snightshade · February 8, 2022 20:38 · Feb 8, 2022
diff --git a/main.rs b/main.rs
@@ -0,0 +1,39 @@
+use std::sync::{Arc, Mutex, PoisonError};
+use std::thread;
+
+fn main() {
+    let the_lock = Arc::new(Mutex::<i32>::new(0));
+
+    {
+        let lock = the_lock.clone();
+        thread::spawn(move || {
+            let mut value = lock.lock().expect("failed to acquire lock on thread 1");
+            for _ in 0..100 {
+                *value += 1;
+            }
+            // 'value' has not fallen out of scope!
+            // the mutex is locked, therefore it is now poisoned
+            // because this thread will now panic.
+            panic!("very naughty");
+        });
+    }
+
+    {
+        let lock = the_lock.clone();
+        thread::spawn(move || {
+            // Just ignore the PoisonError here - we'll check later.
+            let mut value = match lock.lock() {
+                Ok(x) => x,
+                Err(x @ PoisonError { .. }) => x.into_inner()
+            };
+            for _ in 0..1000 {
+                *value += 1;
+            }
+        }).join().ok(); // wait for the thread to end. discard the failure if any happens
+    }
+
+    println!("The number is: {}", match the_lock.lock() {
+        Ok(x) => format!("{}", x), // we're fine
+        Err(x @ PoisonError { .. }) => format!("{1} (MUTEX WAS POISONED: {0})", x.to_string(), x.into_inner())
+    });
+}
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