Similar to Rusts return and try, just use exceptions and pretty-print
them at the highest level (instead of presenting the user with a
stacktrace that's harder to read than the error alone).
Since the addition of doc regeneration - which also spawns a gir process
for every non-sys crate - the process is now incredibly slow and not
well suited for iterative development:
./generator.py --no-fmt 26.25s user 0.79s system 99% cpu 27.044 total
All gir processes are currently ran in serial (the generator waits for
one to complete before spawning the next process) even though there are
no inter-dependencies. Simply spawning all processes at once and
collecting their results + printing them in order after everything has
been spawned yields a significant speedup:
./generator.py --no-fmt 37.99s user 0.88s system 3285% cpu 1.183 total
Note: this is on a 32-core ThreadRipper. The improvement is more modest
on machines with less cores, and also depends on IO speed. A 4-core i5,
before and after:
./generator.py --no-fmt 30.24s user 0.76s system 99% cpu 31.055 total
./generator.py --no-fmt 57.78s user 0.88s system 763% cpu 7.685 total
That's still a sizable gain for simply not blocking on other tasks
anymore.
