How does ICP canister handle asynchronous calls and event queue?

[MCLYang]

I think this is relevant as well.

Atomic messaging

As described here: A function that does not await in its body is guaranteed to execute atomically - in particular, the environment cannot change the state of the actor while the function is executing. If a function performs an await , however, atomicity is no longer guaranteed. Between suspension and resumption around the await , the state of the enclosing actor may change due to concurrent processing of other incoming actor messages. It is the programmer’s responsibility to guard against non-…

If no inter-canister call then everything is fine since the canister state won’t change when program is running. But the atomicity will be broken when inter-canister call happens and still await.

So in my case it should be okay. But getting involved with inter-canister call will be another story.