SERVER-48228 Move slot-based execution engine and supporting changes into the master branch

This is an initial commit for the slot-based execution engine (SBE) which contains:
   * Implementation of the core slot-based engine.
   * The SBE stage builder, which is responsible for translating a QuerySolution tree
     into an SBE plan.
   * Other changes necessary for integration with the find command.

Co-authored-by: Anton Korshunov <anton.korshunov@mongodb.com>
Co-authored-by: Justin Seyster <justin.seyster@mongodb.com>
Co-authored-by: David Storch <david.storch@mongodb.com>

1 files changed, 8 insertions, 5 deletions

diff --git a/src/mongo/db/pipeline/document_source_cursor.cpp b/src/mongo/db/pipeline/document_source_cursor.cpp
index f26604ce3ca..4aa7ce75d11 100644
--- a/src/mongo/db/pipeline/document_source_cursor.cpp
+++ b/src/mongo/db/pipeline/document_source_cursor.cpp
@@ -135,9 +135,12 @@ void DocumentSourceCursor::loadBatch() {
     PlanExecutor::ExecState state;
     Document resultObj;
 
-    AutoGetCollectionForRead autoColl(pExpCtx->opCtx, _exec->nss());
-    uassertStatusOK(repl::ReplicationCoordinator::get(pExpCtx->opCtx)
-                        ->checkCanServeReadsFor(pExpCtx->opCtx, _exec->nss(), true));
+    boost::optional<AutoGetCollectionForRead> autoColl;
+    if (_exec->lockPolicy() == PlanExecutor::LockPolicy::kLockExternally) {
+        autoColl.emplace(pExpCtx->opCtx, _exec->nss());
+        uassertStatusOK(repl::ReplicationCoordinator::get(pExpCtx->opCtx)
+                            ->checkCanServeReadsFor(pExpCtx->opCtx, _exec->nss(), true));
+    }
 
     _exec->restoreState();
 
@@ -160,8 +163,8 @@ void DocumentSourceCursor::loadBatch() {
 
         invariant(state == PlanExecutor::IS_EOF);
 
-        // Special case for tailable cursor -- EOF doesn't preclude more results, so keep the
-        // PlanExecutor alive.
+        // Special case for tailable cursor -- EOF doesn't preclude more results, so keep
+        // the PlanExecutor alive.
         if (pExpCtx->isTailableAwaitData()) {
             _exec->saveState();
             return;