SERVER-40020 Make isCollectionLockHeldForMode take NamespaceString, not StringData

36 files changed, 132 insertions, 135 deletions

diff --git a/src/mongo/db/catalog/collection_compact.cpp b/src/mongo/db/catalog/collection_compact.cpp
index ff34f9f3a3e..c3e886d27eb 100644
--- a/src/mongo/db/catalog/collection_compact.cpp
+++ b/src/mongo/db/catalog/collection_compact.cpp
@@ -45,7 +45,7 @@ namespace mongo {
 StatusWith<CompactStats> compactCollection(OperationContext* opCtx,
                                            Collection* collection,
                                            const CompactOptions* compactOptions) {
-    dassert(opCtx->lockState()->isCollectionLockedForMode(collection->ns().toString(), MODE_X));
+    dassert(opCtx->lockState()->isCollectionLockedForMode(collection->ns(), MODE_X));
 
     DisableDocumentValidation validationDisabler(opCtx);
 
diff --git a/src/mongo/db/catalog/collection_impl.cpp b/src/mongo/db/catalog/collection_impl.cpp
index bb8cc7e4bb6..a11d2461ba1 100644
--- a/src/mongo/db/catalog/collection_impl.cpp
+++ b/src/mongo/db/catalog/collection_impl.cpp
@@ -265,7 +265,7 @@ bool CollectionImpl::requiresIdIndex() const {
 
 std::unique_ptr<SeekableRecordCursor> CollectionImpl::getCursor(OperationContext* opCtx,
                                                                 bool forward) const {
-    dassert(opCtx->lockState()->isCollectionLockedForMode(ns().toString(), MODE_IS));
+    dassert(opCtx->lockState()->isCollectionLockedForMode(ns(), MODE_IS));
     invariant(ok());
 
     return _recordStore->getCursor(opCtx, forward);
@@ -275,7 +275,7 @@ std::unique_ptr<SeekableRecordCursor> CollectionImpl::getCursor(OperationContext
 bool CollectionImpl::findDoc(OperationContext* opCtx,
                              RecordId loc,
                              Snapshotted<BSONObj>* out) const {
-    dassert(opCtx->lockState()->isCollectionLockedForMode(ns().toString(), MODE_IS));
+    dassert(opCtx->lockState()->isCollectionLockedForMode(ns(), MODE_IS));
 
     RecordData rd;
     if (!_recordStore->findRecord(opCtx, loc, &rd))
@@ -456,7 +456,7 @@ Status CollectionImpl::insertDocumentForBulkLoader(OperationContext* opCtx,
         return status;
     }
 
-    dassert(opCtx->lockState()->isCollectionLockedForMode(ns().toString(), MODE_IX));
+    dassert(opCtx->lockState()->isCollectionLockedForMode(ns(), MODE_IX));
 
     // TODO SERVER-30638: using timestamp 0 for these inserts, which are non-oplog so we don't yet
     // care about their correct timestamps.
@@ -494,7 +494,7 @@ Status CollectionImpl::_insertDocuments(OperationContext* opCtx,
                                         const vector<InsertStatement>::const_iterator begin,
                                         const vector<InsertStatement>::const_iterator end,
                                         OpDebug* opDebug) {
-    dassert(opCtx->lockState()->isCollectionLockedForMode(ns().toString(), MODE_IX));
+    dassert(opCtx->lockState()->isCollectionLockedForMode(ns(), MODE_IX));
 
     const size_t count = std::distance(begin, end);
     if (isCapped() && _indexCatalog->haveAnyIndexes() && count > 1) {
@@ -636,7 +636,7 @@ RecordId CollectionImpl::updateDocument(OperationContext* opCtx,
         }
     }
 
-    dassert(opCtx->lockState()->isCollectionLockedForMode(ns().toString(), MODE_IX));
+    dassert(opCtx->lockState()->isCollectionLockedForMode(ns(), MODE_IX));
     invariant(oldDoc.snapshotId() == opCtx->recoveryUnit()->getSnapshotId());
     invariant(newDoc.isOwned());
 
@@ -710,7 +710,7 @@ StatusWith<RecordData> CollectionImpl::updateDocumentWithDamages(
     const char* damageSource,
     const mutablebson::DamageVector& damages,
     CollectionUpdateArgs* args) {
-    dassert(opCtx->lockState()->isCollectionLockedForMode(ns().toString(), MODE_IX));
+    dassert(opCtx->lockState()->isCollectionLockedForMode(ns(), MODE_IX));
     invariant(oldRec.snapshotId() == opCtx->recoveryUnit()->getSnapshotId());
     invariant(updateWithDamagesSupported());
 
@@ -779,7 +779,7 @@ uint64_t CollectionImpl::getIndexSize(OperationContext* opCtx, BSONObjBuilder* d
  * 4) re-write indexes
  */
 Status CollectionImpl::truncate(OperationContext* opCtx) {
-    dassert(opCtx->lockState()->isCollectionLockedForMode(ns().toString(), MODE_X));
+    dassert(opCtx->lockState()->isCollectionLockedForMode(ns(), MODE_X));
     BackgroundOperation::assertNoBgOpInProgForNs(ns());
     invariant(_indexCatalog->numIndexesInProgress(opCtx) == 0);
 
@@ -813,7 +813,7 @@ Status CollectionImpl::truncate(OperationContext* opCtx) {
 }
 
 void CollectionImpl::cappedTruncateAfter(OperationContext* opCtx, RecordId end, bool inclusive) {
-    dassert(opCtx->lockState()->isCollectionLockedForMode(ns().toString(), MODE_X));
+    dassert(opCtx->lockState()->isCollectionLockedForMode(ns(), MODE_X));
     invariant(isCapped());
     BackgroundOperation::assertNoBgOpInProgForNs(ns());
     invariant(_indexCatalog->numIndexesInProgress(opCtx) == 0);
@@ -822,7 +822,7 @@ void CollectionImpl::cappedTruncateAfter(OperationContext* opCtx, RecordId end,
 }
 
 Status CollectionImpl::setValidator(OperationContext* opCtx, BSONObj validatorDoc) {
-    invariant(opCtx->lockState()->isCollectionLockedForMode(ns().toString(), MODE_X));
+    invariant(opCtx->lockState()->isCollectionLockedForMode(ns(), MODE_X));
 
     // Make owned early so that the parsed match expression refers to the owned object.
     if (!validatorDoc.isOwned())
@@ -873,7 +873,7 @@ StringData CollectionImpl::getValidationAction() const {
 }
 
 Status CollectionImpl::setValidationLevel(OperationContext* opCtx, StringData newLevel) {
-    invariant(opCtx->lockState()->isCollectionLockedForMode(ns().toString(), MODE_X));
+    invariant(opCtx->lockState()->isCollectionLockedForMode(ns(), MODE_X));
 
     auto levelSW = _parseValidationLevel(newLevel);
     if (!levelSW.isOK()) {
@@ -891,7 +891,7 @@ Status CollectionImpl::setValidationLevel(OperationContext* opCtx, StringData ne
 }
 
 Status CollectionImpl::setValidationAction(OperationContext* opCtx, StringData newAction) {
-    invariant(opCtx->lockState()->isCollectionLockedForMode(ns().toString(), MODE_X));
+    invariant(opCtx->lockState()->isCollectionLockedForMode(ns(), MODE_X));
 
     auto actionSW = _parseValidationAction(newAction);
     if (!actionSW.isOK()) {
@@ -912,7 +912,7 @@ Status CollectionImpl::updateValidator(OperationContext* opCtx,
                                        BSONObj newValidator,
                                        StringData newLevel,
                                        StringData newAction) {
-    invariant(opCtx->lockState()->isCollectionLockedForMode(ns().toString(), MODE_X));
+    invariant(opCtx->lockState()->isCollectionLockedForMode(ns(), MODE_X));
 
     opCtx->recoveryUnit()->onRollback([
         this,
@@ -1268,7 +1268,7 @@ Status CollectionImpl::validate(OperationContext* opCtx,
                                 std::unique_ptr<Lock::CollectionLock> collLk,
                                 ValidateResults* results,
                                 BSONObjBuilder* output) {
-    dassert(opCtx->lockState()->isCollectionLockedForMode(ns().toString(), MODE_IS));
+    dassert(opCtx->lockState()->isCollectionLockedForMode(ns(), MODE_IS));
 
     try {
         ValidateResultsMap indexNsResultsMap;
diff --git a/src/mongo/db/catalog/collection_info_cache_impl.cpp b/src/mongo/db/catalog/collection_info_cache_impl.cpp
index 5a715d26748..36a5f8acf10 100644
--- a/src/mongo/db/catalog/collection_info_cache_impl.cpp
+++ b/src/mongo/db/catalog/collection_info_cache_impl.cpp
@@ -69,7 +69,7 @@ CollectionInfoCacheImpl::~CollectionInfoCacheImpl() {
 
 const UpdateIndexData& CollectionInfoCacheImpl::getIndexKeys(OperationContext* opCtx) const {
     // This requires "some" lock, and MODE_IS is an expression for that, for now.
-    dassert(opCtx->lockState()->isCollectionLockedForMode(_collection->ns().ns(), MODE_IS));
+    dassert(opCtx->lockState()->isCollectionLockedForMode(_collection->ns(), MODE_IS));
     invariant(_keysComputed);
     return _indexedPaths;
 }
@@ -205,7 +205,7 @@ void CollectionInfoCacheImpl::updatePlanCacheIndexEntries(OperationContext* opCt
 
 void CollectionInfoCacheImpl::init(OperationContext* opCtx) {
     // Requires exclusive collection lock.
-    invariant(opCtx->lockState()->isCollectionLockedForMode(_collection->ns().ns(), MODE_X));
+    invariant(opCtx->lockState()->isCollectionLockedForMode(_collection->ns(), MODE_X));
 
     const bool includeUnfinishedIndexes = false;
     std::unique_ptr<IndexCatalog::IndexIterator> ii =
@@ -220,7 +220,7 @@ void CollectionInfoCacheImpl::init(OperationContext* opCtx) {
 
 void CollectionInfoCacheImpl::addedIndex(OperationContext* opCtx, const IndexDescriptor* desc) {
     // Requires exclusive collection lock.
-    invariant(opCtx->lockState()->isCollectionLockedForMode(_collection->ns().ns(), MODE_X));
+    invariant(opCtx->lockState()->isCollectionLockedForMode(_collection->ns(), MODE_X));
     invariant(desc);
 
     rebuildIndexData(opCtx);
@@ -230,7 +230,7 @@ void CollectionInfoCacheImpl::addedIndex(OperationContext* opCtx, const IndexDes
 
 void CollectionInfoCacheImpl::droppedIndex(OperationContext* opCtx, StringData indexName) {
     // Requires exclusive collection lock.
-    invariant(opCtx->lockState()->isCollectionLockedForMode(_collection->ns().ns(), MODE_X));
+    invariant(opCtx->lockState()->isCollectionLockedForMode(_collection->ns(), MODE_X));
 
     rebuildIndexData(opCtx);
     _indexUsageTracker.unregisterIndex(indexName);
diff --git a/src/mongo/db/catalog/database_catalog_entry.h b/src/mongo/db/catalog/database_catalog_entry.h
index bdc11797461..d68ccbc863c 100644
--- a/src/mongo/db/catalog/database_catalog_entry.h
+++ b/src/mongo/db/catalog/database_catalog_entry.h
@@ -34,6 +34,7 @@
 
 #include "mongo/base/status.h"
 #include "mongo/base/string_data.h"
+#include "mongo/db/namespace_string.h"
 
 namespace mongo {
 
@@ -96,7 +97,7 @@ public:
                                         IndexCatalogEntry* index) = 0;
 
     virtual Status createCollection(OperationContext* opCtx,
-                                    StringData ns,
+                                    const NamespaceString& nss,
                                     const CollectionOptions& options,
                                     bool allocateDefaultSpace) = 0;
 
diff --git a/src/mongo/db/catalog/database_impl.cpp b/src/mongo/db/catalog/database_impl.cpp
index b8b445649b5..e8db845ce50 100644
--- a/src/mongo/db/catalog/database_impl.cpp
+++ b/src/mongo/db/catalog/database_impl.cpp
@@ -851,7 +851,7 @@ Collection* DatabaseImpl::createCollection(OperationContext* opCtx,
     }
 
     massertStatusOK(
-        _dbEntry->createCollection(opCtx, ns, optionsWithUUID, true /*allocateDefaultSpace*/));
+        _dbEntry->createCollection(opCtx, nss, optionsWithUUID, true /*allocateDefaultSpace*/));
 
     opCtx->recoveryUnit()->registerChange(new AddCollectionChange(opCtx, this, ns));
     Collection* collection = _getOrCreateCollectionInstance(opCtx, nss);
diff --git a/src/mongo/db/catalog/database_test.cpp b/src/mongo/db/catalog/database_test.cpp
index 9b44575217e..e1743a76488 100644
--- a/src/mongo/db/catalog/database_test.cpp
+++ b/src/mongo/db/catalog/database_test.cpp
@@ -508,7 +508,7 @@ TEST_F(DatabaseTest, AutoGetCollectionForReadCommandSucceedsWithDeadlineNow) {
     Lock::DBLock dbLock(_opCtx.get(), nss.db(), MODE_X);
     ASSERT(_opCtx.get()->lockState()->isDbLockedForMode(nss.db(), MODE_X));
     Lock::CollectionLock collLock(_opCtx.get()->lockState(), nss.toString(), MODE_X);
-    ASSERT(_opCtx.get()->lockState()->isCollectionLockedForMode(nss.toString(), MODE_X));
+    ASSERT(_opCtx.get()->lockState()->isCollectionLockedForMode(nss, MODE_X));
     try {
         AutoGetCollectionForReadCommand db(
             _opCtx.get(), nss, AutoGetCollection::kViewsForbidden, Date_t::now());
@@ -522,7 +522,7 @@ TEST_F(DatabaseTest, AutoGetCollectionForReadCommandSucceedsWithDeadlineMin) {
     Lock::DBLock dbLock(_opCtx.get(), nss.db(), MODE_X);
     ASSERT(_opCtx.get()->lockState()->isDbLockedForMode(nss.db(), MODE_X));
     Lock::CollectionLock collLock(_opCtx.get()->lockState(), nss.toString(), MODE_X);
-    ASSERT(_opCtx.get()->lockState()->isCollectionLockedForMode(nss.toString(), MODE_X));
+    ASSERT(_opCtx.get()->lockState()->isCollectionLockedForMode(nss, MODE_X));
     try {
         AutoGetCollectionForReadCommand db(
             _opCtx.get(), nss, AutoGetCollection::kViewsForbidden, Date_t());
diff --git a/src/mongo/db/catalog/index_builds_manager.cpp b/src/mongo/db/catalog/index_builds_manager.cpp
index 64a8b795149..ebf96a0eb71 100644
--- a/src/mongo/db/catalog/index_builds_manager.cpp
+++ b/src/mongo/db/catalog/index_builds_manager.cpp
@@ -85,7 +85,7 @@ Status IndexBuildsManager::setUpIndexBuild(OperationContext* opCtx,
     _registerIndexBuild(buildUUID);
 
     const auto& nss = collection->ns();
-    invariant(opCtx->lockState()->isCollectionLockedForMode(nss.ns(), MODE_X),
+    invariant(opCtx->lockState()->isCollectionLockedForMode(nss, MODE_X),
               str::stream() << "Unable to set up index build " << buildUUID << ": collection "
                             << nss.ns()
                             << " is not locked in exclusive mode.");
diff --git a/src/mongo/db/catalog/index_catalog_impl.cpp b/src/mongo/db/catalog/index_catalog_impl.cpp
index 5fdffe0aad3..7f7d98b17c5 100644
--- a/src/mongo/db/catalog/index_catalog_impl.cpp
+++ b/src/mongo/db/catalog/index_catalog_impl.cpp
@@ -290,7 +290,7 @@ std::vector<BSONObj> IndexCatalogImpl::removeExistingIndexes(
 
 StatusWith<BSONObj> IndexCatalogImpl::createIndexOnEmptyCollection(OperationContext* opCtx,
                                                                    BSONObj spec) {
-    invariant(opCtx->lockState()->isCollectionLockedForMode(_collection->ns().toString(), MODE_X));
+    invariant(opCtx->lockState()->isCollectionLockedForMode(_collection->ns(), MODE_X));
     invariant(_collection->numRecords(opCtx) == 0,
               str::stream() << "Collection must be empty. Collection: " << _collection->ns()
                             << " UUID: "
@@ -738,7 +738,7 @@ BSONObj IndexCatalogImpl::getDefaultIdIndexSpec() const {
 void IndexCatalogImpl::dropAllIndexes(OperationContext* opCtx,
                                       bool includingIdIndex,
                                       stdx::function<void(const IndexDescriptor*)> onDropFn) {
-    invariant(opCtx->lockState()->isCollectionLockedForMode(_collection->ns().toString(), MODE_X));
+    invariant(opCtx->lockState()->isCollectionLockedForMode(_collection->ns(), MODE_X));
 
     BackgroundOperation::assertNoBgOpInProgForNs(_collection->ns().ns());
 
@@ -812,7 +812,7 @@ void IndexCatalogImpl::dropAllIndexes(OperationContext* opCtx, bool includingIdI
 }
 
 Status IndexCatalogImpl::dropIndex(OperationContext* opCtx, const IndexDescriptor* desc) {
-    invariant(opCtx->lockState()->isCollectionLockedForMode(_collection->ns().toString(), MODE_X));
+    invariant(opCtx->lockState()->isCollectionLockedForMode(_collection->ns(), MODE_X));
     BackgroundOperation::assertNoBgOpInProgForNs(_collection->ns().ns());
     invariant(_buildingIndexes.size() == 0);
 
@@ -1123,7 +1123,7 @@ std::vector<std::shared_ptr<const IndexCatalogEntry>> IndexCatalogImpl::getAllRe
 
 const IndexDescriptor* IndexCatalogImpl::refreshEntry(OperationContext* opCtx,
                                                       const IndexDescriptor* oldDesc) {
-    invariant(opCtx->lockState()->isCollectionLockedForMode(_collection->ns().ns(), MODE_X));
+    invariant(opCtx->lockState()->isCollectionLockedForMode(_collection->ns(), MODE_X));
     invariant(!BackgroundOperation::inProgForNs(_collection->ns()));
     invariant(_buildingIndexes.size() == 0);
 
diff --git a/src/mongo/db/catalog/index_timestamp_helper.cpp b/src/mongo/db/catalog/index_timestamp_helper.cpp
index 9d1407b26a5..524d5bbc121 100644
--- a/src/mongo/db/catalog/index_timestamp_helper.cpp
+++ b/src/mongo/db/catalog/index_timestamp_helper.cpp
@@ -84,7 +84,7 @@ void IndexTimestampHelper::setGhostCommitTimestampForWrite(OperationContext* opC
     const auto mySnapshot = opCtx->recoveryUnit()->getPointInTimeReadTimestamp();
     // If a lock that blocks writes is held, there can be no uncommitted writes, so there is no
     // need to check snapshot visibility, especially if a caller is not reading with a timestamp.
-    invariant(mySnapshot || opCtx->lockState()->isCollectionLockedForMode(nss.ns(), MODE_S),
+    invariant(mySnapshot || opCtx->lockState()->isCollectionLockedForMode(nss, MODE_S),
               "a write-blocking lock is required when applying a ghost timestamp without a read "
               "timestamp");
     invariant(!mySnapshot || *mySnapshot <= commitTimestamp,
diff --git a/src/mongo/db/catalog/rename_collection_test.cpp b/src/mongo/db/catalog/rename_collection_test.cpp
index c9aa1964cba..439b660eaa7 100644
--- a/src/mongo/db/catalog/rename_collection_test.cpp
+++ b/src/mongo/db/catalog/rename_collection_test.cpp
@@ -455,7 +455,7 @@ void _insertDocument(OperationContext* opCtx, const NamespaceString& nss, const
  * catalog. The caller must hold the appropriate locks from the lock manager.
  */
 Collection* _getCollection_inlock(OperationContext* opCtx, const NamespaceString& nss) {
-    invariant(opCtx->lockState()->isCollectionLockedForMode(nss.ns(), MODE_IS));
+    invariant(opCtx->lockState()->isCollectionLockedForMode(nss, MODE_IS));
     auto databaseHolder = DatabaseHolder::get(opCtx);
     auto* db = databaseHolder->getDb(opCtx, nss.db());
     if (!db) {
diff --git a/src/mongo/db/catalog_raii_test.cpp b/src/mongo/db/catalog_raii_test.cpp
index 5e6aa5a32b7..b8f34187e44 100644
--- a/src/mongo/db/catalog_raii_test.cpp
+++ b/src/mongo/db/catalog_raii_test.cpp
@@ -132,7 +132,7 @@ TEST_F(CatalogRAIITestFixture, AutoGetCollectionCollLockDeadline) {
     Lock::DBLock dbLock1(client1.second.get(), nss.db(), MODE_IX);
     ASSERT(client1.second->lockState()->isDbLockedForMode(nss.db(), MODE_IX));
     Lock::CollectionLock collLock1(client1.second.get()->lockState(), nss.toString(), MODE_X);
-    ASSERT(client1.second->lockState()->isCollectionLockedForMode(nss.toString(), MODE_X));
+    ASSERT(client1.second->lockState()->isCollectionLockedForMode(nss, MODE_X));
     failsWithLockTimeout(
         [&] {
             AutoGetCollection coll(client2.second.get(),
@@ -180,7 +180,7 @@ TEST_F(CatalogRAIITestFixture, AutoGetCollectionDeadlineNow) {
     Lock::DBLock dbLock1(client1.second.get(), nss.db(), MODE_IX);
     ASSERT(client1.second->lockState()->isDbLockedForMode(nss.db(), MODE_IX));
     Lock::CollectionLock collLock1(client1.second.get()->lockState(), nss.toString(), MODE_X);
-    ASSERT(client1.second->lockState()->isCollectionLockedForMode(nss.toString(), MODE_X));
+    ASSERT(client1.second->lockState()->isCollectionLockedForMode(nss, MODE_X));
 
     failsWithLockTimeout(
         [&] {
@@ -198,7 +198,7 @@ TEST_F(CatalogRAIITestFixture, AutoGetCollectionDeadlineMin) {
     Lock::DBLock dbLock1(client1.second.get(), nss.db(), MODE_IX);
     ASSERT(client1.second->lockState()->isDbLockedForMode(nss.db(), MODE_IX));
     Lock::CollectionLock collLock1(client1.second.get()->lockState(), nss.toString(), MODE_X);
-    ASSERT(client1.second->lockState()->isCollectionLockedForMode(nss.toString(), MODE_X));
+    ASSERT(client1.second->lockState()->isCollectionLockedForMode(nss, MODE_X));
 
     failsWithLockTimeout(
         [&] {
diff --git a/src/mongo/db/commands/create_indexes.cpp b/src/mongo/db/commands/create_indexes.cpp
index 5700ad537a1..7b0dbb11cce 100644
--- a/src/mongo/db/commands/create_indexes.cpp
+++ b/src/mongo/db/commands/create_indexes.cpp
@@ -220,7 +220,7 @@ std::vector<BSONObj> resolveDefaultsAndRemoveExistingIndexes(OperationContext* o
 void checkUniqueIndexConstraints(OperationContext* opCtx,
                                  const NamespaceString& nss,
                                  const BSONObj& newIdxKey) {
-    invariant(opCtx->lockState()->isCollectionLockedForMode(nss.ns(), MODE_X));
+    invariant(opCtx->lockState()->isCollectionLockedForMode(nss, MODE_X));
 
     const auto metadata = CollectionShardingState::get(opCtx, nss)->getCurrentMetadata();
     if (!metadata->isSharded())
diff --git a/src/mongo/db/concurrency/d_concurrency_test.cpp b/src/mongo/db/concurrency/d_concurrency_test.cpp
index 29852943be9..4c919292b80 100644
--- a/src/mongo/db/concurrency/d_concurrency_test.cpp
+++ b/src/mongo/db/concurrency/d_concurrency_test.cpp
@@ -1168,7 +1168,7 @@ TEST_F(DConcurrencyTestFixture, IsDbLockedForXMode) {
 }
 
 TEST_F(DConcurrencyTestFixture, IsCollectionLocked_DB_Locked_IS) {
-    const std::string ns("db1.coll");
+    const NamespaceString ns("db1.coll");
 
     auto opCtx = makeOperationContext();
     opCtx->swapLockState(stdx::make_unique<LockerImpl>());
@@ -1177,7 +1177,7 @@ TEST_F(DConcurrencyTestFixture, IsCollectionLocked_DB_Locked_IS) {
     Lock::DBLock dbLock(opCtx.get(), "db1", MODE_IS);
 
     {
-        Lock::CollectionLock collLock(lockState, ns, MODE_IS);
+        Lock::CollectionLock collLock(lockState, ns.ns(), MODE_IS);
 
         ASSERT(lockState->isCollectionLockedForMode(ns, MODE_IS));
         ASSERT(!lockState->isCollectionLockedForMode(ns, MODE_IX));
@@ -1189,7 +1189,7 @@ TEST_F(DConcurrencyTestFixture, IsCollectionLocked_DB_Locked_IS) {
     }
 
     {
-        Lock::CollectionLock collLock(lockState, ns, MODE_S);
+        Lock::CollectionLock collLock(lockState, ns.ns(), MODE_S);
 
         ASSERT(lockState->isCollectionLockedForMode(ns, MODE_IS));
         ASSERT(!lockState->isCollectionLockedForMode(ns, MODE_IX));
@@ -1199,7 +1199,7 @@ TEST_F(DConcurrencyTestFixture, IsCollectionLocked_DB_Locked_IS) {
 }
 
 TEST_F(DConcurrencyTestFixture, IsCollectionLocked_DB_Locked_IX) {
-    const std::string ns("db1.coll");
+    const NamespaceString ns("db1.coll");
 
     auto opCtx = makeOperationContext();
     opCtx->swapLockState(stdx::make_unique<LockerImpl>());
@@ -1208,7 +1208,7 @@ TEST_F(DConcurrencyTestFixture, IsCollectionLocked_DB_Locked_IX) {
     Lock::DBLock dbLock(opCtx.get(), "db1", MODE_IX);
 
     {
-        Lock::CollectionLock collLock(lockState, ns, MODE_IX);
+        Lock::CollectionLock collLock(lockState, ns.ns(), MODE_IX);
 
         // TODO: This is TRUE because Lock::CollectionLock converts IX lock to X
         ASSERT(lockState->isCollectionLockedForMode(ns, MODE_IS));
@@ -1219,7 +1219,7 @@ TEST_F(DConcurrencyTestFixture, IsCollectionLocked_DB_Locked_IX) {
     }
 
     {
-        Lock::CollectionLock collLock(lockState, ns, MODE_X);
+        Lock::CollectionLock collLock(lockState, ns.ns(), MODE_X);
 
         ASSERT(lockState->isCollectionLockedForMode(ns, MODE_IS));
         ASSERT(lockState->isCollectionLockedForMode(ns, MODE_IX));
@@ -1751,7 +1751,7 @@ TEST_F(DConcurrencyTestFixture, CollectionLockTimeout) {
     Lock::DBLock DBL1(opctx1, "testdb"_sd, MODE_IX, Date_t::max());
     ASSERT(opctx1->lockState()->isDbLockedForMode("testdb"_sd, MODE_IX));
     Lock::CollectionLock CL1(opctx1->lockState(), "testdb.test"_sd, MODE_X, Date_t::max());
-    ASSERT(opctx1->lockState()->isCollectionLockedForMode("testdb.test"_sd, MODE_X));
+    ASSERT(opctx1->lockState()->isCollectionLockedForMode(NamespaceString("testdb.test"), MODE_X));
 
     Date_t t1 = Date_t::now();
     Lock::DBLock DBL2(opctx2, "testdb"_sd, MODE_IX, Date_t::max());
diff --git a/src/mongo/db/concurrency/lock_state.cpp b/src/mongo/db/concurrency/lock_state.cpp
index 345652a66c8..9a791148931 100644
--- a/src/mongo/db/concurrency/lock_state.cpp
+++ b/src/mongo/db/concurrency/lock_state.cpp
@@ -561,15 +561,14 @@ bool LockerImpl::isDbLockedForMode(StringData dbName, LockMode mode) const {
     return isLockHeldForMode(resIdDb, mode);
 }
 
-bool LockerImpl::isCollectionLockedForMode(StringData ns, LockMode mode) const {
-    invariant(nsIsFull(ns));
+bool LockerImpl::isCollectionLockedForMode(const NamespaceString& nss, LockMode mode) const {
+    invariant(nss.coll().size());
 
     if (isW())
         return true;
     if (isR() && isSharedLockMode(mode))
         return true;
 
-    const NamespaceString nss(ns);
     const ResourceId resIdDb(RESOURCE_DATABASE, nss.db());
 
     LockMode dbMode = getLockMode(resIdDb);
@@ -585,7 +584,7 @@ bool LockerImpl::isCollectionLockedForMode(StringData ns, LockMode mode) const {
             return isSharedLockMode(mode);
         case MODE_IX:
         case MODE_IS: {
-            const ResourceId resIdColl(RESOURCE_COLLECTION, ns);
+            const ResourceId resIdColl(RESOURCE_COLLECTION, nss.ns());
             return isLockHeldForMode(resIdColl, mode);
         } break;
         case LockModesCount:
diff --git a/src/mongo/db/concurrency/lock_state.h b/src/mongo/db/concurrency/lock_state.h
index 91c6e651d4f..b9ecdc3cbfd 100644
--- a/src/mongo/db/concurrency/lock_state.h
+++ b/src/mongo/db/concurrency/lock_state.h
@@ -179,7 +179,7 @@ public:
     virtual LockMode getLockMode(ResourceId resId) const;
     virtual bool isLockHeldForMode(ResourceId resId, LockMode mode) const;
     virtual bool isDbLockedForMode(StringData dbName, LockMode mode) const;
-    virtual bool isCollectionLockedForMode(StringData ns, LockMode mode) const;
+    virtual bool isCollectionLockedForMode(const NamespaceString& nss, LockMode mode) const;
 
     virtual ResourceId getWaitingResource() const;
 
diff --git a/src/mongo/db/concurrency/locker.h b/src/mongo/db/concurrency/locker.h
index ae951b4715b..158d073ae35 100644
--- a/src/mongo/db/concurrency/locker.h
+++ b/src/mongo/db/concurrency/locker.h
@@ -295,7 +295,7 @@ public:
     // hierarchy is properly locked and because of this they are very expensive to call.
     // Do not use them in performance critical code paths.
     virtual bool isDbLockedForMode(StringData dbName, LockMode mode) const = 0;
-    virtual bool isCollectionLockedForMode(StringData ns, LockMode mode) const = 0;
+    virtual bool isCollectionLockedForMode(const NamespaceString& nss, LockMode mode) const = 0;
 
     /**
      * Returns the resource that this locker is waiting/blocked on (if any). If the locker is
diff --git a/src/mongo/db/concurrency/locker_noop.h b/src/mongo/db/concurrency/locker_noop.h
index 7e46259cbc5..5e53bd6f6de 100644
--- a/src/mongo/db/concurrency/locker_noop.h
+++ b/src/mongo/db/concurrency/locker_noop.h
@@ -154,7 +154,7 @@ public:
         return true;
     }
 
-    virtual bool isCollectionLockedForMode(StringData ns, LockMode mode) const {
+    virtual bool isCollectionLockedForMode(const NamespaceString& nss, LockMode mode) const {
         return true;
     }
 
diff --git a/src/mongo/db/index/index_build_interceptor.cpp b/src/mongo/db/index/index_build_interceptor.cpp
index 439794e390d..f4eb823e47e 100644
--- a/src/mongo/db/index/index_build_interceptor.cpp
+++ b/src/mongo/db/index/index_build_interceptor.cpp
@@ -314,12 +314,12 @@ void IndexBuildInterceptor::_tryYield(OperationContext* opCtx) {
     // Never yield while holding locks that prevent writes to the collection: only yield while
     // holding intent locks. This check considers all locks in the hierarchy that would cover this
     // mode.
-    if (opCtx->lockState()->isCollectionLockedForMode(_indexCatalogEntry->ns(), MODE_S)) {
+    const NamespaceString nss(_indexCatalogEntry->ns());
+    if (opCtx->lockState()->isCollectionLockedForMode(nss, MODE_S)) {
         return;
     }
     DEV {
-        const NamespaceString nss(_indexCatalogEntry->ns());
-        invariant(!opCtx->lockState()->isCollectionLockedForMode(nss.ns(), MODE_X));
+        invariant(!opCtx->lockState()->isCollectionLockedForMode(nss, MODE_X));
         invariant(!opCtx->lockState()->isDbLockedForMode(nss.db(), MODE_X));
     }
 
diff --git a/src/mongo/db/index_builds_coordinator.cpp b/src/mongo/db/index_builds_coordinator.cpp
index 3b8c0c4800f..daca155a742 100644
--- a/src/mongo/db/index_builds_coordinator.cpp
+++ b/src/mongo/db/index_builds_coordinator.cpp
@@ -88,7 +88,7 @@ StatusWith<UUID> getCollectionUUID(OperationContext* opCtx, const NamespaceStrin
 void checkShardKeyRestrictions(OperationContext* opCtx,
                                const NamespaceString& nss,
                                const BSONObj& newIdxKey) {
-    invariant(opCtx->lockState()->isCollectionLockedForMode(nss.ns(), MODE_X));
+    invariant(opCtx->lockState()->isCollectionLockedForMode(nss, MODE_X));
 
     const auto metadata = CollectionShardingState::get(opCtx, nss)->getCurrentMetadata();
     if (!metadata->isSharded())
@@ -1081,7 +1081,7 @@ std::vector<BSONObj> IndexBuildsCoordinator::_addDefaultsAndFilterExistingIndexe
     Collection* collection,
     const NamespaceString& nss,
     const std::vector<BSONObj>& indexSpecs) {
-    invariant(opCtx->lockState()->isCollectionLockedForMode(nss.ns(), MODE_X));
+    invariant(opCtx->lockState()->isCollectionLockedForMode(nss, MODE_X));
     invariant(collection);
 
     // During secondary oplog application, the index specs have already been normalized in the
diff --git a/src/mongo/db/pipeline/pipeline_d.cpp b/src/mongo/db/pipeline/pipeline_d.cpp
index 773321d696c..28f10d4e401 100644
--- a/src/mongo/db/pipeline/pipeline_d.cpp
+++ b/src/mongo/db/pipeline/pipeline_d.cpp
@@ -105,7 +105,7 @@ StatusWith<unique_ptr<PlanExecutor, PlanExecutor::Deleter>> createRandomCursorEx
     Collection* coll, OperationContext* opCtx, long long sampleSize, long long numRecords) {
     // Verify that we are already under a collection lock. We avoid taking locks ourselves in this
     // function because double-locking forces any PlanExecutor we create to adopt a NO_YIELD policy.
-    invariant(opCtx->lockState()->isCollectionLockedForMode(coll->ns().ns(), MODE_IS));
+    invariant(opCtx->lockState()->isCollectionLockedForMode(coll->ns(), MODE_IS));
 
     static const double kMaxSampleRatioForRandCursor = 0.05;
     if (sampleSize > numRecords * kMaxSampleRatioForRandCursor || numRecords <= 100) {
@@ -305,7 +305,7 @@ void PipelineD::prepareCursorSource(Collection* collection,
     }
 
     // We are going to generate an input cursor, so we need to be holding the collection lock.
-    dassert(expCtx->opCtx->lockState()->isCollectionLockedForMode(nss.ns(), MODE_IS));
+    dassert(expCtx->opCtx->lockState()->isCollectionLockedForMode(nss, MODE_IS));
 
     if (!sources.empty()) {
         auto sampleStage = dynamic_cast<DocumentSourceSample*>(sources.front().get());
diff --git a/src/mongo/db/query/plan_executor_impl.cpp b/src/mongo/db/query/plan_executor_impl.cpp
index 88b0da30c31..5ce9ede3350 100644
--- a/src/mongo/db/query/plan_executor_impl.cpp
+++ b/src/mongo/db/query/plan_executor_impl.cpp
@@ -452,7 +452,7 @@ std::shared_ptr<CappedInsertNotifier> PlanExecutorImpl::_getCappedInsertNotifier
 
     // We can only wait if we have a collection; otherwise we should retry immediately when
     // we hit EOF.
-    dassert(_opCtx->lockState()->isCollectionLockedForMode(_nss.ns(), MODE_IS));
+    dassert(_opCtx->lockState()->isCollectionLockedForMode(_nss, MODE_IS));
     auto databaseHolder = DatabaseHolder::get(_opCtx);
     auto db = databaseHolder->getDb(_opCtx, _nss.db());
     invariant(db);
diff --git a/src/mongo/db/repl/oplog.cpp b/src/mongo/db/repl/oplog.cpp
index b383b1b0565..16166e15ca8 100644
--- a/src/mongo/db/repl/oplog.cpp
+++ b/src/mongo/db/repl/oplog.cpp
@@ -1434,26 +1434,17 @@ Status applyOperation_inlock(OperationContext* opCtx,
                 collection);
         requestNss = collection->ns();
         dassert(opCtx->lockState()->isCollectionLockedForMode(
-                    requestNss.ns(), supportsDocLocking() ? MODE_IX : MODE_X),
-                requestNss.ns());
+            requestNss, supportsDocLocking() ? MODE_IX : MODE_X));
     } else {
         uassert(ErrorCodes::InvalidNamespace,
                 "'ns' must be of type String",
                 fieldNs.type() == BSONType::String);
         const StringData ns = fieldNs.valuestrsafe();
         requestNss = NamespaceString(ns);
-        if (nsIsFull(ns)) {
-            if (supportsDocLocking()) {
-                // WiredTiger, and others requires MODE_IX since the applier threads driving
-                // this allow writes to the same collection on any thread.
-                dassert(opCtx->lockState()->isCollectionLockedForMode(ns, MODE_IX),
-                        requestNss.ns());
-            } else {
-                // mmapV1 ensures that all operations to the same collection are executed from
-                // the same worker thread, so it takes an exclusive lock (MODE_X)
-                dassert(opCtx->lockState()->isCollectionLockedForMode(ns, MODE_X), requestNss.ns());
-            }
-        }
+        invariant(requestNss.coll().size());
+        dassert(opCtx->lockState()->isCollectionLockedForMode(
+                    requestNss, supportsDocLocking() ? MODE_IX : MODE_X),
+                requestNss.ns());
         collection = db->getCollection(opCtx, requestNss);
     }
 
diff --git a/src/mongo/db/repl/sync_tail_test_fixture.cpp b/src/mongo/db/repl/sync_tail_test_fixture.cpp
index 7d7037d2ba3..e42d1a7d04f 100644
--- a/src/mongo/db/repl/sync_tail_test_fixture.cpp
+++ b/src/mongo/db/repl/sync_tail_test_fixture.cpp
@@ -153,7 +153,8 @@ void SyncTailTest::_testSyncApplyCrudOperation(ErrorCodes::Error expectedError,
         ASSERT_TRUE(opCtx);
         ASSERT_TRUE(opCtx->lockState()->isDbLockedForMode("test", MODE_IX));
         ASSERT_FALSE(opCtx->lockState()->isDbLockedForMode("test", MODE_X));
-        ASSERT_TRUE(opCtx->lockState()->isCollectionLockedForMode("test.t", MODE_IX));
+        ASSERT_TRUE(
+            opCtx->lockState()->isCollectionLockedForMode(NamespaceString("test.t"), MODE_IX));
         ASSERT_FALSE(opCtx->writesAreReplicated());
         ASSERT_TRUE(documentValidationDisabled(opCtx));
     };
diff --git a/src/mongo/db/s/collection_sharding_runtime.cpp b/src/mongo/db/s/collection_sharding_runtime.cpp
index c3dfb5618c4..05fbb152475 100644
--- a/src/mongo/db/s/collection_sharding_runtime.cpp
+++ b/src/mongo/db/s/collection_sharding_runtime.cpp
@@ -90,7 +90,7 @@ void CollectionShardingRuntime::setFilteringMetadata(OperationContext* opCtx,
                                                      CollectionMetadata newMetadata) {
     invariant(!newMetadata.isSharded() || !isNamespaceAlwaysUnsharded(_nss),
               str::stream() << "Namespace " << _nss.ns() << " must never be sharded.");
-    invariant(opCtx->lockState()->isCollectionLockedForMode(_nss.ns(), MODE_X));
+    invariant(opCtx->lockState()->isCollectionLockedForMode(_nss, MODE_X));
 
     _metadataManager->setFilteringMetadata(std::move(newMetadata));
 }
diff --git a/src/mongo/db/s/collection_sharding_state.cpp b/src/mongo/db/s/collection_sharding_state.cpp
index b9037015042..1ce7bd0f7b2 100644
--- a/src/mongo/db/s/collection_sharding_state.cpp
+++ b/src/mongo/db/s/collection_sharding_state.cpp
@@ -141,7 +141,7 @@ CollectionShardingState::CollectionShardingState(NamespaceString nss)
 CollectionShardingState* CollectionShardingState::get(OperationContext* opCtx,
                                                       const NamespaceString& nss) {
     // Collection lock must be held to have a reference to the collection's sharding state
-    dassert(opCtx->lockState()->isCollectionLockedForMode(nss.ns(), MODE_IS));
+    dassert(opCtx->lockState()->isCollectionLockedForMode(nss, MODE_IS));
 
     auto& collectionsMap = CollectionShardingStateMap::get(opCtx->getServiceContext());
     return &collectionsMap->getOrCreate(nss);
@@ -266,17 +266,17 @@ void CollectionShardingState::checkShardVersionOrThrow(OperationContext* opCtx)
 }
 
 void CollectionShardingState::enterCriticalSectionCatchUpPhase(OperationContext* opCtx, CSRLock&) {
-    invariant(opCtx->lockState()->isCollectionLockedForMode(_nss.ns(), MODE_X));
+    invariant(opCtx->lockState()->isCollectionLockedForMode(_nss, MODE_X));
     _critSec.enterCriticalSectionCatchUpPhase();
 }
 
 void CollectionShardingState::enterCriticalSectionCommitPhase(OperationContext* opCtx, CSRLock&) {
-    invariant(opCtx->lockState()->isCollectionLockedForMode(_nss.ns(), MODE_X));
+    invariant(opCtx->lockState()->isCollectionLockedForMode(_nss, MODE_X));
     _critSec.enterCriticalSectionCommitPhase();
 }
 
 void CollectionShardingState::exitCriticalSection(OperationContext* opCtx, CSRLock&) {
-    invariant(opCtx->lockState()->isCollectionLockedForMode(_nss.ns(), MODE_IX));
+    invariant(opCtx->lockState()->isCollectionLockedForMode(_nss, MODE_IX));
     _critSec.exitCriticalSection();
 }
 
diff --git a/src/mongo/db/s/migration_chunk_cloner_source_legacy.cpp b/src/mongo/db/s/migration_chunk_cloner_source_legacy.cpp
index f9a2fbe6144..20114169c40 100644
--- a/src/mongo/db/s/migration_chunk_cloner_source_legacy.cpp
+++ b/src/mongo/db/s/migration_chunk_cloner_source_legacy.cpp
@@ -341,7 +341,7 @@ void MigrationChunkClonerSourceLegacy::onInsertOp(OperationContext* opCtx,
                                                   const BSONObj& insertedDoc,
                                                   const repl::OpTime& opTime,
                                                   const bool fromPreparedTransactionCommit) {
-    dassert(opCtx->lockState()->isCollectionLockedForMode(_args.getNss().ns(), MODE_IX));
+    dassert(opCtx->lockState()->isCollectionLockedForMode(_args.getNss(), MODE_IX));
 
     BSONElement idElement = insertedDoc["_id"];
     if (idElement.eoo()) {
@@ -377,7 +377,7 @@ void MigrationChunkClonerSourceLegacy::onUpdateOp(OperationContext* opCtx,
                                                   const repl::OpTime& opTime,
                                                   const repl::OpTime& prePostImageOpTime,
                                                   const bool fromPreparedTransactionCommit) {
-    dassert(opCtx->lockState()->isCollectionLockedForMode(_args.getNss().ns(), MODE_IX));
+    dassert(opCtx->lockState()->isCollectionLockedForMode(_args.getNss(), MODE_IX));
 
     BSONElement idElement = updatedDoc["_id"];
     if (idElement.eoo()) {
@@ -413,7 +413,7 @@ void MigrationChunkClonerSourceLegacy::onDeleteOp(OperationContext* opCtx,
                                                   const repl::OpTime& opTime,
                                                   const repl::OpTime& preImageOpTime,
                                                   const bool fromPreparedTransactionCommit) {
-    dassert(opCtx->lockState()->isCollectionLockedForMode(_args.getNss().ns(), MODE_IX));
+    dassert(opCtx->lockState()->isCollectionLockedForMode(_args.getNss(), MODE_IX));
 
     BSONElement idElement = deletedDocId["_id"];
     if (idElement.eoo()) {
@@ -518,7 +518,7 @@ uint64_t MigrationChunkClonerSourceLegacy::getCloneBatchBufferAllocationSize() {
 Status MigrationChunkClonerSourceLegacy::nextCloneBatch(OperationContext* opCtx,
                                                         Collection* collection,
                                                         BSONArrayBuilder* arrBuilder) {
-    dassert(opCtx->lockState()->isCollectionLockedForMode(_args.getNss().ns(), MODE_IS));
+    dassert(opCtx->lockState()->isCollectionLockedForMode(_args.getNss(), MODE_IS));
 
     ElapsedTracker tracker(opCtx->getServiceContext()->getFastClockSource(),
                            internalQueryExecYieldIterations.load(),
@@ -557,7 +557,7 @@ Status MigrationChunkClonerSourceLegacy::nextCloneBatch(OperationContext* opCtx,
 Status MigrationChunkClonerSourceLegacy::nextModsBatch(OperationContext* opCtx,
                                                        Database* db,
                                                        BSONObjBuilder* builder) {
-    dassert(opCtx->lockState()->isCollectionLockedForMode(_args.getNss().ns(), MODE_IS));
+    dassert(opCtx->lockState()->isCollectionLockedForMode(_args.getNss(), MODE_IS));
 
     stdx::lock_guard<stdx::mutex> sl(_mutex);
 
diff --git a/src/mongo/db/s/shard_server_op_observer.cpp b/src/mongo/db/s/shard_server_op_observer.cpp
index e257deaee70..43653b40a2a 100644
--- a/src/mongo/db/s/shard_server_op_observer.cpp
+++ b/src/mongo/db/s/shard_server_op_observer.cpp
@@ -73,7 +73,7 @@ public:
         : _opCtx(opCtx), _nss(nss) {}
 
     void commit(boost::optional<Timestamp>) override {
-        invariant(_opCtx->lockState()->isCollectionLockedForMode(_nss.ns(), MODE_IX));
+        invariant(_opCtx->lockState()->isCollectionLockedForMode(_nss, MODE_IX));
 
         CatalogCacheLoader::get(_opCtx).notifyOfCollectionVersionUpdate(_nss);
 
diff --git a/src/mongo/db/storage/kv/kv_catalog.cpp b/src/mongo/db/storage/kv/kv_catalog.cpp
index 0642ba44ccb..8df05d06f0f 100644
--- a/src/mongo/db/storage/kv/kv_catalog.cpp
+++ b/src/mongo/db/storage/kv/kv_catalog.cpp
@@ -407,28 +407,28 @@ void KVCatalog::getAllCollections(std::vector<std::string>* out) const {
 }
 
 Status KVCatalog::newCollection(OperationContext* opCtx,
-                                StringData ns,
+                                const NamespaceString& nss,
                                 const CollectionOptions& options,
                                 KVPrefix prefix) {
-    invariant(opCtx->lockState()->isDbLockedForMode(nsToDatabaseSubstring(ns), MODE_X));
+    invariant(opCtx->lockState()->isDbLockedForMode(nss.db(), MODE_X));
 
-    const string ident = _newUniqueIdent(ns, "collection");
+    const string ident = _newUniqueIdent(nss.ns(), "collection");
 
     stdx::lock_guard<stdx::mutex> lk(_identsLock);
-    Entry& old = _idents[ns.toString()];
+    Entry& old = _idents[nss.toString()];
     if (!old.ident.empty()) {
         return Status(ErrorCodes::NamespaceExists, "collection already exists");
     }
 
-    opCtx->recoveryUnit()->registerChange(new AddIdentChange(this, ns));
+    opCtx->recoveryUnit()->registerChange(new AddIdentChange(this, nss.ns()));
 
     BSONObj obj;
     {
         BSONObjBuilder b;
-        b.append("ns", ns);
+        b.append("ns", nss.ns());
         b.append("ident", ident);
         BSONCollectionCatalogEntry::MetaData md;
-        md.ns = ns.toString();
+        md.ns = nss.ns();
         md.options = options;
         md.prefix = prefix;
         b.append("md", md.toBSON());
@@ -439,7 +439,7 @@ Status KVCatalog::newCollection(OperationContext* opCtx,
         return res.getStatus();
 
     old = Entry(ident, res.getValue());
-    LOG(1) << "stored meta data for " << ns << " @ " << res.getValue();
+    LOG(1) << "stored meta data for " << nss.ns() << " @ " << res.getValue();
     return Status::OK();
 }
 
diff --git a/src/mongo/db/storage/kv/kv_catalog.h b/src/mongo/db/storage/kv/kv_catalog.h
index bb54bb80019..514d7fef206 100644
--- a/src/mongo/db/storage/kv/kv_catalog.h
+++ b/src/mongo/db/storage/kv/kv_catalog.h
@@ -66,7 +66,7 @@ public:
      * @return error or ident for instance
      */
     Status newCollection(OperationContext* opCtx,
-                         StringData ns,
+                         const NamespaceString& ns,
                          const CollectionOptions& options,
                          KVPrefix prefix);
 
diff --git a/src/mongo/db/storage/kv/kv_collection_catalog_entry_test.cpp b/src/mongo/db/storage/kv/kv_collection_catalog_entry_test.cpp
index 80c1718ff57..0dc09150287 100644
--- a/src/mongo/db/storage/kv/kv_collection_catalog_entry_test.cpp
+++ b/src/mongo/db/storage/kv/kv_collection_catalog_entry_test.cpp
@@ -83,7 +83,7 @@ public:
             WriteUnitOfWork wuow(opCtx.get());
             const bool allocateDefaultSpace = true;
             ASSERT_OK(dbEntry->createCollection(
-                opCtx.get(), _nss.ns(), CollectionOptions(), allocateDefaultSpace));
+                opCtx.get(), _nss, CollectionOptions(), allocateDefaultSpace));
             wuow.commit();
         }
     }
diff --git a/src/mongo/db/storage/kv/kv_database_catalog_entry_base.cpp b/src/mongo/db/storage/kv/kv_database_catalog_entry_base.cpp
index 8860427123b..7709125ea7d 100644
--- a/src/mongo/db/storage/kv/kv_database_catalog_entry_base.cpp
+++ b/src/mongo/db/storage/kv/kv_database_catalog_entry_base.cpp
@@ -226,30 +226,29 @@ RecordStore* KVDatabaseCatalogEntryBase::getRecordStore(StringData ns) const {
 }
 
 Status KVDatabaseCatalogEntryBase::createCollection(OperationContext* opCtx,
-                                                    StringData ns,
+                                                    const NamespaceString& nss,
                                                     const CollectionOptions& options,
                                                     bool allocateDefaultSpace) {
     invariant(opCtx->lockState()->isDbLockedForMode(name(), MODE_X));
 
-    if (ns.empty()) {
-        return Status(ErrorCodes::BadValue, "Collection namespace cannot be empty");
-    }
+    invariant(nss.coll().size() > 0);
 
-    if (_collections.count(ns.toString())) {
-        invariant(_collections[ns.toString()]);
+    if (_collections.count(nss.toString())) {
+        invariant(_collections[nss.toString()]);
         return Status(ErrorCodes::NamespaceExists, "collection already exists");
     }
 
-    KVPrefix prefix = KVPrefix::getNextPrefix(NamespaceString(ns));
+    KVPrefix prefix = KVPrefix::getNextPrefix(nss);
 
     // need to create it
-    Status status = _engine->getCatalog()->newCollection(opCtx, ns, options, prefix);
+    Status status = _engine->getCatalog()->newCollection(opCtx, nss, options, prefix);
     if (!status.isOK())
         return status;
 
-    string ident = _engine->getCatalog()->getCollectionIdent(ns);
+    string ident = _engine->getCatalog()->getCollectionIdent(nss.ns());
 
-    status = _engine->getEngine()->createGroupedRecordStore(opCtx, ns, ident, options, prefix);
+    status =
+        _engine->getEngine()->createGroupedRecordStore(opCtx, nss.ns(), ident, options, prefix);
     if (!status.isOK())
         return status;
 
@@ -263,13 +262,13 @@ Status KVDatabaseCatalogEntryBase::createCollection(OperationContext* opCtx,
         }
     }
 
-    opCtx->recoveryUnit()->registerChange(new AddCollectionChange(opCtx, this, ns, ident));
+    opCtx->recoveryUnit()->registerChange(new AddCollectionChange(opCtx, this, nss.ns(), ident));
 
-    auto rs = _engine->getEngine()->getGroupedRecordStore(opCtx, ns, ident, options, prefix);
+    auto rs = _engine->getEngine()->getGroupedRecordStore(opCtx, nss.ns(), ident, options, prefix);
     invariant(rs);
 
-    _collections[ns.toString()] =
-        new KVCollectionCatalogEntry(_engine, _engine->getCatalog(), ns, ident, std::move(rs));
+    _collections[nss.toString()] = new KVCollectionCatalogEntry(
+        _engine, _engine->getCatalog(), nss.ns(), ident, std::move(rs));
 
     return Status::OK();
 }
diff --git a/src/mongo/db/storage/kv/kv_database_catalog_entry_base.h b/src/mongo/db/storage/kv/kv_database_catalog_entry_base.h
index f9307a11f7f..8e13dee9277 100644
--- a/src/mongo/db/storage/kv/kv_database_catalog_entry_base.h
+++ b/src/mongo/db/storage/kv/kv_database_catalog_entry_base.h
@@ -35,6 +35,8 @@
 
 #include "mongo/db/catalog/database_catalog_entry.h"
 
+#include "mongo/db/namespace_string.h"
+
 namespace mongo {
 
 class KVStorageEngineInterface;
@@ -68,7 +70,7 @@ public:
                                 IndexCatalogEntry* index) override = 0;
 
     Status createCollection(OperationContext* opCtx,
-                            StringData ns,
+                            const NamespaceString& nss,
                             const CollectionOptions& options,
                             bool allocateDefaultSpace) override;
 
diff --git a/src/mongo/db/storage/kv/kv_database_catalog_entry_test.cpp b/src/mongo/db/storage/kv/kv_database_catalog_entry_test.cpp
index f9f701f8096..d3fbb33b16f 100644
--- a/src/mongo/db/storage/kv/kv_database_catalog_entry_test.cpp
+++ b/src/mongo/db/storage/kv/kv_database_catalog_entry_test.cpp
@@ -39,6 +39,7 @@
 #include "mongo/db/storage/kv/kv_prefix.h"
 #include "mongo/db/storage/kv/kv_storage_engine.h"
 #include "mongo/stdx/memory.h"
+#include "mongo/unittest/death_test.h"
 #include "mongo/unittest/unittest.h"
 
 namespace mongo {
@@ -50,24 +51,13 @@ TEST_F(ServiceContextTest, CreateCollectionValidNamespace) {
     storageEngine.finishInit();
     KVDatabaseCatalogEntryMock dbEntry("mydb", &storageEngine);
     OperationContextNoop ctx;
-    ASSERT_OK(dbEntry.createCollection(&ctx, "mydb.mycoll", CollectionOptions(), true));
+    ASSERT_OK(
+        dbEntry.createCollection(&ctx, NamespaceString("mydb.mycoll"), CollectionOptions(), true));
     std::list<std::string> collectionNamespaces;
     dbEntry.getCollectionNamespaces(&collectionNamespaces);
     ASSERT_FALSE(collectionNamespaces.empty());
 }
 
-TEST_F(ServiceContextTest, CreateCollectionEmptyNamespace) {
-    KVStorageEngine storageEngine(
-        new DevNullKVEngine(), KVStorageEngineOptions{}, kvDatabaseCatalogEntryMockFactory);
-    storageEngine.finishInit();
-    KVDatabaseCatalogEntryMock dbEntry("mydb", &storageEngine);
-    OperationContextNoop ctx;
-    ASSERT_NOT_OK(dbEntry.createCollection(&ctx, "", CollectionOptions(), true));
-    std::list<std::string> collectionNamespaces;
-    dbEntry.getCollectionNamespaces(&collectionNamespaces);
-    ASSERT_TRUE(collectionNamespaces.empty());
-}
-
 /**
  * Derived class of devnull KV engine where createRecordStore is overridden to fail
  * on an empty namespace (provided by the test).
@@ -93,11 +83,22 @@ TEST_F(ServiceContextTest, CreateCollectionInvalidRecordStore) {
     storageEngine.finishInit();
     KVDatabaseCatalogEntryMock dbEntry("fail", &storageEngine);
     OperationContextNoop ctx;
-    ASSERT_NOT_OK(dbEntry.createCollection(&ctx, "fail.me", CollectionOptions(), true));
+    ASSERT_NOT_OK(
+        dbEntry.createCollection(&ctx, NamespaceString("fail.me"), CollectionOptions(), true));
     std::list<std::string> collectionNamespaces;
     dbEntry.getCollectionNamespaces(&collectionNamespaces);
     ASSERT_TRUE(collectionNamespaces.empty());
 }
 
+DEATH_TEST_F(ServiceContextTest, CreateCollectionEmptyNamespace, "Invariant failure") {
+    KVStorageEngine storageEngine(
+        new DevNullKVEngine(), KVStorageEngineOptions{}, kvDatabaseCatalogEntryMockFactory);
+    storageEngine.finishInit();
+    KVDatabaseCatalogEntryMock dbEntry("mydb", &storageEngine);
+    OperationContextNoop ctx;
+    Status status = dbEntry.createCollection(&ctx, NamespaceString(""), CollectionOptions(), true);
+}
+
+
 }  // namespace
 }  // namespace mongo
diff --git a/src/mongo/db/storage/kv/kv_engine_test_harness.cpp b/src/mongo/db/storage/kv/kv_engine_test_harness.cpp
index 9a18913ac5e..3e1e507ced6 100644
--- a/src/mongo/db/storage/kv/kv_engine_test_harness.cpp
+++ b/src/mongo/db/storage/kv/kv_engine_test_harness.cpp
@@ -299,8 +299,8 @@ TEST(KVCatalogTest, Coll1) {
     {
         MyOperationContext opCtx(engine);
         WriteUnitOfWork uow(&opCtx);
-        ASSERT_OK(
-            catalog->newCollection(&opCtx, "a.b", CollectionOptions(), KVPrefix::kNotPrefixed));
+        ASSERT_OK(catalog->newCollection(
+            &opCtx, NamespaceString("a.b"), CollectionOptions(), KVPrefix::kNotPrefixed));
         ASSERT_NOT_EQUALS("a.b", catalog->getCollectionIdent("a.b"));
         uow.commit();
     }
@@ -319,7 +319,9 @@ TEST(KVCatalogTest, Coll1) {
         MyOperationContext opCtx(engine);
         WriteUnitOfWork uow(&opCtx);
         catalog->dropCollection(&opCtx, "a.b").transitional_ignore();
-        catalog->newCollection(&opCtx, "a.b", CollectionOptions(), KVPrefix::kNotPrefixed)
+        catalog
+            ->newCollection(
+                &opCtx, NamespaceString("a.b"), CollectionOptions(), KVPrefix::kNotPrefixed)
             .transitional_ignore();
         uow.commit();
     }
@@ -344,8 +346,8 @@ TEST(KVCatalogTest, Idx1) {
     {
         MyOperationContext opCtx(engine);
         WriteUnitOfWork uow(&opCtx);
-        ASSERT_OK(
-            catalog->newCollection(&opCtx, "a.b", CollectionOptions(), KVPrefix::kNotPrefixed));
+        ASSERT_OK(catalog->newCollection(
+            &opCtx, NamespaceString("a.b"), CollectionOptions(), KVPrefix::kNotPrefixed));
         ASSERT_NOT_EQUALS("a.b", catalog->getCollectionIdent("a.b"));
         ASSERT_TRUE(catalog->isUserDataIdent(catalog->getCollectionIdent("a.b")));
         uow.commit();
@@ -428,8 +430,8 @@ TEST(KVCatalogTest, DirectoryPerDb1) {
     {  // collection
         MyOperationContext opCtx(engine);
         WriteUnitOfWork uow(&opCtx);
-        ASSERT_OK(
-            catalog->newCollection(&opCtx, "a.b", CollectionOptions(), KVPrefix::kNotPrefixed));
+        ASSERT_OK(catalog->newCollection(
+            &opCtx, NamespaceString("a.b"), CollectionOptions(), KVPrefix::kNotPrefixed));
         ASSERT_STRING_CONTAINS(catalog->getCollectionIdent("a.b"), "a/");
         ASSERT_TRUE(catalog->isUserDataIdent(catalog->getCollectionIdent("a.b")));
         uow.commit();
@@ -476,8 +478,8 @@ TEST(KVCatalogTest, Split1) {
     {
         MyOperationContext opCtx(engine);
         WriteUnitOfWork uow(&opCtx);
-        ASSERT_OK(
-            catalog->newCollection(&opCtx, "a.b", CollectionOptions(), KVPrefix::kNotPrefixed));
+        ASSERT_OK(catalog->newCollection(
+            &opCtx, NamespaceString("a.b"), CollectionOptions(), KVPrefix::kNotPrefixed));
         ASSERT_STRING_CONTAINS(catalog->getCollectionIdent("a.b"), "collection/");
         ASSERT_TRUE(catalog->isUserDataIdent(catalog->getCollectionIdent("a.b")));
         uow.commit();
@@ -524,8 +526,8 @@ TEST(KVCatalogTest, DirectoryPerAndSplit1) {
     {
         MyOperationContext opCtx(engine);
         WriteUnitOfWork uow(&opCtx);
-        ASSERT_OK(
-            catalog->newCollection(&opCtx, "a.b", CollectionOptions(), KVPrefix::kNotPrefixed));
+        ASSERT_OK(catalog->newCollection(
+            &opCtx, NamespaceString("a.b"), CollectionOptions(), KVPrefix::kNotPrefixed));
         ASSERT_STRING_CONTAINS(catalog->getCollectionIdent("a.b"), "a/collection/");
         ASSERT_TRUE(catalog->isUserDataIdent(catalog->getCollectionIdent("a.b")));
         uow.commit();
@@ -578,7 +580,8 @@ TEST(KVCatalogTest, RestartForPrefixes) {
         {
             MyOperationContext opCtx(engine);
             WriteUnitOfWork uow(&opCtx);
-            ASSERT_OK(catalog->newCollection(&opCtx, "a.b", CollectionOptions(), abCollPrefix));
+            ASSERT_OK(catalog->newCollection(
+                &opCtx, NamespaceString("a.b"), CollectionOptions(), abCollPrefix));
             ASSERT_NOT_EQUALS("a.b", catalog->getCollectionIdent("a.b"));
             ASSERT_TRUE(catalog->isUserDataIdent(catalog->getCollectionIdent("a.b")));
             uow.commit();
diff --git a/src/mongo/db/storage/kv/kv_storage_engine_test.cpp b/src/mongo/db/storage/kv/kv_storage_engine_test.cpp
index 9f5d748e7f9..935bef73175 100644
--- a/src/mongo/db/storage/kv/kv_storage_engine_test.cpp
+++ b/src/mongo/db/storage/kv/kv_storage_engine_test.cpp
@@ -70,7 +70,7 @@ public:
     StatusWith<std::string> createCollection(OperationContext* opCtx, NamespaceString ns) {
         AutoGetDb db(opCtx, ns.db(), LockMode::MODE_X);
         DatabaseCatalogEntry* dbce = _storageEngine->getDatabaseCatalogEntry(opCtx, ns.db());
-        auto ret = dbce->createCollection(opCtx, ns.ns(), CollectionOptions(), false);
+        auto ret = dbce->createCollection(opCtx, ns, CollectionOptions(), false);
         if (!ret.isOK()) {
             return ret;
         }
diff --git a/src/mongo/db/storage/wiredtiger/wiredtiger_record_store.cpp b/src/mongo/db/storage/wiredtiger/wiredtiger_record_store.cpp
index 425a1d470fd..8fa398b4fb0 100644
--- a/src/mongo/db/storage/wiredtiger/wiredtiger_record_store.cpp
+++ b/src/mongo/db/storage/wiredtiger/wiredtiger_record_store.cpp
@@ -2025,7 +2025,7 @@ std::unique_ptr<SeekableRecordCursor> StandardWiredTigerRecordStore::getCursor(
         // If we already have a snapshot we don't know what it can see, unless we know no one
         // else could be writing (because we hold an exclusive lock).
         invariant(!wru->inActiveTxn() ||
-                  opCtx->lockState()->isCollectionLockedForMode(_ns, MODE_X));
+                  opCtx->lockState()->isCollectionLockedForMode(NamespaceString(_ns), MODE_X));
         wru->setIsOplogReader();
     }
 
@@ -2076,7 +2076,7 @@ std::unique_ptr<SeekableRecordCursor> PrefixedWiredTigerRecordStore::getCursor(
         // If we already have a snapshot we don't know what it can see, unless we know no one
         // else could be writing (because we hold an exclusive lock).
         invariant(!wru->inActiveTxn() ||
-                  opCtx->lockState()->isCollectionLockedForMode(_ns, MODE_X));
+                  opCtx->lockState()->isCollectionLockedForMode(NamespaceString(_ns), MODE_X));
         wru->setIsOplogReader();
     }