# HG changeset patch # User Vladimir Homutov # Date 1594650689 -10800 # Node ID 909b989ec08893efc02a37ab3b591dfd5625cfce # Parent 1b9db5c8c29b78116144e2c999d4a4eb24d1d624 QUIC: reworked retransmission mechanism. Instead of timer-based retransmissions with constant packet lifetime, this patch implements ack-based loss detection and probe timeout for the cases, when no ack is received, according to the quic-recovery draft 29. diff --git a/src/event/ngx_event_quic.c b/src/event/ngx_event_quic.c --- a/src/event/ngx_event_quic.c +++ b/src/event/ngx_event_quic.c @@ -247,8 +247,7 @@ static ngx_int_t ngx_quic_send_frames(ng static void ngx_quic_set_packet_number(ngx_quic_header_t *pkt, ngx_quic_send_ctx_t *ctx); static void ngx_quic_pto_handler(ngx_event_t *ev); -static ngx_int_t ngx_quic_detect_lost(ngx_connection_t *c, - ngx_quic_send_ctx_t *ctx, ngx_msec_t *waitp); +static ngx_int_t ngx_quic_detect_lost(ngx_connection_t *c, ngx_uint_t ack); static void ngx_quic_push_handler(ngx_event_t *ev); static void ngx_quic_rbtree_insert_stream(ngx_rbtree_node_t *temp, @@ -2341,7 +2340,7 @@ ngx_quic_handle_ack_frame(ngx_connection } } - return NGX_OK; + return ngx_quic_detect_lost(c, 1); } @@ -3535,34 +3534,15 @@ ngx_quic_set_packet_number(ngx_quic_head static void ngx_quic_pto_handler(ngx_event_t *ev) { - ngx_uint_t i; - ngx_msec_t wait, nswait; - ngx_connection_t *c; - ngx_quic_connection_t *qc; + ngx_connection_t *c; ngx_log_debug0(NGX_LOG_DEBUG_EVENT, ev->log, 0, "quic pto timer"); c = ev->data; - qc = c->quic; - - wait = 0; - - for (i = 0; i < NGX_QUIC_SEND_CTX_LAST; i++) { - if (ngx_quic_detect_lost(c, &qc->send_ctx[i], &nswait) != NGX_OK) { - ngx_quic_close_connection(c, NGX_ERROR); - return; - } - - if (i == 0) { - wait = nswait; - - } else if (nswait > 0 && (wait == 0 || wait > nswait)) { - wait = nswait; - } - } - - if (wait > 0) { - ngx_add_timer(&qc->pto, wait); + + if (ngx_quic_detect_lost(c, 0) != NGX_OK) { + ngx_quic_close_connection(c, NGX_ERROR); + return; } } @@ -3584,70 +3564,96 @@ ngx_quic_push_handler(ngx_event_t *ev) static ngx_int_t -ngx_quic_detect_lost(ngx_connection_t *c, ngx_quic_send_ctx_t *ctx, - ngx_msec_t *waitp) +ngx_quic_detect_lost(ngx_connection_t *c, ngx_uint_t ack) { uint64_t pn; - ngx_msec_t now, wait; + ngx_uint_t i; + ngx_msec_t now, wait, min_wait, thr; ngx_queue_t *q, range; ngx_quic_frame_t *f, *start; + ngx_quic_send_ctx_t *ctx; ngx_quic_connection_t *qc; qc = c->quic; - now = ngx_current_msec; - if (ngx_queue_empty(&ctx->sent)) { - *waitp = 0; - return NGX_OK; + min_wait = 0; + + if (ack) { + thr = NGX_QUIC_TIME_THR * ngx_max(qc->latest_rtt, qc->avg_rtt); + thr = ngx_max(thr, NGX_QUIC_TIME_GRANULARITY); + + } else { + thr = NGX_QUIC_HARDCODED_PTO; } - q = ngx_queue_head(&ctx->sent); - - do { - start = ngx_queue_data(q, ngx_quic_frame_t, queue); - - wait = start->last + qc->ctp.max_ack_delay - + NGX_QUIC_HARDCODED_PTO - now; - - if ((ngx_msec_int_t) wait > 0) { - break; + for (i = 0; i < NGX_QUIC_SEND_CTX_LAST; i++) { + + ctx = &qc->send_ctx[i]; + + if (ngx_queue_empty(&ctx->sent)) { + continue; } - pn = start->pnum; - - ngx_queue_init(&range); - - /* send frames with same packet number to the wire */ + q = ngx_queue_head(&ctx->sent); + do { - f = ngx_queue_data(q, ngx_quic_frame_t, queue); - - if (now - start->first > qc->tp.max_idle_timeout) { - ngx_log_error(NGX_LOG_ERR, c->log, 0, - "quic retransmission timeout"); - return NGX_DECLINED; + start = ngx_queue_data(q, ngx_quic_frame_t, queue); + + wait = start->last + thr - now; + + if ((ngx_msec_int_t) wait >= 0) { + + if (min_wait == 0 || wait < min_wait) { + min_wait = wait; + } + + if (!ack) { + break; + } + + if ((start->pnum > ctx->largest_ack) + || ((ctx->largest_ack - start->pnum) < NGX_QUIC_PKT_THR)) + { + break; + } } - if (f->pnum != pn) { - break; + pn = start->pnum; + + ngx_queue_init(&range); + + /* send frames with same packet number to the wire */ + do { + f = ngx_queue_data(q, ngx_quic_frame_t, queue); + + if (f->pnum != pn) { + break; + } + + q = ngx_queue_next(q); + + ngx_queue_remove(&f->queue); + ngx_queue_insert_tail(&range, &f->queue); + + } while (q != ngx_queue_sentinel(&ctx->sent)); + + ngx_quic_congestion_lost(c, start->last); + + if (ngx_quic_send_frames(c, ctx, &range) != NGX_OK) { + return NGX_ERROR; } - q = ngx_queue_next(q); - - ngx_queue_remove(&f->queue); - ngx_queue_insert_tail(&range, &f->queue); - } while (q != ngx_queue_sentinel(&ctx->sent)); - - ngx_quic_congestion_lost(c, start->last); - - if (ngx_quic_send_frames(c, ctx, &range) != NGX_OK) { - return NGX_ERROR; - } - - } while (q != ngx_queue_sentinel(&ctx->sent)); - - *waitp = wait; + } + + if (qc->pto.timer_set) { + ngx_del_timer(&qc->pto); + } + + if (min_wait > 0) { + ngx_add_timer(&qc->pto, min_wait); + } return NGX_OK; } diff --git a/src/event/ngx_event_quic.h b/src/event/ngx_event_quic.h --- a/src/event/ngx_event_quic.h +++ b/src/event/ngx_event_quic.h @@ -45,6 +45,12 @@ #define NGX_QUIC_INITIAL_RTT 333 /* ms */ #define NGX_QUIC_HARDCODED_PTO 1000 /* 1s, TODO: collect */ +/* quic-recovery, section 6.1.1, Packet Threshold */ +#define NGX_QUIC_PKT_THR 3 /* packets */ +/* quic-recovery, section 6.1.2, Time Threshold */ +#define NGX_QUIC_TIME_THR 1.125 +#define NGX_QUIC_TIME_GRANULARITY 1 /* ms */ + #define NGX_QUIC_CC_MIN_INTERVAL 1000 /* 1s */ #define NGX_QUIC_MIN_INITIAL_SIZE 1200