get build <1s with CacheDir

[BBBmau]

Did a few implementations before getting to the Final result.

First I tried PreCompiled Headers but found that it just wasn't producing significant performance boosts if at all. I was getting at most 0.2 seconds of improvement with added on complexity to the codebase.

I then looked into some other methods and found that we can include ccache into our environment in SConstruct that brought it down to 1.4s

... rest of file ...
env = Environment(
  ENV=os.environ,
  CC='cache gcc',
  CXX='ccache g++',
... rest of file ...
)

This then led to looking into CacheDir which significantly improved the performance since it directly pulls the results from .scons_cache and checks if targets require rebuilding.

└─(20:57:47 on build-under-1s)──> scons -u -j$(nproc) --debug=time                                                                                       ──(Mon,Nov25)─┘
scons: Reading SConscript files ...
SConscript:/Users/mau/Dev/opendbc/opendbc/can/SConscript  took 2.591 ms
SConscript:/Users/mau/Dev/opendbc/opendbc/dbc/SConscript  took 3.831 ms
SConscript:/Users/mau/Dev/opendbc/SConscript  took 6.946 ms
SConscript:/Users/mau/Dev/opendbc/SConstruct  took 358.092 ms
scons: done reading SConscript files.
scons: Building targets ...
Retrieved `opendbc/can/common.os' from cache
Retrieved `opendbc/can/dbc.os' from cache
Command execution time: opendbc/can/common.os: 0.003291 seconds
Command execution time: opendbc/can/dbc.os: 0.002676 seconds
Retrieved `opendbc/can/parser.os' from cache
Command execution time: opendbc/can/parser.os: 0.001277 seconds
Retrieved `opendbc/can/packer.os' from cache
Command execution time: opendbc/can/packer.os: 0.001059 seconds
Retrieved `opendbc/can/packer_pyx.cpp' from cache
Command execution time: opendbc/can/packer_pyx.cpp: 0.002474 seconds
Retrieved `opendbc/can/libdbc.dylib' from cache
Command execution time: opendbc/can/libdbc.dylib: 0.001193 seconds
Retrieved `opendbc/can/packer_pyx.o' from cache
Command execution time: opendbc/can/packer_pyx.o: 0.002424 seconds
Retrieved `opendbc/can/parser_pyx.cpp' from cache
Command execution time: opendbc/can/parser_pyx.cpp: 0.001076 seconds
Retrieved `opendbc/can/packer_pyx.so' from cache
Command execution time: opendbc/can/packer_pyx.so: 0.000941 seconds
Retrieved `opendbc/can/parser_pyx.o' from cache
Command execution time: opendbc/can/parser_pyx.o: 0.003859 seconds
Retrieved `opendbc/dbc/tesla_radar_bosch_generated.dbc' from cache
Retrieved `opendbc/dbc/tesla_radar_continental_generated.dbc' from cache
Retrieved `opendbc/dbc/hyundai_kia_mando_corner_radar_generated.dbc' from cache
Retrieved `opendbc/dbc/hyundai_kia_mando_front_radar_generated.dbc' from cache
Retrieved `opendbc/can/parser_pyx.so' from cache
Retrieved `opendbc/dbc/toyota_tnga_k_pt_generated.dbc' from cache
Command execution time: opendbc/can/parser_pyx.so: 0.001665 seconds
Retrieved `opendbc/dbc/toyota_new_mc_pt_generated.dbc' from cache
Command execution time: opendbc/can: 0.000002 seconds
Retrieved `opendbc/dbc/toyota_nodsu_pt_generated.dbc' from cache
Retrieved `opendbc/dbc/toyota_rav4_prime_generated.dbc' from cache
Retrieved `opendbc/dbc/nissan_leaf_2018_generated.dbc' from cache
Retrieved `opendbc/dbc/nissan_x_trail_2017_generated.dbc' from cache
Retrieved `opendbc/dbc/subaru_forester_2017_generated.dbc' from cache
Retrieved `opendbc/dbc/subaru_outback_2019_generated.dbc' from cache
Retrieved `opendbc/dbc/subaru_global_2017_generated.dbc' from cache
Retrieved `opendbc/dbc/subaru_global_2020_hybrid_generated.dbc' from cache
Retrieved `opendbc/dbc/subaru_outback_2015_generated.dbc' from cache
Retrieved `opendbc/dbc/gm_global_a_powertrain_generated.dbc' from cache
Retrieved `opendbc/dbc/chrysler_ram_hd_generated.dbc' from cache
Retrieved `opendbc/dbc/chrysler_pacifica_2017_hybrid_generated.dbc' from cache
Retrieved `opendbc/dbc/chrysler_ram_dt_generated.dbc' from cache
Retrieved `opendbc/dbc/honda_pilot_2023_can_generated.dbc' from cache
Retrieved `opendbc/dbc/honda_crv_ex_2017_can_generated.dbc' from cache
Retrieved `opendbc/dbc/acura_rdx_2018_can_generated.dbc' from cache
Retrieved `opendbc/dbc/honda_fit_hybrid_2018_can_generated.dbc' from cache
Retrieved `opendbc/dbc/honda_crv_touring_2016_can_generated.dbc' from cache
Retrieved `opendbc/dbc/honda_accord_2018_can_generated.dbc' from cache
Retrieved `opendbc/dbc/honda_insight_ex_2019_can_generated.dbc' from cache
Retrieved `opendbc/dbc/honda_fit_ex_2018_can_generated.dbc' from cache
Retrieved `opendbc/dbc/acura_ilx_2016_can_generated.dbc' from cache
Retrieved `opendbc/dbc/honda_clarity_hybrid_2018_can_generated.dbc' from cache
Retrieved `opendbc/dbc/honda_crv_ex_2017_body_generated.dbc' from cache
Retrieved `opendbc/dbc/honda_odyssey_extreme_edition_2018_china_can_generated.dbc' from cache
Retrieved `opendbc/dbc/honda_crv_executive_2016_can_generated.dbc' from cache
Retrieved `opendbc/dbc/honda_civic_hatchback_ex_2017_can_generated.dbc' from cache
Retrieved `opendbc/dbc/honda_civic_ex_2022_can_generated.dbc' from cache
Retrieved `opendbc/dbc/honda_civic_touring_2016_can_generated.dbc' from cache
Retrieved `opendbc/dbc/acura_rdx_2020_can_generated.dbc' from cache
Retrieved `opendbc/dbc/honda_odyssey_exl_2018_generated.dbc' from cache
Retrieved `opendbc/dbc/tesla_radar_continental_generated.dbc' from cache
Retrieved `opendbc/dbc/tesla_radar_bosch_generated.dbc' from cache
Retrieved `opendbc/dbc/hyundai_kia_mando_front_radar_generated.dbc' from cache
Retrieved `opendbc/dbc/hyundai_kia_mando_corner_radar_generated.dbc' from cache
Command execution time: opendbc/dbc/acura_ilx_2016_can_generated.dbc: 0.028246 seconds
Command execution time: opendbc/dbc: 0.000002 seconds
Command execution time: opendbc: 0.000002 seconds
Command execution time: .: 0.000001 seconds
scons: done building targets.
Total SConsign sync time: 0.004131 seconds
Total build time: 0.534332 seconds
Total SConscript file execution time: 0.358252 seconds
Total SCons execution time: 0.054623 seconds
Total command execution time: 0.121457 seconds

This is ran on my M1 Max so I can imagine that when running on ThreadRipper we'll seen potentially builds at 0.3 seconds

Fixes #1528

[github-actions]

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[adeebshihadeh]

The issue is for an uncached build, so you need to do a scons -c first to properly evaluate this. I'll add that to the original description.

Also this PR only makes a difference in the case that you git clean -xdf then rebuild; opendbc is so small that it's not worth having a cache dir.