Implement pthread_cancel.

examples/demo/demo.odin

@@ -1110,9 +1110,16 @@ prefix_table := [?]string{
 	"Black",
 }
 
+print_mutex := b64(false)
+
 threading_example :: proc() {
 	fmt.println("\n# threading_example")
 
+	did_acquire :: proc(m: ^b64) -> (acquired: bool) {
+		res, ok := intrinsics.atomic_compare_exchange_strong(m, false, true)
+		return ok && res == false
+	}
+
 	{ // Basic Threads
 		fmt.println("\n## Basic Threads")
 		worker_proc :: proc(t: ^thread.Thread) {
@@ -1154,14 +1161,21 @@ threading_example :: proc() {
 		task_proc :: proc(t: thread.Task) {
 			index := t.user_index % len(prefix_table)
 			for iteration in 1..=5 {
+				for !did_acquire(&print_mutex) { thread.yield() } // Allow one thread to print at a time.
+
 				fmt.printf("Worker Task %d is on iteration %d\n", t.user_index, iteration)
 				fmt.printf("`%s`: iteration %d\n", prefix_table[index], iteration)
+
+				print_mutex = false
+
 				time.sleep(1 * time.Millisecond)
 			}
 		}
 
+		N :: 3
+
 		pool: thread.Pool
-		thread.pool_init(pool=&pool, thread_count=3, allocator=context.allocator)
+		thread.pool_init(pool=&pool, thread_count=N, allocator=context.allocator)
 		defer thread.pool_destroy(&pool)
 
 
@@ -1171,6 +1185,19 @@ threading_example :: proc() {
 		}
 
 		thread.pool_start(&pool)
+
+		{
+			// Wait a moment before we cancel a thread
+			time.sleep(5 * time.Millisecond)
+
+			// Allow one thread to print at a time.
+			for !did_acquire(&print_mutex) { thread.yield() }
+
+			thread.terminate(pool.threads[N - 1], 0)
+			fmt.println("Canceled last thread")
+			print_mutex = false
+		}
+
 		thread.pool_finish(&pool)
 	}
 }