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| </pre></div><pre class="rust"><code><span class="comment">// Copyright (C) 2022, Cloudflare, Inc. |
| // All rights reserved. |
| // |
| // Redistribution and use in source and binary forms, with or without |
| // modification, are permitted provided that the following conditions are |
| // met: |
| // |
| // * Redistributions of source code must retain the above copyright notice, |
| // this list of conditions and the following disclaimer. |
| // |
| // * Redistributions in binary form must reproduce the above copyright |
| // notice, this list of conditions and the following disclaimer in the |
| // documentation and/or other materials provided with the distribution. |
| // |
| // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS |
| // IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, |
| // THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR |
| // PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR |
| // CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, |
| // EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, |
| // PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR |
| // PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF |
| // LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING |
| // NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS |
| // SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| |
| </span><span class="kw">use super</span>::<span class="kw-2">*</span>; |
| |
| <span class="comment">// BBR2 Functions on every packet loss event. |
| // |
| // 4.2.4. Per-Loss Steps |
| </span><span class="kw">pub fn </span>bbr2_update_on_loss(r: <span class="kw-2">&mut </span>Recovery, packet: <span class="kw-2">&</span>Sent, now: Instant) { |
| bbr2_handle_lost_packet(r, packet, now); |
| } |
| |
| <span class="comment">// 4.5.6. Updating the Model Upon Packet Loss |
| // 4.5.6.2. Probing for Bandwidth In ProbeBW |
| </span><span class="kw">pub fn </span>bbr2_check_inflight_too_high(r: <span class="kw-2">&mut </span>Recovery, now: Instant) -> bool { |
| <span class="kw">if </span>bbr2_is_inflight_too_high(r) { |
| <span class="kw">if </span>r.bbr2_state.bw_probe_samples { |
| bbr2_handle_inflight_too_high(r, now); |
| } |
| |
| <span class="comment">// inflight too high. |
| </span><span class="kw">return </span><span class="bool-val">true</span>; |
| } |
| |
| <span class="comment">// inflight not too high. |
| </span><span class="bool-val">false |
| </span>} |
| |
| <span class="kw">pub fn </span>bbr2_is_inflight_too_high(r: <span class="kw-2">&mut </span>Recovery) -> bool { |
| r.bbr2_state.lost > (r.bbr2_state.tx_in_flight <span class="kw">as </span>f64 * LOSS_THRESH) <span class="kw">as </span>usize |
| } |
| |
| <span class="kw">fn </span>bbr2_handle_inflight_too_high(r: <span class="kw-2">&mut </span>Recovery, now: Instant) { |
| <span class="comment">// Only react once per bw probe. |
| </span>r.bbr2_state.bw_probe_samples = <span class="bool-val">false</span>; |
| |
| <span class="kw">if </span>!r.delivery_rate.sample_is_app_limited() { |
| r.bbr2_state.inflight_hi = r |
| .bbr2_state |
| .tx_in_flight |
| .max((per_ack::bbr2_target_inflight(r) <span class="kw">as </span>f64 * BETA) <span class="kw">as </span>usize); |
| } |
| |
| <span class="kw">if </span>r.bbr2_state.state == BBR2StateMachine::ProbeBWUP { |
| per_ack::bbr2_start_probe_bw_down(r, now); |
| } |
| } |
| |
| <span class="kw">fn </span>bbr2_handle_lost_packet(r: <span class="kw-2">&mut </span>Recovery, packet: <span class="kw-2">&</span>Sent, now: Instant) { |
| <span class="kw">if </span>!r.bbr2_state.bw_probe_samples { |
| <span class="kw">return</span>; |
| } |
| |
| r.bbr2_state.tx_in_flight = packet.tx_in_flight; |
| r.bbr2_state.lost = (r.bytes_lost - packet.lost) <span class="kw">as </span>usize; |
| |
| r.delivery_rate_update_app_limited(packet.is_app_limited); |
| |
| <span class="kw">if </span>bbr2_is_inflight_too_high(r) { |
| r.bbr2_state.tx_in_flight = bbr2_inflight_hi_from_lost_packet(r, packet); |
| |
| bbr2_handle_inflight_too_high(r, now); |
| } |
| } |
| |
| <span class="kw">fn </span>bbr2_inflight_hi_from_lost_packet(r: <span class="kw-2">&mut </span>Recovery, packet: <span class="kw-2">&</span>Sent) -> usize { |
| <span class="kw">let </span>size = packet.size; |
| <span class="kw">let </span>inflight_prev = r.bbr2_state.tx_in_flight - size; |
| <span class="kw">let </span>lost_prev = r.bbr2_state.lost - size; |
| <span class="kw">let </span>lost_prefix = (LOSS_THRESH * inflight_prev <span class="kw">as </span>f64 - lost_prev <span class="kw">as </span>f64) / |
| (<span class="number">1.0 </span>- LOSS_THRESH); |
| |
| inflight_prev + lost_prefix <span class="kw">as </span>usize |
| } |
| |
| <span class="comment">// 4.5.6.3. When not Probing for Bandwidth |
| </span><span class="kw">pub fn </span>bbr2_update_latest_delivery_signals(r: <span class="kw-2">&mut </span>Recovery) { |
| <span class="kw">let </span>bbr = <span class="kw-2">&mut </span>r.bbr2_state; |
| |
| <span class="comment">// Near start of ACK processing. |
| </span>bbr.loss_round_start = <span class="bool-val">false</span>; |
| bbr.bw_latest = bbr.bw_latest.max(r.delivery_rate.sample_delivery_rate()); |
| bbr.inflight_latest = |
| bbr.inflight_latest.max(r.delivery_rate.sample_delivered()); |
| |
| <span class="kw">if </span>r.delivery_rate.sample_prior_delivered() >= bbr.loss_round_delivered { |
| bbr.loss_round_delivered = r.delivery_rate.delivered(); |
| bbr.loss_round_start = <span class="bool-val">true</span>; |
| } |
| } |
| |
| <span class="kw">pub fn </span>bbr2_advance_latest_delivery_signals(r: <span class="kw-2">&mut </span>Recovery) { |
| <span class="kw">let </span>bbr = <span class="kw-2">&mut </span>r.bbr2_state; |
| |
| <span class="comment">// Near end of ACK processing. |
| </span><span class="kw">if </span>bbr.loss_round_start { |
| bbr.bw_latest = r.delivery_rate.sample_delivery_rate(); |
| bbr.inflight_latest = r.delivery_rate.sample_delivered(); |
| } |
| } |
| |
| <span class="kw">pub fn </span>bbr2_reset_congestion_signals(r: <span class="kw-2">&mut </span>Recovery) { |
| <span class="kw">let </span>bbr = <span class="kw-2">&mut </span>r.bbr2_state; |
| |
| bbr.loss_in_round = <span class="bool-val">false</span>; |
| bbr.loss_events_in_round = <span class="number">0</span>; |
| bbr.bw_latest = <span class="number">0</span>; |
| bbr.inflight_latest = <span class="number">0</span>; |
| } |
| |
| <span class="kw">pub fn </span>bbr2_update_congestion_signals(r: <span class="kw-2">&mut </span>Recovery, packet: <span class="kw-2">&</span>Acked) { |
| <span class="comment">// Update congestion state on every ACK. |
| </span>per_ack::bbr2_update_max_bw(r, packet); |
| |
| <span class="kw">if </span>r.bbr2_state.lost > <span class="number">0 </span>{ |
| r.bbr2_state.loss_in_round = <span class="bool-val">true</span>; |
| r.bbr2_state.loss_events_in_round += <span class="number">1</span>; |
| } |
| |
| <span class="kw">if </span>!r.bbr2_state.loss_round_start { |
| <span class="comment">// Wait until end of round trip. |
| </span><span class="kw">return</span>; |
| } |
| |
| bbr2_adapt_lower_bounds_from_congestion(r); |
| |
| r.bbr2_state.loss_in_round = <span class="bool-val">false</span>; |
| r.bbr2_state.loss_events_in_round = <span class="number">0</span>; |
| } |
| |
| <span class="kw">fn </span>bbr2_adapt_lower_bounds_from_congestion(r: <span class="kw-2">&mut </span>Recovery) { |
| <span class="comment">// Once per round-trip respond to congestion. |
| </span><span class="kw">if </span>bbr2_is_probing_bw(r) { |
| <span class="kw">return</span>; |
| } |
| |
| <span class="kw">if </span>r.bbr2_state.loss_in_round { |
| bbr2_init_lower_bounds(r); |
| bbr2_loss_lower_bounds(r); |
| } |
| } |
| |
| <span class="kw">fn </span>bbr2_init_lower_bounds(r: <span class="kw-2">&mut </span>Recovery) { |
| <span class="kw">let </span>bbr = <span class="kw-2">&mut </span>r.bbr2_state; |
| |
| <span class="comment">// Handle the first congestion episode in this cycle. |
| </span><span class="kw">if </span>bbr.bw_lo == u64::MAX { |
| bbr.bw_lo = bbr.max_bw; |
| } |
| |
| <span class="kw">if </span>bbr.inflight_lo == usize::MAX { |
| bbr.inflight_lo = r.congestion_window; |
| } |
| } |
| |
| <span class="kw">fn </span>bbr2_loss_lower_bounds(r: <span class="kw-2">&mut </span>Recovery) { |
| <span class="kw">let </span>bbr = <span class="kw-2">&mut </span>r.bbr2_state; |
| |
| <span class="comment">// Adjust model once per round based on loss. |
| </span>bbr.bw_lo = bbr.bw_latest.max((bbr.bw_lo <span class="kw">as </span>f64 * BETA) <span class="kw">as </span>u64); |
| bbr.inflight_lo = bbr |
| .inflight_latest |
| .max((bbr.inflight_lo <span class="kw">as </span>f64 * BETA) <span class="kw">as </span>usize); |
| } |
| |
| <span class="kw">pub fn </span>bbr2_reset_lower_bounds(r: <span class="kw-2">&mut </span>Recovery) { |
| <span class="kw">let </span>bbr = <span class="kw-2">&mut </span>r.bbr2_state; |
| |
| bbr.bw_lo = u64::MAX; |
| bbr.inflight_lo = usize::MAX; |
| } |
| |
| <span class="kw">pub fn </span>bbr2_bound_bw_for_model(r: <span class="kw-2">&mut </span>Recovery) { |
| <span class="kw">let </span>bbr = <span class="kw-2">&mut </span>r.bbr2_state; |
| |
| bbr.bw = bbr.max_bw.min(bbr.bw_lo.min(bbr.bw_hi)); |
| } |
| |
| <span class="comment">// This function is not defined in the draft but used. |
| </span><span class="kw">fn </span>bbr2_is_probing_bw(r: <span class="kw-2">&mut </span>Recovery) -> bool { |
| <span class="kw">let </span>state = r.bbr2_state.state; |
| |
| state == BBR2StateMachine::Startup || |
| state == BBR2StateMachine::ProbeBWREFILL || |
| state == BBR2StateMachine::ProbeBWUP |
| } |
| </code></pre></div></section></main></body></html> |
