From f45a3f5de2a11065764c87208d3f0b58e6ebe771 Mon Sep 17 00:00:00 2001
From: Benoit Germain <benoit.germain@ubisoft.com>
Date: Wed, 13 Nov 2024 10:06:37 +0100
Subject: Cleaning up guano

Converted volatile Lane::cancelRequest to std::atomic
---
 src/cancel.cpp   | 2 +-
 src/lane.cpp     | 2 +-
 src/lane.hpp     | 3 ++-
 src/linda.cpp    | 4 ++--
 src/universe.cpp | 2 +-
 5 files changed, 7 insertions(+), 6 deletions(-)

diff --git a/src/cancel.cpp b/src/cancel.cpp
index 8991684..9248b25 100644
--- a/src/cancel.cpp
+++ b/src/cancel.cpp
@@ -54,7 +54,7 @@ THE SOFTWARE.
 {
     auto const* const _lane{ kLanePointerRegKey.readLightUserDataValue<Lane>(L_) };
     // 'lane' is nullptr for the original main state (and no-one can cancel that)
-    return _lane ? _lane->cancelRequest : CancelRequest::None;
+    return _lane ? _lane->cancelRequest.load(std::memory_order_relaxed) : CancelRequest::None;
 }
 
 // #################################################################################################
diff --git a/src/lane.cpp b/src/lane.cpp
index ac3fffa..4caebcb 100644
--- a/src/lane.cpp
+++ b/src/lane.cpp
@@ -939,7 +939,7 @@ CancelResult Lane::cancel(CancelOp const op_, std::chrono::time_point<std::chron
 
 [[nodiscard]] CancelResult Lane::internalCancel(CancelRequest const rq_, std::chrono::time_point<std::chrono::steady_clock> const until_, WakeLane const wakeLane_)
 {
-    cancelRequest = rq_; // it's now signaled to stop
+    cancelRequest.store(rq_, std::memory_order_relaxed); // it's now signaled to stop
     if (rq_ == CancelRequest::Hard) {
         // lane_->thread.get_stop_source().request_stop();
     }
diff --git a/src/lane.hpp b/src/lane.hpp
index 4fd0f6d..1926824 100644
--- a/src/lane.hpp
+++ b/src/lane.hpp
@@ -122,7 +122,8 @@ class Lane
     //
     // When status is Waiting, points on the linda's signal the thread waits on, else nullptr
 
-    CancelRequest volatile cancelRequest{ CancelRequest::None };
+    std::atomic<CancelRequest> cancelRequest{ CancelRequest::None };
+    static_assert(std::atomic<CancelRequest>::is_always_lock_free);
     //
     // M: sets to false, flags true for cancel request
     // S: reads to see if cancel is requested
diff --git a/src/linda.cpp b/src/linda.cpp
index 80f62d3..1536da5 100644
--- a/src/linda.cpp
+++ b/src/linda.cpp
@@ -640,7 +640,7 @@ LUAG_FUNC(linda_receive)
             STACK_CHECK_START_REL(_K, 0);
             for (bool _try_again{ true };;) {
                 if (_lane != nullptr) {
-                    _cancel = _lane->cancelRequest;
+                    _cancel = _lane->cancelRequest.load(std::memory_order_relaxed);
                 }
                 _cancel = (_cancel != CancelRequest::None)
                     ? _cancel
@@ -779,7 +779,7 @@ LUAG_FUNC(linda_send)
                 STACK_CHECK_START_REL(_K, 0);
                 for (bool _try_again{ true };;) {
                     if (_lane != nullptr) {
-                        _cancel = _lane->cancelRequest;
+                        _cancel = _lane->cancelRequest.load(std::memory_order_relaxed);
                     }
                     _cancel = (_cancel != CancelRequest::None)
                         ? _cancel
diff --git a/src/universe.cpp b/src/universe.cpp
index 1aafbff..357aa08 100644
--- a/src/universe.cpp
+++ b/src/universe.cpp
@@ -381,7 +381,7 @@ bool Universe::terminateFreeRunningLanes(lua_Duration const shutdownTimeout_, Ca
                     std::lock_guard<std::mutex> _guard{ selfdestructMutex };
                     Lane* _lane{ selfdestructFirst };
                     while (_lane != SELFDESTRUCT_END) {
-                        if (_lane->cancelRequest != CancelRequest::None)
+                        if (_lane->cancelRequest.load(std::memory_order_relaxed) != CancelRequest::None)
                             ++_n;
                         _lane = _lane->selfdestruct_next;
                     }
-- 
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