MINOR: quic: release Tx buffer on each send

Complete refactor of quic-conn Tx buffer. The buffer is now released
on every send operation completion. This should help to reduce memory
footprint as now Tx buffers are allocated and released on demand.

To simplify allocation/free of quic-conn Tx buffer, two static functions
are created named qc_txb_alloc() and qc_txb_release().

diff --git a/src/xprt_quic.c b/src/xprt_quic.c
index 312c4e705405c993252a5469e84ca14b1733f2ea..45c5a9f2b1ac26406fa14855b5984ff0fce2d9fc 100644 (file)
--- a/src/xprt_quic.c
+++ b/src/xprt_quic.c
@@ -2650,6 +2650,36 @@ static inline void qc_set_dg(struct buffer *buf,
        write_ptr(b_tail(buf) + sizeof(dglen), pkt);
 }
 
+/* Allocate Tx buffer from <qc> quic-conn if needed.
+ *
+ * Returns allocated buffer or NULL on error.
+ */
+static struct buffer *qc_txb_alloc(struct quic_conn *qc)
+{
+       struct buffer *buf = &qc->tx.buf;
+       if (!b_alloc(buf))
+               return NULL;
+
+       return buf;
+}
+
+/* Free Tx buffer from <qc> if it is empty. */
+static void qc_txb_release(struct quic_conn *qc)
+{
+       struct buffer *buf = &qc->tx.buf;
+
+       /* For the moment sending function is responsible to purge the buffer
+        * entirely. It may change in the future but this requires to be able
+        * to reuse old data.
+        */
+       BUG_ON(buf && b_data(buf));
+
+       if (!b_data(buf)) {
+               b_free(buf);
+               offer_buffers(NULL, 1);
+       }
+}
+
 /* Returns 1 if a packet may be built for <qc> from <qel> encryption level
  * with <frms> as ack-eliciting frame list to send, 0 if not.
  * <cc> must equal to 1 if an immediate close was asked, 0 if not.
@@ -3617,7 +3647,7 @@ static int qc_qel_may_rm_hp(struct quic_conn *qc, struct quic_enc_level *qel)
 int qc_send_app_pkts(struct quic_conn *qc, int old_data, struct list *frms)
 {
        int ret;
-       struct buffer *buf = b_alloc(&qc->tx.buf);
+       struct buffer *buf = qc_txb_alloc(qc);
        if (!buf)
                return 0;
 
@@ -3646,10 +3676,12 @@ int qc_send_app_pkts(struct quic_conn *qc, int old_data, struct list *frms)
 
  out:
        qc->flags &= ~QUIC_FL_CONN_RETRANS_OLD_DATA;
+       qc_txb_release(qc);
        return 1;
 
  err:
        qc->flags &= ~QUIC_FL_CONN_RETRANS_OLD_DATA;
+       qc_txb_release(qc);
        TRACE_DEVEL("leaving in error", QUIC_EV_CONN_IO_CB, qc);
        return 0;
 }
@@ -3664,7 +3696,7 @@ int qc_send_hdshk_pkts(struct quic_conn *qc, int old_data,
                        enum quic_tls_enc_level next_tel, struct list *next_tel_frms)
 {
        int ret;
-       struct buffer *buf = b_alloc(&qc->tx.buf);
+       struct buffer *buf = qc_txb_alloc(qc);
        if (!buf)
                return 0;
 
@@ -3689,10 +3721,12 @@ int qc_send_hdshk_pkts(struct quic_conn *qc, int old_data,
 
  out:
        qc->flags &= ~QUIC_FL_CONN_RETRANS_OLD_DATA;
+       qc_txb_release(qc);
        return 1;
 
  err:
        qc->flags &= ~QUIC_FL_CONN_RETRANS_OLD_DATA;
+       qc_txb_release(qc);
        TRACE_DEVEL("leaving in error", QUIC_EV_CONN_IO_CB, qc);
        return 0;
 }
@@ -3924,7 +3958,7 @@ struct task *quic_conn_io_cb(struct task *t, void *context, unsigned int state)
        if (!quic_get_tls_enc_levels(&tel, &next_tel, st, 0))
                goto err;
 
-       buf = b_alloc(&qc->tx.buf);
+       buf = qc_txb_alloc(qc);
        if (!buf)
                goto err;
 
@@ -3957,10 +3991,12 @@ struct task *quic_conn_io_cb(struct task *t, void *context, unsigned int state)
        }
 
  out:
+       qc_txb_release(qc);
        TRACE_LEAVE(QUIC_EV_CONN_IO_CB, qc, &st);
        return t;
 
  err:
+       qc_txb_release(qc);
        TRACE_DEVEL("leaving in error", QUIC_EV_CONN_IO_CB, qc, &st, &ssl_err);
        return t;
 }
@@ -4061,8 +4097,6 @@ static void quic_conn_release(struct quic_conn *qc)
                pool_free(pool_head_quic_rx_packet, pkt);
        }
 
-       b_free(&qc->tx.buf);
-
        if (qc->idle_timer_task) {
                task_destroy(qc->idle_timer_task);
                qc->idle_timer_task = NULL;