From 725f06962192a1c0191535e00cd6f825caef122a Mon Sep 17 00:00:00 2001
From: Jason Volk <jason@zemos.net>
Date: Thu, 11 Jan 2018 18:38:29 -0800
Subject: [PATCH] ircd::net: Add discard_all() convenience.

---
 include/ircd/net/read.h |  3 +++
 ircd/net.cc             | 23 +++++++++++++++++++++++
 2 files changed, 26 insertions(+)

diff --git a/include/ircd/net/read.h b/include/ircd/net/read.h
index 77820ed95..14ce68871 100644
--- a/include/ircd/net/read.h
+++ b/include/ircd/net/read.h
@@ -39,6 +39,9 @@ namespace ircd::net
 	// Alias to read_any();
 	size_t read(socket &, const vector_view<const mutable_buffer> &);
 	size_t read(socket &, const mutable_buffer &);
+
+	// Yields until len has been discarded
+	size_t discard_all(socket &, const size_t &len);
 }
 
 /// Alias to read_any();
diff --git a/ircd/net.cc b/ircd/net.cc
index 605125558..fc717fe2b 100644
--- a/ircd/net.cc
+++ b/ircd/net.cc
@@ -196,6 +196,29 @@ ircd::net::write_one(socket &socket,
 // net/read.h
 //
 
+/// Yields ircd::ctx until len bytes have been received and discarded from the
+/// socket.
+///
+size_t
+ircd::net::discard_all(socket &socket,
+                       const size_t &len)
+{
+	static char buffer[512] alignas(16);
+
+	size_t remain{len}; while(remain)
+	{
+		const mutable_buffer mb
+		{
+			buffer, std::min(remain, sizeof(buffer))
+		};
+
+		__builtin_prefetch(data(mb), 1, 0);    // 1 = write, 0 = no cache
+		read_all(socket, mb);
+	}
+
+	return len;
+}
+
 /// Yields ircd::ctx until buffers are full.
 ///
 /// Use this only if the following are true: