delay add() and remove() for untangling

2 files changed, 70 insertions, 15 deletions

diff --git a/slobrok/src/vespa/slobrok/server/local_rpc_monitor_map.cpp b/slobrok/src/vespa/slobrok/server/local_rpc_monitor_map.cpp
index 3bea2018761..9013717f8b7 100644
--- a/slobrok/src/vespa/slobrok/server/local_rpc_monitor_map.cpp
+++ b/slobrok/src/vespa/slobrok/server/local_rpc_monitor_map.cpp
@@ -10,8 +10,29 @@ namespace slobrok {
 
 #pragma GCC diagnostic ignored "-Winline"
 
+void LocalRpcMonitorMap::DelayedTasks::PerformTask() {
+    {
+        std::vector<MUP> deleteAfterSwap;
+        std::swap(deleteAfterSwap, _deleteList);
+    }
+    std::vector<Event> todo;
+    std::swap(todo, _queue);
+    for (const auto & entry : todo) {
+        switch (entry.type) {
+        case EventType::ADD:
+            _target.doAdd(entry.mapping);
+            break;
+        case EventType::REMOVE:
+            _target.doRemove(entry.mapping);
+            break;
+        default:
+            abort();
+        }
+    }
+}
+
 LocalRpcMonitorMap::LocalRpcMonitorMap(FRT_Supervisor &supervisor)
-  : _delete(supervisor.GetScheduler()),
+  : _delayedTasks(supervisor.GetScheduler(), *this),
     _map(),
     _dispatcher(),
     _history(),
@@ -65,6 +86,14 @@ void LocalRpcMonitorMap::addLocal(const ServiceMapping &mapping,
 }
 
 void LocalRpcMonitorMap::add(const ServiceMapping &mapping) {
+    _delayedTasks.handleLater(Event::add(mapping));
+}
+
+void LocalRpcMonitorMap::remove(const ServiceMapping &mapping) {
+    _delayedTasks.handleLater(Event::remove(mapping));
+}
+
+void LocalRpcMonitorMap::doAdd(const ServiceMapping &mapping) {
     LOG(debug, "try add: mapping %s->%s",
         mapping.name.c_str(), mapping.spec.c_str());
     auto old = _map.find(mapping.name);
@@ -88,14 +117,14 @@ void LocalRpcMonitorMap::add(const ServiceMapping &mapping) {
         if (removed.up) {
             _dispatcher.remove(removed.mapping());
         }
-        _delete.later(std::move(removed.srv));
+        _delayedTasks.deleteLater(std::move(removed.srv));
     }
     auto [ iter, was_inserted ] =
         _map.try_emplace(mapping.name, globalService(mapping));
     LOG_ASSERT(was_inserted);
 }
 
-void LocalRpcMonitorMap::remove(const ServiceMapping &mapping) {
+void LocalRpcMonitorMap::doRemove(const ServiceMapping &mapping) {
     auto iter = _map.find(mapping.name);
     if (iter != _map.end()) {
         PerService removed = std::move(iter->second);
@@ -114,7 +143,7 @@ void LocalRpcMonitorMap::remove(const ServiceMapping &mapping) {
         if (removed.up) {
             _dispatcher.remove(removed.mapping());
         }
-        _delete.later(std::move(removed.srv));
+        _delayedTasks.deleteLater(std::move(removed.srv));
     } else {
         LOG(debug, "tried to remove non-existing mapping %s->%s",
             mapping.name.c_str(), mapping.spec.c_str());
@@ -135,7 +164,7 @@ void LocalRpcMonitorMap::notifyFailedRpcSrv(ManagedRpcServer *rpcsrv, std::strin
             if (removed.up) {
                 _dispatcher.remove(removed.mapping());
             }
-            _delete.later(std::move(removed.srv));
+            _delayedTasks.deleteLater(std::move(removed.srv));
         } else if (psd->up) {
             psd->up = false;
             _dispatcher.remove(psd->mapping());
diff --git a/slobrok/src/vespa/slobrok/server/local_rpc_monitor_map.h b/slobrok/src/vespa/slobrok/server/local_rpc_monitor_map.h
index 5557bca62f6..424ea82c6b5 100644
--- a/slobrok/src/vespa/slobrok/server/local_rpc_monitor_map.h
+++ b/slobrok/src/vespa/slobrok/server/local_rpc_monitor_map.h
@@ -29,26 +29,48 @@ class LocalRpcMonitorMap : public IRpcServerManager,
                            public MapListener
 {
 private:
-    class DeleteTask : public FNET_Task {
+    enum class EventType { ADD, REMOVE };
+
+    struct Event {
+        EventType type;
+        ServiceMapping mapping;
+        static Event add(const ServiceMapping &value) {
+            return Event{EventType::ADD, value};
+        }
+        static Event remove(const ServiceMapping &value) {
+            return Event{EventType::REMOVE, value};
+        }
+    };
+
+    class DelayedTasks : public FNET_Task {
         using MUP = std::unique_ptr<ManagedRpcServer>;
-        std::vector<MUP> _deleteList;
+        std::vector<MUP>    _deleteList;
+        std::vector<Event>  _queue;
+        LocalRpcMonitorMap &_target;
     public:
-        void later(MUP rpcsrv) {
+        void deleteLater(MUP rpcsrv) {
             _deleteList.emplace_back(std::move(rpcsrv));
             ScheduleNow();
         }
-        void PerformTask() override {
-            std::vector<MUP> deleteAfterSwap;
-            std::swap(deleteAfterSwap, _deleteList);
+
+        void handleLater(Event event) {
+            _queue.emplace_back(std::move(event));
+            ScheduleNow();
         }
-        DeleteTask(FNET_Scheduler *scheduler)
+
+        void PerformTask() override;
+
+        DelayedTasks(FNET_Scheduler *scheduler, LocalRpcMonitorMap &target)
           : FNET_Task(scheduler),
-            _deleteList()
+            _deleteList(),
+            _queue(),
+            _target(target)
         {}
-        ~DeleteTask() { Kill(); }
+
+        ~DelayedTasks() { Kill(); }
     };
 
-    DeleteTask _delete;
+    DelayedTasks _delayedTasks;
 
     struct PerService {
         bool up;
@@ -94,6 +116,9 @@ private:
     std::unique_ptr<MapSubscription> _subscription;
     
     PerService *lookup(ManagedRpcServer *rpcsrv);
+
+    void doAdd(const ServiceMapping &mapping);
+    void doRemove(const ServiceMapping &mapping);
     
 public:
     LocalRpcMonitorMap(FRT_Supervisor &_supervisor);
@@ -105,6 +130,7 @@ public:
     /** for use by register API, will call doneHandler() on inflight script */
     void addLocal(const ServiceMapping &mapping,
                   std::unique_ptr<ScriptCommand> inflight);
+
     void add(const ServiceMapping &mapping) override;
     void remove(const ServiceMapping &mapping) override;