instead of inside the fork.
Still doesn't seem to affect runtime. Good.
One nice side effect is jwack.py no longer needs to know anything about our
locks.
That way, if everything is locked, we can determine that with a single
token, reducing context switches.
But mostly this is good because the code is simpler.
Now t/curse passes again when parallelized (except for the countall
mismatch, since we haven't fixed the source of that problem yet). At least
it's consistent now.
There's a bunch of stuff rearranged in here, but the actual important
problem was that we were doing unlink() on the lock fifo even if ENXIO,
which meant a reader could connect in between ENXIO and unlink(), and thus
never get notified of the disconnection. This would cause the build to
randomly freeze.
atoi() was getting redundant, and unfortunately we can't easily load
helpers.py in some places where we'd want to, because it depends on vars.py.
So move it to its own module.
We'll have to stop using nonblocking reads, unfortunately. But this seems
to work better than nothing. There's still a race condition that could
theoretically make GNU make angry, unfortunately, since we briefly set the
socket to nonblocking.
But it seems to be pretty unsolvable in the current form; the problem is
that when you're nesting one jwack inside the other and the jobserver is GNU
make, there's no way to tell the parent jwack not to use up a token. Thus,
if you nest too deeply, it just deadlocks.
So this approach isn't really going to work the way it is.
