Revert "SERVER-19855 Do not perform shard version checking where not necessary"

This reverts commit 31716d2ae526d82d7d36464f6c9fae8b9f38542f.

7 files changed, 131 insertions, 156 deletions

diff --git a/src/mongo/db/db_raii.cpp b/src/mongo/db/db_raii.cpp
index a987062b11b..c7634052710 100644
--- a/src/mongo/db/db_raii.cpp
+++ b/src/mongo/db/db_raii.cpp
@@ -32,7 +32,6 @@
 
 #include "mongo/db/catalog/database_holder.h"
 #include "mongo/db/catalog/collection.h"
-#include "mongo/db/catalog/database.h"
 #include "mongo/db/client.h"
 #include "mongo/db/curop.h"
 #include "mongo/db/repl/replication_coordinator_global.h"
@@ -44,13 +43,6 @@ namespace mongo {
 AutoGetDb::AutoGetDb(OperationContext* txn, StringData ns, LockMode mode)
     : _dbLock(txn->lockState(), ns, mode), _db(dbHolder().get(txn, ns)) {}
 
-AutoGetCollection::AutoGetCollection(OperationContext* txn,
-                                     const NamespaceString& nss,
-                                     LockMode mode)
-    : _autoDb(txn, nss.db(), mode),
-      _collLock(txn->lockState(), nss.ns(), mode),
-      _coll(_autoDb.getDb() ? _autoDb.getDb()->getCollection(nss) : nullptr) {}
-
 AutoGetOrCreateDb::AutoGetOrCreateDb(OperationContext* txn, StringData ns, LockMode mode)
     : _transaction(txn, MODE_IX),
       _dbLock(txn->lockState(), ns, mode),
@@ -68,31 +60,48 @@ AutoGetOrCreateDb::AutoGetOrCreateDb(OperationContext* txn, StringData ns, LockM
 }
 
 AutoGetCollectionForRead::AutoGetCollectionForRead(OperationContext* txn, const std::string& ns)
-    : AutoGetCollectionForRead(txn, NamespaceString(ns)) {}
+    : _txn(txn),
+      _transaction(txn, MODE_IS),
+      _db(_txn, nsToDatabaseSubstring(ns), MODE_IS),
+      _collLock(_txn->lockState(), ns, MODE_IS),
+      _coll(NULL) {
+    _init(ns, nsToCollectionSubstring(ns));
+}
 
 AutoGetCollectionForRead::AutoGetCollectionForRead(OperationContext* txn,
                                                    const NamespaceString& nss)
-    : _txn(txn), _transaction(txn, MODE_IS), _autoColl(txn, nss, MODE_IS) {
+    : _txn(txn),
+      _transaction(txn, MODE_IS),
+      _db(_txn, nss.db(), MODE_IS),
+      _collLock(_txn->lockState(), nss.toString(), MODE_IS),
+      _coll(NULL) {
+    _init(nss.toString(), nss.coll());
+}
+
+void AutoGetCollectionForRead::_init(const std::string& ns, StringData coll) {
+    massert(28535, "need a non-empty collection name", !coll.empty());
+
     // We have both the DB and collection locked, which the prerequisite to do a stable shard
-    // version check
-    ensureShardVersionOKOrThrow(_txn, nss.ns());
+    // version check.
+    ensureShardVersionOKOrThrow(_txn, ns);
 
     auto curOp = CurOp::get(_txn);
     stdx::lock_guard<Client> lk(*_txn->getClient());
-
     // TODO: OldClientContext legacy, needs to be removed
     curOp->ensureStarted();
-    curOp->setNS_inlock(nss.ns());
+    curOp->setNS_inlock(ns);
 
     // At this point, we are locked in shared mode for the database by the DB lock in the
     // constructor, so it is safe to load the DB pointer.
-    if (_autoColl.getDb()) {
+    if (_db.getDb()) {
         // TODO: OldClientContext legacy, needs to be removed
-        curOp->enter_inlock(nss.ns().c_str(), _autoColl.getDb()->getProfilingLevel());
+        curOp->enter_inlock(ns.c_str(), _db.getDb()->getProfilingLevel());
+
+        _coll = _db.getDb()->getCollection(ns);
     }
 
-    if (getCollection()) {
-        if (auto minSnapshot = getCollection()->getMinimumVisibleSnapshot()) {
+    if (_coll) {
+        if (auto minSnapshot = _coll->getMinimumVisibleSnapshot()) {
             if (auto mySnapshot = _txn->recoveryUnit()->getMajorityCommittedSnapshot()) {
                 while (mySnapshot < minSnapshot) {
                     // Wait until a snapshot is available.
diff --git a/src/mongo/db/db_raii.h b/src/mongo/db/db_raii.h
index b6522caad2b..b37112cb267 100644
--- a/src/mongo/db/db_raii.h
+++ b/src/mongo/db/db_raii.h
@@ -45,7 +45,7 @@ class Collection;
  * RAII-style class, which acquires a lock on the specified database in the requested mode and
  * obtains a reference to the database. Used as a shortcut for calls to dbHolder().get().
  *
- * It is guaranteed that the lock will be released when this object goes out of scope, therefore
+ * It is guaranteed that locks will be released when this object goes out of scope, therefore
  * the database reference returned by this class should not be retained.
  */
 class AutoGetDb {
@@ -64,33 +64,6 @@ private:
 };
 
 /**
- * RAII-style class, which acquires a locks on the specified database and collection in the
- * requested mode and obtains references to both.
- *
- * It is guaranteed that locks will be released when this object goes out of scope, therefore
- * the database and the collection references returned by this class should not be retained.
- */
-class AutoGetCollection {
-    MONGO_DISALLOW_COPYING(AutoGetCollection);
-
-public:
-    AutoGetCollection(OperationContext* txn, const NamespaceString& nss, LockMode mode);
-
-    Database* getDb() const {
-        return _autoDb.getDb();
-    }
-
-    Collection* getCollection() const {
-        return _coll;
-    }
-
-private:
-    const AutoGetDb _autoDb;
-    const Lock::CollectionLock _collLock;
-    Collection* const _coll;
-};
-
-/**
  * RAII-style class, which acquires a lock on the specified database in the requested mode and
  * obtains a reference to the database, creating it was non-existing. Used as a shortcut for
  * calls to dbHolder().openDb(), taking care of locking details. The requested mode must be
@@ -127,9 +100,7 @@ private:
 
 /**
  * RAII-style class, which would acquire the appropritate hierarchy of locks for obtaining
- * a particular collection and would retrieve a reference to the collection. In addition, this
- * utility validates the shard version for the specified namespace and sets the current operation's
- * namespace for the duration while this object is alive.
+ * a particular collection and would retrieve a reference to the collection.
  *
  * It is guaranteed that locks will be released when this object goes out of scope, therefore
  * database and collection references returned by this class should not be retained.
@@ -143,11 +114,11 @@ public:
     ~AutoGetCollectionForRead();
 
     Database* getDb() const {
-        return _autoColl.getDb();
+        return _db.getDb();
     }
 
     Collection* getCollection() const {
-        return _autoColl.getCollection();
+        return _coll;
     }
 
 private:
@@ -156,7 +127,10 @@ private:
     const Timer _timer;
     OperationContext* const _txn;
     const ScopedTransaction _transaction;
-    const AutoGetCollection _autoColl;
+    const AutoGetDb _db;
+    const Lock::CollectionLock _collLock;
+
+    Collection* _coll;
 };
 
 /**
diff --git a/src/mongo/db/namespace_string.h b/src/mongo/db/namespace_string.h
index 9078fa2f7e4..28037eb24b4 100644
--- a/src/mongo/db/namespace_string.h
+++ b/src/mongo/db/namespace_string.h
@@ -269,10 +269,6 @@ private:
     size_t _dotIndex;
 };
 
-template <typename StreamType>
-StreamType& operator<<(StreamType& stream, const NamespaceString& value) {
-    return stream << value.ns();
-}
 
 // "database.a.b.c" -> "database"
 inline StringData nsToDatabaseSubstring(StringData ns) {
@@ -354,7 +350,7 @@ struct NamespaceDBEquals {
         return nsDBEquals(a, b);
     }
 };
+}
 
-}  // namespace mongo
 
 #include "mongo/db/namespace_string-inl.h"
diff --git a/src/mongo/db/range_deleter_db_env.cpp b/src/mongo/db/range_deleter_db_env.cpp
index 35279d0e58b..b9971f54b03 100644
--- a/src/mongo/db/range_deleter_db_env.cpp
+++ b/src/mongo/db/range_deleter_db_env.cpp
@@ -46,6 +46,7 @@
 
 namespace mongo {
 
+using std::endl;
 using std::string;
 
 /**
@@ -74,43 +75,44 @@ bool RangeDeleterDBEnv::deleteRange(OperationContext* txn,
 
     *deletedDocs = 0;
     ShardForceVersionOkModeBlock forceVersion(txn->getClient());
+    {
+        Helpers::RemoveSaver removeSaver("moveChunk", ns, taskDetails.options.removeSaverReason);
+        Helpers::RemoveSaver* removeSaverPtr = NULL;
+        if (serverGlobalParams.moveParanoia && !taskDetails.options.removeSaverReason.empty()) {
+            removeSaverPtr = &removeSaver;
+        }
 
-    Helpers::RemoveSaver removeSaver("moveChunk", ns, taskDetails.options.removeSaverReason);
-    Helpers::RemoveSaver* removeSaverPtr = NULL;
-    if (serverGlobalParams.moveParanoia && !taskDetails.options.removeSaverReason.empty()) {
-        removeSaverPtr = &removeSaver;
-    }
-
-    // log the opId so the user can use it to cancel the delete using killOp.
-    unsigned int opId = txn->getOpID();
-    log() << "Deleter starting delete for: " << ns << " from " << inclusiveLower << " -> "
-          << exclusiveUpper << ", with opId: " << opId;
-
-    try {
-        *deletedDocs =
-            Helpers::removeRange(txn,
-                                 KeyRange(ns, inclusiveLower, exclusiveUpper, keyPattern),
-                                 false, /*maxInclusive*/
-                                 writeConcern,
-                                 removeSaverPtr,
-                                 fromMigrate,
-                                 onlyRemoveOrphans);
-
-        if (*deletedDocs < 0) {
-            *errMsg = "collection or index dropped before data could be cleaned";
-            warning() << *errMsg;
+        // log the opId so the user can use it to cancel the delete using killOp.
+        unsigned int opId = txn->getOpID();
+        log() << "Deleter starting delete for: " << ns << " from " << inclusiveLower << " -> "
+              << exclusiveUpper << ", with opId: " << opId << endl;
+
+        try {
+            *deletedDocs =
+                Helpers::removeRange(txn,
+                                     KeyRange(ns, inclusiveLower, exclusiveUpper, keyPattern),
+                                     false, /*maxInclusive*/
+                                     writeConcern,
+                                     removeSaverPtr,
+                                     fromMigrate,
+                                     onlyRemoveOrphans);
+
+            if (*deletedDocs < 0) {
+                *errMsg = "collection or index dropped before data could be cleaned";
+                warning() << *errMsg << endl;
+
+                return false;
+            }
+
+            log() << "rangeDeleter deleted " << *deletedDocs << " documents for " << ns << " from "
+                  << inclusiveLower << " -> " << exclusiveUpper << endl;
+        } catch (const DBException& ex) {
+            *errMsg = str::stream() << "Error encountered while deleting range: "
+                                    << "ns" << ns << " from " << inclusiveLower << " -> "
+                                    << exclusiveUpper << ", cause by:" << causedBy(ex);
 
             return false;
         }
-
-        log() << "rangeDeleter deleted " << *deletedDocs << " documents for " << ns << " from "
-              << inclusiveLower << " -> " << exclusiveUpper;
-    } catch (const DBException& ex) {
-        *errMsg = str::stream() << "Error encountered while deleting range: "
-                                << "ns" << ns << " from " << inclusiveLower << " -> "
-                                << exclusiveUpper << ", cause by:" << causedBy(ex);
-
-        return false;
     }
 
     return true;
@@ -119,11 +121,12 @@ bool RangeDeleterDBEnv::deleteRange(OperationContext* txn,
 void RangeDeleterDBEnv::getCursorIds(OperationContext* txn,
                                      StringData ns,
                                      std::set<CursorId>* openCursors) {
-    AutoGetCollection autoColl(txn, NamespaceString(ns), MODE_IS);
-    if (!autoColl.getCollection())
+    AutoGetCollectionForRead ctx(txn, ns.toString());
+    Collection* collection = ctx.getCollection();
+    if (!collection) {
         return;
+    }
 
-    autoColl.getCollection()->getCursorManager()->getCursorIds(openCursors);
+    collection->getCursorManager()->getCursorIds(openCursors);
+}
 }
-
-}  // namespace mongo
diff --git a/src/mongo/db/s/migration_source_manager.cpp b/src/mongo/db/s/migration_source_manager.cpp
index 34a978ae083..d2e61cc402a 100644
--- a/src/mongo/db/s/migration_source_manager.cpp
+++ b/src/mongo/db/s/migration_source_manager.cpp
@@ -180,7 +180,7 @@ bool MigrationSourceManager::start(OperationContext* txn,
         return false;
     }
 
-    _nss = NamespaceString(ns);
+    _ns = ns;
     _min = min;
     _max = max;
     _shardKeyPattern = shardKeyPattern;
@@ -242,7 +242,7 @@ void MigrationSourceManager::logOp(OperationContext* txn,
     if (!_active)
         return;
 
-    if (_nss != ns)
+    if (_ns != ns)
         return;
 
     // no need to log if this is not an insertion, an update, or an actual deletion
@@ -270,8 +270,8 @@ void MigrationSourceManager::logOp(OperationContext* txn,
 
     if (op == 'u') {
         BSONObj fullDoc;
-        OldClientContext ctx(txn, _nss.ns(), false);
-        if (!Helpers::findById(txn, ctx.db(), _nss.ns().c_str(), idObj, fullDoc)) {
+        OldClientContext ctx(txn, _ns, false);
+        if (!Helpers::findById(txn, ctx.db(), _ns.c_str(), idObj, fullDoc)) {
             warning() << "logOpForSharding couldn't find: " << idObj << " even though should have"
                       << migrateLog;
             dassert(false);  // TODO: Abort the migration.
@@ -303,8 +303,8 @@ bool MigrationSourceManager::transferMods(OperationContext* txn,
         }
 
         // TODO: fix SERVER-16540 race
-        _xfer(txn, _nss.ns(), ctx.getDb(), &_deleted, b, "deleted", size, false);
-        _xfer(txn, _nss.ns(), ctx.getDb(), &_reload, b, "reload", size, true);
+        _xfer(txn, _ns, ctx.getDb(), &_deleted, b, "deleted", size, false);
+        _xfer(txn, _ns, ctx.getDb(), &_reload, b, "reload", size, true);
     }
 
     b.append("size", size);
@@ -316,9 +316,9 @@ bool MigrationSourceManager::storeCurrentLocs(OperationContext* txn,
                                               long long maxChunkSize,
                                               string& errmsg,
                                               BSONObjBuilder& result) {
-    AutoGetCollection autoColl(txn, _getNS(), MODE_IS);
+    AutoGetCollectionForRead ctx(txn, _getNS());
 
-    Collection* collection = autoColl.getCollection();
+    Collection* collection = ctx.getCollection();
     if (!collection) {
         errmsg = "ns not found, should be impossible";
         return false;
@@ -333,7 +333,7 @@ bool MigrationSourceManager::storeCurrentLocs(OperationContext* txn,
 
     if (idx == NULL) {
         errmsg = str::stream() << "can't find index with prefix " << _shardKeyPattern
-                               << " in storeCurrentLocs for " << _nss;
+                               << " in storeCurrentLocs for " << _ns;
         return false;
     }
 
@@ -420,7 +420,7 @@ bool MigrationSourceManager::storeCurrentLocs(OperationContext* txn,
                   << maxRecsWhenFull << " , the maximum chunk size is " << maxChunkSize
                   << " , average document size is " << avgRecSize << ". Found " << recCount
                   << " documents in chunk "
-                  << " ns: " << _nss << " " << _min << " -> " << _max << migrateLog;
+                  << " ns: " << _ns << " " << _min << " -> " << _max << migrateLog;
 
         result.appendBool("chunkTooBig", true);
         result.appendNumber("estimatedChunkSize", (long long)(recCount * avgRecSize));
@@ -440,7 +440,7 @@ bool MigrationSourceManager::clone(OperationContext* txn, string& errmsg, BSONOb
     int allocSize = 0;
 
     {
-        AutoGetCollection autoColl(txn, _getNS(), MODE_IS);
+        AutoGetCollectionForRead ctx(txn, _getNS());
 
         stdx::lock_guard<stdx::mutex> sl(_mutex);
         if (!_active) {
@@ -448,9 +448,9 @@ bool MigrationSourceManager::clone(OperationContext* txn, string& errmsg, BSONOb
             return false;
         }
 
-        Collection* collection = autoColl.getCollection();
+        Collection* collection = ctx.getCollection();
         if (!collection) {
-            errmsg = str::stream() << "collection " << _nss << " does not exist";
+            errmsg = str::stream() << "collection " << _ns << " does not exist";
             return false;
         }
 
@@ -462,7 +462,7 @@ bool MigrationSourceManager::clone(OperationContext* txn, string& errmsg, BSONOb
     bool isBufferFilled = false;
     BSONArrayBuilder clonedDocsArrayBuilder(allocSize);
     while (!isBufferFilled) {
-        AutoGetCollection autoColl(txn, _getNS(), MODE_IS);
+        AutoGetCollectionForRead ctx(txn, _getNS());
 
         stdx::lock_guard<stdx::mutex> sl(_mutex);
         if (!_active) {
@@ -471,9 +471,9 @@ bool MigrationSourceManager::clone(OperationContext* txn, string& errmsg, BSONOb
         }
 
         // TODO: fix SERVER-16540 race
-        Collection* collection = autoColl.getCollection();
+        Collection* collection = ctx.getCollection();
         if (!collection) {
-            errmsg = str::stream() << "collection " << _nss << " does not exist";
+            errmsg = str::stream() << "collection " << _ns << " does not exist";
             return false;
         }
 
@@ -597,9 +597,9 @@ void MigrationSourceManager::_xfer(OperationContext* txn,
     arr.done();
 }
 
-NamespaceString MigrationSourceManager::_getNS() const {
+std::string MigrationSourceManager::_getNS() const {
     stdx::lock_guard<stdx::mutex> lk(_mutex);
-    return _nss;
+    return _ns;
 }
 
 }  // namespace mongo
diff --git a/src/mongo/db/s/migration_source_manager.h b/src/mongo/db/s/migration_source_manager.h
index 4921610332d..0475e771fcd 100644
--- a/src/mongo/db/s/migration_source_manager.h
+++ b/src/mongo/db/s/migration_source_manager.h
@@ -34,7 +34,6 @@
 
 #include "mongo/base/disallow_copying.h"
 #include "mongo/bson/bsonobj.h"
-#include "mongo/db/namespace_string.h"
 #include "mongo/stdx/condition_variable.h"
 
 namespace mongo {
@@ -132,7 +131,7 @@ private:
                long long& size,
                bool explode);
 
-    NamespaceString _getNS() const;
+    std::string _getNS() const;
 
     // All member variables are labeled with one of the following codes indicating the
     // synchronization rules for accessing them.
@@ -167,7 +166,7 @@ private:
     // If a migration is currently active.
     bool _active{false};  // (MG)
 
-    NamespaceString _nss;      // (MG)
+    std::string _ns;           // (MG)
     BSONObj _min;              // (MG)
     BSONObj _max;              // (MG)
     BSONObj _shardKeyPattern;  // (MG)
diff --git a/src/mongo/s/d_split.cpp b/src/mongo/s/d_split.cpp
index 693a032877f..ad6a3f8434f 100644
--- a/src/mongo/s/d_split.cpp
+++ b/src/mongo/s/d_split.cpp
@@ -99,7 +99,7 @@ public:
              int,
              string& errmsg,
              BSONObjBuilder& result) {
-        const NamespaceString nss = NamespaceString(parseNs(dbname, jsobj));
+        std::string ns = parseNs(dbname, jsobj);
         BSONObj keyPattern = jsobj.getObjectField("keyPattern");
 
         if (keyPattern.isEmpty()) {
@@ -119,9 +119,8 @@ public:
             return false;
         }
 
-        AutoGetCollection autoColl(txn, nss, MODE_IS);
-
-        Collection* const collection = autoColl.getCollection();
+        AutoGetCollectionForRead ctx(txn, ns);
+        Collection* collection = ctx.getCollection();
         if (!collection) {
             errmsg = "ns not found";
             return false;
@@ -200,7 +199,7 @@ public:
                 ostringstream os;
                 os << "found missing value in key " << currKey << " for doc: "
                    << (obj.hasField("_id") ? obj.toString() : obj["_id"].toString());
-                log() << "checkShardingIndex for '" << nss << "' failed: " << os.str();
+                log() << "checkShardingIndex for '" << ns << "' failed: " << os.str();
 
                 errmsg = os.str();
                 return false;
@@ -263,7 +262,7 @@ public:
         //     access the actual data.
         //
 
-        const NamespaceString nss = NamespaceString(parseNs(dbname, jsobj));
+        const std::string ns = parseNs(dbname, jsobj);
         BSONObj keyPattern = jsobj.getObjectField("keyPattern");
 
         if (keyPattern.isEmpty()) {
@@ -296,9 +295,8 @@ public:
 
         {
             // Get the size estimate for this namespace
-            AutoGetCollection autoColl(txn, nss, MODE_IS);
-
-            Collection* const collection = autoColl.getCollection();
+            AutoGetCollectionForRead ctx(txn, ns);
+            Collection* collection = ctx.getCollection();
             if (!collection) {
                 errmsg = "ns not found";
                 return false;
@@ -374,7 +372,7 @@ public:
                 return true;
             }
 
-            log() << "request split points lookup for chunk " << nss << " " << min << " -->> "
+            log() << "request split points lookup for chunk " << ns << " " << min << " -->> "
                   << max;
 
             // We'll use the average object size and number of object to find approximately how many
@@ -444,7 +442,7 @@ public:
                     // Stop if we have enough split points.
                     if (maxSplitPoints && (numChunks >= maxSplitPoints)) {
                         log() << "max number of requested split points reached (" << numChunks
-                              << ") before the end of chunk " << nss << " " << min << " -->> "
+                              << ") before the end of chunk " << ns << " " << min << " -->> "
                               << max;
                         break;
                     }
@@ -488,7 +486,7 @@ public:
             for (set<BSONObj>::const_iterator it = tooFrequentKeys.begin();
                  it != tooFrequentKeys.end();
                  ++it) {
-                warning() << "possible low cardinality key detected in " << nss << " - key is "
+                warning() << "possible low cardinality key detected in " << ns << " - key is "
                           << prettyKey(idx->keyPattern(), *it);
             }
 
@@ -496,7 +494,7 @@ public:
             splitKeys.erase(splitKeys.begin());
 
             if (timer.millis() > serverGlobalParams.slowMS) {
-                warning() << "Finding the split vector for " << nss << " over " << keyPattern
+                warning() << "Finding the split vector for " << ns << " over " << keyPattern
                           << " keyCount: " << keyCount << " numSplits: " << splitKeys.size()
                           << " lookedAt: " << currCount << " took " << timer.millis() << "ms";
             }
@@ -510,7 +508,6 @@ public:
         result.append("splitKeys", splitKeys);
         return true;
     }
-
 } cmdSplitVector;
 
 class SplitChunkCommand : public Command {
@@ -555,9 +552,9 @@ public:
         // 1. check whether parameters passed to splitChunk are sound
         //
 
-        const NamespaceString nss = NamespaceString(parseNs(dbname, cmdObj));
-        if (!nss.isValid()) {
-            errmsg = str::stream() << "invalid namespace '" << nss << "' specified for command";
+        const string ns = parseNs(dbname, cmdObj);
+        if (ns.empty()) {
+            errmsg = "need to specify namespace in command";
             return false;
         }
 
@@ -624,12 +621,12 @@ public:
         // 2. lock the collection's metadata and get highest version for the current shard
         //
 
-        const string whyMessage(str::stream() << "splitting chunk [" << minKey << ", " << maxKey
-                                              << ") in " << nss);
-        auto scopedDistLock = grid.catalogManager(txn)->distLock(nss.ns(), whyMessage);
+        string whyMessage(str::stream() << "splitting chunk [" << minKey << ", " << maxKey
+                                        << ") in " << ns);
+        auto scopedDistLock = grid.catalogManager(txn)->distLock(ns, whyMessage);
 
         if (!scopedDistLock.isOK()) {
-            errmsg = str::stream() << "could not acquire collection lock for " << nss
+            errmsg = str::stream() << "could not acquire collection lock for " << ns
                                    << " to split chunk [" << minKey << "," << maxKey << ")"
                                    << causedBy(scopedDistLock.getStatus());
             warning() << errmsg;
@@ -638,7 +635,7 @@ public:
 
         // Always check our version remotely
         ChunkVersion shardVersion;
-        Status refreshStatus = shardingState->refreshMetadataNow(txn, nss.ns(), &shardVersion);
+        Status refreshStatus = shardingState->refreshMetadataNow(txn, ns, &shardVersion);
 
         if (!refreshStatus.isOK()) {
             errmsg = str::stream() << "splitChunk cannot split chunk "
@@ -677,7 +674,7 @@ public:
 
         // Get collection metadata
         const std::shared_ptr<CollectionMetadata> collMetadata(
-            shardingState->getCollectionMetadata(nss.ns()));
+            shardingState->getCollectionMetadata(ns));
         // With nonzero shard version, we must have metadata
         invariant(NULL != collMetadata);
 
@@ -747,9 +744,9 @@ public:
 
             // add the modified (new) chunk information as the update object
             BSONObjBuilder n(op.subobjStart("o"));
-            n.append(ChunkType::name(), Chunk::genID(nss.ns(), startKey));
+            n.append(ChunkType::name(), Chunk::genID(ns, startKey));
             nextChunkVersion.addToBSON(n, ChunkType::DEPRECATED_lastmod());
-            n.append(ChunkType::ns(), nss.ns());
+            n.append(ChunkType::ns(), ns);
             n.append(ChunkType::min(), startKey);
             n.append(ChunkType::max(), endKey);
             n.append(ChunkType::shard(), shardName);
@@ -757,7 +754,7 @@ public:
 
             // add the chunk's _id as the query part of the update statement
             BSONObjBuilder q(op.subobjStart("o2"));
-            q.append(ChunkType::name(), Chunk::genID(nss.ns(), startKey));
+            q.append(ChunkType::name(), Chunk::genID(ns, startKey));
             q.done();
 
             updates.append(op.obj());
@@ -780,7 +777,7 @@ public:
             BSONObjBuilder b;
             b.append("ns", ChunkType::ConfigNS);
             b.append("q",
-                     BSON("query" << BSON(ChunkType::ns(nss.ns())) << "orderby"
+                     BSON("query" << BSON(ChunkType::ns(ns)) << "orderby"
                                   << BSON(ChunkType::DEPRECATED_lastmod() << -1)));
             {
                 BSONObjBuilder bb(b.subobjStart("res"));
@@ -806,8 +803,8 @@ public:
 
         {
             ScopedTransaction transaction(txn, MODE_IX);
-            Lock::DBLock writeLk(txn->lockState(), nss.db(), MODE_IX);
-            Lock::CollectionLock collLock(txn->lockState(), nss.ns(), MODE_X);
+            Lock::DBLock writeLk(txn->lockState(), nsToDatabaseSubstring(ns), MODE_IX);
+            Lock::CollectionLock collLock(txn->lockState(), ns, MODE_X);
 
             // NOTE: The newShardVersion resulting from this split is higher than any
             // other chunk version, so it's also implicitly the newCollVersion
@@ -819,7 +816,7 @@ public:
             // TODO: Revisit this interface, it's a bit clunky
             newShardVersion.incMinor();
 
-            shardingState->splitChunk(txn, nss.ns(), min, max, splitKeys, newShardVersion);
+            shardingState->splitChunk(txn, ns, min, max, splitKeys, newShardVersion);
         }
 
         //
@@ -831,8 +828,8 @@ public:
             appendShortVersion(logDetail.subobjStart("left"), *newChunks[0]);
             appendShortVersion(logDetail.subobjStart("right"), *newChunks[1]);
 
-            grid.catalogManager(txn)->logChange(
-                txn->getClient()->clientAddress(true), "split", nss.ns(), logDetail.obj());
+            grid.catalogManager(txn)
+                ->logChange(txn->getClient()->clientAddress(true), "split", ns, logDetail.obj());
         } else {
             BSONObj beforeDetailObj = logDetail.obj();
             BSONObj firstDetailObj = beforeDetailObj.getOwned();
@@ -845,10 +842,8 @@ public:
                 chunkDetail.append("of", newChunksSize);
                 appendShortVersion(chunkDetail.subobjStart("chunk"), *newChunks[i]);
 
-                grid.catalogManager(txn)->logChange(txn->getClient()->clientAddress(true),
-                                                    "multi-split",
-                                                    nss.ns(),
-                                                    chunkDetail.obj());
+                grid.catalogManager(txn)->logChange(
+                    txn->getClient()->clientAddress(true), "multi-split", ns, chunkDetail.obj());
             }
         }
 
@@ -858,11 +853,10 @@ public:
             // Select chunk to move out for "top chunk optimization".
             KeyPattern shardKeyPattern(collMetadata->getKeyPattern());
 
-            AutoGetCollection autoColl(txn, nss, MODE_IS);
-
-            Collection* const collection = autoColl.getCollection();
+            AutoGetCollectionForRead ctx(txn, ns);
+            Collection* collection = ctx.getCollection();
             if (!collection) {
-                warning() << "will not perform top-chunk checking since " << nss
+                warning() << "will not perform top-chunk checking since " << ns
                           << " does not exist after splitting";
                 return true;
             }