MINOR: quic: support pacing emission on quic_conn layer

Author: a-denoyelle

include/haproxy/quic_pacing-t.h

@@ -7,6 +7,7 @@
 struct quic_pacer {
 	struct list frms;
 	const struct quic_cc_path *path;
+	ullong next;
 };
 
 #endif /* _HAPROXY_QUIC_PACING_T_H */

include/haproxy/quic_pacing.h

@@ -11,6 +11,7 @@ static inline void quic_pacing_init(struct quic_pacer *pacer,
 {
 	LIST_INIT(&pacer->frms);
 	pacer->path = path;
+	pacer->next = 0;
 }
 
 static inline void quic_pacing_reset(struct quic_pacer *pacer)
@@ -29,4 +30,13 @@ static inline struct list *quic_pacing_frms(struct quic_pacer *pacer)
 	return &pacer->frms;
 }
 
+static inline ullong quic_pacing_ns_pkt(const struct quic_pacer *pacer)
+{
+	return pacer->path->loss.srtt * 1000000 / (pacer->path->cwnd / pacer->path->mtu + 1);
+}
+
+int quic_pacing_expired(const struct quic_pacer *pacer);
+
+void quic_pacing_sent_done(struct quic_pacer *pacer, int sent);
+
 #endif /* _HAPROXY_QUIC_PACING_H */

include/haproxy/quic_tx-t.h

@@ -66,6 +66,7 @@ enum qc_build_pkt_err {
 
 enum quic_tx_err {
 	QUIC_TX_ERR_NONE,
+	QUIC_TX_ERR_AGAIN,
 	QUIC_TX_ERR_FATAL,
 };
 

include/haproxy/quic_tx.h

@@ -25,6 +25,7 @@
 #include <haproxy/list-t.h>
 #include <haproxy/quic_conn-t.h>
 #include <haproxy/quic_tls-t.h>
+#include <haproxy/quic_pacing-t.h>
 #include <haproxy/quic_rx-t.h>
 #include <haproxy/quic_tx-t.h>
 
@@ -33,7 +34,8 @@ void qc_txb_release(struct quic_conn *qc);
 int qc_purge_txbuf(struct quic_conn *qc, struct buffer *buf);
 struct buffer *qc_get_txb(struct quic_conn *qc);
 
-enum quic_tx_err qc_send_mux(struct quic_conn *qc, struct list *frms);
+enum quic_tx_err qc_send_mux(struct quic_conn *qc, struct list *frms,
+                             struct quic_pacer *pacer);
 
 void qel_register_send(struct list *send_list, struct quic_enc_level *qel,
                        struct list *frms);

src/mux_quic.c

@@ -2084,7 +2084,7 @@ static int qcc_send_frames(struct qcc *qcc, struct list *frms)
 		return 1;
 	}
 
-	ret = qc_send_mux(qcc->conn->handle.qc, frms);
+	ret = qc_send_mux(qcc->conn->handle.qc, frms, NULL);
 	if (ret == QUIC_TX_ERR_FATAL) {
 		TRACE_DEVEL("error on sending", QMUX_EV_QCC_SEND, qcc->conn);
 		qcc_subscribe_send(qcc);

src/quic_pacing.c

@@ -1 +1,15 @@
 #include <haproxy/quic_pacing.h>
+
+#include <haproxy/quic_tx.h>
+
+struct quic_conn;
+
+int quic_pacing_expired(const struct quic_pacer *pacer)
+{
+	return !pacer->next || pacer->next <= now_mono_time();
+}
+
+void quic_pacing_sent_done(struct quic_pacer *pacer, int sent)
+{
+	pacer->next = now_mono_time() + quic_pacing_ns_pkt(pacer) * sent;
+}

src/quic_tx.c

@@ -20,6 +20,7 @@
 #include <haproxy/trace.h>
 #include <haproxy/quic_cid.h>
 #include <haproxy/quic_conn.h>
+#include <haproxy/quic_pacing.h>
 #include <haproxy/quic_retransmit.h>
 #include <haproxy/quic_retry.h>
 #include <haproxy/quic_sock.h>
@@ -469,11 +470,12 @@ int qc_purge_txbuf(struct quic_conn *qc, struct buffer *buf)
  *
  * Returns the result from qc_send() function.
  */
-enum quic_tx_err qc_send_mux(struct quic_conn *qc, struct list *frms)
+enum quic_tx_err qc_send_mux(struct quic_conn *qc, struct list *frms,
+                             struct quic_pacer *pacer)
 {
 	struct list send_list = LIST_HEAD_INIT(send_list);
 	enum quic_tx_err ret = QUIC_TX_ERR_NONE;
-	int sent;
+	int max_dgram = 0, sent;
 
 	TRACE_ENTER(QUIC_EV_CONN_TXPKT, qc);
 	BUG_ON(qc->mux_state != QC_MUX_READY); /* Only MUX can uses this function so it must be ready. */
@@ -492,11 +494,20 @@ enum quic_tx_err qc_send_mux(struct quic_conn *qc, struct list *frms)
 		qc_send(qc, 0, &send_list, 0);
 	}
 
+	if (pacer)
+		max_dgram = 1;
+
 	TRACE_STATE("preparing data (from MUX)", QUIC_EV_CONN_TXPKT, qc);
 	qel_register_send(&send_list, qc->ael, frms);
-	sent = qc_send(qc, 0, &send_list, 0);
-	if (sent <= 0)
+	sent = qc_send(qc, 0, &send_list, max_dgram);
+	if (sent <= 0) {
 		ret = QUIC_TX_ERR_FATAL;
+	}
+	else if (pacer) {
+		if (max_dgram && max_dgram == sent && !LIST_ISEMPTY(frms))
+			ret = QUIC_TX_ERR_AGAIN;
+		quic_pacing_sent_done(pacer, sent);
+	}
 
 	TRACE_LEAVE(QUIC_EV_CONN_TXPKT, qc);
 	return ret;