Single-file public-domain/open source C libraries with minimal dependencies

Post by biokoda » Sat, Jan 23, 2016, 12:44 PM UTC

djcapelis wrote: post #21

biokoda wrote: post #20

Earlier quoted context omitted.

If all you're doing is passing pointers from one thread to another, lock free is not a very good choice. Try a trivial spinlock based implementation. It will outperform it easily.

I strongly doubt you're going to build a faster thread-safe workqueue by adding spinlocks to it, but if you think what I wrote is too slow, feel free to build something faster and show the speed difference in a benchmark. You can use the code in test/ if you'd like. The code I wrote does leave an optimization or two on the table. Apple's lockfree queue in GCD is faster than mine because of batching. It also has a ton…

Post by rat87 » Sat, Jan 23, 2016, 12:51 PM UTC

kyberias wrote: post #23

rat87 wrote: post #18

Plug for a tiny header library I wrote https://github.com/rtaycher/debug_print_h It's a little thing for simple printf debugging. I got tired as hell of using formatting strings. It prints line, file, and function, expression and value. Since it stands out /greppable it's easier to delete then random printfs. It has support for different colors(to make things stand out) and uses c99 _Generic to support different type…

But... isn't _Generic part of C11, not C99? You actually require C11. Big difference.

Post by biokoda » Sat, Jan 23, 2016, 1:44 PM UTC

djcapelis wrote: post #25

biokoda wrote: post #22

Earlier quoted context omitted.

Locking is cheap, switching a pointer around is cheap. The only expensive thing is waking up a thread that is waiting on a lock. Spinlocks avoid that problem, which is why they outperform other implementations in terms of throughput (of course inversely proportional to the amount of work you do during a lock). Atomic operations have a fixed cost. Spinlocks only really have a cost when contention is high. When you're…

I don't think you've got this quite right. Spinlocks require memory barriers. C11 atomics are, among other things, a standardized way to implement cross platform memory barriers without dropping into platform specific assembly.

Post by djcapelis » Sat, Jan 23, 2016, 2:02 PM UTC

biokoda wrote: post #26

djcapelis wrote: post #25

Earlier quoted context omitted.

I don't think you've got this quite right. Spinlocks require memory barriers. C11 atomics are, among other things, a standardized way to implement cross platform memory barriers without dropping into platform specific assembly.

The only way to test it out is with code. In my own tests spinlocks turned out to provide the highest throughput. I do not care about the problem enough anymore to go try out your implementation. If you implemented a lock free queue, you should be the one testing it out if it actually is better than a simple spinlock.

Post by fsloth » Sat, Jan 23, 2016, 2:40 PM UTC

chubot wrote: post #6

Uh, this stb library [1] seems to follow a horrible pattern: not only combining your code into a single .c file (which is fine, like the sqlite amalgamation), but putting the code into a single .h file. [2] I've never seen a C or C++ codebase that does this. Maybe you can rely on link-time deduplication, but it will still cause duplicate compilation, and thus increased compile times. I haven't thought it about it lat…