libusb > 1.0.7 broken

Sometimes I really feel like I don't understand what's going on with some projects and/or developers. The last time I looked at libusb source code, it was the 1.0.7 release - and everything was working as expected. When you submit a bulk/interrupt read request, then it would do a blocking read until the user-specified timeout has expired.

When recently strace()ing a program using libusb, I found out that with my currently-installed version (1.0.10a), it actually does a non-blocking read (REAPNDELAY), then uses select to implement a 1ms sleep, and starts all over again until the user-specified timeout has expired.

This is really bad. Not only clutters it your strace output with lots of noise, but it actually uses CPU, wastes cache lines, and probably most importantly: eats battery on notebooks!

I'll ask the libusb folks what kind of madness this is. Probably it's time to publicize libausb at some point (the libusb-wrapper that I implemented for async URB handling in the ctapi-cyberjack drivers) - and which now uses a copy of the libusb-1.0.7 functions for blocking bulk read/write, too.