From f035108b0583ae02bbdf7a8713241c4d88e1e5bb Mon Sep 17 00:00:00 2001
From: Lars Wirzenius <liw@liw.fi>
Date: Tue, 6 Apr 2021 11:17:07 +0300
Subject: ref

---
 Cargo.toml  |  1 +
 src/main.rs | 26 ++++++++++++++++++++------
 2 files changed, 21 insertions(+), 6 deletions(-)

diff --git a/Cargo.toml b/Cargo.toml
index 31e161f..a118afb 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -7,4 +7,5 @@ edition = "2018"
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
+rayon = "1.5.0"
 sha2 = "0.9.3"
diff --git a/src/main.rs b/src/main.rs
index 32102f2..c67d111 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,19 +1,28 @@
 use sha2::{Digest, Sha256};
 
+const N: usize = 10;
+const SIZE: usize = 128 * 1024;
+
 fn main() {
-    let blobs = Blobs::new(128 * 1024);
-    for blob in blobs.take(10) {
-        println!("{}", sha256(&blob));
+    println!("sequential");
+    for checksum in Blobs::new(SIZE, N).map(|x| sha256(&x)) {
+        println!("{}", checksum);
     }
+
+    // println!("rayon");
+    // for checksum in blobs.take(N).par_iter().map(|x| sha256(x)) {
+    //     println!("{}", checksum);
+    // }
 }
 
 struct Blobs {
     size: usize,
+    n: usize,
 }
 
 impl Blobs {
-    fn new(size: usize) -> Self {
-        Self { size }
+    fn new(size: usize, n: usize) -> Self {
+        Self { size, n }
     }
 }
 
@@ -21,7 +30,12 @@ impl Iterator for Blobs {
     type Item = Vec<u8>;
 
     fn next(&mut self) -> Option<Self::Item> {
-        Some(vec![0; self.size])
+        if self.n > 0 {
+            self.n -= 1;
+            Some(vec![0; self.size])
+        } else {
+            None
+        }
     }
 }
 
-- 
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