source code
// The Computer Language Benchmarks Game
// http://benchmarksgame.alioth.debian.org/
//
// contributed by the Rust Project Developers
// contributed by TeXitoi
// contributed by Cristi Cobzarenco
// contributed by Matt Brubeck
extern crate typed_arena;
extern crate rayon;
use typed_arena::Arena;
use rayon::prelude::*;
struct Tree<'a> {
children: Option<(&'a Tree<'a>, &'a Tree<'a>)>,
}
fn item_check(tree: &Tree) -> i32 {
if let Some((left, right)) = tree.children {
1 + item_check(right) + item_check(left)
} else {
1
}
}
fn bottom_up_tree<'r>(arena: &'r Arena<Tree<'r>>, depth: i32)
-> &'r Tree<'r> {
let mut tree = arena.alloc(Tree { children: None });
if depth > 0 {
let right = bottom_up_tree(arena, depth - 1);
let left = bottom_up_tree(arena, depth - 1);
tree.children = Some((left, right))
}
tree
}
fn inner(depth: i32, iterations: i32) -> String {
let chk: i32 = (0 .. iterations).into_par_iter().map(|_| {
let arena = Arena::new();
let a = bottom_up_tree(&arena, depth);
item_check(a)
}).sum();
format!("{}\t trees of depth {}\t check: {}", iterations, depth, chk)
}
fn main() {
let n = std::env::args().nth(1)
.and_then(|n| n.parse().ok())
.unwrap_or(10);
let min_depth = 4;
let max_depth = if min_depth + 2 > n { min_depth + 2 } else { n };
{
let arena = Arena::new();
let depth = max_depth + 1;
let tree = bottom_up_tree(&arena, depth);
println!("stretch tree of depth {}\t check: {}", depth, item_check(tree));
}
let long_lived_arena = Arena::new();
let long_lived_tree = bottom_up_tree(&long_lived_arena, max_depth);
let messages = (min_depth/2..max_depth/2 + 1).into_par_iter().map(|half_depth| {
let depth = half_depth * 2;
let iterations = 1 << ((max_depth - depth + min_depth) as u32);
inner(depth, iterations)
}).collect::<Vec<_>>();
for message in messages {
println!("{}", message);
}
println!("long lived tree of depth {}\t check: {}", max_depth, item_check(long_lived_tree));
}