changed posix event implementation to use std::atomic instead of volatile (#547)

3 files changed, 14 insertions, 10 deletions

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 3c2079397..091a7393d 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,9 +1,11 @@
 ##
 - Bumped zenserver data schema (to '5') to wipe corrupted state caused by version 0.2.31/0.2.32
 - Bugfix: Fix hang on ZenServerInstance shutdown on Mac/Linux
+- Improvement: Event implementation now uses `std::atomic_bool` instead of `volatile bool` for correctness
 - Improvement: We now set Sentry to `<username>@<hostname>` if personal information is allowed to be sent
 - Improvement: Removed dependency on cxxopts exception types, to enable use of library versions >3.0.0
 
+
 ## 0.2.33
 - Bugfix: Fix index out of bounds in CacheBucket::CompactState
 - Bugfix: Implement != operator for DiskLocation to avoid comparing uninitialized data
diff --git a/src/zencore/include/zencore/thread.h b/src/zencore/include/zencore/thread.h
index 9f2671610..47f37c9a3 100644
--- a/src/zencore/include/zencore/thread.h
+++ b/src/zencore/include/zencore/thread.h
@@ -10,6 +10,8 @@
 #include <string_view>
 #include <vector>
 
+#define ZEN_USE_WINDOWS_EVENTS ZEN_PLATFORM_WINDOWS
+
 namespace zen {
 
 void SetCurrentThreadName(std::string_view ThreadName);
@@ -107,7 +109,7 @@ public:
 	ZENCORE_API bool Wait(int TimeoutMs = -1);
 	ZENCORE_API void Close();
 
-#if ZEN_PLATFORM_WINDOWS
+#if ZEN_USE_WINDOWS_EVENTS
 	inline void* GetWindowsHandle() { return m_EventHandle; }
 #endif
 
diff --git a/src/zencore/thread.cpp b/src/zencore/thread.cpp
index 758e88350..27a5ec1ae 100644
--- a/src/zencore/thread.cpp
+++ b/src/zencore/thread.cpp
@@ -152,12 +152,12 @@ RwLock::ReleaseExclusive() noexcept
 
 //////////////////////////////////////////////////////////////////////////
 
-#if !ZEN_PLATFORM_WINDOWS
+#if !ZEN_USE_WINDOWS_EVENTS
 struct EventInner
 {
 	std::mutex				Mutex;
 	std::condition_variable CondVar;
-	bool volatile bSet = false;
+	std::atomic_bool		bSet{false};
 };
 #endif	// !ZEN_PLATFORM_WINDOWS
 
@@ -166,7 +166,7 @@ Event::Event()
 	bool bManualReset  = true;
 	bool bInitialState = false;
 
-#if ZEN_PLATFORM_WINDOWS
+#if ZEN_USE_WINDOWS_EVENTS
 	m_EventHandle = CreateEvent(nullptr, bManualReset, bInitialState, nullptr);
 #else
 	ZEN_UNUSED(bManualReset);
@@ -184,7 +184,7 @@ Event::~Event()
 void
 Event::Set()
 {
-#if ZEN_PLATFORM_WINDOWS
+#if ZEN_USE_WINDOWS_EVENTS
 	SetEvent(m_EventHandle);
 #else
 	auto* Inner	  = (EventInner*)m_EventHandle;
@@ -199,7 +199,7 @@ Event::Set()
 void
 Event::Reset()
 {
-#if ZEN_PLATFORM_WINDOWS
+#if ZEN_USE_WINDOWS_EVENTS
 	ResetEvent(m_EventHandle);
 #else
 	auto* Inner = (EventInner*)m_EventHandle;
@@ -213,7 +213,7 @@ Event::Reset()
 void
 Event::Close()
 {
-#if ZEN_PLATFORM_WINDOWS
+#if ZEN_USE_WINDOWS_EVENTS
 	CloseHandle(m_EventHandle);
 #else
 	auto* Inner = (EventInner*)m_EventHandle;
@@ -225,7 +225,7 @@ Event::Close()
 bool
 Event::Wait(int TimeoutMs)
 {
-#if ZEN_PLATFORM_WINDOWS
+#if ZEN_USE_WINDOWS_EVENTS
 	using namespace std::literals;
 
 	const DWORD Timeout = (TimeoutMs < 0) ? INFINITE : TimeoutMs;
@@ -250,14 +250,14 @@ Event::Wait(int TimeoutMs)
 			return true;
 		}
 
-		return Inner->CondVar.wait_for(Lock, std::chrono::milliseconds(TimeoutMs), [&] { return Inner->bSet; });
+		return Inner->CondVar.wait_for(Lock, std::chrono::milliseconds(TimeoutMs), [&] { return Inner->bSet.load(); });
 	}
 
 	std::unique_lock Lock(Inner->Mutex);
 
 	if (!Inner->bSet)
 	{
-		Inner->CondVar.wait(Lock, [&] { return Inner->bSet; });
+		Inner->CondVar.wait(Lock, [&] { return Inner->bSet.load(); });
 	}
 
 	return true;