DER decoding of empty sequences is incredibly slow

[knecht]

DER decoding of empty sequences is incredibly slow

[XAMPPRocky]

Thank you for your issue! Yeah performance hasn't been a focus as the focus has been on correctness, I reckon this can be improved significantly by improving how parse_encoded_contents to better reduce work done.

[knecht]

It might have to do with parsing empty slices which results in errors. Both gdb and flamegraph show a lot of backtrace gathering related stack frames. Although no backtrace becomes visible, it looks as if they are being produced and discarded unless the occurrence of these frame is simply a result of the debugging procedure.

[XAMPPRocky]

Yeah, I reckon that's also it, we could probably make it better by making the loop internal to parse_encoded_contents, that way we can skip calling it entirely if there's zero length.

[XAMPPRocky]

I've fixed this with the above commit, this is the output of the above code post that commit. FYI in the future, it would be great if this was written with criterion or iai because then we can commit it to our benches. Thank you for your issue!

decoding 1x 206 bytes took 0 ms
decoding 100x 206 bytes took 6 ms
now decoding on 4 threads, 100x 206 bytes on each
decoding 100x 206 bytes took 10 ms
decoding 100x 206 bytes took 10 ms
decoding 100x 206 bytes took 10 ms
decoding 100x 206 bytes took 11 ms