rust/src/test/bench/task-perf-alloc-unwind.rs

// xfail-win32

extern mod std;

use std::list::{List, Cons, Nil};
use std::time::precise_time_s;

fn main() {
    let (repeat, depth) = if os::getenv(~"RUST_BENCH").is_some() {
        (50, 1000)
    } else {
        (10, 10)
    };

    run(repeat, depth);
}

fn run(repeat: int, depth: int) {
    for iter::repeat(repeat as uint) {
        debug!("starting %.4f", precise_time_s());
        do task::try {
            recurse_or_fail(depth, None)
        };
        debug!("stopping %.4f", precise_time_s());
    }
}

type nillist = List<()>;

// Filled with things that have to be unwound
enum st {
    st_({
        box: @nillist,
        unique: ~nillist,
        fn_box: fn@() -> @nillist,
        fn_unique: fn~() -> ~nillist,
        tuple: (@nillist, ~nillist),
        vec: ~[@nillist],
        res: r
    })
}

struct r {
  _l: @nillist,
}

impl r : Drop {
    fn finalize(&self) {}
}

fn r(l: @nillist) -> r {
    r {
        _l: l
    }
}

fn recurse_or_fail(depth: int, st: Option<st>) {
    if depth == 0 {
        debug!("unwinding %.4f", precise_time_s());
        fail;
    } else {
        let depth = depth - 1;

        let st = match st {
          None => {
            st_({
                box: @Nil,
                unique: ~Nil,
                fn_box: fn@() -> @nillist { @Nil::<()> },
                fn_unique: fn~() -> ~nillist { ~Nil::<()> },
                tuple: (@Nil, ~Nil),
                vec: ~[@Nil],
                res: r(@Nil)
            })
          }
          Some(st) => {
            let fn_box = st.fn_box;
            let fn_unique = copy st.fn_unique;

            st_({
                box: @Cons((), st.box),
                unique: ~Cons((), @*st.unique),
                fn_box: fn@() -> @nillist { @Cons((), fn_box()) },
                fn_unique: fn~(move fn_unique) -> ~nillist
                    { ~Cons((), @*fn_unique()) },
                tuple: (@Cons((), st.tuple.first()),
                        ~Cons((), @*st.tuple.second())),
                vec: st.vec + ~[@Cons((), st.vec.last())],
                res: r(@Cons((), st.res._l))
            })
          }
        };

        recurse_or_fail(depth, Some(move st));
    }
}