SERVER-76987 Make oplog notification robust to step-up

1 files changed, 4 insertions, 0 deletions

diff --git a/src/mongo/db/repl/replication_coordinator_external_state_impl.cpp b/src/mongo/db/repl/replication_coordinator_external_state_impl.cpp
index 7c7640c7be5..ea28a21a1f3 100644
--- a/src/mongo/db/repl/replication_coordinator_external_state_impl.cpp
+++ b/src/mongo/db/repl/replication_coordinator_external_state_impl.cpp
@@ -516,6 +516,10 @@ OpTime ReplicationCoordinatorExternalStateImpl::onTransitionToPrimary(OperationC
                      << ReplicationCoordinator::newPrimaryMsg));
             wuow.commit();
         });
+    // As far as the storage system is concerned, we're still secondary here, and will be until we
+    // change readWriteAbility.  So new and resumed lock-free reads will read from lastApplied.  We
+    // just advanced lastApplied by writing the no-op, so we need to signal oplog waiters.
+    signalOplogWaiters();
     const auto loadLastOpTimeAndWallTimeResult = loadLastOpTimeAndWallTime(opCtx);
     fassert(28665, loadLastOpTimeAndWallTimeResult);
     auto opTimeToReturn = loadLastOpTimeAndWallTimeResult.getValue().opTime;