From 8000d1db294811645e4efdcb9d4adc4f73029f67 Mon Sep 17 00:00:00 2001
From: Quaternions <krakow20@gmail.com>
Date: Wed, 4 Oct 2023 01:57:18 -0700
Subject: [PATCH] gpt: park thread

---
 src/worker.rs | 42 +++++++++++++++++++++++-------------------
 1 file changed, 23 insertions(+), 19 deletions(-)

diff --git a/src/worker.rs b/src/worker.rs
index e7dcb5b..2898d04 100644
--- a/src/worker.rs
+++ b/src/worker.rs
@@ -1,15 +1,16 @@
 use std::thread;
 use std::sync::{mpsc,Arc};
 use parking_lot::{Mutex,Condvar};
+use std::sync::atomic::{AtomicBool, Ordering};
 
 struct Worker {
     id: usize,
     receiver: Arc<(Mutex<mpsc::Receiver<Task>>, Condvar)>,
-    is_active: Arc<Mutex<bool>>,
+    is_active: Arc<AtomicBool>,
 }
 
 impl Worker {
-    fn new(id: usize, receiver: Arc<(Mutex<mpsc::Receiver<Task>>, Condvar)>, is_active: Arc<Mutex<bool>>) -> Worker {
+    fn new(id: usize, receiver: Arc<(Mutex<mpsc::Receiver<Task>>, Condvar)>, is_active: Arc<AtomicBool>) -> Worker {
         Worker { id, receiver, is_active }
     }
 
@@ -31,8 +32,8 @@ impl Worker {
             }
 
             // Set is_active to false when the worker is done
-            *self.is_active.lock() = false;
-            self.receiver.1.notify_all();
+            self.is_active.store(false, Ordering::SeqCst);
+            self.receiver.1.notify_one();
         });
     }
 }
@@ -42,38 +43,41 @@ type Task = String;
 fn main() {
     let (sender, receiver) = mpsc::channel::<Task>();
     let receiver = Arc::new((Mutex::new(receiver), Condvar::new()));
-    let is_active = Arc::new(Mutex::new(true));
+    let is_active = Arc::new(AtomicBool::new(true));
 
-    // Create the first worker thread
+    // Create the worker thread
     let worker = Worker::new(1, Arc::clone(&receiver), Arc::clone(&is_active));
 
-    // Start the first worker thread
+    // Start the worker thread
     worker.start();
 
-    // Send tasks to the first worker
+    // Send tasks to the worker
     for i in 0..5 {
         let task = format!("Task {}", i);
         sender.send(task).unwrap();
     }
 
-    // Optional: Signal the first worker to stop (in a real-world scenario)
+    // Optional: Signal the worker to stop (in a real-world scenario)
     // sender.send("STOP".to_string()).unwrap();
 
-    // Sleep to allow the first worker thread to finish processing
+    // Sleep to allow the worker thread to finish processing
     thread::sleep(std::time::Duration::from_secs(2));
 
-    // Check if the first worker is still active
-    let is_first_worker_active = *is_active.lock();
+    // Check if the worker is still active
+    let is_worker_active = is_active.load(Ordering::SeqCst);
 
-    if !is_first_worker_active {
-        // If the first worker is done, spawn a new worker
-        let new_worker = Worker::new(2, Arc::clone(&receiver), Arc::clone(&is_active));
-        new_worker.start();
+    if !is_worker_active {
+        // If the worker is done, signal it to process a new task
+        is_active.store(true, Ordering::SeqCst);
+        let (ref lock, ref cvar) = &*receiver;
+        cvar.notify_one();
+
+        // Send a new task
         sender.send("New Task".to_string()).unwrap();
 
-        // Wait for the new worker to finish processing
-        let _ = receiver.1.wait_while(is_active.lock(), |&active| active);
+        // Wait for the worker to finish processing
+        cvar.wait_while(lock.lock(), |&active| active);
     } else {
-        println!("First worker is still active. Skipping new worker.");
+        println!("Worker is still active. Skipping new task.");
     }
 }