CatgirlIntelligenceAgency/libraries/array/readme.md

Array Library

The array library offers easy allocation of large memory mapped files with less performance overhead than the traditional buffers[i].get(j)-style constructions java often leads to given its suffocating 2 Gb ByteBuffer size limitation.

It accomplishes this by delegating block oerations down to the appropriate page. If the operation crosses a page boundary, it is not delegated and a bit slower.

It's a very C++-style library that does unidiomatic things with interface default functions to get diamond inheritance.

Quick demo:

var array = LongArray.mmapForWriting(Path.of("/tmp/test"), 1<<16);

array.transformEach(50, 1000, (pos, val) -> Long.hashCode(pos));
array.quickSort(50, 1000);
if (array.binarySearch(array.get(100), 50, 1000) >= 0) {
    System.out.println("Nevermind, I found it!");
}

array.range(50, 1000).fill(0, 950, 1);
array.forEach(0, 100, (pos, val) -> {
    System.out.println(pos + ":" + val);
});

Query Buffers

The library offers many operations for sorting and dealing with sorted data. Especially noteworthy are the operations retain() and reject() in (IntArraySearch and LongArraySearch) which act upon the classes IntQueryBuffer and LongQueryBuffer; they keep or remove all items in the buffer that exist in the range. These are used to offer an intersection operation for the B-Tree that has in practice sub-linear run time.