src/liblsquic/lsquic_send_ctl.h

/* Copyright (c) 2017 - 2019 LiteSpeed Technologies Inc.  See LICENSE. */
#ifndef LSQUIC_SEND_CTL_H
#define LSQUIC_SEND_CTL_H 1

#include <sys/queue.h>

#include "lsquic_types.h"

#ifndef LSQUIC_SEND_STATS
#   define LSQUIC_SEND_STATS 1
#endif

TAILQ_HEAD(lsquic_packets_tailq, lsquic_packet_out);

struct lsquic_packet_out;
struct ack_info;
struct lsquic_alarmset;
struct lsquic_engine_public;
struct lsquic_conn_public;
struct ver_neg;

enum buf_packet_type { BPT_HIGHEST_PRIO, BPT_OTHER_PRIO, };

#define MAX_BPQ_COUNT 10
struct buf_packet_q
{
    struct lsquic_packets_tailq     bpq_packets;
    unsigned                        bpq_count;
};

enum send_ctl_flags {
    SC_TCID0        = (1 << 0),
    SC_LOST_ACK     = (1 << 1),
    SC_NSTP         = (1 << 2),
    SC_PACE         = (1 << 3),
    SC_SCHED_TICK   = (1 << 4),
    SC_BUFFER_STREAM= (1 << 5),
    SC_WAS_QUIET    = (1 << 6),
};

typedef struct lsquic_send_ctl {
    /* The first section consists of struct members which are used in the
     * time-critical lsquic_send_ctl_got_ack() in the approximate order
     * of usage.
     */
    lsquic_senhist_t                sc_senhist;
    enum send_ctl_flags             sc_flags;
    unsigned                        sc_n_stop_waiting;
    struct lsquic_packets_tailq     sc_unacked_packets;
    lsquic_packno_t                 sc_largest_acked_packno;
    lsquic_time_t                   sc_largest_acked_sent_time;
    unsigned                        sc_bytes_out;
    unsigned                        sc_bytes_unacked_retx;
    unsigned                        sc_bytes_scheduled;
    unsigned                        sc_pack_size;
    struct lsquic_cubic             sc_cubic;
    struct lsquic_engine_public    *sc_enpub;
    unsigned                        sc_bytes_unacked_all;
    unsigned                        sc_n_in_flight_all;
    unsigned                        sc_n_in_flight_retx;
    unsigned                        sc_n_consec_rtos;
    unsigned                        sc_n_hsk;
    unsigned                        sc_n_tlp;
    struct lsquic_alarmset         *sc_alset;

    /* Second section: everything else. */
    struct lsquic_packets_tailq     sc_scheduled_packets,
                                    sc_lost_packets;
    struct buf_packet_q             sc_buffered_packets[BPT_OTHER_PRIO + 1];
    const struct ver_neg           *sc_ver_neg;
    struct lsquic_conn_public      *sc_conn_pub;
    struct pacer                    sc_pacer;
    lsquic_packno_t                 sc_cur_packno;
    lsquic_packno_t                 sc_largest_sent_at_cutback;
    lsquic_packno_t                 sc_max_rtt_packno;
    /* sc_largest_ack2ed is the packet number sent by peer that we acked and
     * we know that our ACK was received by peer.  This is used to determine
     * the receive history cutoff point for the purposes of generating ACK
     * frames in the absense of STOP_WAITING frames.  Used when NSTP option
     * is set.  (The "ack2ed" is odd enough to not be confused with anything
     * else and it is not insanely long.)
     */
    lsquic_packno_t                 sc_largest_ack2ed;
    /* sc_largest_acked is the largest packet number in PNS_APP packet number
     * space sent by peer for which we generated (not necessarily sent) an ACK.
     * This information is used to drop stale ACK frames from packets in
     * buffered queues.
     */
    lsquic_packno_t                 sc_largest_acked;
    lsquic_time_t                   sc_loss_to;
    struct
    {
        uint32_t                stream_id;
        enum buf_packet_type    packet_type;
    }                               sc_cached_bpt;
    unsigned                        sc_next_limit;
    unsigned                        sc_n_scheduled;
    enum packno_bits                sc_max_packno_bits;
#if LSQUIC_SEND_STATS
    struct {
        unsigned            n_total_sent,
                            n_resent,
                            n_delayed;
    }                               sc_stats;
#endif
} lsquic_send_ctl_t;

void
lsquic_send_ctl_init (lsquic_send_ctl_t *, struct lsquic_alarmset *,
          struct lsquic_engine_public *, const struct ver_neg *,
          struct lsquic_conn_public *, unsigned short max_packet_size);

int
lsquic_send_ctl_sent_packet (lsquic_send_ctl_t *, struct lsquic_packet_out *,
                             int);

int
lsquic_send_ctl_got_ack (lsquic_send_ctl_t *, const struct ack_info *,
                                                            lsquic_time_t);

lsquic_packno_t
lsquic_send_ctl_smallest_unacked (lsquic_send_ctl_t *ctl);

int
lsquic_send_ctl_have_unacked_stream_frames (const lsquic_send_ctl_t *);

void
lsquic_send_ctl_cleanup (lsquic_send_ctl_t *);

int
lsquic_send_ctl_can_send (lsquic_send_ctl_t *ctl);

void
lsquic_send_ctl_scheduled_one (lsquic_send_ctl_t *, struct lsquic_packet_out *);

void
lsquic_send_ctl_delayed_one (lsquic_send_ctl_t *, struct lsquic_packet_out *);

struct lsquic_packet_out *
lsquic_send_ctl_next_packet_to_send (lsquic_send_ctl_t *);

void
lsquic_send_ctl_expire_all (lsquic_send_ctl_t *ctl);

#define lsquic_send_ctl_n_in_flight(ctl) (+(ctl)->sc_n_in_flight)

#define lsquic_send_ctl_n_scheduled(ctl) (+(ctl)->sc_n_scheduled)

#define lsquic_send_ctl_largest_ack2ed(ctl) (+(ctl)->sc_largest_ack2ed)

#if LSQUIC_EXTRA_CHECKS
void
lsquic_send_ctl_sanity_check (const lsquic_send_ctl_t *ctl);
#else
#   define lsquic_send_ctl_sanity_check(ctl)
#endif

int
lsquic_send_ctl_have_outgoing_stream_frames (const lsquic_send_ctl_t *);

int
lsquic_send_ctl_have_outgoing_retx_frames (const lsquic_send_ctl_t *);

#define lsquic_send_ctl_last_scheduled(ctl) \
            TAILQ_LAST(&(ctl)->sc_scheduled_packets, lsquic_packets_tailq)

struct lsquic_packet_out *
lsquic_send_ctl_new_packet_out (lsquic_send_ctl_t *, unsigned);

struct lsquic_packet_out *
lsquic_send_ctl_get_writeable_packet (lsquic_send_ctl_t *,
                                      unsigned need_at_least, int *is_err);

struct lsquic_packet_out *
lsquic_send_ctl_get_packet_for_stream (lsquic_send_ctl_t *,
                        unsigned need_at_least, const struct lsquic_stream *);

unsigned
lsquic_send_ctl_reschedule_packets (lsquic_send_ctl_t *);

#define lsquic_send_ctl_lost_ack(ctl) ((ctl)->sc_flags & SC_LOST_ACK)

#define lsquic_send_ctl_scheduled_ack(ctl, packno) do {             \
    (ctl)->sc_flags &= ~SC_LOST_ACK;                                \
    (ctl)->sc_largest_acked = packno;                               \
} while (0)

void
lsquic_send_ctl_set_tcid0 (lsquic_send_ctl_t *, int);

#define lsquic_send_ctl_turn_nstp_on(ctl) ((ctl)->sc_flags |= SC_NSTP)

void
lsquic_send_ctl_elide_stream_frames (lsquic_send_ctl_t *, uint32_t);

int
lsquic_send_ctl_squeeze_sched (lsquic_send_ctl_t *);

#define lsquic_send_ctl_maybe_squeeze_sched(ctl) (                  \
    (ctl)->sc_n_scheduled && lsquic_send_ctl_squeeze_sched(ctl)     \
)

/* Same return value as for squeezing, but without actual squeezing. */
int
lsquic_send_ctl_have_delayed_packets (const lsquic_send_ctl_t *ctl);

void
lsquic_send_ctl_reset_packnos (lsquic_send_ctl_t *);

void
lsquic_send_ctl_ack_to_front (lsquic_send_ctl_t *);

#define lsquic_send_ctl_n_stop_waiting(ctl) (+(ctl)->sc_n_stop_waiting)

#define lsquic_send_ctl_n_stop_waiting_reset(ctl) do {      \
    (ctl)->sc_n_stop_waiting = 0;                           \
} while (0)

void
lsquic_send_ctl_drop_scheduled (lsquic_send_ctl_t *);

#define lsquic_send_ctl_tick(ctl, now) do {                 \
    if ((ctl)->sc_flags & SC_PACE)                          \
    {                                                       \
        (ctl)->sc_flags |= SC_SCHED_TICK;                   \
        pacer_tick(&(ctl)->sc_pacer, now);                  \
    }                                                       \
} while (0)

#define lsquic_send_ctl_next_pacer_time(ctl) (              \
    ((ctl)->sc_flags & SC_PACE)                             \
        && pacer_delayed(&(ctl)->sc_pacer)                  \
        ? pacer_next_sched(&(ctl)->sc_pacer)                \
        : 0 )

enum packno_bits
lsquic_send_ctl_packno_bits (lsquic_send_ctl_t *);

int
lsquic_send_ctl_schedule_buffered (lsquic_send_ctl_t *, enum buf_packet_type);

#define lsquic_send_ctl_has_buffered(ctl) (                                 \
    TAILQ_FIRST(&(ctl)->sc_buffered_packets[BPT_HIGHEST_PRIO].bpq_packets)  \
 || TAILQ_FIRST(&(ctl)->sc_buffered_packets[BPT_OTHER_PRIO].bpq_packets  ))

#define lsquic_send_ctl_invalidate_bpt_cache(ctl) do {      \
    (ctl)->sc_cached_bpt.stream_id = 0;                     \
} while (0)

#ifndef NDEBUG
enum packno_bits
lsquic_send_ctl_guess_packno_bits (struct lsquic_send_ctl *);

int
lsquic_send_ctl_schedule_stream_packets_immediately (struct lsquic_send_ctl *);

enum buf_packet_type
lsquic_send_ctl_determine_bpt (struct lsquic_send_ctl *,
                                            const struct lsquic_stream *);

enum packno_bits
lsquic_send_ctl_calc_packno_bits (struct lsquic_send_ctl *);
#endif

size_t
lsquic_send_ctl_mem_used (const struct lsquic_send_ctl *);

#define lsquic_send_ctl_set_buffer_stream_packets(ctl, b) do {  \
    (ctl)->sc_flags &= ~SC_BUFFER_STREAM;                       \
    (ctl)->sc_flags |= -!!(b) & SC_BUFFER_STREAM;               \
} while (0)

int
lsquic_send_ctl_turn_on_fin (struct lsquic_send_ctl *,
                             const struct lsquic_stream *);

int
lsquic_send_ctl_pacer_blocked (struct lsquic_send_ctl *);

#define lsquic_send_ctl_incr_pack_sz(ctl, packet, delta) do {   \
    (packet)->po_data_sz += delta;                              \
    if ((packet)->po_flags & PO_SCHED)                          \
        (ctl)->sc_bytes_scheduled += delta;                     \
    lsquic_send_ctl_sanity_check(ctl);                          \
} while (0)

int
lsquic_send_ctl_sched_is_blocked (const struct lsquic_send_ctl *);

int
lsquic_send_ctl_buffered_and_same_prio_as_headers (struct lsquic_send_ctl *,
                                                const struct lsquic_stream *);

void
lsquic_send_ctl_verneg_done (struct lsquic_send_ctl *);

#endif