SERVER-81534 DDL locks musn't be acquired during step down or shutdown

Author: silviasuhu

src/mongo/db/repl/primary_only_service.cpp

@@ -514,14 +514,13 @@ void PrimaryOnlyService::onStepDown() {
                "numInstances"_attr = _activeInstances.size(),
                "numOperationContexts"_attr = _opCtxs.size());
 
+    _onServiceTermination();
     _interruptInstances(lk,
                         {ErrorCodes::InterruptedDueToReplStateChange,
                          "PrimaryOnlyService interrupted due to stepdown"});
 
     _setState(State::kPaused, lk);
     _rebuildStatus = Status::OK();
-
-    _afterStepDown();
 }
 
 void PrimaryOnlyService::shutdown() {
@@ -540,6 +539,7 @@ void PrimaryOnlyService::shutdown() {
 
         // If the _state is already kPaused, the instances have already been interrupted.
         if (_state != State::kPaused) {
+            _onServiceTermination();
             _interruptInstances(lk,
                                 {ErrorCodes::InterruptedAtShutdown,
                                  "PrimaryOnlyService interrupted due to shutdown"});

src/mongo/db/repl/primary_only_service.h

@@ -459,11 +459,9 @@ class PrimaryOnlyService {
     };
 
     /**
-     * Called at the end of the service stepdown procedure.
-     * In order to not block the stepdown procedure, no blocking work must be done in this
-     * function.
+     * Called as part of the POS onStepDown/onShutdown hooks before interrupting instances.
      */
-    virtual void _afterStepDown() {}
+    virtual void _onServiceTermination() {}
 
     /**
      * Called as part of onStepUp.  Queries the state document collection for this

src/mongo/db/s/sharding_ddl_coordinator_service.cpp

@@ -234,7 +234,7 @@ void ShardingDDLCoordinatorService::waitForOngoingCoordinatorsToFinish(
     }
 }
 
-void ShardingDDLCoordinatorService::_afterStepDown() {
+void ShardingDDLCoordinatorService::_onServiceTermination() {
     stdx::lock_guard lg(_mutex);
     _state = State::kPaused;
     _numCoordinatorsToWait = 0;

src/mongo/db/s/sharding_ddl_coordinator_service.h

@@ -121,7 +121,7 @@ class ShardingDDLCoordinatorService final : public repl::PrimaryOnlyService {
     ExecutorFuture<void> _rebuildService(std::shared_ptr<executor::ScopedTaskExecutor> executor,
                                          const CancellationToken& token) override;
 
-    void _afterStepDown() override;
+    void _onServiceTermination() override;
     size_t _countCoordinatorDocs(OperationContext* opCtx);
 
     void _transitionToRecovered(WithLock lk, OperationContext* opCtx);