This is a temporary solution to fix the problem with sessions that
turned to be invalid at the time of analysis.
Currently, 'FirSession's and associated 'FirFile's are reused
between threads. When an exception, which might be an ordinary one
or 'ProcessCancelledException', occurs during an analysis of a module
file, a 'FirSession' for that module becomes invalid.
As there is currently a single resolution lock in the K2 IDE, other
threads might be waiting for resolution on the same session.
These threads are unaware that the session cannot be safely used
anymore, as it was correct before the lock.
The previous approach with cancelling analysis in all waiting threads
with manual 'ProcessCancelledException' throwing right inside the lock
showed it's incorrect. While some actions might be prepared to sudden
PCEs and can restart themselves, such behavior is not granted
by the platform.
The fix patches a few common places so the diagnostic list and
a file structure tree can be built safely. It is expected that in
some places exceptions caused by an inconsistent FIR tree can revive.
The right, ultimate fix to the problem involves modifying transformers,
so the FIR tree will mutate only when the analysis is complete. Although
it's planned work, it is expected to take quite a time.
Yan Zhulanow
cb825f664f