The idea of optimization is simple – delay in-block modification
until the end of a write action.
Q: Why the end of write action?
A: We have to publish the result of modification somewhere during
write action to be sure that the next read action will see the
updated result. We can't publish the result somewhere later
because we can't guarantee that the modification will be visible
to all customers.
In the case of out-of-block modification, we still have to publish
the result immediately because it is hard to evaluate the consequences
of the opposite decision yet.
If an out-of-block modification happens, we can drop all previous
in-block modifications from the queue because they don't make sense
due to invalidation of the entire KtModule.
A corner case is the analysis under write action. The delay means that
there is no longer any guarantee that all PSI changes will be reflected
into FIR tree immediately. So now we can guaranty only that at
the start of `analyze` block you will have the up-to-date FIR tree.
^KT-60611 Fixed
Dmitrii Gridin
ce900063c0