SERVER-50984 Add CollectionPtr to replace usage of const Collection*

It implements a yieldable interface that is used to re-load the
Collection pointer from the catalog after a yield that released locks.
With lock-free reads and copy-on-write on Collection instances releasing
locks without notifying an AutoGetCollection at a higher level may cause
its pointers to dangle if a MODE_X writer installs a new Collection
instance in the catalog.

CollectionPtr should be passed by const reference so a yield can notify
all the way up.

1 files changed, 3 insertions, 3 deletions

diff --git a/src/mongo/dbtests/querytests.cpp b/src/mongo/dbtests/querytests.cpp
index 4ba7d36c94c..2bd9ba0a18c 100644
--- a/src/mongo/dbtests/querytests.cpp
+++ b/src/mongo/dbtests/querytests.cpp
@@ -74,7 +74,7 @@ public:
             }
             collection = _database->createCollection(&_opCtx, nss());
             wunit.commit();
-            _collection = collection;
+            _collection = std::move(collection);
         }
 
         addIndex(IndexSpec().addKey("a").unique(false));
@@ -129,7 +129,7 @@ protected:
             wunit.commit();
         }
         abortOnExit.dismiss();
-        _collection = collection.get();
+        _collection = collection.get().detached();
     }
 
     void insert(const char* s) {
@@ -161,7 +161,7 @@ protected:
     OldClientContext _context;
 
     Database* _database;
-    const Collection* _collection;
+    CollectionPtr _collection;
 };
 
 class FindOneOr : public Base {