refactor: Synchronize naming of GC public API

[WojciechMazur]

• Rename public scalanative_* functions to scalanative_GC_* to keep Boehm GC naming convention (eg. GC_alloc, GC_collect)
• Synchronize remaining GC env variables to use GC_ prefix instead of SCALANATIVE_
• Merge spurious GCScalaNative.h into existing ScalaNativeGC.h header defining a common API GC should implement or stub.

[ekrich]

Great that you are finishing this up. Just as a note, there could be a couple more that can be shared with Boehm - https://github.com/ivmai/bdwgc/blob/master/docs/README.environment.

We also could support shared macros for special GC building if needed too.
https://github.com/ivmai/bdwgc/blob/master/docs/README.macros

[WojciechMazur]

Thank you for the links Eric! Yes, some of these might be integrated as well, but this might require some additional work. One interesting would be adding improved logging mechanism, altough the BoehmGC specificaiton seems to not be perfect. It is using:

• GC_PRINT_STATS - Turn on GC logging.
• GC_LOG_FILE - The name of the log file. Stderr by default.
• GC_PRINT_VERBOSE_STATS - Turn on even more logging.

I don't think we should follow that. Instead we should define GC_LOG_ENABLE which would define GC_PRINT_STATS for Boehm GC under the hood, and do similary with GC_LOG_VERBOSE which should set a BoehmGCs GC_PRINT_VERBOSE_STATS.

In the Immix/Commix to should redirect all outputs within DEBUG_PRINT macros to the log file if it's enabled. We would need to create some dedicated function for that.
We also probably should keep a seperate ENABLE_GC_STATS, GC_STATS_FILE only for the stats (we might adjust the naming here as well). These might produce CSV output and can be produced concurrently by multiple threads to different output files (in Commix).

Because it would require way more work I'd leave it for a follow up PR at some point in the future or if some volunteer shows up.

[ekrich]

Sure thing. I agree that the Boehm macros are not ideal.

I don't think we should follow that. Instead we should define GC_LOG_ENABLE which would define GC_PRINT_STATS for Boehm GC under the hood, and do similary with GC_LOG_VERBOSE which should set a BoehmGCs GC_PRINT_VERBOSE_STATS.

This is certainly a good idea.

[ekrich]

Oops, this should have been GC_FREE_RATIO. Seems to be fine in the code.