From 02e09728a50cd5784f6e635a53d3814e86273a2c Mon Sep 17 00:00:00 2001
From: Jason Volk <jason@zemos.net>
Date: Mon, 17 Apr 2023 21:36:09 -0700
Subject: [PATCH] ircd::rest: Add option to supply temporary/headers buffer in
 lieu of allocating.

---
 include/ircd/rest.h |  4 ++++
 ircd/rest.cc        | 40 ++++++++++++++++++++++++++++++++--------
 2 files changed, 36 insertions(+), 8 deletions(-)

diff --git a/include/ircd/rest.h b/include/ircd/rest.h
index 313c74108..94152c42e 100644
--- a/include/ircd/rest.h
+++ b/include/ircd/rest.h
@@ -100,6 +100,10 @@ struct ircd::rest::opts
 	/// receiving dynamic content. Supply an empty unique_buffer instance.
 	unique_const_buffer *out {nullptr};
 
+	/// Optionally supply the temporary buffer for headers in/out in lieu of
+	/// any internally allocated.
+	mutable_buffer buf;
+
 	/// Timeout for the yielding/synchronous calls of this interface.
 	seconds timeout {20s};
 
diff --git a/ircd/rest.cc b/ircd/rest.cc
index eb5c90fa1..6abf15433 100644
--- a/ircd/rest.cc
+++ b/ircd/rest.cc
@@ -14,13 +14,25 @@ ircd::rest::request::request(const rfc3986::uri &uri,
 	if(!opts.remote)
 		opts.remote = net::hostport{uri};
 
-	const unique_mutable_buffer buf
+	const bool need_alloc
 	{
-		empty(opts.sout.head) || empty(opts.sin.head)?
-			16_KiB: 0_KiB
+		empty(opts.buf)
+		&& (empty(opts.sout.head) || empty(opts.sin.head))
+	};
+
+	const unique_mutable_buffer _buf
+	{
+		need_alloc? 16_KiB: 0_KiB
+	};
+
+	if(!empty(_buf))
+		opts.buf = _buf;
+
+	window_buffer window
+	{
+		opts.buf
 	};
 
-	window_buffer window{buf};
 	if(empty(opts.sout.head))
 	{
 		assert(opts.remote);
@@ -80,13 +92,25 @@ ircd::rest::request::request(const mutable_buffer &out,
 	if(!opts.remote)
 		opts.remote = net::hostport{uri};
 
-	const unique_mutable_buffer buf
+	const bool need_alloc
 	{
-		empty(opts.sout.head) || empty(opts.sin.head)?
-			16_KiB: 0_KiB
+		empty(opts.buf)
+		&& (empty(opts.sout.head) || empty(opts.sin.head))
+	};
+
+	const unique_mutable_buffer _buf
+	{
+		need_alloc? 16_KiB: 0_KiB
+	};
+
+	if(!empty(_buf))
+		opts.buf = _buf;
+
+	window_buffer window
+	{
+		opts.buf
 	};
 
-	window_buffer window{buf};
 	if(empty(opts.sout.head))
 	{
 		assert(opts.remote);