From 6bd22494e9a2d3ce03ab0a6ec71bd9fc87f2a706 Mon Sep 17 00:00:00 2001
From: Guillaume Pinot <texitoi@texitoi.eu>
Date: Thu, 28 Nov 2013 20:46:59 +0100
Subject: [PATCH] shootout-spectralnorm resurection with parallelization

---
 src/test/bench/shootout-spectralnorm.rs | 97 +++++++++++++++++--------
 1 file changed, 66 insertions(+), 31 deletions(-)

diff --git a/src/test/bench/shootout-spectralnorm.rs b/src/test/bench/shootout-spectralnorm.rs
index 6a9837fb832ca..87cd01f9aad2e 100644
--- a/src/test/bench/shootout-spectralnorm.rs
+++ b/src/test/bench/shootout-spectralnorm.rs
@@ -8,59 +8,94 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-// xfail-test reading from os::args()[1] - bogus!
+extern mod extra;
 
 use std::from_str::FromStr;
+use std::iter::count;
+use std::num::min;
 use std::os;
-use std::vec;
+use std::vec::from_elem;
+use extra::arc::Arc;
+use extra::arc::RWArc;
 
-#[inline]
-fn A(i: i32, j: i32) -> i32 {
-    (i+j) * (i+j+1) / 2 + i + 1
+fn A(i: uint, j: uint) -> f64 {
+    ((i + j) * (i + j + 1) / 2 + i + 1) as f64
 }
 
 fn dot(v: &[f64], u: &[f64]) -> f64 {
     let mut sum = 0.0;
-    for (i, &v_i) in v.iter().enumerate() {
-        sum += v_i * u[i];
+    for (&v_i, &u_i) in v.iter().zip(u.iter()) {
+        sum += v_i * u_i;
     }
     sum
 }
 
-fn mult_Av(v: &mut [f64], out: &mut [f64]) {
-    for (i, out_i) in out.mut_iter().enumerate() {
-        let mut sum = 0.0;
-        for (j, &v_j) in v.mut_iter().enumerate() {
-            sum += v_j / (A(i as i32, j as i32) as f64);
+fn mult(v: RWArc<~[f64]>, out: RWArc<~[f64]>, f: fn(&~[f64], uint) -> f64) {
+    let wait = Arc::new(());
+    let len = out.read(|out| out.len());
+    let chunk = len / 100 + 1;
+    for chk in count(0, chunk) {
+        if chk >= len {break;}
+        let w = wait.clone();
+        let v = v.clone();
+        let out = out.clone();
+        do spawn {
+            for i in range(chk, min(len, chk + chunk)) {
+                let val = v.read(|v| f(v, i));
+                out.write(|out| out[i] = val);
+            }
+            let _ = w;
         }
-        *out_i = sum;
     }
+    let _ = wait.unwrap();
 }
 
-fn mult_Atv(v: &mut [f64], out: &mut [f64]) {
-    for (i, out_i) in out.mut_iter().enumerate() {
-        let mut sum = 0.0;
-        for (j, &v_j) in v.mut_iter().enumerate() {
-            sum += v_j / (A(j as i32, i as i32) as f64);
-        }
-        *out_i = sum;
+fn mult_Av_impl(v: &~[f64], i: uint) -> f64 {
+    let mut sum = 0.;
+    for (j, &v_j) in v.iter().enumerate() {
+        sum += v_j / A(i, j);
     }
+    sum
+}
+
+fn mult_Av(v: RWArc<~[f64]>, out: RWArc<~[f64]>) {
+    mult(v, out, mult_Av_impl);
 }
 
-fn mult_AtAv(v: &mut [f64], out: &mut [f64], tmp: &mut [f64]) {
-    mult_Av(v, tmp);
+fn mult_Atv_impl(v: &~[f64], i: uint) -> f64 {
+    let mut sum = 0.;
+    for (j, &v_j) in v.iter().enumerate() {
+        sum += v_j / A(j, i);
+    }
+    sum
+}
+
+fn mult_Atv(v: RWArc<~[f64]>, out: RWArc<~[f64]>) {
+    mult(v, out, mult_Atv_impl);
+}
+
+fn mult_AtAv(v: RWArc<~[f64]>, out: RWArc<~[f64]>, tmp: RWArc<~[f64]>) {
+    mult_Av(v, tmp.clone());
     mult_Atv(tmp, out);
 }
 
 fn main() {
-    let n: uint = FromStr::from_str(os::args()[1]).unwrap();
-    let mut u = vec::from_elem(n, 1f64);
-    let mut v = u.clone();
-    let mut tmp = u.clone();
-    for _ in range(0, 8u) {
-        mult_AtAv(u, v, tmp);
-        mult_AtAv(v, u, tmp);
+    let args = os::args();
+    let n = if os::getenv("RUST_BENCH").is_some() {
+        5500
+    } else if args.len() < 2 {
+        2000
+    } else {
+        FromStr::from_str(args[1]).unwrap()
+    };
+    let u = RWArc::new(from_elem(n, 1.));
+    let v = RWArc::new(from_elem(n, 1.));
+    let tmp = RWArc::new(from_elem(n, 1.));
+    for _ in range(0, 10) {
+        mult_AtAv(u.clone(), v.clone(), tmp.clone());
+        mult_AtAv(v.clone(), u.clone(), tmp.clone());
     }
-
-    println!("{:.9f}", (dot(u,v) / dot(v,v)).sqrt() as float);
+    let u = u.unwrap();
+    let v = v.unwrap();
+    println!("{:.9f}", (dot(u,v) / dot(v,v)).sqrt());
 }