From 7af8e5774c356e3557fc7e14266e8fef1712cc49 Mon Sep 17 00:00:00 2001
From: Jason Volk <jason@zemos.net>
Date: Fri, 5 Jul 2019 17:34:42 -0700
Subject: [PATCH] ircd::ios: Add no-op synchronous defer overload; use w/
 this_ctx::yield().

---
 include/ircd/ios.h |  3 +++
 ircd/ctx.cc        | 15 +++--------
 ircd/ios.cc        | 63 +++++++++++++++++++++++++++++++++++++++++-----
 3 files changed, 63 insertions(+), 18 deletions(-)

diff --git a/include/ircd/ios.h b/include/ircd/ios.h
index 307abed20..5f490b732 100644
--- a/include/ircd/ios.h
+++ b/include/ircd/ios.h
@@ -77,6 +77,7 @@ struct ircd::ios::dispatch
 {
 	dispatch(descriptor &, std::function<void ()>);
 	dispatch(descriptor &, synchronous_t, const std::function<void ()> &);
+	dispatch(descriptor &, synchronous_t);
 	dispatch(std::function<void ()>);
 	dispatch(synchronous_t, const std::function<void ()> &);
 };
@@ -85,6 +86,7 @@ struct ircd::ios::defer
 {
 	defer(descriptor &, std::function<void ()>);
 	defer(descriptor &, synchronous_t, const std::function<void ()> &);
+	defer(descriptor &, synchronous_t);
 	defer(std::function<void ()>);
 	defer(synchronous_t, const std::function<void ()> &);
 };
@@ -93,6 +95,7 @@ struct ircd::ios::post
 {
 	post(descriptor &, std::function<void ()>);
 	post(descriptor &, synchronous_t, const std::function<void ()> &);
+	post(descriptor &, synchronous_t);
 	post(std::function<void ()>);
 	post(synchronous_t, const std::function<void ()> &);
 };
diff --git a/ircd/ctx.cc b/ircd/ctx.cc
index 28e254d04..0c21295c2 100644
--- a/ircd/ctx.cc
+++ b/ircd/ctx.cc
@@ -638,19 +638,10 @@ ircd::ctx::this_ctx::yield()
 		"ircd::ctx courtesy yield"
 	};
 
-	bool done(false);
-	const auto restore([&done, &me(cur())]
+	ircd::defer
 	{
-		done = true;
-		notify(me);
-	});
-
-	// All spurious notifications are ignored until `done`
-	ircd::defer(descriptor, restore); do
-	{
-		wait();
-	}
-	while(!done);
+		descriptor, ios::synchronous
+	};
 }
 
 ulong
diff --git a/ircd/ios.cc b/ircd/ios.cc
index 1f904ca53..137017013 100644
--- a/ircd/ios.cc
+++ b/ircd/ios.cc
@@ -290,14 +290,31 @@ ircd::ios::dispatch_desc
 };
 
 ircd::ios::dispatch::dispatch(std::function<void ()> function)
+:dispatch
+{
+	dispatch_desc, std::move(function)
+}
 {
-	dispatch(dispatch_desc, std::move(function));
 }
 
 ircd::ios::dispatch::dispatch(synchronous_t,
                               const std::function<void ()> &function)
+:dispatch
+{
+	dispatch_desc, synchronous, std::move(function)
+}
+{
+}
+
+ircd::ios::dispatch::dispatch(descriptor &descriptor,
+                              synchronous_t)
+:dispatch
+{
+	dispatch_desc, synchronous, []
+	{
+	}
+}
 {
-	dispatch(dispatch_desc, synchronous, std::move(function));
 }
 
 ircd::ios::dispatch::dispatch(descriptor &descriptor,
@@ -337,14 +354,31 @@ ircd::ios::defer_desc
 };
 
 ircd::ios::defer::defer(std::function<void ()> function)
+:defer
+{
+	defer_desc, std::move(function)
+}
 {
-	defer(defer_desc, std::move(function));
 }
 
 ircd::ios::defer::defer(synchronous_t,
                         const std::function<void ()> &function)
+:defer
+{
+	defer_desc, synchronous, function
+}
+{
+}
+
+ircd::ios::defer::defer(descriptor &descriptor,
+                        synchronous_t)
+:defer
+{
+	defer_desc, synchronous, []
+	{
+	}
+}
 {
-	defer(defer_desc, synchronous, function);
 }
 
 ircd::ios::defer::defer(descriptor &descriptor,
@@ -384,14 +418,31 @@ ircd::ios::post_desc
 };
 
 ircd::ios::post::post(std::function<void ()> function)
+:post
+{
+	post_desc, std::move(function)
+}
 {
-	post(post_desc, std::move(function));
 }
 
 ircd::ios::post::post(synchronous_t,
                       const std::function<void ()> &function)
+:post
+{
+	post_desc, synchronous, function
+}
+{
+}
+
+ircd::ios::post::post(descriptor &descriptor,
+                      synchronous_t)
+:post
+{
+	descriptor, synchronous, []
+	{
+	}
+}
 {
-	post(post_desc, synchronous, function);
 }
 
 ircd::ios::post::post(descriptor &descriptor,