//! Complete-key read-only block cache and pinned eviction guest probe.

use super::*;
use os_vfs_ro_cache::{Cache, Error, Key};

fn key(inode: u64, block: u64) -> Key {
    Key {volume: 1, mount_generation: 7, media_generation: 3,
        inode, block}
}

pub fn run(allocator: &mut memory::FrameAllocator) -> Result<(), &'static str> {
    let frames_before = allocator.remaining_pages();
    let mut cache = Cache::new();
    let first = key(2, 0);
    let second = key(2, 1);
    let third = key(3, 0);
    let fourth = key(4, 0);
    if cache.insert(first, [b'A'; 16]) != Ok(None)
        || cache.insert(second, [b'B'; 16]) != Ok(None)
        || cache.get(first) != Ok(Some([b'A'; 16]))
        || cache.insert(third, [b'C'; 16]) != Ok(Some(second))
        || cache.get(second) != Ok(None) {
        return Err("k1595-lru");
    }
    write_line("TURKOS/OS/K1595-CACHE: LRU=SECOND-EVICTED");

    let stale_mount = Key {mount_generation: 8, ..first};
    let changed_media = Key {media_generation: 4, ..first};
    if cache.get(stale_mount) != Ok(None)
        || cache.get(changed_media) != Ok(None)
        || cache.get(first) != Ok(Some([b'A'; 16])) {
        return Err("k1595-key");
    }
    write_line("TURKOS/OS/K1595-CACHE: GENERATION=MISS");

    cache.pin(first).map_err(|_| "k1595-pin-first")?;
    cache.pin(third).map_err(|_| "k1595-pin-third")?;
    let before_pinned = cache;
    if cache.insert(fourth, [b'D'; 16]) != Err(Error::Busy)
        || cache.invalidate_mount(1, 7) != Err(Error::Busy)
        || cache != before_pinned {
        return Err("k1595-pinned");
    }
    write_line("TURKOS/OS/K1595-CACHE: PINNED=RETAINED");

    cache.unpin(third).map_err(|_| "k1595-unpin-third")?;
    if cache.insert(fourth, [b'D'; 16]) != Ok(Some(third))
        || cache.get(first) != Ok(Some([b'A'; 16]))
        || cache.get(fourth) != Ok(Some([b'D'; 16])) {
        return Err("k1595-evict");
    }
    write_line("TURKOS/OS/K1595-CACHE: UNPINNED=EVICTED");

    cache.unpin(first).map_err(|_| "k1595-unpin-first")?;
    if cache.invalidate_mount(1, 7) != Ok(2)
        || cache.get(first) != Ok(None)
        || cache.get(fourth) != Ok(None)
        || allocator.remaining_pages() != frames_before {
        return Err("k1595-invalidate");
    }
    write_line("TURKOS/OS/K1595-CACHE: INVALIDATE=EMPTY FRAMES=UNCHANGED");
    Ok(())
}