1002 Add option to disable signal handlers in vt::finalize

[JacobDomagala]

Fixes #1002

[JacobDomagala]

Worth Noting:
Signal handlers are setup in Runtime constructor, so calling vt::finalize(disable_sig = true) and then vt::initialize() will not re-enable signal handlers.

[codecov]

Codecov Report

Merging #1027 into develop will decrease coverage by 0.00%.
The diff coverage is 78.57%.

@@             Coverage Diff             @@
##           develop    #1027      +/-   ##
===========================================
- Coverage    77.61%   77.60%   -0.01%     
===========================================
  Files          672      672              
  Lines        25761    25770       +9     
===========================================
+ Hits         19994    20000       +6     
- Misses        5767     5770       +3     

Impacted Files	Coverage Δ
src/vt/runtime/runtime.h	80.00% <ø> (ø)
src/vt/runtime/runtime.cc	61.00% <76.92%> (+0.11%)	⬆️
tests/unit/pipe/test_signal_cleanup.cc	100.00% <100.00%> (ø)

[pnstickne]

What if the option has to be controlled via the normal Args? (And perhaps defaults to true..)

What if the handlers always disabled on the finalize (and always re-added if specified) in initialize?

Is there a case that code might wish to only sometimes disable on finalize?

Is there a reason not to ensure the handlers are (re-setup) in initialize, if done?

[JacobDomagala]

Adding an option to re-enable handlers in initalize() is a good idea i think

[JacobDomagala]

Ok so i added the flag which will indicate whether the signal handlers were disabled on last vt::finalize() call. This flag is now used inside vt::initialize() together with finalized_ field which indicates if Runtime component is being re-initialized.

Based on the comment on top of the runtime.cc file i assume that contents of arg_config_ variable will be valid during vt::initialize() call (setupSignalHandler() and setupSignalHandlerINT() use arg_config_ to determine which handlers to setup)

After Runtime::finalize() is called but before the pack is destroyed, we extract the ArgConfig from the component and put it back in arg_config_ for use after.
From then on, until the vt::Runtime is destroyed or VT is re-initialized arg_config_ will contain the configuration.

[JacobDomagala]

@PhilMiller @lifflander Should we also disable termination handler?

[cz4rs]

the code looks good (I don't know if there's anything missing from the functional point of view?)

[pnstickne]

Could also be in the positive case: sig_handlers_attached_ = false;.

[lifflander]

@JacobDomagala From now on, can you start your branch names with just the issue number, not a #? Thanks!

[lifflander]

Looks good to me