Maya's Exiting Behaviour

[daniel-faust]

Hello,

I'm a bit confused here.

I have set up 2 callbacks in a plug-in. This plug-in also registers a bunch of locators.

One is MSceneMessage::kMayaExiting, and the other one is a MDGMessage::addNodeRemovedCallback

I have set up asserts in both callbacks, as well as one in the uninitializePlugin function. I use them to halt Maya to see the order in which these three functions are called.

When I have a scene containing locators from the plug-in, and close Maya by pressing the top-right "X" widget which is on the right of the minimize/maximize widget, then I only get a pop up from the kMayaExiting callback.

Shouldn't I first receive a couple of assertions in NodeRemoved (one for each node), then one for uninitializePlugin, and finally one for kMayaExiting.

My problem is that I need to unload the plug-in cleanly because else I do get a crash caused by some threading issues.

I know that I can use kMayaExiting in order to notify the plug-in that it should perform cleanup tasks and shut down any running thread immediately before kMayaExiting returns, but I also need to unload the entire scene cleanly (so that NodeRemoved gets called for each node); can this be done in the kMayaExiting callback?

Thanks in advance,
Daniel

[joojaa]

sholdnt you handle the cleanup in the node destructor?

[daniel-faust]

The plug-in is a bit complex by itself. Inside the plug-in there is a system which uses Maya as a front end. The locators it provides register themselves into the system which then creates an object linked to the corresponding locator. The object resides in a library which is linked against the mll, it is this library which imposes a lot of constraints, so that the locator can only be used as a gateway into and out of Maya. The main work of the plug-in is done in that library, in threads other than Maya's threads, and they only have access to the mirroring object inside the library and not to the locators.

Due to this the locators use the NodeAdded and NodeRemoved callback to know about their existence in the scene, if the exist, then a mirroring object exists in the library, else the mirroring object is deleted. This is to avoid the existence of a mirroring object when a node is deleted but still inside in the undo queue.

Since a NodeRemoved gets called at least once before a locator gets destroyed, there is no need to call the destructor. I insterted a MFileIO::new() in the kMayaExiting so that the scene closes cleanly, and this solves the problem of the NodeRemoved not being called, but not the problem of uninitializePlugin not being called (which isn't that dramatic). The important thing is to deregister those nodes cleanly from the library.