SERVER-35480 Fix op observer for free monitoring

3 files changed, 26 insertions, 3 deletions

diff --git a/src/mongo/db/free_mon/free_mon_op_observer.cpp b/src/mongo/db/free_mon/free_mon_op_observer.cpp
index b3457a687a6..8dde8c8b53e 100644
--- a/src/mongo/db/free_mon/free_mon_op_observer.cpp
+++ b/src/mongo/db/free_mon/free_mon_op_observer.cpp
@@ -32,6 +32,7 @@
 
 #include "mongo/db/free_mon/free_mon_controller.h"
 #include "mongo/db/free_mon/free_mon_storage.h"
+#include "mongo/db/operation_context.h"
 
 namespace mongo {
 namespace {
@@ -44,6 +45,8 @@ bool isStandaloneOrPrimary(OperationContext* opCtx) {
                           repl::MemberState::RS_PRIMARY);
 }
 
+const auto getFreeMonDeleteState = OperationContext::declareDecoration<bool>();
+
 }  // namespace
 
 FreeMonOpObserver::FreeMonOpObserver() = default;
@@ -111,6 +114,18 @@ void FreeMonOpObserver::onUpdate(OperationContext* opCtx, const OplogUpdateEntry
     }
 }
 
+void FreeMonOpObserver::aboutToDelete(OperationContext* opCtx,
+                                      const NamespaceString& nss,
+                                      const BSONObj& doc) {
+
+    bool isFreeMonDoc = (nss == NamespaceString::kServerConfigurationNamespace) &&
+        (doc["_id"].str() == FreeMonStorage::kFreeMonDocIdKey);
+
+    // Set a flag that indicates whether the document to be delete is the free monitoring state
+    // document
+    getFreeMonDeleteState(opCtx) = isFreeMonDoc;
+}
+
 void FreeMonOpObserver::onDelete(OperationContext* opCtx,
                                  const NamespaceString& nss,
                                  OptionalCollectionUUID uuid,
@@ -125,7 +140,7 @@ void FreeMonOpObserver::onDelete(OperationContext* opCtx,
         return;
     }
 
-    if (deletedDoc.get()["_id"].str() == FreeMonStorage::kFreeMonDocIdKey) {
+    if (getFreeMonDeleteState(opCtx) == true) {
         auto controller = FreeMonController::get(opCtx->getServiceContext());
 
         if (controller != nullptr) {
diff --git a/src/mongo/db/free_mon/free_mon_op_observer.h b/src/mongo/db/free_mon/free_mon_op_observer.h
index c084c440dd2..05d16a21e4a 100644
--- a/src/mongo/db/free_mon/free_mon_op_observer.h
+++ b/src/mongo/db/free_mon/free_mon_op_observer.h
@@ -61,7 +61,7 @@ public:
 
     void aboutToDelete(OperationContext* opCtx,
                        const NamespaceString& nss,
-                       const BSONObj& doc) final {}
+                       const BSONObj& doc) final;
 
     void onDelete(OperationContext* opCtx,
                   const NamespaceString& nss,
diff --git a/src/mongo/db/free_mon/free_mon_processor.cpp b/src/mongo/db/free_mon/free_mon_processor.cpp
index c192ab21d93..4ff1411145e 100644
--- a/src/mongo/db/free_mon/free_mon_processor.cpp
+++ b/src/mongo/db/free_mon/free_mon_processor.cpp
@@ -791,6 +791,11 @@ void FreeMonProcessor::doAsyncMetricsComplete(
         auto opCtxUnique = client->makeOperationContext();
         FreeMonStorage::deleteState(opCtxUnique.get());
 
+        _state->setState(StorageStateEnum::pending);
+
+        // Clear out the in-memory state
+        _lastReadState = boost::none;
+
         return;
     }
 
@@ -945,7 +950,10 @@ void FreeMonProcessor::doNotifyOnDelete(Client* client) {
     // the same and stop free monitoring. We continue collecting though.
 
     // So we mark the internal state as disabled which stop registration and metrics send
-    _state->setState(StorageStateEnum::disabled);
+    _state->setState(StorageStateEnum::pending);
+
+    // Clear out the in-memory state
+    _lastReadState = boost::none;
 }
 
 void FreeMonProcessor::doNotifyOnRollback(Client* client) {