extsort

Exposes external sorting (i.e. on disk sorting) capability on arbitrarily sized iterator, even if the generated content of the iterator doesn't fit in memory. Once sorted, it returns a new sorted iterator. In order to remain efficient for all implementations, the crate doesn't handle serialization, but leaves that to the user.

Example

extern crate extsort;
extern crate byteorder;

use extsort::*;
use byteorder::{ReadBytesExt, WriteBytesExt};
use std::io::{Read, Write};

#[derive(Debug, Eq, PartialEq, Ord, PartialOrd)]
struct MyStruct(u32);

impl Sortable<MyStruct> for MyStruct {
    fn encode(item: &MyStruct, write: &mut Write) {
        write.write_u32::<byteorder::LittleEndian>(item.0).unwrap();
    }

    fn decode(read: &mut Read) -> Option<MyStruct> {
        read.read_u32::<byteorder::LittleEndian>()
            .ok()
            .map(MyStruct)
    }
}

let sorter = ExternalSorter::new();
let reversed_data = (0..1000).rev().map(MyStruct).into_iter();
let sorted_iter = sorter.sort(reversed_data).unwrap();
let sorted_data: Vec<MyStruct> = sorted_iter.collect();

let expected_data = (0..1000).map(MyStruct).collect::<Vec<MyStruct>>();
assert_eq!(sorted_data, expected_data);