SERVER-50492 Split BaseCloner into InitialSyncBaseCloner and TenantMigrationBaseCloner

20 files changed, 476 insertions, 248 deletions

diff --git a/jstests/replsets/initial_sync_rename_collection.js b/jstests/replsets/initial_sync_rename_collection.js
index 82576400c60..d571e83c869 100644
--- a/jstests/replsets/initial_sync_rename_collection.js
+++ b/jstests/replsets/initial_sync_rename_collection.js
@@ -161,8 +161,8 @@ runRenameTest({
 });
 
 const expectedLogFor5and7 = isJsonLogNoConn()
-    ? '`Initial Sync retrying cloner stage due to error","attr":{"cloner":"CollectionCloner","stage":"query","error":{"code":175,"codeName":"QueryPlanKilled","errmsg":"collection renamed from \'${nss}\' to \'${rnss}\'. UUID ${uuid}"}}}`'
-    : "`Initial Sync retrying CollectionCloner stage query due to QueryPlanKilled: collection renamed from '${nss}' to '${rnss}'. UUID ${uuid}`";
+    ? '`Sync process retrying cloner stage due to error","attr":{"cloner":"CollectionCloner","stage":"query","error":{"code":175,"codeName":"QueryPlanKilled","errmsg":"collection renamed from \'${nss}\' to \'${rnss}\'. UUID ${uuid}"}}}`'
+    : "`Sync process retrying CollectionCloner stage query due to QueryPlanKilled: collection renamed from '${nss}' to '${rnss}'. UUID ${uuid}`";
 
 jsTestLog("[5] Testing rename between getMores.");
 runRenameTest({
@@ -188,10 +188,10 @@ if (isJsonLogNoConn()) {
 if (TwoPhaseDropCollectionTest.supportsDropPendingNamespaces(replTest)) {
     if (isJsonLogNoConn()) {
         expectedLogFor6and8 =
-            '`Initial Sync retrying cloner stage due to error","attr":{"cloner":"CollectionCloner","stage":"query","error":{"code":175,"codeName":"QueryPlanKilled","errmsg":"collection renamed from \'${nss}\' to \'${dropPendingNss}\'. UUID ${uuid}`';
+            '`Sync process retrying cloner stage due to error","attr":{"cloner":"CollectionCloner","stage":"query","error":{"code":175,"codeName":"QueryPlanKilled","errmsg":"collection renamed from \'${nss}\' to \'${dropPendingNss}\'. UUID ${uuid}`';
     } else {
         expectedLogFor6and8 =
-            "`Initial Sync retrying CollectionCloner stage query due to QueryPlanKilled: collection renamed from '${nss}' to '${dropPendingNss}'. UUID ${uuid}`";
+            "`Sync process retrying CollectionCloner stage query due to QueryPlanKilled: collection renamed from '${nss}' to '${dropPendingNss}'. UUID ${uuid}`";
     }
 }
 
diff --git a/src/mongo/db/repl/SConscript b/src/mongo/db/repl/SConscript
index 479434c95a5..6bb2fc91044 100644
--- a/src/mongo/db/repl/SConscript
+++ b/src/mongo/db/repl/SConscript
@@ -982,6 +982,7 @@ env.Library(
         'all_database_cloner.cpp',
         'collection_cloner.cpp',
         'database_cloner.cpp',
+        'initial_sync_base_cloner.cpp',
     ],
     LIBDEPS = [
         '$BUILD_DIR/mongo/base',
@@ -1011,6 +1012,7 @@ env.Library(
         'tenant_all_database_cloner.cpp',
         'tenant_collection_cloner.cpp',
         'tenant_database_cloner.cpp',
+        'tenant_migration_base_cloner.cpp',
     ],
     LIBDEPS = [
         '$BUILD_DIR/mongo/base',
diff --git a/src/mongo/db/repl/all_database_cloner.cpp b/src/mongo/db/repl/all_database_cloner.cpp
index 527f7a64837..1e961f306d1 100644
--- a/src/mongo/db/repl/all_database_cloner.cpp
+++ b/src/mongo/db/repl/all_database_cloner.cpp
@@ -47,7 +47,8 @@ AllDatabaseCloner::AllDatabaseCloner(InitialSyncSharedData* sharedData,
                                      DBClientConnection* client,
                                      StorageInterface* storageInterface,
                                      ThreadPool* dbPool)
-    : BaseCloner("AllDatabaseCloner"_sd, sharedData, source, client, storageInterface, dbPool),
+    : InitialSyncBaseCloner(
+          "AllDatabaseCloner"_sd, sharedData, source, client, storageInterface, dbPool),
       _connectStage("connect", this, &AllDatabaseCloner::connectStage),
       _getInitialSyncIdStage("getInitialSyncId", this, &AllDatabaseCloner::getInitialSyncIdStage),
       _listDatabasesStage("listDatabases", this, &AllDatabaseCloner::listDatabasesStage) {}
diff --git a/src/mongo/db/repl/all_database_cloner.h b/src/mongo/db/repl/all_database_cloner.h
index 434a5e189b0..c6a9f9f126c 100644
--- a/src/mongo/db/repl/all_database_cloner.h
+++ b/src/mongo/db/repl/all_database_cloner.h
@@ -31,15 +31,15 @@
 
 #include <vector>
 
-#include "mongo/base/checked_cast.h"
 #include "mongo/db/repl/base_cloner.h"
 #include "mongo/db/repl/database_cloner.h"
+#include "mongo/db/repl/initial_sync_base_cloner.h"
 #include "mongo/db/repl/initial_sync_shared_data.h"
 
 namespace mongo {
 namespace repl {
 
-class AllDatabaseCloner final : public BaseCloner {
+class AllDatabaseCloner final : public InitialSyncBaseCloner {
 public:
     struct Stats {
         size_t databasesCloned{0};
@@ -65,10 +65,6 @@ public:
 protected:
     ClonerStages getStages() final;
 
-    InitialSyncSharedData* getSharedData() const final {
-        return checked_cast<InitialSyncSharedData*>(BaseCloner::getSharedData());
-    }
-
 private:
     friend class AllDatabaseClonerTest;
     class ConnectStage : public ClonerStage<AllDatabaseCloner> {
diff --git a/src/mongo/db/repl/base_cloner.cpp b/src/mongo/db/repl/base_cloner.cpp
index 521fcf05e3c..271b950c865 100644
--- a/src/mongo/db/repl/base_cloner.cpp
+++ b/src/mongo/db/repl/base_cloner.cpp
@@ -32,8 +32,6 @@
 #include "mongo/platform/basic.h"
 
 #include "mongo/db/repl/base_cloner.h"
-#include "mongo/db/repl/replication_consistency_markers_gen.h"
-#include "mongo/db/repl/replication_consistency_markers_impl.h"
 #include "mongo/logv2/log.h"
 #include "mongo/util/scopeguard.h"
 
@@ -41,15 +39,11 @@ namespace mongo {
 namespace {
 MONGO_FAIL_POINT_DEFINE(hangBeforeClonerStage);
 MONGO_FAIL_POINT_DEFINE(hangBeforeRetryingClonerStage);
-MONGO_FAIL_POINT_DEFINE(hangBeforeCheckingRollBackIdClonerStage);
 MONGO_FAIL_POINT_DEFINE(hangAfterClonerStage);
 }  // namespace
 using executor::TaskExecutor;
 
 namespace repl {
-// These failpoints are shared with initial_syncer and so must not be in the unnamed namespace.
-MONGO_FAIL_POINT_DEFINE(initialSyncFuzzerSynchronizationPoint1);
-MONGO_FAIL_POINT_DEFINE(initialSyncFuzzerSynchronizationPoint2);
 
 BaseCloner::BaseCloner(StringData clonerName,
                        ReplSyncSharedData* sharedData,
@@ -106,36 +100,6 @@ bool BaseCloner::isMyFailPoint(const BSONObj& data) const {
     return data["cloner"].str() == getClonerName();
 }
 
-void BaseCloner::pauseForFuzzer(BaseClonerStage* stage) {
-    // These are the stages that the initial sync fuzzer expects to be able to pause on using the
-    // syncronization fail points.
-    static const auto initialSyncPauseStages =
-        std::vector<std::string>{"listCollections", "listIndexes", "listDatabases"};
-
-    if (MONGO_unlikely(initialSyncFuzzerSynchronizationPoint1.shouldFail())) {
-        if (std::find(initialSyncPauseStages.begin(),
-                      initialSyncPauseStages.end(),
-                      stage->getName()) != initialSyncPauseStages.end()) {
-            // These failpoints are set and unset by the InitialSyncTest fixture to cause initial
-            // sync to pause so that the Initial Sync Fuzzer can run commands on the sync source.
-            // nb: This log message is specifically checked for in
-            // initial_sync_test_fixture_test.js, so if you change it here you will need to change
-            // it there.
-            LOGV2(21066,
-                  "Collection Cloner scheduled a remote command on the {stage}",
-                  "Collection Cloner scheduled a remote command",
-                  "stage"_attr = describeForFuzzer(stage));
-            LOGV2(21067, "initialSyncFuzzerSynchronizationPoint1 fail point enabled");
-            initialSyncFuzzerSynchronizationPoint1.pauseWhileSet();
-
-            if (MONGO_unlikely(initialSyncFuzzerSynchronizationPoint2.shouldFail())) {
-                LOGV2(21068, "initialSyncFuzzerSynchronizationPoint2 fail point enabled");
-                initialSyncFuzzerSynchronizationPoint2.pauseWhileSet();
-            }
-        }
-    }
-}
-
 BaseCloner::AfterStageBehavior BaseCloner::runStage(BaseClonerStage* stage) {
     LOGV2_DEBUG(21069,
                 1,
@@ -181,81 +145,6 @@ BaseCloner::AfterStageBehavior BaseCloner::runStage(BaseClonerStage* stage) {
     return afterStageBehavior;
 }
 
-void BaseCloner::clearRetryingState() {
-    _retryableOp = boost::none;
-}
-
-Status BaseCloner::checkSyncSourceIsStillValid() {
-    WireVersion wireVersion;
-    {
-        stdx::lock_guard<ReplSyncSharedData> lk(*_sharedData);
-        auto wireVersionOpt = _sharedData->getSyncSourceWireVersion(lk);
-        // The wire version should always have been set by the time this is called.
-        invariant(wireVersionOpt);
-        wireVersion = *wireVersionOpt;
-    }
-    if (wireVersion >= WireVersion::RESUMABLE_INITIAL_SYNC) {
-        auto status = checkInitialSyncIdIsUnchanged();
-        if (!status.isOK())
-            return status;
-    }
-    return checkRollBackIdIsUnchanged();
-}
-
-Status BaseCloner::checkInitialSyncIdIsUnchanged() {
-    uassert(ErrorCodes::InitialSyncFailure,
-            "Sync source was downgraded and no longer supports resumable initial sync",
-            getClient()->getMaxWireVersion() >= WireVersion::RESUMABLE_INITIAL_SYNC);
-    BSONObj initialSyncId;
-    try {
-        initialSyncId = getClient()->findOne(
-            ReplicationConsistencyMarkersImpl::kDefaultInitialSyncIdNamespace.toString(), Query());
-    } catch (DBException& e) {
-        if (ErrorCodes::isRetriableError(e)) {
-            auto status = e.toStatus().withContext(
-                ": failed while attempting to retrieve initial sync ID after re-connect");
-            LOGV2_DEBUG(
-                4608505, 1, "Retrieving Initial Sync ID retriable error", "error"_attr = status);
-            return status;
-        }
-        throw;
-    }
-    uassert(ErrorCodes::InitialSyncFailure,
-            "Cannot retrieve sync source initial sync ID",
-            !initialSyncId.isEmpty());
-    InitialSyncIdDocument initialSyncIdDoc =
-        InitialSyncIdDocument::parse(IDLParserErrorContext("initialSyncId"), initialSyncId);
-
-    stdx::lock_guard<ReplSyncSharedData> lk(*_sharedData);
-    uassert(ErrorCodes::InitialSyncFailure,
-            "Sync source has been resynced since we started syncing from it",
-            _sharedData->getInitialSyncSourceId(lk) == initialSyncIdDoc.get_id());
-    return Status::OK();
-}
-
-Status BaseCloner::checkRollBackIdIsUnchanged() {
-    BSONObj info;
-    try {
-        getClient()->simpleCommand("admin", &info, "replSetGetRBID");
-    } catch (DBException& e) {
-        if (ErrorCodes::isRetriableError(e)) {
-            static constexpr char errorMsg[] =
-                "Failed while attempting to retrieve rollBackId after re-connect";
-            LOGV2_DEBUG(21073, 1, errorMsg, "error"_attr = e);
-            return e.toStatus().withContext(errorMsg);
-        }
-        throw;
-    }
-    uassert(
-        31298, "Sync source returned invalid result from replSetGetRBID", info["rbid"].isNumber());
-    auto rollBackId = info["rbid"].numberInt();
-    uassert(ErrorCodes::UnrecoverableRollbackError,
-            str::stream() << "Rollback occurred on our sync source " << getSource()
-                          << " during initial sync",
-            rollBackId == _sharedData->getRollBackId());
-    return Status::OK();
-}
-
 BaseCloner::AfterStageBehavior BaseCloner::runStageWithRetries(BaseClonerStage* stage) {
     ON_BLOCK_EXIT([this] { clearRetryingState(); });
     Status lastError = Status::OK();
@@ -283,48 +172,14 @@ BaseCloner::AfterStageBehavior BaseCloner::runStageWithRetries(BaseClonerStage*
                     },
                     isThisStageFailPoint);
                 LOGV2(21075,
-                      "Initial Sync retrying {cloner} stage {stage} due to "
+                      "Sync process retrying {cloner} stage {stage} due to "
                       "{error}",
-                      "Initial Sync retrying cloner stage due to error",
+                      "Sync process retrying cloner stage due to error",
                       "cloner"_attr = getClonerName(),
                       "stage"_attr = stage->getName(),
                       "error"_attr = lastError);
-                bool shouldRetry = [&] {
-                    stdx::lock_guard<ReplSyncSharedData> lk(*_sharedData);
-                    return _sharedData->shouldRetryOperation(lk, &_retryableOp);
-                }();
-                if (!shouldRetry) {
-                    auto status = lastError.withContext(
-                        str::stream() << ": Exceeded initialSyncTransientErrorRetryPeriodSeconds "
-                                      << _sharedData->getAllowedOutageDuration(
-                                             stdx::lock_guard<ReplSyncSharedData>(*_sharedData)));
-                    setSyncFailedStatus(status);
-                    uassertStatusOK(status);
-                }
-                hangBeforeCheckingRollBackIdClonerStage.executeIf(
-                    [&](const BSONObj& data) {
-                        LOGV2(21076,
-                              "Cloner {cloner} hanging before checking rollBackId for stage "
-                              "{stage}",
-                              "Cloner hanging before checking rollBackId",
-                              "cloner"_attr = getClonerName(),
-                              "stage"_attr = stage->getName());
-                        while (!mustExit() &&
-                               hangBeforeCheckingRollBackIdClonerStage.shouldFail(
-                                   isThisStageFailPoint)) {
-                            sleepmillis(100);
-                        }
-                    },
-                    isThisStageFailPoint);
-                if (stage->checkSyncSourceValidityOnRetry()) {
-                    // If checkSyncSourceIsStillValid fails without throwing, it means a network
-                    // error occurred and it's safe to continue (which will cause another retry).
-                    if (!checkSyncSourceIsStillValid().isOK())
-                        continue;
-                    // After successfully checking the sync source validity, the client should
-                    // always be OK.
-                    invariant(!getClient()->isFailed());
-                }
+                // Execute any per-retry logic needed by the cloner.
+                handleStageAttemptFailed(stage, lastError);
             }
             return stage->run();
         } catch (DBException& e) {
diff --git a/src/mongo/db/repl/base_cloner.h b/src/mongo/db/repl/base_cloner.h
index f20eac12433..4ff4a5f7346 100644
--- a/src/mongo/db/repl/base_cloner.h
+++ b/src/mongo/db/repl/base_cloner.h
@@ -59,7 +59,7 @@ public:
     /**
      * run() catches all database exceptions and stores them in _status, to simplify error
      * handling in the caller above.  It returns its own _status if that is not OK, otherwise
-     * the shared initial sync status.
+     * the shared sync status.
      */
     Status run();
 
@@ -97,7 +97,7 @@ protected:
     // isTransientError() method determines whether the exception is retryable or not; usually
     // network errors will be retryable and other errors will not.  If the error is retryable,
     // the BaseCloner framework will attempt to reconnect the client and run the stage again.  If
-    // it is not, the exception will be propagated up and fail the initial sync attempt entirely.
+    // it is not, the exception will be propagated up and fail the sync attempt entirely.
     class BaseClonerStage {
     public:
         BaseClonerStage(std::string name) : _name(name){};
@@ -201,7 +201,7 @@ protected:
     void setSyncFailedStatus(Status status);
 
     /**
-     * Takes the initial sync status lock and checks the initial sync status.
+     * Takes the sync status lock and checks the sync status.
      * Used to make sure failpoints exit on process shutdown.
      */
     bool mustExit();
@@ -210,54 +210,52 @@ protected:
      * A stage may, but is not required, to call this when we should clear the retrying state
      * because the operation has at least partially succeeded.  If the stage does not call this,
      * the retrying state is cleared upon successful completion of the entire stage.
+     *
+     * Left blank here but may be overriden.
      */
-    void clearRetryingState();
-
-private:
-    virtual ClonerStages getStages() = 0;
+    virtual void clearRetryingState() {}
 
     /**
-     * Code to be run before and after the stages respectively.  This code is not subject to the
-     * retry logic used in the cloner stages.
+     * Called every time the base cloner receives an error from a stage. Use this to
+     * execute any cloner-specific logic such as evaluating retry eligibility, running
+     * checks on the sync source, etc.
+     *
+     * Left blank here but may be overriden.
      */
-    virtual void preStage() {}
-    virtual void postStage() {}
-
-    AfterStageBehavior runStage(BaseClonerStage* stage);
-
-    AfterStageBehavior runStageWithRetries(BaseClonerStage* stage);
+    virtual void handleStageAttemptFailed(BaseClonerStage* stage, Status lastError) {}
 
     /**
-     * Make sure the initial sync ID on the sync source has not changed.  Throws an exception
-     * if it has.  Returns a not-OK status if a network error occurs.
+     * Supports pausing at certain stages for a fuzzer test framework.
+     *
+     * Left blank but may be overriden.
      */
-    Status checkInitialSyncIdIsUnchanged();
+    virtual void pauseForFuzzer(BaseClonerStage* stage) {}
 
     /**
-     * Make sure the rollback ID has not changed.  Throws an exception if it has.  Returns
-     * a not-OK status if a network error occurs.
+     * Provides part of a log message for the sync process describing the namespace the
+     * cloner is operating on.  It must start with the database name, followed by the
+     * string ' db: { ', followed by the stage name, followed by ': ' and the collection UUID
+     * if known.
+     *
+     * Left blank but may be overriden.
      */
-    Status checkRollBackIdIsUnchanged();
+    virtual std::string describeForFuzzer(BaseClonerStage*) const {
+        return "";
+    }
 
-    /**
-     * Does validity checks on the sync source.  If the sync source is now no longer usable,
-     * throws an exception. Returns a not-OK status if a network error occurs or if the sync
-     * source is temporarily unusable (e.g. restarting).
-     */
-    Status checkSyncSourceIsStillValid();
+private:
+    virtual ClonerStages getStages() = 0;
 
     /**
-     * Supports pausing at certain stages for the initial sync fuzzer test framework.
+     * Code to be run before and after the stages respectively.  This code is not subject to the
+     * retry logic used in the cloner stages.
      */
-    void pauseForFuzzer(BaseClonerStage* stage);
+    virtual void preStage() {}
+    virtual void postStage() {}
 
-    /**
-     * Provides part of a log message for the initial sync describing the namespace the
-     * cloner is operating on.  It must start with the database name, followed by the
-     * string ' db: { ', followed by the stage name, followed by ': ' and the collection UUID
-     * if known.
-     */
-    virtual std::string describeForFuzzer(BaseClonerStage*) const = 0;
+    AfterStageBehavior runStage(BaseClonerStage* stage);
+
+    AfterStageBehavior runStageWithRetries(BaseClonerStage* stage);
 
     AfterStageBehavior runStages();
 
@@ -287,9 +285,6 @@ private:
     // _stopAfterStage is used for unit testing and causes the cloner to exit after a given
     // stage.
     std::string _stopAfterStage;  // (X)
-
-    // Operation that may currently be retrying.
-    ReplSyncSharedData::RetryableOperation _retryableOp;  // (X)
 };
 
 }  // namespace repl
diff --git a/src/mongo/db/repl/collection_cloner.cpp b/src/mongo/db/repl/collection_cloner.cpp
index f5d4c6a0847..77a37ee1a38 100644
--- a/src/mongo/db/repl/collection_cloner.cpp
+++ b/src/mongo/db/repl/collection_cloner.cpp
@@ -61,7 +61,8 @@ CollectionCloner::CollectionCloner(const NamespaceString& sourceNss,
                                    DBClientConnection* client,
                                    StorageInterface* storageInterface,
                                    ThreadPool* dbPool)
-    : BaseCloner("CollectionCloner"_sd, sharedData, source, client, storageInterface, dbPool),
+    : InitialSyncBaseCloner(
+          "CollectionCloner"_sd, sharedData, source, client, storageInterface, dbPool),
       _sourceNss(sourceNss),
       _collectionOptions(collectionOptions),
       _sourceDbAndUuid(NamespaceString("UNINITIALIZED")),
diff --git a/src/mongo/db/repl/collection_cloner.h b/src/mongo/db/repl/collection_cloner.h
index 8c171c4021a..7a2033d0192 100644
--- a/src/mongo/db/repl/collection_cloner.h
+++ b/src/mongo/db/repl/collection_cloner.h
@@ -32,8 +32,8 @@
 #include <memory>
 #include <vector>
 
-#include "mongo/base/checked_cast.h"
 #include "mongo/db/repl/base_cloner.h"
+#include "mongo/db/repl/initial_sync_base_cloner.h"
 #include "mongo/db/repl/initial_sync_shared_data.h"
 #include "mongo/db/repl/task_runner.h"
 #include "mongo/util/progress_meter.h"
@@ -46,7 +46,7 @@ const int kProgressMeterSecondsBetween = 60;
 const int kProgressMeterCheckInterval = 128;
 }  // namespace
 
-class CollectionCloner final : public BaseCloner {
+class CollectionCloner final : public InitialSyncBaseCloner {
 public:
     struct Stats {
         static constexpr StringData kDocumentsToCopyFieldName = "documentsToCopy"_sd;
@@ -124,10 +124,6 @@ protected:
 
     bool isMyFailPoint(const BSONObj& data) const final;
 
-    InitialSyncSharedData* getSharedData() const override {
-        return checked_cast<InitialSyncSharedData*>(BaseCloner::getSharedData());
-    }
-
 private:
     friend class CollectionClonerTest;
 
diff --git a/src/mongo/db/repl/database_cloner.cpp b/src/mongo/db/repl/database_cloner.cpp
index 26c0bcb2a40..3686d5a2cb1 100644
--- a/src/mongo/db/repl/database_cloner.cpp
+++ b/src/mongo/db/repl/database_cloner.cpp
@@ -48,7 +48,8 @@ DatabaseCloner::DatabaseCloner(const std::string& dbName,
                                DBClientConnection* client,
                                StorageInterface* storageInterface,
                                ThreadPool* dbPool)
-    : BaseCloner("DatabaseCloner"_sd, sharedData, source, client, storageInterface, dbPool),
+    : InitialSyncBaseCloner(
+          "DatabaseCloner"_sd, sharedData, source, client, storageInterface, dbPool),
       _dbName(dbName),
       _listCollectionsStage("listCollections", this, &DatabaseCloner::listCollectionsStage) {
     invariant(!dbName.empty());
diff --git a/src/mongo/db/repl/database_cloner.h b/src/mongo/db/repl/database_cloner.h
index e1787ad7a5e..c172c80876a 100644
--- a/src/mongo/db/repl/database_cloner.h
+++ b/src/mongo/db/repl/database_cloner.h
@@ -31,15 +31,15 @@
 
 #include <vector>
 
-#include "mongo/base/checked_cast.h"
 #include "mongo/db/repl/base_cloner.h"
 #include "mongo/db/repl/collection_cloner.h"
+#include "mongo/db/repl/initial_sync_base_cloner.h"
 #include "mongo/db/repl/initial_sync_shared_data.h"
 
 namespace mongo {
 namespace repl {
 
-class DatabaseCloner final : public BaseCloner {
+class DatabaseCloner final : public InitialSyncBaseCloner {
 public:
     struct Stats {
         std::string dbname;
@@ -74,11 +74,6 @@ protected:
 
     bool isMyFailPoint(const BSONObj& data) const final;
 
-    InitialSyncSharedData* getSharedData() const override {
-        return checked_cast<InitialSyncSharedData*>(BaseCloner::getSharedData());
-    }
-
-
 private:
     friend class DatabaseClonerTest;
 
diff --git a/src/mongo/db/repl/initial_sync_base_cloner.cpp b/src/mongo/db/repl/initial_sync_base_cloner.cpp
new file mode 100644
index 00000000000..2840191d985
--- /dev/null
+++ b/src/mongo/db/repl/initial_sync_base_cloner.cpp
@@ -0,0 +1,209 @@
+/**
+ *    Copyright (C) 2020-present MongoDB, Inc.
+ *
+ *    This program is free software: you can redistribute it and/or modify
+ *    it under the terms of the Server Side Public License, version 1,
+ *    as published by MongoDB, Inc.
+ *
+ *    This program is distributed in the hope that it will be useful,
+ *    but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *    Server Side Public License for more details.
+ *
+ *    You should have received a copy of the Server Side Public License
+ *    along with this program. If not, see
+ *    <http://www.mongodb.com/licensing/server-side-public-license>.
+ *
+ *    As a special exception, the copyright holders give permission to link the
+ *    code of portions of this program with the OpenSSL library under certain
+ *    conditions as described in each individual source file and distribute
+ *    linked combinations including the program with the OpenSSL library. You
+ *    must comply with the Server Side Public License in all respects for
+ *    all of the code used other than as permitted herein. If you modify file(s)
+ *    with this exception, you may extend this exception to your version of the
+ *    file(s), but you are not obligated to do so. If you do not wish to do so,
+ *    delete this exception statement from your version. If you delete this
+ *    exception statement from all source files in the program, then also delete
+ *    it in the license file.
+ */
+
+#define MONGO_LOGV2_DEFAULT_COMPONENT ::mongo::logv2::LogComponent::kReplicationInitialSync
+
+#include "mongo/platform/basic.h"
+
+#include "mongo/db/repl/initial_sync_base_cloner.h"
+#include "mongo/db/repl/replication_consistency_markers_gen.h"
+#include "mongo/db/repl/replication_consistency_markers_impl.h"
+#include "mongo/logv2/log.h"
+
+namespace mongo {
+namespace {
+MONGO_FAIL_POINT_DEFINE(hangBeforeCheckingRollBackIdClonerStage);
+}  // namespace
+namespace repl {
+
+// These failpoints are shared with initial_syncer and so must not be in the unnamed namespace.
+MONGO_FAIL_POINT_DEFINE(initialSyncFuzzerSynchronizationPoint1);
+MONGO_FAIL_POINT_DEFINE(initialSyncFuzzerSynchronizationPoint2);
+
+InitialSyncBaseCloner::InitialSyncBaseCloner(StringData clonerName,
+                                             InitialSyncSharedData* sharedData,
+                                             const HostAndPort& source,
+                                             DBClientConnection* client,
+                                             StorageInterface* storageInterface,
+                                             ThreadPool* dbPool)
+    : BaseCloner(clonerName, sharedData, source, client, storageInterface, dbPool) {}
+
+void InitialSyncBaseCloner::clearRetryingState() {
+    _retryableOp = boost::none;
+}
+
+void InitialSyncBaseCloner::handleStageAttemptFailed(BaseClonerStage* stage, Status lastError) {
+    auto isThisStageFailPoint = [this, stage](const BSONObj& data) {
+        return data["stage"].str() == stage->getName() && isMyFailPoint(data);
+    };
+
+    bool shouldRetry = [&] {
+        stdx::lock_guard<InitialSyncSharedData> lk(*getSharedData());
+        return getSharedData()->shouldRetryOperation(lk, &_retryableOp);
+    }();
+    if (!shouldRetry) {
+        auto status = lastError.withContext(
+            str::stream() << ": Exceeded initialSyncTransientErrorRetryPeriodSeconds "
+                          << getSharedData()->getAllowedOutageDuration(
+                                 stdx::lock_guard<InitialSyncSharedData>(*getSharedData())));
+        setSyncFailedStatus(status);
+        uassertStatusOK(status);
+    }
+    hangBeforeCheckingRollBackIdClonerStage.executeIf(
+        [&](const BSONObj& data) {
+            LOGV2(21076,
+                  "Initial sync cloner {cloner} hanging before checking rollBackId for stage "
+                  "{stage}",
+                  "Initial sync cloner hanging before checking rollBackId",
+                  "cloner"_attr = getClonerName(),
+                  "stage"_attr = stage->getName());
+            while (!mustExit() &&
+                   hangBeforeCheckingRollBackIdClonerStage.shouldFail(isThisStageFailPoint)) {
+                sleepmillis(100);
+            }
+        },
+        isThisStageFailPoint);
+
+    // This includes checking the sync source member state, checking the rollback ID,
+    // and checking the sync source initial sync ID.
+    if (stage->checkSyncSourceValidityOnRetry()) {
+        // If checkSyncSourceIsStillValid fails without throwing, it means a network
+        // error occurred and it's safe to continue (which will cause another retry).
+        if (!checkSyncSourceIsStillValid().isOK())
+            return;
+        // After successfully checking the sync source validity, the client should
+        // always be OK.
+        invariant(!getClient()->isFailed());
+    }
+}
+
+Status InitialSyncBaseCloner::checkSyncSourceIsStillValid() {
+
+    WireVersion wireVersion;
+    {
+        stdx::lock_guard<ReplSyncSharedData> lk(*getSharedData());
+        auto wireVersionOpt = getSharedData()->getSyncSourceWireVersion(lk);
+        // The wire version should always have been set by the time this is called.
+        invariant(wireVersionOpt);
+        wireVersion = *wireVersionOpt;
+    }
+    if (wireVersion >= WireVersion::RESUMABLE_INITIAL_SYNC) {
+        auto status = checkInitialSyncIdIsUnchanged();
+        if (!status.isOK())
+            return status;
+    }
+    return checkRollBackIdIsUnchanged();
+}
+
+Status InitialSyncBaseCloner::checkInitialSyncIdIsUnchanged() {
+    uassert(ErrorCodes::InitialSyncFailure,
+            "Sync source was downgraded and no longer supports resumable initial sync",
+            getClient()->getMaxWireVersion() >= WireVersion::RESUMABLE_INITIAL_SYNC);
+    BSONObj initialSyncId;
+    try {
+        initialSyncId = getClient()->findOne(
+            ReplicationConsistencyMarkersImpl::kDefaultInitialSyncIdNamespace.toString(), Query());
+    } catch (DBException& e) {
+        if (ErrorCodes::isRetriableError(e)) {
+            auto status = e.toStatus().withContext(
+                ": failed while attempting to retrieve initial sync ID after re-connect");
+            LOGV2_DEBUG(
+                4608505, 1, "Retrieving Initial Sync ID retriable error", "error"_attr = status);
+            return status;
+        }
+        throw;
+    }
+    uassert(ErrorCodes::InitialSyncFailure,
+            "Cannot retrieve sync source initial sync ID",
+            !initialSyncId.isEmpty());
+    InitialSyncIdDocument initialSyncIdDoc =
+        InitialSyncIdDocument::parse(IDLParserErrorContext("initialSyncId"), initialSyncId);
+
+    stdx::lock_guard<ReplSyncSharedData> lk(*getSharedData());
+    uassert(ErrorCodes::InitialSyncFailure,
+            "Sync source has been resynced since we started syncing from it",
+            getSharedData()->getInitialSyncSourceId(lk) == initialSyncIdDoc.get_id());
+    return Status::OK();
+}
+
+Status InitialSyncBaseCloner::checkRollBackIdIsUnchanged() {
+    BSONObj info;
+    try {
+        getClient()->simpleCommand("admin", &info, "replSetGetRBID");
+    } catch (DBException& e) {
+        if (ErrorCodes::isRetriableError(e)) {
+            static constexpr char errorMsg[] =
+                "Failed while attempting to retrieve rollBackId after re-connect";
+            LOGV2_DEBUG(21073, 1, errorMsg, "error"_attr = e);
+            return e.toStatus().withContext(errorMsg);
+        }
+        throw;
+    }
+    uassert(
+        31298, "Sync source returned invalid result from replSetGetRBID", info["rbid"].isNumber());
+    auto rollBackId = info["rbid"].numberInt();
+    uassert(ErrorCodes::UnrecoverableRollbackError,
+            str::stream() << "Rollback occurred on our sync source " << getSource()
+                          << " during initial sync",
+            rollBackId == getSharedData()->getRollBackId());
+    return Status::OK();
+}
+
+void InitialSyncBaseCloner::pauseForFuzzer(BaseClonerStage* stage) {
+    // These are the stages that the initial sync fuzzer expects to be able to pause on using the
+    // syncronization fail points.
+    static const auto initialSyncPauseStages =
+        std::vector<std::string>{"listCollections", "listIndexes", "listDatabases"};
+
+    if (MONGO_unlikely(initialSyncFuzzerSynchronizationPoint1.shouldFail())) {
+        if (std::find(initialSyncPauseStages.begin(),
+                      initialSyncPauseStages.end(),
+                      stage->getName()) != initialSyncPauseStages.end()) {
+            // These failpoints are set and unset by the InitialSyncTest fixture to cause initial
+            // sync to pause so that the Initial Sync Fuzzer can run commands on the sync source.
+            // nb: This log message is specifically checked for in
+            // initial_sync_test_fixture_test.js, so if you change it here you will need to change
+            // it there.
+            LOGV2(21066,
+                  "Collection Cloner scheduled a remote command on the {stage}",
+                  "Collection Cloner scheduled a remote command",
+                  "stage"_attr = describeForFuzzer(stage));
+            LOGV2(21067, "initialSyncFuzzerSynchronizationPoint1 fail point enabled");
+            initialSyncFuzzerSynchronizationPoint1.pauseWhileSet();
+
+            if (MONGO_unlikely(initialSyncFuzzerSynchronizationPoint2.shouldFail())) {
+                LOGV2(21068, "initialSyncFuzzerSynchronizationPoint2 fail point enabled");
+                initialSyncFuzzerSynchronizationPoint2.pauseWhileSet();
+            }
+        }
+    }
+}
+
+}  // namespace repl
+}  // namespace mongo
\ No newline at end of file
diff --git a/src/mongo/db/repl/initial_sync_base_cloner.h b/src/mongo/db/repl/initial_sync_base_cloner.h
new file mode 100644
index 00000000000..ff1f28142a9
--- /dev/null
+++ b/src/mongo/db/repl/initial_sync_base_cloner.h
@@ -0,0 +1,95 @@
+/**
+ *    Copyright (C) 2020-present MongoDB, Inc.
+ *
+ *    This program is free software: you can redistribute it and/or modify
+ *    it under the terms of the Server Side Public License, version 1,
+ *    as published by MongoDB, Inc.
+ *
+ *    This program is distributed in the hope that it will be useful,
+ *    but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *    Server Side Public License for more details.
+ *
+ *    You should have received a copy of the Server Side Public License
+ *    along with this program. If not, see
+ *    <http://www.mongodb.com/licensing/server-side-public-license>.
+ *
+ *    As a special exception, the copyright holders give permission to link the
+ *    code of portions of this program with the OpenSSL library under certain
+ *    conditions as described in each individual source file and distribute
+ *    linked combinations including the program with the OpenSSL library. You
+ *    must comply with the Server Side Public License in all respects for
+ *    all of the code used other than as permitted herein. If you modify file(s)
+ *    with this exception, you may extend this exception to your version of the
+ *    file(s), but you are not obligated to do so. If you do not wish to do so,
+ *    delete this exception statement from your version. If you delete this
+ *    exception statement from all source files in the program, then also delete
+ *    it in the license file.
+ */
+
+#pragma once
+
+#include "mongo/base/checked_cast.h"
+#include "mongo/db/repl/base_cloner.h"
+#include "mongo/db/repl/initial_sync_shared_data.h"
+
+namespace mongo {
+namespace repl {
+
+class InitialSyncBaseCloner : public BaseCloner {
+public:
+    InitialSyncBaseCloner(StringData clonerName,
+                          InitialSyncSharedData* sharedData,
+                          const HostAndPort& source,
+                          DBClientConnection* client,
+                          StorageInterface* storageInterface,
+                          ThreadPool* dbPool);
+    virtual ~InitialSyncBaseCloner() = default;
+
+protected:
+    InitialSyncSharedData* getSharedData() const final {
+        return checked_cast<InitialSyncSharedData*>(BaseCloner::getSharedData());
+    }
+
+private:
+    /**
+     * Make sure the initial sync ID on the sync source has not changed.  Throws an exception
+     * if it has.  Returns a not-OK status if a network error occurs.
+     */
+    Status checkInitialSyncIdIsUnchanged();
+
+    /**
+     * Make sure the rollback ID has not changed.  Throws an exception if it has.  Returns
+     * a not-OK status if a network error occurs.
+     */
+    Status checkRollBackIdIsUnchanged();
+
+    /**
+     * Does validity checks on the sync source.  If the sync source is now no longer usable,
+     * throws an exception. Returns a not-OK status if a network error occurs or if the sync
+     * source is temporarily unusable (e.g. restarting).
+     */
+    Status checkSyncSourceIsStillValid();
+
+    /**
+     * Clears _retryableOp.
+     */
+    void clearRetryingState() final;
+
+    /**
+     * Checks to see if we are still within our allowed outage duration.
+     * Also probes the sync source for clone-fatal conditions, such as rollback.
+     */
+    void handleStageAttemptFailed(BaseClonerStage* stage, Status lastError);
+
+    /**
+     * Allows the initial sync fuzzer to pause cloner execution at specific points.
+     */
+    void pauseForFuzzer(BaseClonerStage* stage) final;
+
+    // Operation that may currently be retrying.
+    ReplSyncSharedData::RetryableOperation _retryableOp;
+};
+
+}  // namespace repl
+}  // namespace mongo
\ No newline at end of file
diff --git a/src/mongo/db/repl/tenant_all_database_cloner.cpp b/src/mongo/db/repl/tenant_all_database_cloner.cpp
index 6a4533bf8f2..5aaf3a116c7 100644
--- a/src/mongo/db/repl/tenant_all_database_cloner.cpp
+++ b/src/mongo/db/repl/tenant_all_database_cloner.cpp
@@ -53,7 +53,7 @@ TenantAllDatabaseCloner::TenantAllDatabaseCloner(TenantMigrationSharedData* shar
                                                  StorageInterface* storageInterface,
                                                  ThreadPool* dbPool,
                                                  StringData tenantId)
-    : BaseCloner(
+    : TenantMigrationBaseCloner(
           "TenantAllDatabaseCloner"_sd, sharedData, source, client, storageInterface, dbPool),
       _tenantId(tenantId),
       _listDatabasesStage("listDatabases", this, &TenantAllDatabaseCloner::listDatabasesStage) {}
diff --git a/src/mongo/db/repl/tenant_all_database_cloner.h b/src/mongo/db/repl/tenant_all_database_cloner.h
index 07405375e46..681e7a2bf4e 100644
--- a/src/mongo/db/repl/tenant_all_database_cloner.h
+++ b/src/mongo/db/repl/tenant_all_database_cloner.h
@@ -31,15 +31,15 @@
 
 #include <vector>
 
-#include "mongo/base/checked_cast.h"
 #include "mongo/db/repl/base_cloner.h"
 #include "mongo/db/repl/tenant_database_cloner.h"
+#include "mongo/db/repl/tenant_migration_base_cloner.h"
 #include "mongo/db/repl/tenant_migration_shared_data.h"
 
 namespace mongo {
 namespace repl {
 
-class TenantAllDatabaseCloner final : public BaseCloner {
+class TenantAllDatabaseCloner final : public TenantMigrationBaseCloner {
 public:
     struct Stats {
         size_t databasesCloned{0};
@@ -68,10 +68,6 @@ public:
 protected:
     ClonerStages getStages() final;
 
-    TenantMigrationSharedData* getSharedData() const override {
-        return checked_cast<TenantMigrationSharedData*>(BaseCloner::getSharedData());
-    }
-
 private:
     friend class TenantAllDatabaseClonerTest;
 
@@ -100,10 +96,6 @@ private:
      */
     void postStage() final;
 
-    std::string describeForFuzzer(BaseClonerStage* stage) const final {
-        return "admin db: { " + stage->getName() + ": 1 }";
-    }
-
     // All member variables are labeled with one of the following codes indicating the
     // synchronization rules for accessing them.
     //
diff --git a/src/mongo/db/repl/tenant_collection_cloner.cpp b/src/mongo/db/repl/tenant_collection_cloner.cpp
index 5f70673ed3b..8d90c77a2d3 100644
--- a/src/mongo/db/repl/tenant_collection_cloner.cpp
+++ b/src/mongo/db/repl/tenant_collection_cloner.cpp
@@ -71,7 +71,8 @@ TenantCollectionCloner::TenantCollectionCloner(const NamespaceString& sourceNss,
                                                StorageInterface* storageInterface,
                                                ThreadPool* dbPool,
                                                StringData tenantId)
-    : BaseCloner("TenantCollectionCloner"_sd, sharedData, source, client, storageInterface, dbPool),
+    : TenantMigrationBaseCloner(
+          "TenantCollectionCloner"_sd, sharedData, source, client, storageInterface, dbPool),
       _sourceNss(sourceNss),
       _collectionOptions(collectionOptions),
       _sourceDbAndUuid(NamespaceString("UNINITIALIZED")),
diff --git a/src/mongo/db/repl/tenant_collection_cloner.h b/src/mongo/db/repl/tenant_collection_cloner.h
index b86a259972b..76b44cbfca3 100644
--- a/src/mongo/db/repl/tenant_collection_cloner.h
+++ b/src/mongo/db/repl/tenant_collection_cloner.h
@@ -32,16 +32,16 @@
 #include <memory>
 #include <vector>
 
-#include "mongo/base/checked_cast.h"
 #include "mongo/db/repl/base_cloner.h"
 #include "mongo/db/repl/task_runner.h"
+#include "mongo/db/repl/tenant_migration_base_cloner.h"
 #include "mongo/db/repl/tenant_migration_shared_data.h"
 #include "mongo/util/progress_meter.h"
 
 namespace mongo {
 namespace repl {
 
-class TenantCollectionCloner : public BaseCloner {
+class TenantCollectionCloner : public TenantMigrationBaseCloner {
 public:
     struct Stats {
         static constexpr StringData kDocumentsToCopyFieldName = "documentsToCopy"_sd;
@@ -117,10 +117,6 @@ protected:
 
     bool isMyFailPoint(const BSONObj& data) const final;
 
-    TenantMigrationSharedData* getSharedData() const override {
-        return checked_cast<TenantMigrationSharedData*>(BaseCloner::getSharedData());
-    }
-
 private:
     friend class TenantCollectionClonerTest;
     friend class TenantCollectionClonerStage;
@@ -139,11 +135,6 @@ private:
         }
     };
 
-    std::string describeForFuzzer(BaseClonerStage* stage) const final {
-        return _sourceNss.db() + " db: { " + stage->getName() + ": UUID(\"" +
-            _sourceDbAndUuid.uuid()->toString() + "\") coll: " + _sourceNss.coll() + " }";
-    }
-
     /**
      * The preStage sets the start time in _stats.
      */
diff --git a/src/mongo/db/repl/tenant_database_cloner.cpp b/src/mongo/db/repl/tenant_database_cloner.cpp
index dfa6ef52d0b..2d83fa28018 100644
--- a/src/mongo/db/repl/tenant_database_cloner.cpp
+++ b/src/mongo/db/repl/tenant_database_cloner.cpp
@@ -55,7 +55,8 @@ TenantDatabaseCloner::TenantDatabaseCloner(const std::string& dbName,
                                            StorageInterface* storageInterface,
                                            ThreadPool* dbPool,
                                            StringData tenantId)
-    : BaseCloner("TenantDatabaseCloner"_sd, sharedData, source, client, storageInterface, dbPool),
+    : TenantMigrationBaseCloner(
+          "TenantDatabaseCloner"_sd, sharedData, source, client, storageInterface, dbPool),
       _dbName(dbName),
       _listCollectionsStage("listCollections", this, &TenantDatabaseCloner::listCollectionsStage),
       _tenantId(tenantId) {
diff --git a/src/mongo/db/repl/tenant_database_cloner.h b/src/mongo/db/repl/tenant_database_cloner.h
index 4730381f485..87ba04ea3a5 100644
--- a/src/mongo/db/repl/tenant_database_cloner.h
+++ b/src/mongo/db/repl/tenant_database_cloner.h
@@ -31,15 +31,15 @@
 
 #include <vector>
 
-#include "mongo/base/checked_cast.h"
 #include "mongo/db/repl/base_cloner.h"
 #include "mongo/db/repl/tenant_collection_cloner.h"
+#include "mongo/db/repl/tenant_migration_base_cloner.h"
 #include "mongo/db/repl/tenant_migration_shared_data.h"
 
 namespace mongo {
 namespace repl {
 
-class TenantDatabaseCloner final : public BaseCloner {
+class TenantDatabaseCloner final : public TenantMigrationBaseCloner {
 public:
     struct Stats {
         std::string dbname;
@@ -75,10 +75,6 @@ protected:
 
     bool isMyFailPoint(const BSONObj& data) const final;
 
-    TenantMigrationSharedData* getSharedData() const override {
-        return checked_cast<TenantMigrationSharedData*>(BaseCloner::getSharedData());
-    }
-
 private:
     friend class TenantDatabaseClonerTest;
 
@@ -111,10 +107,6 @@ private:
      */
     void postStage() final;
 
-    std::string describeForFuzzer(BaseClonerStage* stage) const final {
-        return _dbName + " db: { " + stage->getName() + ": 1 } ";
-    }
-
     // All member variables are labeled with one of the following codes indicating the
     // synchronization rules for accessing them.
     //
diff --git a/src/mongo/db/repl/tenant_migration_base_cloner.cpp b/src/mongo/db/repl/tenant_migration_base_cloner.cpp
new file mode 100644
index 00000000000..977ddb5247f
--- /dev/null
+++ b/src/mongo/db/repl/tenant_migration_base_cloner.cpp
@@ -0,0 +1,49 @@
+/**
+ *    Copyright (C) 2020-present MongoDB, Inc.
+ *
+ *    This program is free software: you can redistribute it and/or modify
+ *    it under the terms of the Server Side Public License, version 1,
+ *    as published by MongoDB, Inc.
+ *
+ *    This program is distributed in the hope that it will be useful,
+ *    but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *    Server Side Public License for more details.
+ *
+ *    You should have received a copy of the Server Side Public License
+ *    along with this program. If not, see
+ *    <http://www.mongodb.com/licensing/server-side-public-license>.
+ *
+ *    As a special exception, the copyright holders give permission to link the
+ *    code of portions of this program with the OpenSSL library under certain
+ *    conditions as described in each individual source file and distribute
+ *    linked combinations including the program with the OpenSSL library. You
+ *    must comply with the Server Side Public License in all respects for
+ *    all of the code used other than as permitted herein. If you modify file(s)
+ *    with this exception, you may extend this exception to your version of the
+ *    file(s), but you are not obligated to do so. If you do not wish to do so,
+ *    delete this exception statement from your version. If you delete this
+ *    exception statement from all source files in the program, then also delete
+ *    it in the license file.
+ */
+
+#define MONGO_LOGV2_DEFAULT_COMPONENT ::mongo::logv2::LogComponent::kReplicationInitialSync
+
+#include "mongo/platform/basic.h"
+
+#include "mongo/db/repl/tenant_migration_base_cloner.h"
+#include "mongo/logv2/log.h"
+
+namespace mongo {
+namespace repl {
+
+TenantMigrationBaseCloner::TenantMigrationBaseCloner(StringData clonerName,
+                                                     TenantMigrationSharedData* sharedData,
+                                                     const HostAndPort& source,
+                                                     DBClientConnection* client,
+                                                     StorageInterface* storageInterface,
+                                                     ThreadPool* dbPool)
+    : BaseCloner(clonerName, sharedData, source, client, storageInterface, dbPool) {}
+
+}  // namespace repl
+}  // namespace mongo
\ No newline at end of file
diff --git a/src/mongo/db/repl/tenant_migration_base_cloner.h b/src/mongo/db/repl/tenant_migration_base_cloner.h
new file mode 100644
index 00000000000..9f9d6509a75
--- /dev/null
+++ b/src/mongo/db/repl/tenant_migration_base_cloner.h
@@ -0,0 +1,56 @@
+/**
+ *    Copyright (C) 2020-present MongoDB, Inc.
+ *
+ *    This program is free software: you can redistribute it and/or modify
+ *    it under the terms of the Server Side Public License, version 1,
+ *    as published by MongoDB, Inc.
+ *
+ *    This program is distributed in the hope that it will be useful,
+ *    but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *    Server Side Public License for more details.
+ *
+ *    You should have received a copy of the Server Side Public License
+ *    along with this program. If not, see
+ *    <http://www.mongodb.com/licensing/server-side-public-license>.
+ *
+ *    As a special exception, the copyright holders give permission to link the
+ *    code of portions of this program with the OpenSSL library under certain
+ *    conditions as described in each individual source file and distribute
+ *    linked combinations including the program with the OpenSSL library. You
+ *    must comply with the Server Side Public License in all respects for
+ *    all of the code used other than as permitted herein. If you modify file(s)
+ *    with this exception, you may extend this exception to your version of the
+ *    file(s), but you are not obligated to do so. If you do not wish to do so,
+ *    delete this exception statement from your version. If you delete this
+ *    exception statement from all source files in the program, then also delete
+ *    it in the license file.
+ */
+
+#pragma once
+
+#include "mongo/base/checked_cast.h"
+#include "mongo/db/repl/base_cloner.h"
+#include "mongo/db/repl/tenant_migration_shared_data.h"
+
+namespace mongo {
+namespace repl {
+
+class TenantMigrationBaseCloner : public BaseCloner {
+public:
+    TenantMigrationBaseCloner(StringData clonerName,
+                              TenantMigrationSharedData* sharedData,
+                              const HostAndPort& source,
+                              DBClientConnection* client,
+                              StorageInterface* storageInterface,
+                              ThreadPool* dbPool);
+    virtual ~TenantMigrationBaseCloner() = default;
+
+protected:
+    TenantMigrationSharedData* getSharedData() const override {
+        return checked_cast<TenantMigrationSharedData*>(BaseCloner::getSharedData());
+    }
+};
+
+}  // namespace repl
+}  // namespace mongo
\ No newline at end of file