SERVER-25694 Eliminate race in PlanExecutor cleanup.

Ensures that a collection lock is held in at least MODE_IS while
deregistering a PlanExecutor from the cursor manager. Introduces new
PlanExecutor::dispose() and ClientCursor::dispose() methods that must be
called before destruction of those classes, and ensures they are called
before destruction. These calls will thread an OperationContext all the
way through to DocumentSource::dispose() for each stage in a Pipeline,
which will give DocumentSourceCursor a chance to acquire locks and
deregister its PlanExecutor if necessary.

1 files changed, 5 insertions, 4 deletions

diff --git a/src/mongo/db/catalog/capped_utils.cpp b/src/mongo/db/catalog/capped_utils.cpp
index 1140c54b1e9..6b4119d5a12 100644
--- a/src/mongo/db/catalog/capped_utils.cpp
+++ b/src/mongo/db/catalog/capped_utils.cpp
@@ -164,10 +164,11 @@ Status cloneCollectionAsCapped(OperationContext* opCtx,
 
     long long excessSize = fromCollection->dataSize(opCtx) - allocatedSpaceGuess;
 
-    std::unique_ptr<PlanExecutor> exec(InternalPlanner::collectionScan(
-        opCtx, fromNss.ns(), fromCollection, PlanExecutor::YIELD_MANUAL, InternalPlanner::FORWARD));
-
-    exec->setYieldPolicy(PlanExecutor::WRITE_CONFLICT_RETRY_ONLY, fromCollection);
+    auto exec = InternalPlanner::collectionScan(opCtx,
+                                                fromNss.ns(),
+                                                fromCollection,
+                                                PlanExecutor::WRITE_CONFLICT_RETRY_ONLY,
+                                                InternalPlanner::FORWARD);
 
     Snapshotted<BSONObj> objToClone;
     RecordId loc;