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

This reverts commit 045cd1070cae1e7827255850c2fe35194e48b24e.

1 files changed, 34 insertions, 8 deletions

diff --git a/src/mongo/db/db_raii.h b/src/mongo/db/db_raii.h
index b37112cb267..b6522caad2b 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 locks will be released when this object goes out of scope, therefore
+ * It is guaranteed that the lock will be released when this object goes out of scope, therefore
  * the database reference returned by this class should not be retained.
  */
 class AutoGetDb {
@@ -64,6 +64,33 @@ 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
@@ -100,7 +127,9 @@ 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.
+ * 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.
  *
  * 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.
@@ -114,11 +143,11 @@ public:
     ~AutoGetCollectionForRead();
 
     Database* getDb() const {
-        return _db.getDb();
+        return _autoColl.getDb();
     }
 
     Collection* getCollection() const {
-        return _coll;
+        return _autoColl.getCollection();
     }
 
 private:
@@ -127,10 +156,7 @@ private:
     const Timer _timer;
     OperationContext* const _txn;
     const ScopedTransaction _transaction;
-    const AutoGetDb _db;
-    const Lock::CollectionLock _collLock;
-
-    Collection* _coll;
+    const AutoGetCollection _autoColl;
 };
 
 /**