From 97f8b67ac77d0623e536d302eb1e08666be7d411 Mon Sep 17 00:00:00 2001
From: Guus Sliepen <guus@sliepen.org>
Date: Sun, 29 Mar 2020 16:21:51 +0200
Subject: [PATCH] Don't call the poll callback unnecessarily.

Currently we call the poll callback if there is any free space in the send
buffer, every time we call utcp_timeout(). However, if the application
does not send anything inside the callback, then it most likely won't send
anything the next time if the free space in the send buffer did not change.
So only call the callback when more space has been made available in the
send buffer.
---
 utcp.c      | 10 ++++++++--
 utcp_priv.h |  2 ++
 2 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/utcp.c b/utcp.c
index 0b36de1..6aa985f 100644
--- a/utcp.c
+++ b/utcp.c
@@ -749,6 +749,7 @@ ssize_t utcp_send(struct utcp_connection *c, const void *data, size_t len) {
 	if(!is_reliable(c)) {
 		c->snd.una = c->snd.nxt = c->snd.last;
 		buffer_discard(&c->sndbuf, c->sndbuf.used);
+		c->do_poll = true;
 	}
 
 	if(is_reliable(c) && !timespec_isset(&c->rtrx_timeout)) {
@@ -1484,6 +1485,7 @@ synack:
 
 		if(data_acked) {
 			buffer_discard(&c->sndbuf, data_acked);
+			c->do_poll = true;
 		}
 
 		// Also advance snd.nxt if possible
@@ -2001,8 +2003,9 @@ struct timespec utcp_timeout(struct utcp *utcp) {
 		}
 
 		if(c->poll) {
-			if((c->state == ESTABLISHED || c->state == CLOSE_WAIT)) {
-				uint32_t len =  buffer_free(&c->sndbuf);
+			if((c->state == ESTABLISHED || c->state == CLOSE_WAIT) && c->do_poll) {
+				c->do_poll = false;
+				uint32_t len = buffer_free(&c->sndbuf);
 
 				if(len) {
 					c->poll(c, len);
@@ -2205,6 +2208,8 @@ void utcp_set_sndbuf(struct utcp_connection *c, size_t size) {
 	if(c->sndbuf.maxsize != size) {
 		c->sndbuf.maxsize = -1;
 	}
+
+	c->do_poll = buffer_free(&c->sndbuf);
 }
 
 size_t utcp_get_rcvbuf(struct utcp_connection *c) {
@@ -2272,6 +2277,7 @@ void utcp_set_recv_cb(struct utcp_connection *c, utcp_recv_t recv) {
 void utcp_set_poll_cb(struct utcp_connection *c, utcp_poll_t poll) {
 	if(c) {
 		c->poll = poll;
+		c->do_poll = buffer_free(&c->sndbuf);
 	}
 }
 
diff --git a/utcp_priv.h b/utcp_priv.h
index 1cf9e87..0b2efe4 100644
--- a/utcp_priv.h
+++ b/utcp_priv.h
@@ -106,6 +106,7 @@ struct utcp_connection {
 	uint32_t flags;
 
 	bool reapable;
+	bool do_poll;
 
 	// Callbacks
 
@@ -145,6 +146,7 @@ struct utcp_connection {
 
 	// Buffers
 
+	uint32_t prev_free;
 	struct buffer sndbuf;
 	struct buffer rcvbuf;
 	struct sack sacks[NSACKS];
-- 
2.39.2