fix(sleeper-thread): synchronize control flags with atomics

SleeperThread control flags were shared across threads without consistent
synchronization.

I converted the run/signal flags to atomics and updated wait predicates and
lifecycle transitions to use explicit atomic loads/stores.

Signed-off-by: Austin Horstman <khaneliman12@gmail.com>

include/util/sleeper_thread.hpp

@@ -1,5 +1,6 @@
 #pragma once
 
+#include <atomic>
 #include <chrono>
 #include <condition_variable>
 #include <ctime>
@@ -31,8 +32,8 @@ class SleeperThread {
 
   SleeperThread(std::function<void()> func)
       : thread_{[this, func] {
-          while (do_run_) {
-            signal_ = false;
+          while (do_run_.load(std::memory_order_relaxed)) {
+            signal_.store(false, std::memory_order_relaxed);
             func();
           }
         }} {
@@ -48,12 +49,12 @@ class SleeperThread {
     }
     {
       std::lock_guard<std::mutex> lck(mutex_);
-      do_run_ = true;
-      signal_ = false;
+      do_run_.store(true, std::memory_order_relaxed);
+      signal_.store(false, std::memory_order_relaxed);
     }
     thread_ = std::thread([this, func] {
-      while (do_run_) {
-        signal_ = false;
+      while (do_run_.load(std::memory_order_relaxed)) {
+        signal_.store(false, std::memory_order_relaxed);
         func();
       }
     });
@@ -65,12 +66,15 @@ class SleeperThread {
     return *this;
   }
 
-  bool isRunning() const { return do_run_; }
+  bool isRunning() const { return do_run_.load(std::memory_order_relaxed); }
 
   auto sleep() {
     std::unique_lock lk(mutex_);
     CancellationGuard cancel_lock;
-    return condvar_.wait(lk, [this] { return signal_ || !do_run_; });
+    return condvar_.wait(lk, [this] {
+      return signal_.load(std::memory_order_relaxed) ||
+             !do_run_.load(std::memory_order_relaxed);
+    });
   }
 
   auto sleep_for(std::chrono::system_clock::duration dur) {
@@ -82,7 +86,10 @@ class SleeperThread {
     if (now < max_time_point - dur) {
       wait_end = now + dur;
     }
-    return condvar_.wait_until(lk, wait_end, [this] { return signal_ || !do_run_; });
+    return condvar_.wait_until(lk, wait_end, [this] {
+      return signal_.load(std::memory_order_relaxed) ||
+             !do_run_.load(std::memory_order_relaxed);
+    });
   }
 
   auto sleep_until(
@@ -90,13 +97,16 @@ class SleeperThread {
           time_point) {
     std::unique_lock lk(mutex_);
     CancellationGuard cancel_lock;
-    return condvar_.wait_until(lk, time_point, [this] { return signal_ || !do_run_; });
+    return condvar_.wait_until(lk, time_point, [this] {
+      return signal_.load(std::memory_order_relaxed) ||
+             !do_run_.load(std::memory_order_relaxed);
+    });
   }
 
   void wake_up() {
     {
       std::lock_guard<std::mutex> lck(mutex_);
-      signal_ = true;
+      signal_.store(true, std::memory_order_relaxed);
     }
     condvar_.notify_all();
   }
@@ -104,8 +114,8 @@ class SleeperThread {
   void stop() {
     {
       std::lock_guard<std::mutex> lck(mutex_);
-      signal_ = true;
-      do_run_ = false;
+      signal_.store(true, std::memory_order_relaxed);
+      do_run_.store(false, std::memory_order_relaxed);
     }
     condvar_.notify_all();
     auto handle = thread_.native_handle();
@@ -127,8 +137,8 @@ class SleeperThread {
   std::thread thread_;
   std::condition_variable condvar_;
   std::mutex mutex_;
-  bool do_run_ = true;
-  bool signal_ = false;
+  std::atomic<bool> do_run_ = true;
+  std::atomic<bool> signal_ = false;
   sigc::connection connection_;
 };