From 96d5b6fe57521bd8de6387933dac3388037d0d2b Mon Sep 17 00:00:00 2001
From: Jason Volk <jason@zemos.net>
Date: Mon, 20 Feb 2023 18:14:22 -0800
Subject: [PATCH] ircd::ctx::list: Add mid-list insertion suite to interface.

---
 include/ircd/ctx/list.h |  3 ++
 ircd/ctx.cc             | 61 +++++++++++++++++++++++++++++++++++++++++
 2 files changed, 64 insertions(+)

diff --git a/include/ircd/ctx/list.h b/include/ircd/ctx/list.h
index f737a2d84..c532e0275 100644
--- a/include/ircd/ctx/list.h
+++ b/include/ircd/ctx/list.h
@@ -64,8 +64,11 @@ struct ircd::ctx::list
 	bool empty() const noexcept;
 	size_t size() const noexcept;
 
+	void push_before(ctx *, ctx * = current) noexcept;
+	void push_after(ctx *, ctx * = current) noexcept;
 	void push_front(ctx * = current) noexcept;
 	void push_back(ctx * = current) noexcept;
+	void push_sort(ctx * = current) noexcept;              // weak/partial
 	void push(ctx * = current) noexcept;                   // push_back
 
 	ctx *pop_front() noexcept;
diff --git a/ircd/ctx.cc b/ircd/ctx.cc
index 33f75cf95..6a2cf4f1b 100644
--- a/ircd/ctx.cc
+++ b/ircd/ctx.cc
@@ -3074,6 +3074,21 @@ noexcept
 	return head;
 }
 
+void
+ircd::ctx::list::push_sort(ctx *const c)
+noexcept
+{
+	assert(c);
+	for(ctx *o{head}; o; o = next(o))
+		if(ircd::ctx::id(*c) < ircd::ctx::id(*o))
+		{
+			push_before(o, c);
+			return;
+		}
+
+	push_back(c);
+}
+
 [[gnu::hot]]
 void
 ircd::ctx::list::push_front(ctx *const c)
@@ -3118,6 +3133,52 @@ noexcept
 	tail = c;
 }
 
+[[gnu::hot]]
+void
+ircd::ctx::list::push_after(ctx *const o,
+                            ctx *const c)
+noexcept
+{
+	assert(o != c);
+	assert(next(c) == nullptr);
+	assert(prev(c) == nullptr);
+	assert(prev(o) || o == head);
+	assert(next(o) || o == tail);
+
+	prev(c) = o;
+	next(c) = next(o);
+	next(o) = c;
+
+	if(next(c))
+		prev(next(c)) = c;
+
+	if(tail == o)
+		tail = c;
+}
+
+[[gnu::hot]]
+void
+ircd::ctx::list::push_before(ctx *const o,
+                             ctx *const c)
+noexcept
+{
+	assert(o != c);
+	assert(next(c) == nullptr);
+	assert(prev(c) == nullptr);
+	assert(prev(o) || o == head);
+	assert(next(o) || o == tail);
+
+	next(c) = o;
+	prev(c) = prev(o);
+	prev(o) = c;
+
+	if(prev(c))
+		next(prev(c)) = c;
+
+	if(head == o)
+		head = c;
+}
+
 size_t
 ircd::ctx::list::size()
 const noexcept