SERVER-22541 Manage aggregation cursors on global cursor manager.

Moves registration of aggregation cursors to the global cursor manager.
This simplifies the logic for acquiring locks and resolving view
namespaces within the getMore and killCursors commands.

1 files changed, 37 insertions, 11 deletions

diff --git a/src/mongo/db/db_raii.h b/src/mongo/db/db_raii.h
index 8060d06f000..42444775bad 100644
--- a/src/mongo/db/db_raii.h
+++ b/src/mongo/db/db_raii.h
@@ -35,6 +35,7 @@
 #include "mongo/db/concurrency/d_concurrency.h"
 #include "mongo/db/namespace_string.h"
 #include "mongo/db/operation_context.h"
+#include "mongo/db/stats/top.h"
 #include "mongo/db/views/view.h"
 #include "mongo/util/timer.h"
 
@@ -170,6 +171,36 @@ private:
 };
 
 /**
+ * RAII-style class which automatically tracks the operation namespace in CurrentOp and records the
+ * operation via Top upon destruction.
+ */
+class AutoStatsTracker {
+    MONGO_DISALLOW_COPYING(AutoStatsTracker);
+
+public:
+    /**
+     * Sets the namespace of the CurOp object associated with 'opCtx' to be 'nss' and starts the
+     * CurOp timer. 'lockType' describes which type of lock is held by this operation, and will be
+     * used for reporting via Top. If 'dbProfilingLevel' is not given, this constructor will acquire
+     * and then drop a database lock in order to determine the database's profiling level.
+     */
+    AutoStatsTracker(OperationContext* opCtx,
+                     const NamespaceString& nss,
+                     Top::LockType lockType,
+                     boost::optional<int> dbProfilingLevel);
+
+    /**
+     * Records stats about the current operation via Top.
+     */
+    ~AutoStatsTracker();
+
+private:
+    const Timer _timer;
+    OperationContext* _opCtx;
+    Top::LockType _lockType;
+};
+
+/**
  * RAII-style class, which would acquire the appropriate hierarchy of locks for obtaining
  * a particular collection and would retrieve a reference to the collection. In addition, this
  * utility will ensure that the read will be performed against an appropriately committed snapshot
@@ -236,8 +267,6 @@ public:
         : AutoGetCollectionForReadCommand(
               opCtx, nss, AutoGetCollection::ViewMode::kViewsForbidden) {}
 
-    ~AutoGetCollectionForReadCommand();
-
     Database* getDb() const {
         return _autoCollForRead->getDb();
     }
@@ -246,21 +275,18 @@ public:
         return _autoCollForRead->getCollection();
     }
 
-private:
-    OperationContext* const _opCtx;
-    const Timer _timer;
-
 protected:
     AutoGetCollectionForReadCommand(OperationContext* opCtx,
                                     const NamespaceString& nss,
                                     AutoGetCollection::ViewMode viewMode);
 
-    /**
-     * This protected section must come after the private section because
-     * AutoGetCollectionOrViewForRead needs access to _autoColl, but _autoColl must be initialized
-     * after _transaction.
-     */
+    // '_autoCollForRead' may need to be reset by AutoGetCollectionOrViewForReadCommand, so needs to
+    // be a boost::optional.
     boost::optional<AutoGetCollectionForRead> _autoCollForRead;
+
+    // This needs to be initialized after 'autoCollForRead', since we need to consult the Database
+    // object to get the profiling level. Thus, it needs to be a boost::optional.
+    boost::optional<AutoStatsTracker> _statsTracker;
 };
 
 /**