add rayon examples

Author: smallnest

rayon_examples/Cargo.toml

@@ -6,3 +6,4 @@ edition = "2021"
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
+rayon = "1.5.3"

rayon_examples/src/lib.rs

@@ -0,0 +1,87 @@
+use rayon::prelude::*;
+
+pub fn rayon_par_iter() {
+    let v = vec![1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
+    let sum = v.par_iter().map(|x| x * x).sum::<i32>();
+    println!("sum: {}", sum);
+
+    let mut left = vec![42; 10];
+    let mut right = vec![-1; 10];
+
+    (10..15)
+        .into_par_iter()
+        .enumerate()
+        .unzip_into_vecs(&mut left, &mut right);
+
+    assert_eq!(left, [0, 1, 2, 3, 4]);
+    assert_eq!(right, [10, 11, 12, 13, 14]);
+}
+
+pub fn rayon_scope_example() {
+    rayon::scope(|s| {
+        s.spawn(|_| {
+            println!("Hello from a thread!");
+        });
+    });
+}
+
+pub fn rayon_scope_example2() {
+    let mut value_a = None;
+    let mut value_b = None;
+    let mut value_c = None;
+    rayon::scope(|s| {
+        s.spawn(|s1| {
+            value_a = Some(22);
+
+            s1.spawn(|_| {
+                value_b = Some(44);
+            });
+        });
+
+        s.spawn(|_| {
+            value_c = Some(66);
+        });
+    });
+    assert_eq!(value_a, Some(22));
+    assert_eq!(value_b, Some(44));
+    assert_eq!(value_c, Some(66));
+}
+
+
+pub fn rayon_scopefifo_example() {
+    rayon::scope_fifo(|s| {
+        s.spawn_fifo(|s| { // task s.1
+            println!("s.1");
+            s.spawn_fifo(|_s| { // task s.1.1
+                println!("s.1.1");
+                rayon::scope_fifo(|t| {
+                    t.spawn_fifo(|_| println!("t.1")); // task t.1
+                    t.spawn_fifo(|_| println!("t.2")); // task t.2
+                });
+            });
+        });
+        s.spawn_fifo(|_s| { // task s.2
+            println!("s.2");
+        });
+        // point mid
+    });
+}
+
+pub fn rayon_threadpool_example() {
+    fn fib(n: usize) -> usize {
+        if n == 0 || n == 1 {
+            return n;
+        }
+        let (a, b) = rayon::join(|| fib(n - 1), || fib(n - 2)); // runs inside of `pool`
+        return a + b;
+    }
+
+    let pool = rayon::ThreadPoolBuilder::new()
+        .num_threads(4)
+        .build()
+        .unwrap();
+
+    let n = pool.install(|| fib(20));
+
+    println!("{}", n);
+}

rayon_examples/src/main.rs

@@ -1,3 +1,11 @@
+
+use rayon_examples::*;
+
 fn main() {
-    println!("Hello, world!");
+    rayon_par_iter();
+
+    rayon_scope_example();
+    rayon_scope_example2();
+    rayon_scopefifo_example();
+    rayon_threadpool_example();
 }