CursorId cursorId = 22LL;
-    auto metadataObj = makeOplogBatchMetadata(replSetMetadata, boost::none);
-    auto entry = makeNoopOplogEntry(Seconds(456));
-
-    ASSERT_EQUALS(ErrorCodes::OplogStartMissing,
-                  processSingleBatch(makeFirstBatch(cursorId, {entry}, metadataObj))->getStatus());
-    ASSERT_FALSE(dataReplicatorExternalState->metadataWasProcessed);
-}
-
 TEST_F(OplogFetcherTest, MetadataIsNotProcessedOnBatchThatTriggersRollback) {
     CursorId cursorId = 22LL;
     auto metadataObj = makeOplogBatchMetadata(replSetMetadata, oqMetadata);
@@ -958,14 +944,6 @@ TEST_F(OplogFetcherTest, MetadataIsNotProcessedOnBatchThatTriggersRollback) {
     ASSERT_FALSE(dataReplicatorExternalState->metadataWasProcessed);
 }
 
-TEST_F(OplogFetcherTest, EmptyMetadataIsNotProcessed) {
-    CursorId cursorId = 0LL;
-    auto entry = makeNoopOplogEntry(lastFetched);
-
-    ASSERT_OK(processSingleBatch(makeFirstBatch(cursorId, {entry}, {}))->getStatus());
-    ASSERT_FALSE(dataReplicatorExternalState->metadataWasProcessed);
-}
-
 TEST_F(OplogFetcherTest, FailingInitialCreateNewCursorNoRetriesShutsDownOplogFetcher) {
     ASSERT_EQUALS(ErrorCodes::InvalidSyncSource, processSingleBatch(Message())->getStatus());
 }
@@ -1448,8 +1426,9 @@ TEST_F(OplogFetcherTest, CursorIsDeadShutsDownOplogFetcherWithSuccessfulStatus)
 
 TEST_F(OplogFetcherTest, EmptyFirstBatchStopsOplogFetcherWithOplogStartMissingError) {
     CursorId cursorId = 22LL;
+    auto metadataObj = makeOplogBatchMetadata(replSetMetadata, oqMetadata);
     ASSERT_EQUALS(ErrorCodes::OplogStartMissing,
-                  processSingleBatch(makeFirstBatch(cursorId, {}, {}))->getStatus());
+                  processSingleBatch(makeFirstBatch(cursorId, {}, {metadataObj}))->getStatus());
 }
 
 TEST_F(OplogFetcherTest, MissingOpTimeInFirstDocumentCausesOplogFetcherToStopWithInvalidBSONError) {
@@ -1695,16 +1674,6 @@ TEST_F(OplogFetcherTest, OplogFetcherShouldReportErrorsThrownFromEnqueueDocument
     ASSERT_EQ(Status(ErrorCodes::InternalError, "my custom error"), shutdownState->getStatus());
 }
 
-TEST_F(OplogFetcherTest, FailedSyncSourceCheckWithoutMetadataStopsTheOplogFetcher) {
-    testSyncSourceChecking(boost::none, boost::none);
-
-    // Sync source optime and "hasSyncSource" are not available if the response does not
-    // contain metadata.
-    ASSERT_EQUALS(source, dataReplicatorExternalState->lastSyncSourceChecked);
-    ASSERT_EQUALS(OpTime(), dataReplicatorExternalState->syncSourceLastOpTime);
-    ASSERT_FALSE(dataReplicatorExternalState->syncSourceHasSyncSource);
-}
-
 TEST_F(OplogFetcherTest, FailedSyncSourceCheckWithBothMetadatasStopsTheOplogFetcher) {
     testSyncSourceChecking(replSetMetadata, oqMetadata);
 
diff --git a/src/mongo/db/repl/replication_coordinator_impl.cpp b/src/mongo/db/repl/replication_coordinator_impl.cpp
index e9eb073f8e7..80d548b7716 100644
--- a/src/mongo/db/repl/replication_coordinator_impl.cpp
+++ b/src/mongo/db/repl/replication_coordinator_impl.cpp
@@ -4471,10 +4471,9 @@ void ReplicationCoordinatorImpl::resetLastOpTimesFromOplog(OperationContext* opC
     _reportUpstream_inlock(std::move(lock));
 }
 
-bool ReplicationCoordinatorImpl::shouldChangeSyncSource(
-    const HostAndPort& currentSource,
-    const rpc::ReplSetMetadata& replMetadata,
-    boost::optional<rpc::OplogQueryMetadata> oqMetadata) {
+bool ReplicationCoordinatorImpl::shouldChangeSyncSource(const HostAndPort& currentSource,
+                                                        const rpc::ReplSetMetadata& replMetadata,
+                                                        const rpc::OplogQueryMetadata& oqMetadata) {
     stdx::lock_guard<Latch> lock(_mutex);
     return _topCoord->shouldChangeSyncSource(
         currentSource, replMetadata, oqMetadata, _replExecutor->now());
diff --git a/src/mongo/db/repl/replication_coordinator_impl.h b/src/mongo/db/repl/replication_coordinator_impl.h
index 56cf436a91e..fc9e4a39888 100644
--- a/src/mongo/db/repl/replication_coordinator_impl.h
+++ b/src/mongo/db/repl/replication_coordinator_impl.h
@@ -276,10 +276,9 @@ public:
     virtual void resetLastOpTimesFromOplog(OperationContext* opCtx,
                                            DataConsistency consistency) override;
 
-    virtual bool shouldChangeSyncSource(
-        const HostAndPort& currentSource,
-        const rpc::ReplSetMetadata& replMetadata,
-        boost::optional<rpc::OplogQueryMetadata> oqMetadata) override;
+    virtual bool shouldChangeSyncSource(const HostAndPort& currentSource,
+                                        const rpc::ReplSetMetadata& replMetadata,
+                                        const rpc::OplogQueryMetadata& oqMetadata) override;
 
     virtual OpTime getLastCommittedOpTime() const override;
     virtual OpTimeAndWallTime getLastCommittedOpTimeAndWallTime() const override;
diff --git a/src/mongo/db/repl/replication_coordinator_mock.cpp b/src/mongo/db/repl/replication_coordinator_mock.cpp
index 171db3035cd..6ddd4d4e84f 100644
--- a/src/mongo/db/repl/replication_coordinator_mock.cpp
+++ b/src/mongo/db/repl/replication_coordinator_mock.cpp
@@ -450,10 +450,9 @@ bool ReplicationCoordinatorMock::lastOpTimesWereReset() const {
     return _resetLastOpTimesCalled;
 }
 
-bool ReplicationCoordinatorMock::shouldChangeSyncSource(
-    const HostAndPort& currentSource,
-    const rpc::ReplSetMetadata& replMetadata,
-    boost::optional<rpc::OplogQueryMetadata> oqMetadata) {
+bool ReplicationCoordinatorMock::shouldChangeSyncSource(const HostAndPort& currentSource,
+                                                        const rpc::ReplSetMetadata& replMetadata,
+                                                        const rpc::OplogQueryMetadata& oqMetadata) {
     MONGO_UNREACHABLE;
 }
 
diff --git a/src/mongo/db/repl/replication_coordinator_mock.h b/src/mongo/db/repl/replication_coordinator_mock.h
index e5a8b1edb7a..7a4b8db79a0 100644
--- a/src/mongo/db/repl/replication_coordinator_mock.h
+++ b/src/mongo/db/repl/replication_coordinator_mock.h
@@ -243,7 +243,7 @@ public:
 
     virtual bool shouldChangeSyncSource(const HostAndPort& currentSource,
                                         const rpc::ReplSetMetadata& replMetadata,
-                                        boost::optional<rpc::OplogQueryMetadata> oqMetadata);
+                                        const rpc::OplogQueryMetadata& oqMetadata);
 
     virtual OpTime getLastCommittedOpTime() const;
 
diff --git a/src/mongo/db/repl/replication_coordinator_noop.cpp b/src/mongo/db/repl/replication_coordinator_noop.cpp
index 60334f18742..d0e52db43a2 100644
--- a/src/mongo/db/repl/replication_coordinator_noop.cpp
+++ b/src/mongo/db/repl/replication_coordinator_noop.cpp
@@ -387,7 +387,7 @@ void ReplicationCoordinatorNoOp::resetLastOpTimesFromOplog(OperationContext*, Da
 
 bool ReplicationCoordinatorNoOp::shouldChangeSyncSource(const HostAndPort&,
                                                         const rpc::ReplSetMetadata&,
-                                                        boost::optional<rpc::OplogQueryMetadata>) {
+                                                        const rpc::OplogQueryMetadata&) {
     MONGO_UNREACHABLE;
 }
 
diff --git a/src/mongo/db/repl/replication_coordinator_noop.h b/src/mongo/db/repl/replication_coordinator_noop.h
index 89ec7039f39..382073c21fb 100644
--- a/src/mongo/db/repl/replication_coordinator_noop.h
+++ b/src/mongo/db/repl/replication_coordinator_noop.h
@@ -208,7 +208,7 @@ public:
 
     bool shouldChangeSyncSource(const HostAndPort&,
                                 const rpc::ReplSetMetadata&,
-                                boost::optional<rpc::OplogQueryMetadata>) final;
+                                const rpc::OplogQueryMetadata&) final;
 
     OpTime getLastCommittedOpTime() const final;
 
diff --git a/src/mongo/db/repl/sync_source_selector.h b/src/mongo/db/repl/sync_source_selector.h
index c21a5e82a14..ab159a2a9d8 100644
--- a/src/mongo/db/repl/sync_source_selector.h
+++ b/src/mongo/db/repl/sync_source_selector.h
@@ -83,14 +83,10 @@ public:
      * source and only has data up to "myLastOpTime", returns true.
      *
      * "now" is used to skip over currently blacklisted sync sources.
-     *
-     * OplogQueryMetadata is optional for compatibility with 3.4 servers that do not know to
-     * send OplogQueryMetadata.
-     * TODO (SERVER-27668): Make OplogQueryMetadata non-optional in mongodb 3.8.
      */
     virtual bool shouldChangeSyncSource(const HostAndPort& currentSource,
                                         const rpc::ReplSetMetadata& replMetadata,
-                                        boost::optional<rpc::OplogQueryMetadata> oqMetadata) = 0;
+                                        const rpc::OplogQueryMetadata& oqMetadata) = 0;
 };
 
 }  // namespace repl
diff --git a/src/mongo/db/repl/sync_source_selector_mock.cpp b/src/mongo/db/repl/sync_source_selector_mock.cpp
index f55cb4bb9fe..67c3a44f67d 100644
--- a/src/mongo/db/repl/sync_source_selector_mock.cpp
+++ b/src/mongo/db/repl/sync_source_selector_mock.cpp
@@ -56,10 +56,9 @@ void SyncSourceSelectorMock::setChooseNewSyncSourceHook_forTest(
     _chooseNewSyncSourceHook = hook;
 }
 
-bool SyncSourceSelectorMock::shouldChangeSyncSource(
-    const HostAndPort&,
-    const rpc::ReplSetMetadata&,
-    boost::optional<rpc::OplogQueryMetadata> oqMetadata) {
+bool SyncSourceSelectorMock::shouldChangeSyncSource(const HostAndPort&,
+                                                    const rpc::ReplSetMetadata&,
+                                                    const rpc::OplogQueryMetadata& oqMetadata) {
     return false;
 }
 
diff --git a/src/mongo/db/repl/sync_source_selector_mock.h b/src/mongo/db/repl/sync_source_selector_mock.h
index 9bf7bf4daba..78c548ab702 100644
--- a/src/mongo/db/repl/sync_source_selector_mock.h
+++ b/src/mongo/db/repl/sync_source_selector_mock.h
@@ -55,7 +55,7 @@ public:
     void blacklistSyncSource(const HostAndPort& host, Date_t until) override;
     bool shouldChangeSyncSource(const HostAndPort&,
                                 const rpc::ReplSetMetadata&,
-                                boost::optional<rpc::OplogQueryMetadata> oqMetadata) override;
+                                const rpc::OplogQueryMetadata& oqMetadata) override;
 
     /**
      * Sets a function that will be run every time chooseNewSyncSource() is called.
diff --git a/src/mongo/db/repl/topology_coordinator.cpp b/src/mongo/db/repl/topology_coordinator.cpp
index c901b7098f8..e1ffa9a6339 100644
--- a/src/mongo/db/repl/topology_coordinator.cpp
+++ b/src/mongo/db/repl/topology_coordinator.cpp
@@ -2882,11 +2882,10 @@ long long TopologyCoordinator::getTerm() const {
 
 // TODO(siyuan): Merge _hddata into _slaveInfo, so that we have a single view of the
 // replset. Passing metadata is unnecessary.
-bool TopologyCoordinator::shouldChangeSyncSource(
-    const HostAndPort& currentSource,
-    const rpc::ReplSetMetadata& replMetadata,
-    boost::optional<rpc::OplogQueryMetadata> oqMetadata,
-    Date_t now) const {
+bool TopologyCoordinator::shouldChangeSyncSource(const HostAndPort& currentSource,
+                                                 const rpc::ReplSetMetadata& replMetadata,
+                                                 const rpc::OplogQueryMetadata& oqMetadata,
+                                                 Date_t now) const {
     // Methodology:
     // If there exists a viable sync source member other than currentSource, whose oplog has
     // reached an optime greater than _options.maxSyncSourceLagSecs later than currentSource's,
@@ -2940,30 +2939,14 @@ bool TopologyCoordinator::shouldChangeSyncSource(
 
     invariant(currentSourceIndex != _selfIndex);
 
-    // If OplogQueryMetadata was provided, use its values, otherwise use the ones in
-    // ReplSetMetadata.
-    OpTime currentSourceOpTime;
-    int syncSourceIndex = -1;
-    int primaryIndex = -1;
-    if (oqMetadata) {
-        currentSourceOpTime =
-            std::max(oqMetadata->getLastOpApplied(),
-                     _memberData.at(currentSourceIndex).getHeartbeatAppliedOpTime());
-        syncSourceIndex = oqMetadata->getSyncSourceIndex();
-        primaryIndex = oqMetadata->getPrimaryIndex();
-    } else {
-        currentSourceOpTime =
-            std::max(replMetadata.getLastOpVisible(),
-                     _memberData.at(currentSourceIndex).getHeartbeatAppliedOpTime());
-        syncSourceIndex = replMetadata.getSyncSourceIndex();
-        primaryIndex = replMetadata.getPrimaryIndex();
-    }
+    OpTime currentSourceOpTime =
+        std::max(oqMetadata.getLastOpApplied(),
+                 _memberData.at(currentSourceIndex).getHeartbeatAppliedOpTime());
 
-    if (currentSourceOpTime.isNull()) {
-        // Haven't received a heartbeat from the sync source yet, so can't tell if we should
-        // change.
-        return false;
-    }
+    fassert(4612000, !currentSourceOpTime.isNull());
+
+    int syncSourceIndex = oqMetadata.getSyncSourceIndex();
+    int primaryIndex = oqMetadata.getPrimaryIndex();
 
     // Change sync source if they are not ahead of us, and don't have a sync source,
     // unless they are primary.
diff --git a/src/mongo/db/repl/topology_coordinator.h b/src/mongo/db/repl/topology_coordinator.h
index 8b1444c8d45..0e9f90aef21 100644
--- a/src/mongo/db/repl/topology_coordinator.h
+++ b/src/mongo/db/repl/topology_coordinator.h
@@ -228,12 +228,10 @@ public:
      * ("syncSourceHasSyncSource" is false), and only has data up to "myLastOpTime", returns true.
      *
      * "now" is used to skip over currently blacklisted sync sources.
-     *
-     * TODO (SERVER-27668): Make OplogQueryMetadata non-optional in mongodb 3.8.
      */
     bool shouldChangeSyncSource(const HostAndPort& currentSource,
                                 const rpc::ReplSetMetadata& replMetadata,
-                                boost::optional<rpc::OplogQueryMetadata> oqMetadata,
+                                const rpc::OplogQueryMetadata& oqMetadata,
                                 Date_t now) const;
 
     /**
diff --git a/src/mongo/db/repl/topology_coordinator_v1_test.cpp b/src/mongo/db/repl/topology_coordinator_v1_test.cpp
index 7363a4e1385..88f4ee2b3d7 100644
--- a/src/mongo/db/repl/topology_coordinator_v1_test.cpp
+++ b/src/mongo/db/repl/topology_coordinator_v1_test.cpp
@@ -988,10 +988,6 @@ TEST_F(TopoCoordTest, ChooseRequestedSyncSourceOnlyTheFirstTimeAfterTheSyncSourc
         HostAndPort("h2"), makeReplSetMetadata(), makeOplogQueryMetadata(oldOpTime), now()));
     ASSERT_TRUE(getTopoCoord().shouldChangeSyncSource(
         HostAndPort("h3"), makeReplSetMetadata(), makeOplogQueryMetadata(newOpTime), now()));
-    ASSERT_TRUE(getTopoCoord().shouldChangeSyncSource(
-        HostAndPort("h2"), makeReplSetMetadata(oldOpTime), boost::none, now()));
-    ASSERT_TRUE(getTopoCoord().shouldChangeSyncSource(
-        HostAndPort("h3"), makeReplSetMetadata(newOpTime), boost::none, now()));
     getTopoCoord().chooseNewSyncSource(now()++,
                                        OpTime(),
                                        TopologyCoordinator::ChainingPreference::kUseConfiguration,
@@ -4095,13 +4091,6 @@ TEST_F(HeartbeatResponseTestV1,
                                                       now()));
     stopCapturingLogMessages();
     ASSERT_EQUALS(1, countLogLinesContaining("Choosing new sync source"));
-
-    // set up complete, time for actual check
-    startCapturingLogMessages();
-    ASSERT_TRUE(getTopoCoord().shouldChangeSyncSource(
-        HostAndPort("host2"), makeReplSetMetadata(lastOpTimeApplied), boost::none, now()));
-    stopCapturingLogMessages();
-    ASSERT_EQUALS(1, countLogLinesContaining("Choosing new sync source"));
 }
 
 TEST_F(HeartbeatResponseTestV1,
@@ -4120,8 +4109,6 @@ TEST_F(HeartbeatResponseTestV1,
                                                        makeReplSetMetadata(),
                                                        makeOplogQueryMetadata(lastOpTimeApplied, 1),
                                                        now()));
-    ASSERT_FALSE(getTopoCoord().shouldChangeSyncSource(
-        HostAndPort("host2"), makeReplSetMetadata(lastOpTimeApplied, 1), boost::none, now()));
 
     // Show that we also like host2 while it has a sync source.
     nextAction = receiveUpHeartbeat(
@@ -4132,8 +4119,6 @@ TEST_F(HeartbeatResponseTestV1,
                                               makeReplSetMetadata(),
                                               makeOplogQueryMetadata(lastOpTimeApplied, 2, 2),
                                               now()));
-    ASSERT_FALSE(getTopoCoord().shouldChangeSyncSource(
-        HostAndPort("host2"), makeReplSetMetadata(lastOpTimeApplied, 2, 2), boost::none, now()));
 
     // Show that we do not like it when it is not PRIMARY and lacks a sync source and lacks progress
     // beyond our own.
@@ -4144,8 +4129,6 @@ TEST_F(HeartbeatResponseTestV1,
                                                  makeReplSetMetadata(),
                                                  makeOplogQueryMetadata(lastOpTimeApplied),
                                                  now()));
-    ASSERT(getTopoCoord().shouldChangeSyncSource(
-        HostAndPort("host2"), makeReplSetMetadata(lastOpTimeApplied), boost::none, now()));
 
     // Sometimes the heartbeat is stale and the metadata says it's the primary. Trust the metadata.
     ASSERT_FALSE(getTopoCoord().shouldChangeSyncSource(
@@ -4154,11 +4137,6 @@ TEST_F(HeartbeatResponseTestV1,
         makeOplogQueryMetadata(
             lastOpTimeApplied, 1 /* host2 is primary */, -1 /* no sync source */),
         now()));
-    ASSERT_FALSE(getTopoCoord().shouldChangeSyncSource(
-        HostAndPort("host2"),
-        makeReplSetMetadata(lastOpTimeApplied, 1 /* host2 is primary */, -1 /* no sync source */),
-        boost::none,
-        now()));
 
     // But if it is secondary and has some progress beyond our own, we still like it.
     OpTime newerThanLastOpTimeApplied = OpTime(Timestamp(500, 0), 0);
@@ -4173,8 +4151,6 @@ TEST_F(HeartbeatResponseTestV1,
                                               makeReplSetMetadata(),
                                               makeOplogQueryMetadata(newerThanLastOpTimeApplied),
                                               now()));
-    ASSERT_FALSE(getTopoCoord().shouldChangeSyncSource(
-        HostAndPort("host2"), makeReplSetMetadata(newerThanLastOpTimeApplied), boost::none, now()));
 }
 
 TEST_F(HeartbeatResponseTestV1, ShouldNotChangeSyncSourceWhenFresherMemberIsDown) {
@@ -4211,9 +4187,6 @@ TEST_F(HeartbeatResponseTestV1, ShouldNotChangeSyncSourceWhenFresherMemberIsDown
                                                        makeReplSetMetadata(),
                                                        makeOplogQueryMetadata(syncSourceOpTime),
                                                        now()));
-
-    ASSERT_FALSE(getTopoCoord().shouldChangeSyncSource(
-        HostAndPort("host2"), makeReplSetMetadata(syncSourceOpTime), boost::none, now()));
 }
 
 TEST_F(HeartbeatResponseTestV1, ShouldNotChangeSyncSourceWhileFresherMemberIsBlackListed) {
@@ -4244,8 +4217,6 @@ TEST_F(HeartbeatResponseTestV1, ShouldNotChangeSyncSourceWhileFresherMemberIsBla
                                                        makeReplSetMetadata(),
                                                        makeOplogQueryMetadata(syncSourceOpTime),
                                                        now()));
-    ASSERT_FALSE(getTopoCoord().shouldChangeSyncSource(
-        HostAndPort("host2"), makeReplSetMetadata(syncSourceOpTime), boost::none, now()));
 
     // unblacklist with too early a time (node should remained blacklisted)
     getTopoCoord().unblacklistSyncSource(HostAndPort("host3"), now() + Milliseconds(90));
@@ -4253,8 +4224,6 @@ TEST_F(HeartbeatResponseTestV1, ShouldNotChangeSyncSourceWhileFresherMemberIsBla
                                                        makeReplSetMetadata(),
                                                        makeOplogQueryMetadata(syncSourceOpTime),
                                                        now()));
-    ASSERT_FALSE(getTopoCoord().shouldChangeSyncSource(
-        HostAndPort("host2"), makeReplSetMetadata(syncSourceOpTime), boost::none, now()));
 
     // unblacklist and it should succeed
     getTopoCoord().unblacklistSyncSource(HostAndPort("host3"), now() + Milliseconds(100));
@@ -4265,12 +4234,6 @@ TEST_F(HeartbeatResponseTestV1, ShouldNotChangeSyncSourceWhileFresherMemberIsBla
                                                       now()));
     stopCapturingLogMessages();
     ASSERT_EQUALS(1, countLogLinesContaining("Choosing new sync source"));
-
-    startCapturingLogMessages();
-    ASSERT_TRUE(getTopoCoord().shouldChangeSyncSource(
-        HostAndPort("host2"), makeReplSetMetadata(syncSourceOpTime), boost::none, now()));
-    stopCapturingLogMessages();
-    ASSERT_EQUALS(1, countLogLinesContaining("Choosing new sync source"));
 }
 
 TEST_F(HeartbeatResponseTestV1, ShouldNotChangeSyncSourceIfNodeIsFreshByHeartbeatButNotMetadata) {
@@ -4299,12 +4262,6 @@ TEST_F(HeartbeatResponseTestV1, ShouldNotChangeSyncSourceIfNodeIsFreshByHeartbea
                                                        now()));
     stopCapturingLogMessages();
     ASSERT_EQUALS(0, countLogLinesContaining("Choosing new sync source"));
-
-    startCapturingLogMessages();
-    ASSERT_FALSE(getTopoCoord().shouldChangeSyncSource(
-        HostAndPort("host2"), makeReplSetMetadata(lastOpTimeApplied), boost::none, now()));
-    stopCapturingLogMessages();
-    ASSERT_EQUALS(0, countLogLinesContaining("Choosing new sync source"));
 }
 
 TEST_F(HeartbeatResponseTestV1, ShouldNotChangeSyncSourceIfNodeIsStaleByHeartbeatButNotMetadata) {
@@ -4334,12 +4291,6 @@ TEST_F(HeartbeatResponseTestV1, ShouldNotChangeSyncSourceIfNodeIsStaleByHeartbea
                                               now()));
     stopCapturingLogMessages();
     ASSERT_EQUALS(0, countLogLinesContaining("Choosing new sync source"));
-    // set up complete, time for actual check
-    startCapturingLogMessages();
-    ASSERT_FALSE(getTopoCoord().shouldChangeSyncSource(
-        HostAndPort("host2"), makeReplSetMetadata(fresherLastOpTimeApplied), boost::none, now()));
-    stopCapturingLogMessages();
-    ASSERT_EQUALS(0, countLogLinesContaining("Choosing new sync source"));
 }
 
 TEST_F(HeartbeatResponseTestV1, ShouldChangeSyncSourceWhenFresherMemberExists) {
@@ -4367,20 +4318,16 @@ TEST_F(HeartbeatResponseTestV1, ShouldChangeSyncSourceWhenFresherMemberExists) {
                                                       now()));
     stopCapturingLogMessages();
     ASSERT_EQUALS(1, countLogLinesContaining("Choosing new sync source"));
-
-    // set up complete, time for actual check
-    startCapturingLogMessages();
-    ASSERT_TRUE(getTopoCoord().shouldChangeSyncSource(
-        HostAndPort("host2"), makeReplSetMetadata(lastOpTimeApplied), boost::none, now()));
-    stopCapturingLogMessages();
-    ASSERT_EQUALS(1, countLogLinesContaining("Choosing new sync source"));
 }
 
 TEST_F(HeartbeatResponseTestV1, ShouldNotChangeSyncSourceWhenMemberHasYetToHeartbeatUs) {
     // In this test, the TopologyCoordinator should not tell us to change sync sources away from
     // "host2" since we do not use the member's heartbeatdata in pv1.
-    ASSERT_FALSE(getTopoCoord().shouldChangeSyncSource(
-        HostAndPort("host2"), makeReplSetMetadata(), makeOplogQueryMetadata(), now()));
+    OpTime lastOpTimeApplied = OpTime(Timestamp(4, 0), 0);
+    ASSERT_FALSE(getTopoCoord().shouldChangeSyncSource(HostAndPort("host2"),
+                                                       makeReplSetMetadata(),
+                                                       makeOplogQueryMetadata(lastOpTimeApplied),
+                                                       now()));
 }
 
 TEST_F(HeartbeatResponseTestV1, ShouldNotChangeSyncSourceWhenMemberNotInConfig) {
@@ -6870,9 +6817,6 @@ TEST_F(HeartbeatResponseTestV1, ShouldNotChangeSyncSourceWhenFresherMemberDoesNo
                                                        makeReplSetMetadata(),
                                                        makeOplogQueryMetadata(syncSourceOpTime),
                                                        now()));
-    // set up complete, time for actual check
-    ASSERT_FALSE(getTopoCoord().shouldChangeSyncSource(
-        HostAndPort("host2"), makeReplSetMetadata(syncSourceOpTime), boost::none, now()));
 }
 
 TEST_F(HeartbeatResponseTestV1, ShouldNotChangeSyncSourceWhenFresherMemberIsNotReadable) {
@@ -6901,10 +6845,6 @@ TEST_F(HeartbeatResponseTestV1, ShouldNotChangeSyncSourceWhenFresherMemberIsNotR
                                                        makeReplSetMetadata(),
                                                        makeOplogQueryMetadata(syncSourceOpTime),
                                                        now()));
-
-    // set up complete, time for actual check
-    ASSERT_FALSE(getTopoCoord().shouldChangeSyncSource(
-        HostAndPort("host2"), makeReplSetMetadata(syncSourceOpTime), boost::none, now()));
 }
 
 TEST_F(HeartbeatResponseTestV1, ShouldNotChangeSyncSourceIfSyncSourceHasDifferentConfigVersion) {
@@ -6938,11 +6878,6 @@ TEST_F(HeartbeatResponseTestV1, ShouldNotChangeSyncSourceIfSyncSourceHasDifferen
         makeReplSetMetadata(OpTime(), -1, -1, 8 /* different config version */),
         makeOplogQueryMetadata(syncSourceOpTime),
         now()));
-    ASSERT_FALSE(
-        getTopoCoord().shouldChangeSyncSource(HostAndPort("host2"),
-                                              makeReplSetMetadata(syncSourceOpTime, -1, -1, 8),
-                                              boost::none,
-                                              now()));
 }
 
 class HeartbeatResponseTestOneRetryV1 : public HeartbeatResponseTestV1 {