If we track how many pending batches a kickoff()
has in flight, we can endStep() it properly when
that number hits zero.
This double sync.WaitGroup trick is pretty neat.
Now we're thinking with portals...
Added some comments to prevent myself falling in
the trap of assuming we'll have runtime.NumCPU()
batches... rounding the batch size up means we'll
sometimes have fewer.
Change-Id: If50615c204485862462c240b9bbdfd4ddbad43b2
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/366142
Reviewed-by: Eric Boren <borenet@google.com>
420c8a505e