From 7346e366f1928dd727ecbb53253454fdaecaebb7 Mon Sep 17 00:00:00 2001
From: skywind3000 <skywind3000@163.com>
Date: Sat, 16 May 2026 01:21:36 +0800
Subject: [PATCH] simple pacing

---
 ikcp.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/ikcp.c b/ikcp.c
index 2575239..1f32039 100644
--- a/ikcp.c
+++ b/ikcp.c
@@ -981,6 +981,7 @@ void ikcp_flush(ikcpcb *kcp)
 	IUINT32 rtomin;
 	IUINT32 prior_cwnd;
 	IUINT32 eff_cwnd, cur_inflight;
+	IINT32 pacing_budget = -1;
 	struct IQUEUEHEAD *p;
 	int change = 0;
 	int lost = 0;
@@ -993,6 +994,10 @@ void ikcp_flush(ikcpcb *kcp)
 		kcp->ccops->on_tick(kcp);
 	}
 
+	if (kcp->ccops && kcp->ccops->pacing_rate) {
+		pacing_budget = (IINT32)kcp->ccops->pacing_rate(kcp);
+	}
+
 	prior_cwnd = kcp->cwnd;
 
 	seg.conv = kcp->conv;
@@ -1149,6 +1154,10 @@ void ikcp_flush(ikcpcb *kcp)
 			segment->wnd = seg.wnd;
 			segment->una = kcp->rcv_nxt;
 
+			if (pacing_budget >= 0 && pacing_budget < (IINT32)segment->len) {
+				break;
+			}
+
 			if (kcp->ccops && kcp->ccops->on_pkt_sent) {
 				kcp->ccops->on_pkt_sent(kcp, segment->sn, current,
 						segment->len, kcp->nsnd_buf, segment->xmit);
@@ -1169,6 +1178,10 @@ void ikcp_flush(ikcpcb *kcp)
 				ptr += segment->len;
 			}
 
+			if (pacing_budget >= 0) {
+				pacing_budget -= (IINT32)segment->len;
+			}
+
 			if (segment->xmit >= kcp->dead_link) {
 				kcp->state = (IUINT32)-1;
 			}