[ui] Correctly determine if a graph is being computed locally and update nodes' statuses accordingly

[cbentejac]

Description

This PR fixes two bugs related to local graph computations:

• When computing a graph in an instance of Meshroom, and opening the same computing graph in another instance of Meshroom, the second instance of Meshroom behaves as if it was performing the computations even though it was not. As a consequence, trying to open a new graph was failing (Meshroom would try stopping the computations, but fail since they were carried out by the first instance), and so was closing the instance, with a "Please stop any local computation before exiting Meshroom" error message. Only the chunks' statuses were taken into account to determine whether local computations were ongoing.
• When loading a new graph while the opened one was locally computing nodes, computations were automatically stopped to be able to load the new graph. However, the computing chunks' statuses were not being updated before the graphs were switched up. This meant that opening that previously computing graph again was leading to a display in which nodes appeared to be computing although there was no ongoing computations. The only way to get back to a correct state was manually unlocking the nodes and clearing the pending statuses.

Features list

• Take the Meshroom instance's session ID when determining whether computations are made locally, and not only the chunks' statuses.
• Clear locally submitted nodes before loading a new graph to avoid stopping the computations without updating the chunks' statuses.

[fabiencastan]

Should we not also change the meaning of isExtern?

Meshroom/meshroom/core/node.py

Line 435 in b08f835

def isExtern(self):

Instead of:

    def isExtern(self):
        return self._status.execMode == ExecMode.EXTERN

Use:

    def isExtern(self):
        return self._status.execMode == ExecMode.EXTERN or (
                self._status.execMode == ExecMode.LOCAL and self._status.sessionUid != sessionUi)

[cbentejac]

Should we not also change the meaning of isExtern?

Meshroom/meshroom/core/node.py

Line 435 in b08f835

def isExtern(self):

Instead of:

    def isExtern(self):
        return self._status.execMode == ExecMode.EXTERN

Use:

    def isExtern(self):
        return self._status.execMode == ExecMode.EXTERN or (
                self._status.execMode == ExecMode.LOCAL and self._status.sessionUid != sessionUi)

You're totally right, it's done!