brk/crates/brk_vecs/examples/main.rs

use std::{fs, path::Path};

use brk_core::Result;
use brk_vecs::{File, PAGE_SIZE};

fn main() -> Result<()> {
    let _ = fs::remove_dir_all("vecs");

    let file = File::open(Path::new("vecs"))?;

    // file.set_min_len(PAGE_SIZE * 1_000_000)?;

    let region1_i = file.create_region_if_needed("region1")?;

    {
        let layout = file.layout();
        assert!(layout.start_to_index().len() == 1);
        assert!(layout.start_to_index().first_key_value() == Some((&0, &0)));
        assert!(layout.start_to_hole().is_empty());

        let regions = file.regions();
        assert!(
            regions
                .get_region_index_from_id("region1")
                .is_some_and(|i| i == region1_i)
        );

        let region = file.get_region(region1_i)?;
        assert!(region.start() == 0);
        assert!(region.len() == 0);
        assert!(region.reserved() == PAGE_SIZE);
    }

    file.write_all_to_region(region1_i, &[0, 1, 2, 3, 4])?;

    {
        let region = file.get_region(region1_i)?;
        assert!(region.start() == 0);
        assert!(region.len() == 5);
        assert!(region.reserved() == PAGE_SIZE);

        assert!(file.mmap()[0..10] == [0, 1, 2, 3, 4, 0, 0, 0, 0, 0]);
    }

    file.write_all_to_region(region1_i, &[5, 6, 7, 8, 9])?;

    {
        let region = file.get_region(region1_i)?;
        assert!(region.start() == 0);
        assert!(region.len() == 10);
        assert!(region.reserved() == PAGE_SIZE);

        assert!(file.mmap()[0..10] == [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]);
    }

    file.write_all_to_region_at(region1_i, &[1, 2], 0)?;

    {
        let region = file.get_region(region1_i)?;
        assert!(region.start() == 0);
        assert!(region.len() == 10);
        assert!(region.reserved() == PAGE_SIZE);

        assert!(file.mmap()[0..10] == [1, 2, 2, 3, 4, 5, 6, 7, 8, 9]);
    }

    file.write_all_to_region_at(region1_i, &[10, 11, 12, 13, 14, 15, 16, 17, 18], 4)?;

    {
        let region = file.get_region(region1_i)?;
        assert!(region.start() == 0);
        assert!(region.len() == 13);
        assert!(region.reserved() == PAGE_SIZE);

        assert!(
            file.mmap()[0..20]
                == [
                    1, 2, 2, 3, 10, 11, 12, 13, 14, 15, 16, 17, 18, 0, 0, 0, 0, 0, 0, 0
                ]
        );
    }

    file.write_all_to_region_at(region1_i, &[1], 18)?;

    {
        let region = file.get_region(region1_i)?;
        assert!(region.start() == 0);
        assert!(region.len() == 19);
        assert!(region.reserved() == PAGE_SIZE);

        assert!(
            file.mmap()[0..20]
                == [
                    1, 2, 2, 3, 10, 11, 12, 13, 14, 15, 16, 17, 18, 0, 0, 0, 0, 0, 1, 0
                ]
        );
    }

    file.write_all_to_region_at(region1_i, &[1; 8000], 0)?;

    {
        let region = file.get_region(region1_i)?;
        assert!(region.start() == 0);
        assert!(region.len() == 8000);
        assert!(region.reserved() == PAGE_SIZE * 2);

        assert!(file.mmap()[0..8000] == [1; 8000]);
        assert!(file.mmap()[8000..8001] == [0]);
    }

    println!("Disk usage - pre sync: {}", file.disk_usage());
    file.sync_data()?;
    println!("Disk usage - post sync: {}", file.disk_usage());

    file.truncate_region(region1_i, 10)?;

    {
        let region = file.get_region(region1_i)?;
        assert!(region.start() == 0);
        assert!(region.len() == 10);
        assert!(region.reserved() == PAGE_SIZE * 2);
        // We only punch a hole in whole pages (4096 bytes)
        // Thus the last byte of the page where the is still data wasn't overwritten when truncating
        // And the first byte of the punched page was set to 0
        assert!(file.mmap()[4095..=4096] == [1, 0]);
    }

    file.sync_data()?;
    println!("Disk usage - post trunc: {}", file.disk_usage());

    file.remove_region(region1_i)?;

    println!("Disk usage - post remove: {}", file.disk_usage());

    {
        let regions = file.regions();
        let index_to_region = regions.index_to_region();
        assert!(index_to_region.len() == 1);
        assert!(index_to_region[0].is_none());
        assert!(regions.id_to_index().is_empty());

        let layout = file.layout();
        assert!(layout.start_to_index().is_empty());
        assert!(layout.start_to_hole().is_empty());
    }

    let region1_i = file.create_region_if_needed("region1")?;
    let region2_i = file.create_region_if_needed("region2")?;
    let region3_i = file.create_region_if_needed("region3")?;

    {
        let regions = file.regions();
        let index_to_region = regions.index_to_region();
        assert!(index_to_region.len() == 3);
        let region1 = file.get_region(region1_i)?;
        assert!(region1.start() == 0);
        assert!(region1.len() == 0);
        assert!(region1.reserved() == PAGE_SIZE);
        let region2 = file.get_region(region2_i)?;
        assert!(region2.start() == PAGE_SIZE);
        assert!(region2.len() == 0);
        assert!(region2.reserved() == PAGE_SIZE);
        let region3 = file.get_region(region3_i)?;
        assert!(region3.start() == PAGE_SIZE * 2);
        assert!(region3.len() == 0);
        assert!(region3.reserved() == PAGE_SIZE);
        let id_to_index = regions.id_to_index();
        assert!(id_to_index.len() == 3);
        assert!(id_to_index.get("region1") == Some(&0));
        assert!(id_to_index.get("region2") == Some(&1));
        assert!(id_to_index.get("region3") == Some(&2));

        let layout = file.layout();
        let start_to_index = layout.start_to_index();
        assert!(start_to_index.len() == 3);
        assert!(start_to_index.get(&0) == Some(&0));
        assert!(start_to_index.get(&PAGE_SIZE) == Some(&1));
        assert!(start_to_index.get(&(PAGE_SIZE * 2)) == Some(&2));
        assert!(layout.start_to_hole().is_empty());
    }

    file.remove_region(region2_i)?;

    {
        let regions = file.regions();
        let index_to_region = regions.index_to_region();
        assert!(index_to_region.len() == 3);
        let region1 = file.get_region(region1_i)?;
        assert!(region1.start() == 0);
        assert!(region1.len() == 0);
        assert!(region1.reserved() == PAGE_SIZE);
        assert!(file.get_region(region2_i).is_err());
        assert!(
            index_to_region
                .get(region2_i)
                .is_some_and(|opt| opt.is_none())
        );
        let region3 = file.get_region(region3_i)?;
        assert!(region3.start() == PAGE_SIZE * 2);
        assert!(region3.len() == 0);
        assert!(region3.reserved() == PAGE_SIZE);
        let id_to_index = regions.id_to_index();
        assert!(id_to_index.len() == 2);
        assert!(id_to_index.get("region1") == Some(&0));
        assert!(id_to_index.get("region2").is_none());
        assert!(id_to_index.get("region3") == Some(&2));

        let layout = file.layout();
        let start_to_index = layout.start_to_index();
        assert!(start_to_index.len() == 2);
        assert!(start_to_index.get(&0) == Some(&region1_i));
        assert!(start_to_index.get(&(PAGE_SIZE * 2)) == Some(&region3_i));
        let start_to_hole = layout.start_to_hole();
        assert!(start_to_hole.len() == 1);
        assert!(start_to_hole.get(&PAGE_SIZE) == Some(&PAGE_SIZE));

        drop(regions);
        drop(layout);
        assert!(file.remove_region(region2_i).is_ok_and(|o| o.is_none()));
    }

    let region2_i = file.create_region_if_needed("region2")?;

    {
        assert!(region2_i == 1)
    }

    file.remove_region(region2_i)?;

    {
        let regions = file.regions();
        let index_to_region = regions.index_to_region();
        assert!(index_to_region.len() == 3);
        let region1 = file.get_region(region1_i)?;
        assert!(region1.start() == 0);
        assert!(region1.len() == 0);
        assert!(region1.reserved() == PAGE_SIZE);
        assert!(file.get_region(region2_i).is_err());
        assert!(
            index_to_region
                .get(region2_i)
                .is_some_and(|opt| opt.is_none())
        );
        let region3 = file.get_region(region3_i)?;
        assert!(region3.start() == PAGE_SIZE * 2);
        assert!(region3.len() == 0);
        assert!(region3.reserved() == PAGE_SIZE);
        let id_to_index = regions.id_to_index();
        assert!(id_to_index.len() == 2);
        assert!(id_to_index.get("region1") == Some(&0));
        assert!(id_to_index.get("region2").is_none());
        assert!(id_to_index.get("region3") == Some(&2));

        let layout = file.layout();
        let start_to_index = layout.start_to_index();
        assert!(start_to_index.len() == 2);
        assert!(start_to_index.get(&0) == Some(&region1_i));
        assert!(start_to_index.get(&(PAGE_SIZE * 2)) == Some(&region3_i));
        let start_to_hole = layout.start_to_hole();
        assert!(start_to_hole.len() == 1);
        assert!(start_to_hole.get(&PAGE_SIZE) == Some(&PAGE_SIZE));

        drop(regions);
        drop(layout);
        assert!(file.remove_region(region2_i).is_ok_and(|o| o.is_none()));
    }

    file.write_all_to_region_at(region1_i, &[1; 8000], 0)?;

    {
        let regions = file.regions();
        let index_to_region = regions.index_to_region();
        assert!(index_to_region.len() == 3);
        let region1 = file.get_region(region1_i)?;
        assert!(region1.start() == 0);
        assert!(region1.len() == 8000);
        assert!(region1.reserved() == 2 * PAGE_SIZE);
        assert!(file.get_region(region2_i).is_err());
        assert!(
            index_to_region
                .get(region2_i)
                .is_some_and(|opt| opt.is_none())
        );
        let region3 = file.get_region(region3_i)?;
        assert!(region3.start() == PAGE_SIZE * 2);
        assert!(region3.len() == 0);
        assert!(region3.reserved() == PAGE_SIZE);
        let id_to_index = regions.id_to_index();
        assert!(id_to_index.len() == 2);
        assert!(id_to_index.get("region1") == Some(&0));
        assert!(id_to_index.get("region2").is_none());
        assert!(id_to_index.get("region3") == Some(&2));

        let layout = file.layout();
        let start_to_index = layout.start_to_index();
        assert!(start_to_index.len() == 2);
        assert!(start_to_index.get(&0) == Some(&region1_i));
        assert!(start_to_index.get(&(PAGE_SIZE * 2)) == Some(&region3_i));
        let start_to_hole = layout.start_to_hole();
        assert!(start_to_hole.is_empty());
    }

    let region2_i = file.create_region_if_needed("region2")?;

    {
        let regions = file.regions();
        let index_to_region = regions.index_to_region();
        assert!(index_to_region.len() == 3);
        let region1 = file.get_region(region1_i)?;
        assert!(region1.start() == 0);
        assert!(region1.len() == 8000);
        assert!(region1.reserved() == 2 * PAGE_SIZE);
        let region2 = file.get_region(region2_i)?;
        assert!(region2.start() == PAGE_SIZE * 3);
        assert!(region2.len() == 0);
        assert!(region2.reserved() == PAGE_SIZE);
        let region3 = file.get_region(region3_i)?;
        assert!(region3.start() == PAGE_SIZE * 2);
        assert!(region3.len() == 0);
        assert!(region3.reserved() == PAGE_SIZE);
        let id_to_index = regions.id_to_index();
        assert!(id_to_index.len() == 3);
        assert!(id_to_index.get("region1") == Some(&0));
        assert!(id_to_index.get("region2") == Some(&1));
        assert!(id_to_index.get("region3") == Some(&2));

        let layout = file.layout();
        let start_to_index = layout.start_to_index();
        assert!(start_to_index.len() == 3);
        assert!(start_to_index.get(&0) == Some(&region1_i));
        assert!(start_to_index.get(&(PAGE_SIZE * 2)) == Some(&region3_i));
        assert!(start_to_index.get(&(PAGE_SIZE * 3)) == Some(&region2_i));
        let start_to_hole = layout.start_to_hole();
        assert!(start_to_hole.is_empty());
    }

    file.remove_region(region3_i)?;

    {
        let regions = file.regions();
        let index_to_region = regions.index_to_region();
        assert!(index_to_region.len() == 3);
        let region1 = file.get_region(region1_i)?;
        assert!(region1.start() == 0);
        assert!(region1.len() == 8000);
        assert!(region1.reserved() == 2 * PAGE_SIZE);
        let region2 = file.get_region(region2_i)?;
        assert!(region2.start() == PAGE_SIZE * 3);
        assert!(region2.len() == 0);
        assert!(region2.reserved() == PAGE_SIZE);
        assert!(file.get_region(region3_i).is_err());
        let id_to_index = regions.id_to_index();
        assert!(id_to_index.len() == 2);
        assert!(id_to_index.get("region1") == Some(&0));
        assert!(id_to_index.get("region2") == Some(&1));
        assert!(id_to_index.get("region3").is_none());

        let layout = file.layout();
        let start_to_index = layout.start_to_index();
        assert!(start_to_index.len() == 2);
        assert!(start_to_index.get(&0) == Some(&region1_i));
        assert!(start_to_index.get(&(PAGE_SIZE * 3)) == Some(&region2_i));
        let start_to_hole = layout.start_to_hole();
        assert!(start_to_hole.get(&(PAGE_SIZE * 2)) == Some(&PAGE_SIZE));
    }

    file.write_all_to_region(region1_i, &[1; 8000])?;

    {
        let regions = file.regions();
        let index_to_region = regions.index_to_region();
        assert!(index_to_region.len() == 3);
        let region1 = file.get_region(region1_i)?;
        assert!(region1.start() == PAGE_SIZE * 4);
        assert!(region1.len() == 16_000);
        assert!(region1.reserved() == 4 * PAGE_SIZE);
        let region2 = file.get_region(region2_i)?;
        assert!(region2.start() == PAGE_SIZE * 3);
        assert!(region2.len() == 0);
        assert!(region2.reserved() == PAGE_SIZE);
        assert!(file.get_region(region3_i).is_err());
        let id_to_index = regions.id_to_index();
        assert!(id_to_index.len() == 2);
        assert!(id_to_index.get("region1") == Some(&0));
        assert!(id_to_index.get("region2") == Some(&1));
        assert!(id_to_index.get("region3").is_none());

        let layout = file.layout();
        let start_to_index = layout.start_to_index();
        assert!(start_to_index.len() == 2);
        assert!(start_to_index.get(&(PAGE_SIZE * 4)) == Some(&region1_i));
        assert!(start_to_index.get(&(PAGE_SIZE * 3)) == Some(&region2_i));
        let start_to_hole = layout.start_to_hole();
        assert!(start_to_hole.get(&0) == Some(&(PAGE_SIZE * 3)));
    }

    file.write_all_to_region(region2_i, &[1; 6000])?;

    let region4_i = file.create_region_if_needed("region4")?;
    file.remove_region(region2_i);
    file.remove_region(region4_i);

    dbg!(file.regions());
    dbg!(file.layout());

    Ok(())
}