1 files changed, 593 insertions, 0 deletions

diff --git a/src/contrib/libngtcp2/ngtcp2/lib/ngtcp2_cc.c b/src/contrib/libngtcp2/ngtcp2/lib/ngtcp2_cc.c
new file mode 100644
index 0000000..ef311ff
--- /dev/null
+++ b/src/contrib/libngtcp2/ngtcp2/lib/ngtcp2_cc.c
@@ -0,0 +1,593 @@
+/*
+ * ngtcp2
+ *
+ * Copyright (c) 2018 ngtcp2 contributors
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+ * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+ * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+#include "ngtcp2_cc.h"
+
+#include <assert.h>
+#include <string.h>
+
+#if defined(_MSC_VER)
+#  include <intrin.h>
+#endif
+
+#include "ngtcp2_log.h"
+#include "ngtcp2_macro.h"
+#include "ngtcp2_mem.h"
+#include "ngtcp2_rcvry.h"
+#include "ngtcp2_conn_stat.h"
+#include "ngtcp2_unreachable.h"
+
+/* NGTCP2_CC_DELIVERY_RATE_SEC_FILTERLEN is the window length of
+   delivery rate filter driven by ACK clocking. */
+#define NGTCP2_CC_DELIVERY_RATE_SEC_FILTERLEN 10
+
+uint64_t ngtcp2_cc_compute_initcwnd(size_t max_udp_payload_size) {
+  uint64_t n = 2 * max_udp_payload_size;
+  n = ngtcp2_max(n, 14720);
+  return ngtcp2_min(10 * max_udp_payload_size, n);
+}
+
+ngtcp2_cc_pkt *ngtcp2_cc_pkt_init(ngtcp2_cc_pkt *pkt, int64_t pkt_num,
+                                  size_t pktlen, ngtcp2_pktns_id pktns_id,
+                                  ngtcp2_tstamp sent_ts, uint64_t lost,
+                                  uint64_t tx_in_flight, int is_app_limited) {
+  pkt->pkt_num = pkt_num;
+  pkt->pktlen = pktlen;
+  pkt->pktns_id = pktns_id;
+  pkt->sent_ts = sent_ts;
+  pkt->lost = lost;
+  pkt->tx_in_flight = tx_in_flight;
+  pkt->is_app_limited = is_app_limited;
+
+  return pkt;
+}
+
+static void reno_cc_reset(ngtcp2_cc_reno *reno) {
+  ngtcp2_window_filter_init(&reno->delivery_rate_sec_filter,
+                            NGTCP2_CC_DELIVERY_RATE_SEC_FILTERLEN);
+  reno->ack_count = 0;
+  reno->target_cwnd = 0;
+  reno->pending_add = 0;
+}
+
+void ngtcp2_cc_reno_init(ngtcp2_cc_reno *reno, ngtcp2_log *log) {
+  memset(reno, 0, sizeof(*reno));
+
+  reno->cc.log = log;
+  reno->cc.on_pkt_acked = ngtcp2_cc_reno_cc_on_pkt_acked;
+  reno->cc.congestion_event = ngtcp2_cc_reno_cc_congestion_event;
+  reno->cc.on_persistent_congestion =
+      ngtcp2_cc_reno_cc_on_persistent_congestion;
+  reno->cc.on_ack_recv = ngtcp2_cc_reno_cc_on_ack_recv;
+  reno->cc.reset = ngtcp2_cc_reno_cc_reset;
+
+  reno_cc_reset(reno);
+}
+
+static int in_congestion_recovery(const ngtcp2_conn_stat *cstat,
+                                  ngtcp2_tstamp sent_time) {
+  return cstat->congestion_recovery_start_ts != UINT64_MAX &&
+         sent_time <= cstat->congestion_recovery_start_ts;
+}
+
+void ngtcp2_cc_reno_cc_on_pkt_acked(ngtcp2_cc *cc, ngtcp2_conn_stat *cstat,
+                                    const ngtcp2_cc_pkt *pkt,
+                                    ngtcp2_tstamp ts) {
+  ngtcp2_cc_reno *reno = ngtcp2_struct_of(cc, ngtcp2_cc_reno, cc);
+  uint64_t m;
+  (void)ts;
+
+  if (in_congestion_recovery(cstat, pkt->sent_ts)) {
+    return;
+  }
+
+  if (reno->target_cwnd && reno->target_cwnd < cstat->cwnd) {
+    return;
+  }
+
+  if (cstat->cwnd < cstat->ssthresh) {
+    cstat->cwnd += pkt->pktlen;
+    ngtcp2_log_info(reno->cc.log, NGTCP2_LOG_EVENT_CCA,
+                    "pkn=%" PRId64 " acked, slow start cwnd=%" PRIu64,
+                    pkt->pkt_num, cstat->cwnd);
+    return;
+  }
+
+  m = cstat->max_tx_udp_payload_size * pkt->pktlen + reno->pending_add;
+  reno->pending_add = m % cstat->cwnd;
+
+  cstat->cwnd += m / cstat->cwnd;
+}
+
+void ngtcp2_cc_reno_cc_congestion_event(ngtcp2_cc *cc, ngtcp2_conn_stat *cstat,
+                                        ngtcp2_tstamp sent_ts,
+                                        ngtcp2_tstamp ts) {
+  ngtcp2_cc_reno *reno = ngtcp2_struct_of(cc, ngtcp2_cc_reno, cc);
+  uint64_t min_cwnd;
+
+  if (in_congestion_recovery(cstat, sent_ts)) {
+    return;
+  }
+
+  cstat->congestion_recovery_start_ts = ts;
+  cstat->cwnd >>= NGTCP2_LOSS_REDUCTION_FACTOR_BITS;
+  min_cwnd = 2 * cstat->max_tx_udp_payload_size;
+  cstat->cwnd = ngtcp2_max(cstat->cwnd, min_cwnd);
+  cstat->ssthresh = cstat->cwnd;
+
+  reno->pending_add = 0;
+
+  ngtcp2_log_info(reno->cc.log, NGTCP2_LOG_EVENT_CCA,
+                  "reduce cwnd because of packet loss cwnd=%" PRIu64,
+                  cstat->cwnd);
+}
+
+void ngtcp2_cc_reno_cc_on_persistent_congestion(ngtcp2_cc *cc,
+                                                ngtcp2_conn_stat *cstat,
+                                                ngtcp2_tstamp ts) {
+  (void)cc;
+  (void)ts;
+
+  cstat->cwnd = 2 * cstat->max_tx_udp_payload_size;
+  cstat->congestion_recovery_start_ts = UINT64_MAX;
+}
+
+void ngtcp2_cc_reno_cc_on_ack_recv(ngtcp2_cc *cc, ngtcp2_conn_stat *cstat,
+                                   const ngtcp2_cc_ack *ack, ngtcp2_tstamp ts) {
+  ngtcp2_cc_reno *reno = ngtcp2_struct_of(cc, ngtcp2_cc_reno, cc);
+  uint64_t target_cwnd, initcwnd;
+  uint64_t max_delivery_rate_sec;
+  (void)ack;
+  (void)ts;
+
+  ++reno->ack_count;
+
+  ngtcp2_window_filter_update(&reno->delivery_rate_sec_filter,
+                              cstat->delivery_rate_sec, reno->ack_count);
+
+  max_delivery_rate_sec =
+      ngtcp2_window_filter_get_best(&reno->delivery_rate_sec_filter);
+
+  if (cstat->min_rtt != UINT64_MAX && max_delivery_rate_sec) {
+    target_cwnd = max_delivery_rate_sec * cstat->smoothed_rtt / NGTCP2_SECONDS;
+    initcwnd = ngtcp2_cc_compute_initcwnd(cstat->max_tx_udp_payload_size);
+    reno->target_cwnd = ngtcp2_max(initcwnd, target_cwnd) * 289 / 100;
+
+    ngtcp2_log_info(reno->cc.log, NGTCP2_LOG_EVENT_CCA,
+                    "target_cwnd=%" PRIu64 " max_delivery_rate_sec=%" PRIu64
+                    " smoothed_rtt=%" PRIu64,
+                    reno->target_cwnd, max_delivery_rate_sec,
+                    cstat->smoothed_rtt);
+  }
+}
+
+void ngtcp2_cc_reno_cc_reset(ngtcp2_cc *cc, ngtcp2_conn_stat *cstat,
+                             ngtcp2_tstamp ts) {
+  ngtcp2_cc_reno *reno = ngtcp2_struct_of(cc, ngtcp2_cc_reno, cc);
+  (void)cstat;
+  (void)ts;
+
+  reno_cc_reset(reno);
+}
+
+static void cubic_cc_reset(ngtcp2_cc_cubic *cubic) {
+  ngtcp2_window_filter_init(&cubic->delivery_rate_sec_filter,
+                            NGTCP2_CC_DELIVERY_RATE_SEC_FILTERLEN);
+  cubic->ack_count = 0;
+  cubic->target_cwnd = 0;
+  cubic->w_last_max = 0;
+  cubic->w_tcp = 0;
+  cubic->origin_point = 0;
+  cubic->epoch_start = UINT64_MAX;
+  cubic->k = 0;
+
+  cubic->prior.cwnd = 0;
+  cubic->prior.ssthresh = 0;
+  cubic->prior.w_last_max = 0;
+  cubic->prior.w_tcp = 0;
+  cubic->prior.origin_point = 0;
+  cubic->prior.epoch_start = UINT64_MAX;
+  cubic->prior.k = 0;
+
+  cubic->rtt_sample_count = 0;
+  cubic->current_round_min_rtt = UINT64_MAX;
+  cubic->last_round_min_rtt = UINT64_MAX;
+  cubic->window_end = -1;
+}
+
+void ngtcp2_cc_cubic_init(ngtcp2_cc_cubic *cubic, ngtcp2_log *log) {
+  memset(cubic, 0, sizeof(*cubic));
+
+  cubic->cc.log = log;
+  cubic->cc.on_pkt_acked = ngtcp2_cc_cubic_cc_on_pkt_acked;
+  cubic->cc.congestion_event = ngtcp2_cc_cubic_cc_congestion_event;
+  cubic->cc.on_spurious_congestion = ngtcp2_cc_cubic_cc_on_spurious_congestion;
+  cubic->cc.on_persistent_congestion =
+      ngtcp2_cc_cubic_cc_on_persistent_congestion;
+  cubic->cc.on_ack_recv = ngtcp2_cc_cubic_cc_on_ack_recv;
+  cubic->cc.on_pkt_sent = ngtcp2_cc_cubic_cc_on_pkt_sent;
+  cubic->cc.new_rtt_sample = ngtcp2_cc_cubic_cc_new_rtt_sample;
+  cubic->cc.reset = ngtcp2_cc_cubic_cc_reset;
+  cubic->cc.event = ngtcp2_cc_cubic_cc_event;
+
+  cubic_cc_reset(cubic);
+}
+
+uint64_t ngtcp2_cbrt(uint64_t n) {
+  int d;
+  uint64_t a;
+
+  if (n == 0) {
+    return 0;
+  }
+
+#if defined(_MSC_VER)
+  {
+    unsigned long index;
+#  if defined(_WIN64)
+    if (_BitScanReverse64(&index, n)) {
+      d = 61 - index;
+    } else {
+      ngtcp2_unreachable();
+    }
+#  else  /* !defined(_WIN64) */
+    if (_BitScanReverse(&index, (unsigned int)(n >> 32))) {
+      d = 31 - index;
+    } else {
+      d = 32 + 31 - _BitScanReverse(&index, (unsigned int)n);
+    }
+#  endif /* !defined(_WIN64) */
+  }
+#else  /* !defined(_MSC_VER) */
+  d = __builtin_clzll(n);
+#endif /* !defined(_MSC_VER) */
+  a = 1ULL << ((64 - d) / 3 + 1);
+
+  for (; a * a * a > n;) {
+    a = (2 * a + n / a / a) / 3;
+  }
+  return a;
+}
+
+/* HyStart++ constants */
+#define NGTCP2_HS_MIN_SSTHRESH 16
+#define NGTCP2_HS_N_RTT_SAMPLE 8
+#define NGTCP2_HS_MIN_ETA (4 * NGTCP2_MILLISECONDS)
+#define NGTCP2_HS_MAX_ETA (16 * NGTCP2_MILLISECONDS)
+
+void ngtcp2_cc_cubic_cc_on_pkt_acked(ngtcp2_cc *cc, ngtcp2_conn_stat *cstat,
+                                     const ngtcp2_cc_pkt *pkt,
+                                     ngtcp2_tstamp ts) {
+  ngtcp2_cc_cubic *cubic = ngtcp2_struct_of(cc, ngtcp2_cc_cubic, cc);
+  ngtcp2_duration t, eta;
+  uint64_t target, cwnd_thres;
+  uint64_t tx, kx, time_delta, delta;
+  uint64_t add, tcp_add;
+  uint64_t m;
+
+  if (pkt->pktns_id == NGTCP2_PKTNS_ID_APPLICATION && cubic->window_end != -1 &&
+      cubic->window_end <= pkt->pkt_num) {
+    cubic->window_end = -1;
+  }
+
+  if (in_congestion_recovery(cstat, pkt->sent_ts)) {
+    return;
+  }
+
+  if (cstat->cwnd < cstat->ssthresh) {
+    /* slow-start */
+    if (cubic->target_cwnd == 0 || cubic->target_cwnd > cstat->cwnd) {
+      cstat->cwnd += pkt->pktlen;
+    }
+
+    ngtcp2_log_info(cubic->cc.log, NGTCP2_LOG_EVENT_CCA,
+                    "pkn=%" PRId64 " acked, slow start cwnd=%" PRIu64,
+                    pkt->pkt_num, cstat->cwnd);
+
+    if (cubic->last_round_min_rtt != UINT64_MAX &&
+        cubic->current_round_min_rtt != UINT64_MAX &&
+        cstat->cwnd >=
+            NGTCP2_HS_MIN_SSTHRESH * cstat->max_tx_udp_payload_size &&
+        cubic->rtt_sample_count >= NGTCP2_HS_N_RTT_SAMPLE) {
+      eta = cubic->last_round_min_rtt / 8;
+
+      if (eta < NGTCP2_HS_MIN_ETA) {
+        eta = NGTCP2_HS_MIN_ETA;
+      } else if (eta > NGTCP2_HS_MAX_ETA) {
+        eta = NGTCP2_HS_MAX_ETA;
+      }
+
+      if (cubic->current_round_min_rtt >= cubic->last_round_min_rtt + eta) {
+        ngtcp2_log_info(cubic->cc.log, NGTCP2_LOG_EVENT_CCA,
+                        "HyStart++ exit slow start");
+
+        cubic->w_last_max = cstat->cwnd;
+        cstat->ssthresh = cstat->cwnd;
+      }
+    }
+
+    return;
+  }
+
+  /* congestion avoidance */
+
+  if (cubic->epoch_start == UINT64_MAX) {
+    cubic->epoch_start = ts;
+    if (cstat->cwnd < cubic->w_last_max) {
+      cubic->k = ngtcp2_cbrt((cubic->w_last_max - cstat->cwnd) * 10 / 4 /
+                             cstat->max_tx_udp_payload_size);
+      cubic->origin_point = cubic->w_last_max;
+    } else {
+      cubic->k = 0;
+      cubic->origin_point = cstat->cwnd;
+    }
+
+    cubic->w_tcp = cstat->cwnd;
+
+    ngtcp2_log_info(cubic->cc.log, NGTCP2_LOG_EVENT_CCA,
+                    "cubic-ca epoch_start=%" PRIu64 " k=%" PRIu64
+                    " origin_point=%" PRIu64,
+                    cubic->epoch_start, cubic->k, cubic->origin_point);
+
+    cubic->pending_add = 0;
+    cubic->pending_w_add = 0;
+  }
+
+  t = ts - cubic->epoch_start;
+
+  tx = (t << 10) / NGTCP2_SECONDS;
+  kx = (cubic->k << 10);
+
+  if (tx > kx) {
+    time_delta = tx - kx;
+  } else {
+    time_delta = kx - tx;
+  }
+
+  delta = cstat->max_tx_udp_payload_size *
+          ((((time_delta * time_delta) >> 10) * time_delta) >> 10) * 4 / 10;
+  delta >>= 10;
+
+  if (tx > kx) {
+    target = cubic->origin_point + delta;
+  } else {
+    target = cubic->origin_point - delta;
+  }
+
+  cwnd_thres =
+      (target * (((t + cstat->smoothed_rtt) << 10) / NGTCP2_SECONDS)) >> 10;
+  if (cwnd_thres < cstat->cwnd) {
+    target = cstat->cwnd;
+  } else if (2 * cwnd_thres > 3 * cstat->cwnd) {
+    target = cstat->cwnd * 3 / 2;
+  } else {
+    target = cwnd_thres;
+  }
+
+  if (target > cstat->cwnd) {
+    m = cubic->pending_add +
+        cstat->max_tx_udp_payload_size * (target - cstat->cwnd);
+    add = m / cstat->cwnd;
+    cubic->pending_add = m % cstat->cwnd;
+  } else {
+    m = cubic->pending_add + cstat->max_tx_udp_payload_size;
+    add = m / (100 * cstat->cwnd);
+    cubic->pending_add = m % (100 * cstat->cwnd);
+  }
+
+  m = cubic->pending_w_add + cstat->max_tx_udp_payload_size * pkt->pktlen;
+
+  cubic->w_tcp += m / cstat->cwnd;
+  cubic->pending_w_add = m % cstat->cwnd;
+
+  if (cubic->w_tcp > cstat->cwnd) {
+    tcp_add = cstat->max_tx_udp_payload_size * (cubic->w_tcp - cstat->cwnd) /
+              cstat->cwnd;
+    if (tcp_add > add) {
+      add = tcp_add;
+    }
+  }
+
+  if (cubic->target_cwnd == 0 || cubic->target_cwnd > cstat->cwnd) {
+    cstat->cwnd += add;
+  }
+
+  ngtcp2_log_info(cubic->cc.log, NGTCP2_LOG_EVENT_CCA,
+                  "pkn=%" PRId64 " acked, cubic-ca cwnd=%" PRIu64 " t=%" PRIu64
+                  " k=%" PRIi64 " time_delta=%" PRIu64 " delta=%" PRIu64
+                  " target=%" PRIu64 " w_tcp=%" PRIu64,
+                  pkt->pkt_num, cstat->cwnd, t, cubic->k, time_delta >> 4,
+                  delta, target, cubic->w_tcp);
+}
+
+void ngtcp2_cc_cubic_cc_congestion_event(ngtcp2_cc *cc, ngtcp2_conn_stat *cstat,
+                                         ngtcp2_tstamp sent_ts,
+                                         ngtcp2_tstamp ts) {
+  ngtcp2_cc_cubic *cubic = ngtcp2_struct_of(cc, ngtcp2_cc_cubic, cc);
+  uint64_t min_cwnd;
+
+  if (in_congestion_recovery(cstat, sent_ts)) {
+    return;
+  }
+
+  if (cubic->prior.cwnd < cstat->cwnd) {
+    cubic->prior.cwnd = cstat->cwnd;
+    cubic->prior.ssthresh = cstat->ssthresh;
+    cubic->prior.w_last_max = cubic->w_last_max;
+    cubic->prior.w_tcp = cubic->w_tcp;
+    cubic->prior.origin_point = cubic->origin_point;
+    cubic->prior.epoch_start = cubic->epoch_start;
+    cubic->prior.k = cubic->k;
+  }
+
+  cstat->congestion_recovery_start_ts = ts;
+
+  cubic->epoch_start = UINT64_MAX;
+  if (cstat->cwnd < cubic->w_last_max) {
+    cubic->w_last_max = cstat->cwnd * 17 / 10 / 2;
+  } else {
+    cubic->w_last_max = cstat->cwnd;
+  }
+
+  min_cwnd = 2 * cstat->max_tx_udp_payload_size;
+  cstat->ssthresh = cstat->cwnd * 7 / 10;
+  cstat->ssthresh = ngtcp2_max(cstat->ssthresh, min_cwnd);
+  cstat->cwnd = cstat->ssthresh;
+
+  ngtcp2_log_info(cubic->cc.log, NGTCP2_LOG_EVENT_CCA,
+                  "reduce cwnd because of packet loss cwnd=%" PRIu64,
+                  cstat->cwnd);
+}
+
+void ngtcp2_cc_cubic_cc_on_spurious_congestion(ngtcp2_cc *cc,
+                                               ngtcp2_conn_stat *cstat,
+                                               ngtcp2_tstamp ts) {
+  ngtcp2_cc_cubic *cubic = ngtcp2_struct_of(cc, ngtcp2_cc_cubic, cc);
+  (void)ts;
+
+  if (cstat->cwnd >= cubic->prior.cwnd) {
+    return;
+  }
+
+  cstat->congestion_recovery_start_ts = UINT64_MAX;
+
+  cstat->cwnd = cubic->prior.cwnd;
+  cstat->ssthresh = cubic->prior.ssthresh;
+  cubic->w_last_max = cubic->prior.w_last_max;
+  cubic->w_tcp = cubic->prior.w_tcp;
+  cubic->origin_point = cubic->prior.origin_point;
+  cubic->epoch_start = cubic->prior.epoch_start;
+  cubic->k = cubic->prior.k;
+
+  cubic->prior.cwnd = 0;
+  cubic->prior.ssthresh = 0;
+  cubic->prior.w_last_max = 0;
+  cubic->prior.w_tcp = 0;
+  cubic->prior.origin_point = 0;
+  cubic->prior.epoch_start = UINT64_MAX;
+  cubic->prior.k = 0;
+
+  ngtcp2_log_info(cubic->cc.log, NGTCP2_LOG_EVENT_CCA,
+                  "spurious congestion is detected and congestion state is "
+                  "restored cwnd=%" PRIu64,
+                  cstat->cwnd);
+}
+
+void ngtcp2_cc_cubic_cc_on_persistent_congestion(ngtcp2_cc *cc,
+                                                 ngtcp2_conn_stat *cstat,
+                                                 ngtcp2_tstamp ts) {
+  (void)cc;
+  (void)ts;
+
+  cstat->cwnd = 2 * cstat->max_tx_udp_payload_size;
+  cstat->congestion_recovery_start_ts = UINT64_MAX;
+}
+
+void ngtcp2_cc_cubic_cc_on_ack_recv(ngtcp2_cc *cc, ngtcp2_conn_stat *cstat,
+                                    const ngtcp2_cc_ack *ack,
+                                    ngtcp2_tstamp ts) {
+  ngtcp2_cc_cubic *cubic = ngtcp2_struct_of(cc, ngtcp2_cc_cubic, cc);
+  uint64_t target_cwnd, initcwnd;
+  uint64_t max_delivery_rate_sec;
+  (void)ack;
+  (void)ts;
+
+  ++cubic->ack_count;
+
+  ngtcp2_window_filter_update(&cubic->delivery_rate_sec_filter,
+                              cstat->delivery_rate_sec, cubic->ack_count);
+
+  max_delivery_rate_sec =
+      ngtcp2_window_filter_get_best(&cubic->delivery_rate_sec_filter);
+
+  if (cstat->min_rtt != UINT64_MAX && max_delivery_rate_sec) {
+    target_cwnd = max_delivery_rate_sec * cstat->smoothed_rtt / NGTCP2_SECONDS;
+    initcwnd = ngtcp2_cc_compute_initcwnd(cstat->max_tx_udp_payload_size);
+    cubic->target_cwnd = ngtcp2_max(initcwnd, target_cwnd) * 289 / 100;
+
+    ngtcp2_log_info(cubic->cc.log, NGTCP2_LOG_EVENT_CCA,
+                    "target_cwnd=%" PRIu64 " max_delivery_rate_sec=%" PRIu64
+                    " smoothed_rtt=%" PRIu64,
+                    cubic->target_cwnd, max_delivery_rate_sec,
+                    cstat->smoothed_rtt);
+  }
+}
+
+void ngtcp2_cc_cubic_cc_on_pkt_sent(ngtcp2_cc *cc, ngtcp2_conn_stat *cstat,
+                                    const ngtcp2_cc_pkt *pkt) {
+  ngtcp2_cc_cubic *cubic = ngtcp2_struct_of(cc, ngtcp2_cc_cubic, cc);
+  (void)cstat;
+
+  if (pkt->pktns_id != NGTCP2_PKTNS_ID_APPLICATION || cubic->window_end != -1) {
+    return;
+  }
+
+  cubic->window_end = pkt->pkt_num;
+  cubic->last_round_min_rtt = cubic->current_round_min_rtt;
+  cubic->current_round_min_rtt = UINT64_MAX;
+  cubic->rtt_sample_count = 0;
+}
+
+void ngtcp2_cc_cubic_cc_new_rtt_sample(ngtcp2_cc *cc, ngtcp2_conn_stat *cstat,
+                                       ngtcp2_tstamp ts) {
+  ngtcp2_cc_cubic *cubic = ngtcp2_struct_of(cc, ngtcp2_cc_cubic, cc);
+  (void)ts;
+
+  if (cubic->window_end == -1) {
+    return;
+  }
+
+  cubic->current_round_min_rtt =
+      ngtcp2_min(cubic->current_round_min_rtt, cstat->latest_rtt);
+  ++cubic->rtt_sample_count;
+}
+
+void ngtcp2_cc_cubic_cc_reset(ngtcp2_cc *cc, ngtcp2_conn_stat *cstat,
+                              ngtcp2_tstamp ts) {
+  ngtcp2_cc_cubic *cubic = ngtcp2_struct_of(cc, ngtcp2_cc_cubic, cc);
+  (void)cstat;
+  (void)ts;
+
+  cubic_cc_reset(cubic);
+}
+
+void ngtcp2_cc_cubic_cc_event(ngtcp2_cc *cc, ngtcp2_conn_stat *cstat,
+                              ngtcp2_cc_event_type event, ngtcp2_tstamp ts) {
+  ngtcp2_cc_cubic *cubic = ngtcp2_struct_of(cc, ngtcp2_cc_cubic, cc);
+  ngtcp2_tstamp last_ts;
+
+  if (event != NGTCP2_CC_EVENT_TYPE_TX_START ||
+      cubic->epoch_start == UINT64_MAX) {
+    return;
+  }
+
+  last_ts = cstat->last_tx_pkt_ts[NGTCP2_PKTNS_ID_APPLICATION];
+  if (last_ts == UINT64_MAX || last_ts <= cubic->epoch_start) {
+    return;
+  }
+
+  assert(ts >= last_ts);
+
+  cubic->epoch_start += ts - last_ts;
+}