From 7225a7759cf8e6646b2796160bf84e4dfe2764e6 Mon Sep 17 00:00:00 2001
From: ADAM David Alan Martin <adam@recursive.engineer>
Date: Wed, 13 Dec 2023 00:10:05 -0500
Subject: [PATCH] Some thread interruption defensiveness.

---
 Thread.cc             |  8 ++++----
 Utility/ScopedState.h | 28 ++++++++++++++++++++++++++++
 2 files changed, 32 insertions(+), 4 deletions(-)
 create mode 100644 Utility/ScopedState.h

diff --git a/Thread.cc b/Thread.cc
index 82fcb1e..bb05a54 100644
--- a/Thread.cc
+++ b/Thread.cc
@@ -8,6 +8,7 @@ static_assert( __cplusplus > 2020'99 );
 
 #include <Alepha/Utility/StaticValue.h>
 #include <Alepha/Utility/evaluation_helpers.h>
+#include <Alepha/Utility/ScopedState.h>
 
 #include "error.h"
 
@@ -131,6 +132,7 @@ namespace Alepha::Hydrogen::detail::Thread_m
 		while( impl().state == Opening )
 		{
 			impl().var.wait( lock );
+			assert( not impl().threadBlocked );
 		}
 
 		if( impl().state == Open )
@@ -167,9 +169,9 @@ namespace Alepha::Hydrogen::detail::Thread_m
 	{
 		if( impl().state == Waiting )
 		{
-			impl().threadBlocked= true;
 			while( impl().state == Waiting )
 			{
+				Utility::ScopedState state{ impl().threadBlocked };
 				impl().var.wait( lock );
 			}
 			assert( not impl().threadBlocked );
@@ -179,9 +181,7 @@ namespace Alepha::Hydrogen::detail::Thread_m
 		else if( impl().state == Synchronizing )
 		{
 			impl().state= Opening;
-			const bool unblock= impl().threadBlocked;
-			impl().threadBlocked= false;
-			if( unblock )
+			if( impl().threadBlocked )
 			{
 				impl().var.notify_one();
 
diff --git a/Utility/ScopedState.h b/Utility/ScopedState.h
new file mode 100644
index 0000000..e356187
--- /dev/null
+++ b/Utility/ScopedState.h
@@ -0,0 +1,28 @@
+static_assert( __cplusplus > 2020'00 );
+
+#pragma once
+
+#include <Alepha/Alepha.h>
+
+#include <boost/noncopyable.hpp>
+
+namespace Alepha::Hydrogen::Utility  ::detail::  ScopedState_m
+{
+	inline namespace exports
+	{
+		class ScopedState : boost::noncopyable
+		{
+			private:
+				bool &state;
+
+			public:
+				~ScopedState() { state= false; }
+				explicit ScopedState( bool &state ) : state( state ) { state= true; }
+		};
+	}
+}
+
+namespace Alepha::Hydrogen::Utility::inline exports::inline ScopedState_m
+{
+	using namespace detail::ScopedState_m::exports;
+}