Crate cql_u64

This crate implements various CqlType derivatives for storing u64 values in a CQL database.

Will allocate 8 bytes per value linked.

Benchmarks

Benchmarks supplied below are fairly rudimentary (and rounded) and are there to give a rough idea of relative costs. Full benchmark code can be found in github and can be run with rustup run nightly cargo bench.

Operation	Database dimensions	Mean time (ns)
Single point read	1	1 830 (+/- 300)
Single point read	4	11 130 (+/- 1 700)
Single point write	1	2 385 (+/- 600)
Single point write	4	12 500 (+/- 2 200)
Stream read 1 point	1	1 800 (+/- 300)
Stream read 1 point	4	11 050 (+/- 1 700)
Stream read 50 000 points	1	16 150 900 (+/- 200 000)
Stream read 50 000 points	4	18 900 000 (+/- 160 000)

Examples

The following creates a 1D database, writes 2 values to it, and then streams them into an array.

const N_VALUES_TO_READ: usize = 3;

let base_point = [0];
let value1 = 1;
let value3 = 5;

cql_db::create_db::<U64>(
    DATABASE_LOCATION,
    &[3]
);

cql_db::write_value::<U64>(
    DATABASE_LOCATION,
    &base_point,
    value1
);

cql_db::write_value::<U64>(
    DATABASE_LOCATION,
    &[base_point[0] + 2],
    value3
);

let mut result = [0; N_VALUES_TO_READ];
let mut stream = Cursor::new(Vec::new());

cql_db::read_to_stream::<U64>(
    DATABASE_LOCATION,
    &mut stream,
    &base_point,
    N_VALUES_TO_READ as u64
);

stream.seek(SeekFrom::Start(0)).unwrap();
unpack_stream(&mut stream, N_VALUES_TO_READ, |idx, value| {
    result[idx] = value
});

assert_eq!(result[0], value1);
assert_eq!(result[1], 0);
assert_eq!(result[2], value3);

Structs

U64	Static struct for declaring that you want to work with u64 values in a CQL database.

Functions

unpack_stream

Unpacks n_values of u64 from a stream, calling res with each value and it's index.