JPerf

JPerf is a cool Java library that helps create perfect hash functions. You might have heard about perfect hashing before, but not everyone uses it. The main idea behind it is to make hash tables work better by figuring out the best hash function ahead of time, which is tailored just for the specific keys you’re using. This can really cut down on the average constant overhead and help save some memory too.

Why Use Perfect Hashing?

Finding that perfect hash function can be tricky, especially when you’re dealing with different cases. But once you have it, those run-time savings are worth it! Just keep in mind that while you're saving time later, creating the map initially might take a bit longer.

C Programming Language Users

If you’re into C programming, you probably know about gperf. It’s a more comprehensive tool that generates C source code for perfect hashes. A big shoutout goes to Douglas C Schmidt's paper; it was super helpful in making this library happen!

The Structure of JPerf

So how does JPerf work? Well, first off, you create a PerfectMapGenerator. After that, you add your key-value pairs into it and then ask it to whip up a Map for you. The result? A perfect hash based on what you've given it! The JPerf library has a general-purpose PerfectMapGenerator for Java Objects and also one specifically for Java Strings.

Future Plans for JPerf

Looking ahead, future versions of this library might even be able to generate source code or create a Class at runtime using the asm library. But here's something to think about: because of how Java works, these options might not give any real performance boost compared to the already generated Map. The only thing saved would be generation time—which could be quite significant!

If you're interested in checking out JPerf and downloading it yourself, click here: Download JPerf.