Update Ch20

hello/src/lib.rs

@@ -2,7 +2,7 @@
 use std::thread;
 
 pub struct ThreadPool {
-    threads: Vec<thread::JoinHandle<()>>,
+    workers: Vec<Worker>,
 }
 
 impl ThreadPool {
@@ -19,10 +19,10 @@ impl ThreadPool {
         let mut threads = Vec::with_capacity(size);
 
         for _ in 0..size {
-            // 创建出一些线程并将他们存储在那个矢量中
+            workers.push(Worker::new(id));
         }
 
-        ThreadPool { threads }
+        ThreadPool { workers }
     }
 
     pub fn execute<F>(&self, f: F)
@@ -31,3 +31,16 @@ impl ThreadPool {
     {
     }
 }
+
+struct Worker {
+    id: usize,
+    thread: thread::JoinHandle<()>,
+}
+
+impl Worker {
+    fn new(id: usize) -> Worker {
+        let thread = thread::spawn(|| {});
+
+        Worker { id, thread }
+    }
+}