On Wed, Nov 17, 2021 at 10:31:01AM +0300, Roman Arutyunyan wrote:
> # HG changeset patch
> # User Roman Arutyunyan <arut@nginx.com>
> # Date 1637133234 -10800
> # Wed Nov 17 10:13:54 2021 +0300
> # Branch quic
> # Node ID 4e3a7fc0533192f51a01042a1e9dd2b595881420
> # Parent 4ad8fc79cb33257c928a9098a87324b350576551
> QUIC: update stream flow control credit on STREAM_DATA_BLOCKED.
>
> Previously, after receiving STREAM_DATA_BLOCKED, current flow control limit
> was sent to client. Now, if the limit can be updated to the full window size,
> it is updated and the new value is sent to client, otherwise nothing is sent.
>
> The change lets client update flow control credit on demand. Also, it saves
> traffic by not sending MAX_STREAM_DATA with the same value twice.
>
> diff --git a/src/event/quic/ngx_event_quic_streams.c b/src/event/quic/ngx_event_quic_streams.c
> --- a/src/event/quic/ngx_event_quic_streams.c
> +++ b/src/event/quic/ngx_event_quic_streams.c
> @@ -31,6 +31,7 @@ static size_t ngx_quic_max_stream_flow(n
> static void ngx_quic_stream_cleanup_handler(void *data);
> static ngx_int_t ngx_quic_control_flow(ngx_connection_t *c, uint64_t last);
> static ngx_int_t ngx_quic_update_flow(ngx_connection_t *c, uint64_t last);
> +static ngx_int_t ngx_quic_update_max_stream_data(ngx_connection_t *c);
>
>
> ngx_connection_t *
> @@ -1190,8 +1191,6 @@ ngx_int_t
> ngx_quic_handle_stream_data_blocked_frame(ngx_connection_t *c,
> ngx_quic_header_t *pkt, ngx_quic_stream_data_blocked_frame_t *f)
> {
> - uint64_t limit;
> - ngx_quic_frame_t *frame;
> ngx_quic_stream_t *qs;
> ngx_quic_connection_t *qc;
>
> @@ -1217,29 +1216,10 @@ ngx_quic_handle_stream_data_blocked_fram
> return NGX_OK;
> }
>
> - limit = qs->recv_max_data;
> -
> - if (ngx_quic_init_stream(qs) != NGX_OK) {
> - return NGX_ERROR;
> - }
> -
> - } else {
> - limit = qs->recv_max_data;
> + return ngx_quic_init_stream(qs);
> }
>
> - frame = ngx_quic_alloc_frame(c);
> - if (frame == NULL) {
> - return NGX_ERROR;
> - }
> -
> - frame->level = pkt->level;
> - frame->type = NGX_QUIC_FT_MAX_STREAM_DATA;
> - frame->u.max_stream_data.id = f->id;
> - frame->u.max_stream_data.limit = limit;
> -
> - ngx_quic_queue_frame(qc, frame);
> -
> - return NGX_OK;
> + return ngx_quic_update_max_stream_data(qs->connection);
> }
>
>
> @@ -1587,22 +1567,9 @@ ngx_quic_update_flow(ngx_connection_t *c
> if (!rev->pending_eof && !rev->error
> && qs->recv_max_data <= qs->recv_offset + qs->recv_window / 2)
> {
> - qs->recv_max_data = qs->recv_offset + qs->recv_window;
> -
> - ngx_log_debug1(NGX_LOG_DEBUG_EVENT, c->log, 0,
> - "quic flow update msd:%uL", qs->recv_max_data);
> -
> - frame = ngx_quic_alloc_frame(pc);
> - if (frame == NULL) {
> + if (ngx_quic_update_max_stream_data(c) != NGX_OK) {
> return NGX_ERROR;
> }
> -
> - frame->level = ssl_encryption_application;
> - frame->type = NGX_QUIC_FT_MAX_STREAM_DATA;
> - frame->u.max_stream_data.id = qs->id;
> - frame->u.max_stream_data.limit = qs->recv_max_data;
> -
> - ngx_quic_queue_frame(qc, frame);
> }
>
> qc->streams.recv_offset += len;
> @@ -1632,6 +1599,44 @@ ngx_quic_update_flow(ngx_connection_t *c
> }
>
>
> +static ngx_int_t
> +ngx_quic_update_max_stream_data(ngx_connection_t *c)
> +{
> + uint64_t recv_max_data;
> + ngx_quic_frame_t *frame;
> + ngx_quic_stream_t *qs;
> + ngx_quic_connection_t *qc;
> +
> + qs = c->quic;
> + qc = ngx_quic_get_connection(qs->parent);
> +
> + recv_max_data = qs->recv_offset + qs->recv_window;
> +
> + if (qs->recv_max_data == recv_max_data) {
> + return NGX_OK;
> + }
> +
> + qs->recv_max_data = recv_max_data;
> +
> + ngx_log_debug1(NGX_LOG_DEBUG_EVENT, c->log, 0,
> + "quic flow update msd:%uL", qs->recv_max_data);
> +
> + frame = ngx_quic_alloc_frame(c);

The argument should be "pc":

frame = ngx_quic_alloc_frame(pc);

> + if (frame == NULL) {
> + return NGX_ERROR;
> + }
> +
> + frame->level = ssl_encryption_application;
> + frame->type = NGX_QUIC_FT_MAX_STREAM_DATA;
> + frame->u.max_stream_data.id = qs->id;
> + frame->u.max_stream_data.limit = qs->recv_max_data;
> +
> + ngx_quic_queue_frame(qc, frame);
> +
> + return NGX_OK;
> +}
> +
> +
> ngx_int_t
> ngx_quic_handle_read_event(ngx_event_t *rev, ngx_uint_t flags)
> {
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--
Roman Arutyunyan
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