SERVER-75657: Add an interface for the Cloner class

3 files changed, 97 insertions, 49 deletions

diff --git a/src/mongo/db/cloner.cpp b/src/mongo/db/cloner.cpp
index 60a2dae15a6..0041768fe28 100644
--- a/src/mongo/db/cloner.cpp
+++ b/src/mongo/db/cloner.cpp
@@ -75,7 +75,7 @@ MONGO_FAIL_POINT_DEFINE(movePrimaryFailPoint);
 
 BSONElement getErrField(const BSONObj& o);
 
-BSONObj Cloner::_getIdIndexSpec(const std::list<BSONObj>& indexSpecs) {
+BSONObj DefaultClonerImpl::_getIdIndexSpec(const std::list<BSONObj>& indexSpecs) {
     for (auto&& indexSpec : indexSpecs) {
         BSONElement indexName;
         uassertStatusOK(bsonExtractTypedField(
@@ -87,9 +87,7 @@ BSONObj Cloner::_getIdIndexSpec(const std::list<BSONObj>& indexSpecs) {
     return BSONObj();
 }
 
-Cloner::Cloner() {}
-
-struct Cloner::BatchHandler {
+struct DefaultClonerImpl::BatchHandler {
     BatchHandler(OperationContext* opCtx, const std::string& dbName)
         : lastLog(0), opCtx(opCtx), _dbName(dbName), numSeen(0), saveLast(0) {}
 
@@ -242,11 +240,11 @@ struct Cloner::BatchHandler {
 /**
  * Copy the specified collection.
  */
-void Cloner::_copy(OperationContext* opCtx,
-                   const std::string& toDBName,
-                   const NamespaceString& nss,
-                   const BSONObj& from_opts,
-                   const BSONObj& from_id_index) {
+void DefaultClonerImpl::_copy(OperationContext* opCtx,
+                              const std::string& toDBName,
+                              const NamespaceString& nss,
+                              const BSONObj& from_opts,
+                              const BSONObj& from_id_index) {
     LOGV2_DEBUG(20414,
                 2,
                 "\t\tcloning collection",
@@ -272,11 +270,11 @@ void Cloner::_copy(OperationContext* opCtx,
     }
 }
 
-void Cloner::_copyIndexes(OperationContext* opCtx,
-                          const std::string& toDBName,
-                          const NamespaceString& nss,
-                          const BSONObj& from_opts,
-                          const std::list<BSONObj>& from_indexes) {
+void DefaultClonerImpl::_copyIndexes(OperationContext* opCtx,
+                                     const std::string& toDBName,
+                                     const NamespaceString& nss,
+                                     const BSONObj& from_opts,
+                                     const std::list<BSONObj>& from_indexes) {
     LOGV2_DEBUG(20415,
                 2,
                 "\t\t copyIndexes",
@@ -312,7 +310,7 @@ void Cloner::_copyIndexes(OperationContext* opCtx,
     });
 }
 
-StatusWith<std::vector<BSONObj>> Cloner::_filterCollectionsForClone(
+StatusWith<std::vector<BSONObj>> DefaultClonerImpl::_filterCollectionsForClone(
     const std::string& fromDBName, const std::list<BSONObj>& initialCollections) {
     std::vector<BSONObj> finalCollections;
     for (auto&& collection : initialCollections) {
@@ -346,7 +344,7 @@ StatusWith<std::vector<BSONObj>> Cloner::_filterCollectionsForClone(
     return finalCollections;
 }
 
-Status Cloner::_createCollectionsForDb(
+Status DefaultClonerImpl::_createCollectionsForDb(
     OperationContext* opCtx,
     const std::vector<CreateCollectionParams>& createCollectionParams,
     const std::string& dbName) {
@@ -441,9 +439,9 @@ Status Cloner::_createCollectionsForDb(
     return Status::OK();
 }
 
-Status Cloner::setupConn(OperationContext* opCtx,
-                         const std::string& dBName,
-                         const std::string& masterHost) {
+Status DefaultClonerImpl::setupConn(OperationContext* opCtx,
+                                    const std::string& dBName,
+                                    const std::string& masterHost) {
     invariant(!_conn);
     invariant(!opCtx->lockState()->isLocked());
     auto statusWithMasterHost = ConnectionString::parse(masterHost);
@@ -487,9 +485,8 @@ Status Cloner::setupConn(OperationContext* opCtx,
     return Status::OK();
 }
 
-StatusWith<std::vector<BSONObj>> Cloner::getListOfCollections(OperationContext* opCtx,
-                                                              const std::string& dBName,
-                                                              const std::string& masterHost) {
+StatusWith<std::vector<BSONObj>> DefaultClonerImpl::getListOfCollections(
+    OperationContext* opCtx, const std::string& dBName, const std::string& masterHost) {
     invariant(!opCtx->lockState()->isLocked());
     std::vector<BSONObj> collsToClone;
     if (!_conn) {
@@ -505,11 +502,11 @@ StatusWith<std::vector<BSONObj>> Cloner::getListOfCollections(OperationContext*
     return _filterCollectionsForClone(dBName, initialCollections);
 }
 
-Status Cloner::copyDb(OperationContext* opCtx,
-                      const std::string& dBName,
-                      const std::string& masterHost,
-                      const std::vector<NamespaceString>& shardedColls,
-                      std::set<std::string>* clonedColls) {
+Status DefaultClonerImpl::copyDb(OperationContext* opCtx,
+                                 const std::string& dBName,
+                                 const std::string& masterHost,
+                                 const std::vector<NamespaceString>& shardedColls,
+                                 std::set<std::string>* clonedColls) {
     invariant(clonedColls && clonedColls->empty(), str::stream() << masterHost << ":" << dBName);
     // This function can potentially block for a long time on network activity, so holding of locks
     // is disallowed.
@@ -615,4 +612,20 @@ Status Cloner::copyDb(OperationContext* opCtx,
     return Status::OK();
 }
 
+Cloner::Cloner() : Cloner(std::make_unique<DefaultClonerImpl>()) {}
+
+Status Cloner::copyDb(OperationContext* opCtx,
+                      const std::string& dBName,
+                      const std::string& masterHost,
+                      const std::vector<NamespaceString>& shardedColls,
+                      std::set<std::string>* clonedColls) {
+    return _clonerImpl->copyDb(opCtx, dBName, masterHost, shardedColls, clonedColls);
+}
+
+StatusWith<std::vector<BSONObj>> Cloner::getListOfCollections(OperationContext* opCtx,
+                                                              const std::string& dBName,
+                                                              const std::string& masterHost) {
+    return _clonerImpl->getListOfCollections(opCtx, dBName, masterHost);
+}
+
 }  // namespace mongo
diff --git a/src/mongo/db/cloner.h b/src/mongo/db/cloner.h
index 761da5a052c..5adce5521b2 100644
--- a/src/mongo/db/cloner.h
+++ b/src/mongo/db/cloner.h
@@ -45,15 +45,25 @@ class DBClientBase;
 class NamespaceString;
 class OperationContext;
 
-// TODO SERVER-75657: Create an interface for the Cloner.
+class ClonerImpl {
+public:
+    virtual ~ClonerImpl() = default;
+    virtual Status copyDb(OperationContext* opCtx,
+                          const std::string& dBName,
+                          const std::string& masterHost,
+                          const std::vector<NamespaceString>& shardedColls,
+                          std::set<std::string>* clonedColls) = 0;
 
-class Cloner {
-    Cloner(const Cloner&) = delete;
-    Cloner& operator=(const Cloner&) = delete;
+    virtual Status setupConn(OperationContext* opCtx,
+                             const std::string& dBName,
+                             const std::string& masterHost) = 0;
+
+    virtual StatusWith<std::vector<BSONObj>> getListOfCollections(
+        OperationContext* opCtx, const std::string& dBName, const std::string& masterHost) = 0;
+};
 
+class DefaultClonerImpl : public ClonerImpl {
 public:
-    Cloner();
-    virtual ~Cloner() {}
     /**
      * Copies an entire database from the specified host.
      * clonedColls: the function will return with this populated with a list of the collections that
@@ -62,21 +72,21 @@ public:
      *              that are cloned.  When opts.createCollections is true, this parameter is
      *              ignored and the collection list is fetched from the remote via _conn.
      */
-    virtual Status copyDb(OperationContext* opCtx,
-                          const std::string& dBName,
-                          const std::string& masterHost,
-                          const std::vector<NamespaceString>& shardedColls,
-                          std::set<std::string>* clonedColls);
+    Status copyDb(OperationContext* opCtx,
+                  const std::string& dBName,
+                  const std::string& masterHost,
+                  const std::vector<NamespaceString>& shardedColls,
+                  std::set<std::string>* clonedColls) override;
 
-    virtual Status setupConn(OperationContext* opCtx,
-                             const std::string& dBName,
-                             const std::string& masterHost);
+    Status setupConn(OperationContext* opCtx,
+                     const std::string& dBName,
+                     const std::string& masterHost) override;
 
-    virtual StatusWith<std::vector<BSONObj>> getListOfCollections(OperationContext* opCtx,
-                                                                  const std::string& dBName,
-                                                                  const std::string& masterHost);
+    StatusWith<std::vector<BSONObj>> getListOfCollections(OperationContext* opCtx,
+                                                          const std::string& dBName,
+                                                          const std::string& masterHost) override;
 
-protected:
+private:
     std::unique_ptr<ScopedDbConnection> _conn;
 
     // Filters a database's collection list and removes collections that should not be cloned.
@@ -121,4 +131,29 @@ protected:
     }
 };
 
+class Cloner {
+
+public:
+    Cloner(std::unique_ptr<ClonerImpl> clonerImpl) : _clonerImpl(std::move(clonerImpl)) {}
+
+    Cloner();
+
+    Cloner(const Cloner&) = delete;
+
+    Cloner& operator=(const Cloner&) = delete;
+
+    Status copyDb(OperationContext* opCtx,
+                  const std::string& dBName,
+                  const std::string& masterHost,
+                  const std::vector<NamespaceString>& shardedColls,
+                  std::set<std::string>* clonedColls);
+
+    StatusWith<std::vector<BSONObj>> getListOfCollections(OperationContext* opCtx,
+                                                          const std::string& dBName,
+                                                          const std::string& masterHost);
+
+private:
+    std::unique_ptr<ClonerImpl> _clonerImpl;
+};
+
 }  // namespace mongo
diff --git a/src/mongo/db/s/move_primary/move_primary_recipient_service_test.cpp b/src/mongo/db/s/move_primary/move_primary_recipient_service_test.cpp
index b6822c9184f..2b02e8bb20d 100644
--- a/src/mongo/db/s/move_primary/move_primary_recipient_service_test.cpp
+++ b/src/mongo/db/s/move_primary/move_primary_recipient_service_test.cpp
@@ -81,7 +81,7 @@ static HostAndPort makeHostAndPort(const ShardId& shardId) {
 }
 }  // namespace
 
-class ClonerForTest : public Cloner {
+class TestClonerImpl : public ClonerImpl {
     Status copyDb(OperationContext* opCtx,
                   const std::string& dBName,
                   const std::string& masterHost,
@@ -144,7 +144,7 @@ public:
             recipientStateDoc,
             std::make_shared<MovePrimaryRecipientExternalStateForTest>(),
             _serviceContext,
-            std::make_unique<ClonerForTest>());
+            std::make_unique<Cloner>(std::make_unique<TestClonerImpl>()));
     }
 
     StringData getServiceName() const {
@@ -718,7 +718,7 @@ TEST_F(MovePrimaryRecipientServiceTest, AbortsOnUnrecoverableClonerError) {
     // Step Down to register new POS before Step Up.
     stepDown(_serviceCtx, _registry);
 
-    class FailingCloner : public ClonerForTest {
+    class FailingCloner : public TestClonerImpl {
         Status copyDb(OperationContext* opCtx,
                       const std::string& dBName,
                       const std::string& masterHost,
@@ -744,7 +744,7 @@ TEST_F(MovePrimaryRecipientServiceTest, AbortsOnUnrecoverableClonerError) {
                 recipientStateDoc,
                 std::make_shared<MovePrimaryRecipientExternalStateForTest>(),
                 _serviceContext,
-                std::make_unique<FailingCloner>());
+                std::make_unique<Cloner>(std::make_unique<FailingCloner>()));
         }
 
         StringData getServiceName() const override {