From da34142bf1719cbd18107229352c330ff7a64ff3 Mon Sep 17 00:00:00 2001
From: ADAM David Alan Martin <adam@recursive.engineer>
Date: Fri, 5 Jan 2024 23:57:47 -0500
Subject: [PATCH] Fix stalls due to lacking custom terminal notifications.

`Dropbox` and `Mailbox` should be roughly the same interface, but
with different stall semantics.  However, terminal operations don't
wait.  `finish( custom )` should be a handoff without wait.

`Dropbox`'s primary thread-coordination works in terms of an
acquire/release semantic whereby `release` doesn't block, so this
naturally works.  However, `Mailbox` works in terms of the `Interlock`
primitive which allows for a terminal-case `checkpoint`.  Therefore
`finish( custom )` has to call the `checkpoint` api in `Mailbox`
---
 Atomic/Dropbox.h | 10 +++++++++-
 Atomic/Mailbox.h | 15 ++++++++++++++-
 2 files changed, 23 insertions(+), 2 deletions(-)

diff --git a/Atomic/Dropbox.h b/Atomic/Dropbox.h
index 5967c24..312fddb 100644
--- a/Atomic/Dropbox.h
+++ b/Atomic/Dropbox.h
@@ -153,10 +153,18 @@ namespace Alepha::Hydrogen::Atomic  ::detail::  Dropbox_m
 				sendoff();
 			}
 
+			void
+			finish( auto newNotification )
+			{
+				auto &preparing= drops.producer.acquireBox();
+				preparing.notification= std::make_exception_ptr( std::move( newNotification ) );
+				sendoff();
+			}
+
 			void
 			finish()
 			{
-				notify( build_exception< FinishedCondition >( "" ) );
+				finish( build_exception< FinishedCondition >( "" ) );
 			}
 	};
 }
diff --git a/Atomic/Mailbox.h b/Atomic/Mailbox.h
index 12ac6ba..d420327 100644
--- a/Atomic/Mailbox.h
+++ b/Atomic/Mailbox.h
@@ -241,6 +241,19 @@ namespace Alepha::Hydrogen::Atomic  ::detail::  Mailbox_m
 				checkpoint( lock );
 			}
 
+			/*!
+			 * @brief      This function will pump the mailbox, and deliver a custom notification
+			 *             event to the other side, without waiting (last step).
+			 */
+			void
+			finish( auto newNotification )
+			{
+				auto notification_ptr= std::make_exception_ptr( std::move( newNotification ) );
+				Alepha::unique_lock lock( access );
+				notification= std::move( notification_ptr );
+				checkpoint( lock );
+			}
+
 
 			/*!
 			 * @brief      This function will pump the mailbox, and deliver a custom notification
@@ -249,7 +262,7 @@ namespace Alepha::Hydrogen::Atomic  ::detail::  Mailbox_m
 			void
 			notify( auto newNotification )
 			{
-				auto notification_ptr= std::make_exception_ptr( std::move( notification ) );
+				auto notification_ptr= std::make_exception_ptr( std::move( newNotification ) );
 				Alepha::unique_lock lock( access );
 				assertion( not finished );
 				notification= std::move( notification_ptr );