SERVER-24755 fix explain to handle collection drop during yield

3 files changed, 16 insertions, 1 deletions

diff --git a/src/mongo/db/query/explain.cpp b/src/mongo/db/query/explain.cpp
index 944c730ebf4..ab63567f770 100644
--- a/src/mongo/db/query/explain.cpp
+++ b/src/mongo/db/query/explain.cpp
@@ -722,13 +722,18 @@ void Explain::explainStages(PlanExecutor* exec,
         executePlanStatus = exec->executePlan();
     }
 
+    // If executing the query failed because it was killed, then the collection may no longer be
+    // valid. We indicate this by setting our collection pointer to null.
+    if (executePlanStatus == ErrorCodes::QueryPlanKilled) {
+        collection = nullptr;
+    }
+
     // Get stats for the winning plan. If there is only a single candidate plan, it is considered
     // the winner.
     unique_ptr<PlanStageStats> winningStats(
         mps ? std::move(mps->getStats()->children[mps->bestPlanIdx()])
             : std::move(exec->getStats()));
 
-
     //
     // Use the stats trees to produce explain BSON.
     //
diff --git a/src/mongo/db/query/plan_executor.cpp b/src/mongo/db/query/plan_executor.cpp
index ec4d3bf0c1d..d162e998bab 100644
--- a/src/mongo/db/query/plan_executor.cpp
+++ b/src/mongo/db/query/plan_executor.cpp
@@ -530,12 +530,18 @@ Status PlanExecutor::executePlan() {
     }
 
     if (PlanExecutor::DEAD == state || PlanExecutor::FAILURE == state) {
+        if (killed()) {
+            return Status(ErrorCodes::QueryPlanKilled,
+                          str::stream() << "Operation aborted because: " << *_killReason);
+        }
+
         return Status(ErrorCodes::OperationFailed,
                       str::stream() << "Exec error: " << WorkingSetCommon::toStatusString(obj)
                                     << ", state: "
                                     << PlanExecutor::statestr(state));
     }
 
+    invariant(!killed());
     invariant(PlanExecutor::IS_EOF == state);
     return Status::OK();
 }
diff --git a/src/mongo/db/query/plan_executor.h b/src/mongo/db/query/plan_executor.h
index a321ded213d..207fc6765c2 100644
--- a/src/mongo/db/query/plan_executor.h
+++ b/src/mongo/db/query/plan_executor.h
@@ -298,6 +298,10 @@ public:
      * underlying tree without getting results back.
      *
      * If a YIELD_AUTO policy is set on this executor, then this will automatically yield.
+     *
+     * Returns ErrorCodes::QueryPlanKilled if the plan executor was killed during a yield. If this
+     * error occurs, it is illegal to subsequently access the collection, since it may have been
+     * dropped.
      */
     Status executePlan();