[PATCH 2 of 2] HTTP/3: delayed Insert Count Increment instruction
Roman Arutyunyan
arut at nginx.com
Tue Nov 16 12:56:18 UTC 2021
On Thu, Nov 11, 2021 at 06:20:59PM +0300, Sergey Kandaurov wrote:
>
> > On 21 Oct 2021, at 16:41, Roman Arutyunyan <arut at nginx.com> wrote:
> >
> > # HG changeset patch
> > # User Roman Arutyunyan <arut at nginx.com>
> > # Date 1634804424 -10800
> > # Thu Oct 21 11:20:24 2021 +0300
> > # Branch quic
> > # Node ID e2d65b59ccb9035cbd619358a121ba5bcca3404a
> > # Parent 8b049432ef2dcdb8d1a8ec1a5e41c0a340285b65
> > HTTP/3: delayed Insert Count Increment instruction.
> >
> > Sending the instruction is delayed until the end of the current event cycle.
> > Delaying the instruction is allowed by quic-qpack-21, section 2.2.2.3.
> > The goal is to reduce the amount of data sent back to client by accumulating
> > inserts.
>
> Or it may be not sent at all if there are no blocked streams.
Sure.
HTTP/3: delayed Insert Count Increment instruction.
Sending the instruction is delayed until the end of the current event cycle.
Delaying the instruction is allowed by quic-qpack-21, section 2.2.2.3.
The goal is to reduce the amount of data sent back to client by accumulating
several inserts in one instruction and sometimes not sending the instruction at
all, if Section Acknowledgement was sent just before it.
> >
> > diff --git a/src/http/v3/ngx_http_v3.c b/src/http/v3/ngx_http_v3.c
> > --- a/src/http/v3/ngx_http_v3.c
> > +++ b/src/http/v3/ngx_http_v3.c
> > @@ -47,6 +47,10 @@ ngx_http_v3_init_session(ngx_connection_
> > h3c->keepalive.handler = ngx_http_v3_keepalive_handler;
> > h3c->keepalive.cancelable = 1;
> >
> > + h3c->table.send_insert_count.log = pc->log;
> > + h3c->table.send_insert_count.data = pc;
> > + h3c->table.send_insert_count.handler = ngx_http_v3_inc_insert_count_handler;
> > +
> > cln = ngx_pool_cleanup_add(pc->pool, 0);
> > if (cln == NULL) {
> > return NGX_ERROR;
> > @@ -85,6 +89,10 @@ ngx_http_v3_cleanup_session(void *data)
> > if (h3c->keepalive.timer_set) {
> > ngx_del_timer(&h3c->keepalive);
> > }
> > +
> > + if (h3c->table.send_insert_count.posted) {
> > + ngx_delete_posted_event(&h3c->table.send_insert_count);
> > + }
> > }
> >
> >
> > diff --git a/src/http/v3/ngx_http_v3_parse.c b/src/http/v3/ngx_http_v3_parse.c
> > --- a/src/http/v3/ngx_http_v3_parse.c
> > +++ b/src/http/v3/ngx_http_v3_parse.c
> > @@ -395,6 +395,8 @@ done:
> > if (ngx_http_v3_send_ack_section(c, c->quic->id) != NGX_OK) {
> > return NGX_ERROR;
> > }
> > +
> > + ngx_http_v3_ack_insert_count(c, st->prefix.insert_count);
> > }
> >
> > st->state = sw_start;
> > diff --git a/src/http/v3/ngx_http_v3_tables.c b/src/http/v3/ngx_http_v3_tables.c
> > --- a/src/http/v3/ngx_http_v3_tables.c
> > +++ b/src/http/v3/ngx_http_v3_tables.c
> > @@ -232,11 +232,9 @@ ngx_http_v3_insert(ngx_connection_t *c,
> > dt->elts[dt->nelts++] = field;
> > dt->size += size;
> >
> > - /* TODO increment can be sent less often */
> > + dt->insert_count++;
> >
> > - if (ngx_http_v3_send_inc_insert_count(c, 1) != NGX_OK) {
> > - return NGX_ERROR;
> > - }
> > + ngx_post_event(&dt->send_insert_count, &ngx_posted_events);
> >
> > if (ngx_http_v3_new_entry(c) != NGX_OK) {
> > return NGX_ERROR;
> > @@ -246,6 +244,34 @@ ngx_http_v3_insert(ngx_connection_t *c,
> > }
> >
> >
> > +void
> > +ngx_http_v3_inc_insert_count_handler(ngx_event_t *ev)
> > +{
> > + ngx_connection_t *c;
> > + ngx_http_v3_session_t *h3c;
> > + ngx_http_v3_dynamic_table_t *dt;
> > +
> > + c = ev->data;
> > +
> > + ngx_log_debug0(NGX_LOG_DEBUG_HTTP, c->log, 0,
> > + "http3 inc insert count handler");
> > +
> > + h3c = ngx_http_v3_get_session(c);
> > + dt = &h3c->table;
> > +
> > + if (dt->insert_count > dt->ack_insert_count) {
> > + if (ngx_http_v3_send_inc_insert_count(c,
> > + dt->insert_count - dt->ack_insert_count)
> > + != NGX_OK)
> > + {
> > + return;
> > + }
> > +
> > + dt->ack_insert_count = dt->insert_count;
> > + }
> > +}
> > +
> > +
> > ngx_int_t
> > ngx_http_v3_set_capacity(ngx_connection_t *c, ngx_uint_t capacity)
> > {
> > @@ -603,6 +629,21 @@ ngx_http_v3_check_insert_count(ngx_conne
> > }
> >
> >
> > +void
> > +ngx_http_v3_ack_insert_count(ngx_connection_t *c, uint64_t insert_count)
> > +{
> > + ngx_http_v3_session_t *h3c;
> > + ngx_http_v3_dynamic_table_t *dt;
> > +
> > + h3c = ngx_http_v3_get_session(c);
> > + dt = &h3c->table;
> > +
> > + if (dt->ack_insert_count < insert_count) {
> > + dt->ack_insert_count = insert_count;
> > + }
> > +}
> > +
> > +
> > static void
> > ngx_http_v3_unblock(void *data)
> > {
> > diff --git a/src/http/v3/ngx_http_v3_tables.h b/src/http/v3/ngx_http_v3_tables.h
> > --- a/src/http/v3/ngx_http_v3_tables.h
> > +++ b/src/http/v3/ngx_http_v3_tables.h
> > @@ -26,9 +26,13 @@ typedef struct {
> > ngx_uint_t base;
> > size_t size;
> > size_t capacity;
> > + uint64_t insert_count;
> > + uint64_t ack_insert_count;
> > + ngx_event_t send_insert_count;
> > } ngx_http_v3_dynamic_table_t;
> >
> >
> > +void ngx_http_v3_inc_insert_count_handler(ngx_event_t *ev);
> > void ngx_http_v3_cleanup_table(ngx_http_v3_session_t *h3c);
> > ngx_int_t ngx_http_v3_ref_insert(ngx_connection_t *c, ngx_uint_t dynamic,
> > ngx_uint_t index, ngx_str_t *value);
> > @@ -46,6 +50,7 @@ ngx_int_t ngx_http_v3_decode_insert_coun
> > ngx_uint_t *insert_count);
> > ngx_int_t ngx_http_v3_check_insert_count(ngx_connection_t *c,
> > ngx_uint_t insert_count);
> > +void ngx_http_v3_ack_insert_count(ngx_connection_t *c, uint64_t insert_count);
> > ngx_int_t ngx_http_v3_set_param(ngx_connection_t *c, uint64_t id,
> > uint64_t value);
> >
>
> Looks good.
>
> --
> Sergey Kandaurov
>
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--
Roman Arutyunyan
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