From 85097e245029ec973182e07ef79b966e748d0efa Mon Sep 17 00:00:00 2001
From: Stefan Boberg <stefan@boberg.org>
Date: Thu, 16 Nov 2023 17:24:36 +0100
Subject: further posix event improvements (#549)

* changed posix event implementation to use std::atomic instead of volatile
* ensure Event::Close() can take lock before deleting the inner object
* don't try to take the Event lock if the event is already signaled
* changed logic around Event::Wait without time-out. this works around some apparent issues on MacOS/Linux
* fix logic for posix process exit wait
---
 src/zencore/thread.cpp | 29 +++++++++++++++++++++++------
 1 file changed, 23 insertions(+), 6 deletions(-)

(limited to 'src/zencore/thread.cpp')

diff --git a/src/zencore/thread.cpp b/src/zencore/thread.cpp
index 27a5ec1ae..1174f902f 100644
--- a/src/zencore/thread.cpp
+++ b/src/zencore/thread.cpp
@@ -190,7 +190,7 @@ Event::Set()
 	auto* Inner	  = (EventInner*)m_EventHandle;
 	{
 		std::unique_lock Lock(Inner->Mutex);
-		Inner->bSet = true;
+		Inner->bSet.store(true);
 	}
 	Inner->CondVar.notify_all();
 #endif
@@ -205,7 +205,7 @@ Event::Reset()
 	auto* Inner = (EventInner*)m_EventHandle;
 	{
 		std::unique_lock Lock(Inner->Mutex);
-		Inner->bSet = false;
+		Inner->bSet.store(false);
 	}
 #endif
 }
@@ -217,6 +217,10 @@ Event::Close()
 	CloseHandle(m_EventHandle);
 #else
 	auto* Inner = (EventInner*)m_EventHandle;
+	{
+		std::unique_lock Lock(Inner->Mutex);
+		Inner->bSet.store(true);
+	}
 	delete Inner;
 #endif
 	m_EventHandle = nullptr;
@@ -239,13 +243,18 @@ Event::Wait(int TimeoutMs)
 
 	return (Result == WAIT_OBJECT_0);
 #else
-	auto* Inner = (EventInner*)m_EventHandle;
+	auto* Inner = reinterpret_cast<EventInner*>(m_EventHandle);
+
+	if (Inner->bSet.load())
+	{
+		return true;
+	}
 
 	if (TimeoutMs >= 0)
 	{
 		std::unique_lock Lock(Inner->Mutex);
 
-		if (Inner->bSet)
+		if (Inner->bSet.load())
 		{
 			return true;
 		}
@@ -253,11 +262,15 @@ Event::Wait(int TimeoutMs)
 		return Inner->CondVar.wait_for(Lock, std::chrono::milliseconds(TimeoutMs), [&] { return Inner->bSet.load(); });
 	}
 
+	// Infinite wait. This does not actually call the wait() function to work around
+	// an apparent issue in the underlying implementation.
+
 	std::unique_lock Lock(Inner->Mutex);
 
-	if (!Inner->bSet)
+	if (!Inner->bSet.load())
 	{
-		Inner->CondVar.wait(Lock, [&] { return Inner->bSet.load(); });
+		while (!Inner->CondVar.wait_for(Lock, std::chrono::milliseconds(1000), [&] { return Inner->bSet.load(); }))
+			;
 	}
 
 	return true;
@@ -656,6 +669,9 @@ ProcessHandle::Wait(int TimeoutMs)
 	{
 		int WaitState = 0;
 		int Res		  = waitpid(m_Pid, &WaitState, WNOHANG | WCONTINUED | WUNTRACED);
+#	if 1
+		ZEN_UNUSED(Res);
+#	else
 		if (Res == -1)
 		{
 			int32_t LastError = zen::GetLastError();
@@ -665,6 +681,7 @@ ProcessHandle::Wait(int TimeoutMs)
 			}
 			ThrowSystemError(static_cast<uint32_t>(LastError), "Process::Wait waitpid failed"sv);
 		}
+#	endif
 
 		if (kill(m_Pid, 0) < 0)
 		{
-- 
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