Add non-copying version of murmur3_32 that reads directly from a byte buffer

[eamsden]

I'm using murmur3 on very large in-memory buffers. My initial approach was to create a wrapper type around my buffers that implements read(), but the overhead of the call to this function for each 4 bytes in very large buffers made the hashing unreasonably slow.

This PR adds an implementation which directly hashes a byte buffer, without the necessity of copying into a local 4-byte buffer. It immediately and significantly improved the performance of my application.

[stusmall]

This looks fantastic. I appreciate you putting this together. It should knock two items off my list, better performance and an easy path to no_std support. I've got two asks for it:

1. The new method should get added to the unit tests, proptests and bench.rs. That's needed to merge.
2. Maybe name it murmur3_32_of_slice? I'm not hung up on that name so I can easily be talked into leaving it as is or to something else.

Once those are taken care of and CI turns green I'll merge it.

I'd love to get this added to all the other hashing methods. I'm happy to merge this without the others but probably won't be releasing a new version of the crate until I can find some time to do that. If you can help with that I'd appreciate it.

[eamsden]

@stusmall the name change is fine. And sure I can add it to tests and benchmarks.

I am seeing a clippy failure in CI but can't replicate it locally. Perhaps I'm doing something wrong? I passed the same flags to cargo clippy that CI passed to ~/.cargo/bin/clippy

[eamsden]

I haven't looked at the other hashing methods (we only use the 32 bit version) but if they're as easy as this was I can knock out the _of_slice versions for them into a short time.

[stusmall]

@stusmall the name change is fine. And sure I can add it to tests and benchmarks.

I am seeing a clippy failure in CI but can't replicate it locally. Perhaps I'm doing something wrong? I passed the same flags to cargo clippy that CI passed to ~/.cargo/bin/clippy

What version are you running? Clippy regularly adds checks with new releases. I'd try updating to the newest clippy.

Side note: it seems like this lint failure existed before your change. I'm guessing it must have been adding very recently. CI always uses the newest stable toolchain and the last run didn't have this warning but it is appearing on master now

[eamsden]

I'm using nix for my rust environment so I have clippy 1.60. I'll fiddle with it later today and get it all the way up to date.

[eamsden]

Also notably the benchmarks only build with rust nightly because of the testing feature, so I'll need to get that toolchain going.

[eamsden]

[eamsden]

@stusmall latest commit adds unit/prop tests. I'd like to get this passing CI and merged, and I can open and self-assign an issue to make the other of_slice variants in a separate PR.