OpenSSL is much more portable and optimized (important for aarch64) and most systems already have a version.
Unfortunately, OpenSSL likes to break their ABI. Thankfully, Velocity's natives system is very flexible largely, so we can provide multiple versions of this crypto.
Versions of the dynamically-linked crypto were compiled on CentOS 7 (still supported until 2024, uses OpenSSL 1.0.x) and Debian 9 (the oldest distro including OpenSSL 1.1.0, whose LTS supports ends in 2022). The choice of distros was intended to cover most modern distributions (2014 and afterwards).
An ARM compilation (using Debian 9) will be published soon.
libdeflate is significantly faster than vanilla zlib, zlib-ng, and Cloudflare zlib. It is also MIT-licensed (so no licensing concerns). In addition, it simplifies a lot of the native code (something that's been tricky to get right).
While we're at it, I have also taken the time to fine-time compression in Velocity in general. Thanks to this work, native compression only requires one JNI call, an improvement from the more than 2 (sometimes up to 5) that were possible before. This optimization also extends to the existing Java compressors, though they require potentially two JNI calls.
zlib-ng boasts higher throughput than regular zlib, by combining patches
from Cloudflare, zlib, and ARM's improvements to zlib along with a more
modern codebase.
Profiling consistently shows that compression is the largest CPU expense
by far, so even a minor speed-up here is significant.
We now try to work within the boundaries given by the native. In the
case of Java natives, we work with byte arrays. With natives, always use
direct buffers.
However, the numbers do favor the natives, since they work with direct
byte buffers, without any copying. For the most part, this commit is
intended to improve the lives of Velocity users on Windows.
