gistfile1.rs

    pub unsafe fn allocMegaGroup(mblocks: nat) -> ~Block {
        let n = MBLOCK_GROUP_BLOCKS(mblocks);
        enum SearchResult<'a> {
            PerfectMatch(~Block),
            BestMatch(&'a mut BlockData, &'a mut BlockMeta),
            NoMatch
        }
        fn go<'a>(n: uint,
                  prev_link: &'a mut Option<~Block>,
                  best: Option<(&'a mut BlockData, &'a mut BlockMeta)>)
          -> SearchResult<'a> {
            match prev_link {
                &None => match best {
                    None => NoMatch,
                    Some((data, meta)) => BestMatch(data, meta)
                },
                &Some(_) if bd.meta.blocks as uint == n => PerfectMatch(prev_link.take().unwrap()),
                &Some(ref mut bd) => if (bd.meta.blocks as uint > n && match best {
                    None => true,
                    Some((_, ref best_meta)) => bd.meta.blocks < best_meta.blocks
                }) {
                    go(n, &mut bd.link.p, Some((&mut bd.data, &mut bd.meta)))
                } else {
                    go(n, &mut bd.link.p, best)
                }
            }
        }
        match go(n, &mut free_mblock_list.p, None) {
            // We found a perfect match and removed it from the list
            PerfectMatch(p) => return p,
            // Take our chunk off the end of the best match
            BestMatch(_, _) => fail!("ni"),
            // Nothing in the free list was big enough, so allocate
            NoMatch => fail!("ni"),
        }
    }