From e26bc568ac196e511fed9469fadc098aa1d100e8 Mon Sep 17 00:00:00 2001
From: julianknodt <julianknodt@gmail.com>
Date: Sat, 30 Mar 2024 19:25:48 -0700
Subject: [PATCH] Change example with race conditions

---
 FAQ.md | 11 ++++-------
 1 file changed, 4 insertions(+), 7 deletions(-)

diff --git a/FAQ.md b/FAQ.md
index 745f03399..96964a94b 100644
--- a/FAQ.md
+++ b/FAQ.md
@@ -211,15 +211,12 @@ this shortest route, you can just stop and avoid wasted effort. In
 sequential land, you might model this "best result" as a shared value
 like `Rc<Cell<usize>>` (here the `usize` represents the length of best
 path found so far); in parallel land, you'd use a `Arc<AtomicUsize>`.
-Now we can make our search function look like:
 
 ```rust
-fn search(path: &Path, cost_so_far: usize, best_cost: &Arc<AtomicUsize>) {
-    if cost_so_far >= best_cost.load(Ordering::SeqCst) {
-        return;
-    }
-    ...
-    best_cost.store(...);
+fn search(path: &Path, cost_so_far: usize, best_cost: &AtomicUsize) {
+    let total_cost = cost_so_far + ...;
+    // Using `fetch_min` to avoid a race condition, in case it changed since `load`.
+    best_cost.fetch_min(cost_so_far, Ordering::SeqCst);
 }
 ```