add collections example

Author: chaoyuepan

collections/src/lib.rs

@@ -0,0 +1,22 @@
+use std::{sync::{Arc, Mutex}, collections::HashMap};
+
+
+pub fn common_thread_safe_collections() {
+    let map: HashMap<i32, i32> = HashMap::new();
+    let m = Arc::new(Mutex::new(map));
+
+    let mut handles = vec![];
+    for i in 0..10 {
+        let m = Arc::clone(&m);
+        handles.push(std::thread::spawn(move || {
+            let mut map = m.lock().unwrap();
+            map.insert(i, i);
+        }));
+    }
+
+    for handle in handles {
+        handle.join().unwrap();
+    }
+
+    println!("HashMap: {:?}", *m.lock().unwrap());
+}

collections/src/main.rs

@@ -1,5 +1,5 @@
-use collections;
+use collections::*;    
 
 fn main() {
-    println!("Hello, world!");
+    common_thread_safe_collections();
 }