[eve7] Clear a scene's output after streaming it to a new connection

graf3d/eve7/inc/ROOT/REveScene.hxx

@@ -107,6 +107,7 @@ public:
 
    void StreamMotionChanges(nlohmann::json &arr);
    void SendChangesToSubscribers();
+   void ClearOutput();
 
    /// Output of the last StreamElements() or StreamRepresentationChanges().
    const std::string &GetOutputJson() const { return fOutputJson; }

graf3d/eve7/src/REveManager.cxx

@@ -889,6 +889,9 @@ void REveManager::StreamToNewConnection(unsigned connid)
    Send(connid, fWorld->fOutputJson);
    printf("   for now assume world-scene has no render data, binary-size=%d\n", fWorld->fTotalBinarySize);
    assert(fWorld->fTotalBinarySize == 0);
+   // Sent to this connection only; the next SendSceneChanges() must not send
+   // it to everyone again.
+   fWorld->ClearOutput();
 
    for (auto &c : fScenes->RefChildren()) {
       REveScene *scene = dynamic_cast<REveScene *>(c);
@@ -911,6 +914,7 @@ void REveManager::StreamToNewConnection(unsigned connid)
       } else {
          printf("   NOT sending binary, len = %d\n", scene->fTotalBinarySize);
       }
+      scene->ClearOutput();
    }
 
    fServerState.fCV.notify_all();
@@ -1302,6 +1306,9 @@ void REveManager::MIRExecThread()
             Send(mir->fConnId, scene->fOutputJson);
             if (scene->fTotalBinarySize > 0)
                SendBinary(mir->fConnId, &scene->fOutputBinary[0], scene->fTotalBinarySize);
+            // Streamed to this connection only; SendSceneChanges() below must
+            // not send it to every subscriber.
+            scene->ClearOutput();
          }
 
          SendSceneChanges();

graf3d/eve7/src/REveScene.cxx

@@ -371,6 +371,17 @@ void REveScene::SendChangesToSubscribers()
       }
       REX::gEve->SceneSubscriberWaitingResponse(client->fId);
    }
+   ClearOutput();
+}
+
+////////////////////////////////////////////////////////////////////////////////
+/// Drop the output of the last StreamElements() or
+/// StreamRepresentationChanges() once it has been sent, so that the next
+/// SendChangesToSubscribers() does not send it again. REveManager calls this
+/// after streaming a scene directly to one new connection.
+
+void REveScene::ClearOutput()
+{
    fOutputJson.clear();
    fOutputBinary.clear();
    fTotalBinarySize = 0;