[Feature Request] Extend delay simulation for sync/async mixed graphs and allow delay variation during an episode.

[bheijden]

🚀 Feature

• Allow users to specify the expected computational delay of a node callback
• Allow delay variation (both computation and input delays).
• Relay effective output delay by appending it to output messages
• Infer effective callback output delay from computational delay, blocking characteristic of all input channels and their delays.

Motivation

The inter-node communication delays within a graph can be modeled as a combination of computational and communication delays. The delay of upstream nodes affect the effective delay of downstream nodes when intermediate connections are blocking. For realistic delay simulation in mixed graphs (graphs with both blocking and non-blocking connections), this should be modeled appropriately.

Moreover, delays are often not fixed but stochastic. Users should be allowed to vary (communication, computation) delays during an episodes. Allow delays to vary may lead to unintended behavior such as message reordering when a message is delayed by so much that it is "overtaken" by the following message. Should reordering be optional, or should we block it all together?

Checklist

• I have checked that there is no similar issue in the repo (required)