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Simple HTTP client with HTTP/1.1, HTTP/2, and HTTP/3 support

Security advisory: This version has known vulnerabilities. View advisories
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hackney c_src lsquic src liblsquic lsquic_pacer.c
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c_src/lsquic/src/liblsquic/lsquic_pacer.c 

/* Copyright (c) 2017 - 2022 LiteSpeed Technologies Inc.  See LICENSE. */

#include <assert.h>

#include <inttypes.h>

#include <stdint.h>

#include <string.h>

#ifdef WIN32

#include <vc_compat.h>

#endif



#include "lsquic_types.h"

#include "lsquic_int_types.h"

#include "lsquic_pacer.h"

#include "lsquic_packet_common.h"

#include "lsquic_packet_gquic.h"

#include "lsquic_packet_out.h"

#include "lsquic_util.h"



#define LSQUIC_LOGGER_MODULE LSQLM_PACER

#define LSQUIC_LOG_CONN_ID lsquic_conn_log_cid(pacer->pa_conn)

#include "lsquic_logger.h"



#ifndef MAX

#   define MAX(a, b) ((a) > (b) ? (a) : (b))

#endif





void

lsquic_pacer_init (struct pacer *pacer, const struct lsquic_conn *conn,

                                                unsigned clock_granularity)

{

    memset(pacer, 0, sizeof(*pacer));

    pacer->pa_burst_tokens = 10;

    pacer->pa_conn = conn;

    pacer->pa_clock_granularity = clock_granularity;

}





void

lsquic_pacer_cleanup (struct pacer *pacer)

{

#ifndef NDEBUG

    LSQ_DEBUG("scheduled calls: %u", pacer->pa_stats.n_scheduled);

#endif

}





void

lsquic_pacer_packet_scheduled (struct pacer *pacer, unsigned n_in_flight,

                            int in_recovery, tx_time_f tx_time, void *tx_ctx)

{

    lsquic_time_t delay, sched_time;

    int app_limited, making_up;



#ifndef NDEBUG

    ++pacer->pa_stats.n_scheduled;

#endif

    ++pacer->pa_n_scheduled;



    if (n_in_flight == 0 && !in_recovery)

    {

        pacer->pa_burst_tokens = 10;

        LSQ_DEBUG("%s: replenish tokens: %u", __func__, pacer->pa_burst_tokens);

    }



    if (pacer->pa_burst_tokens > 0)

    {

        --pacer->pa_burst_tokens;

        pacer->pa_flags &= ~PA_LAST_SCHED_DELAYED;

        pacer->pa_next_sched = 0;

        pacer->pa_last_delayed = 0;

        LSQ_DEBUG("%s: tokens: %u", __func__, pacer->pa_burst_tokens);

        return;

    }



    sched_time = pacer->pa_now;

    delay = tx_time(tx_ctx);

    if (pacer->pa_flags & PA_LAST_SCHED_DELAYED)

    {

        pacer->pa_next_sched += delay;

        app_limited = pacer->pa_last_delayed != 0

            && pacer->pa_last_delayed + delay <= sched_time;

        making_up = pacer->pa_next_sched <= sched_time;

        LSQ_DEBUG("making up: %d; app limited; %d", making_up, app_limited);

        if (making_up && !app_limited)

            pacer->pa_last_delayed = sched_time;

        else

        {

            pacer->pa_flags &= ~PA_LAST_SCHED_DELAYED;

            pacer->pa_last_delayed = 0;

        }

    }

    else

        pacer->pa_next_sched = MAX(pacer->pa_next_sched + delay,

                                                    sched_time + delay);

    LSQ_DEBUG("next_sched is set to %"PRIu64" usec from now",

                                pacer->pa_next_sched - pacer->pa_now);

}





void

lsquic_pacer_loss_event (struct pacer *pacer)

{

    pacer->pa_burst_tokens = 0;

    LSQ_DEBUG("%s: tokens: %u", __func__, pacer->pa_burst_tokens);

}





int

lsquic_pacer_can_schedule (struct pacer *pacer, unsigned n_in_flight)

{

    int can;



    if (pacer->pa_burst_tokens > 0 || n_in_flight == 0)

        can = 1;

    else if (pacer->pa_next_sched > pacer->pa_now + pacer->pa_clock_granularity)

    {

        pacer->pa_flags |= PA_LAST_SCHED_DELAYED;

        can = 0;

    }

    else

        can = 1;



    LSQ_DEBUG("%s: %d", __func__, can);

    return can;

}





int

lsquic_pacer_can_schedule_probe (const struct pacer *pacer,

                                    unsigned n_in_flight, lsquic_time_t tx_time)

{

    return pacer->pa_burst_tokens > 1 /* Double packet size, want two tokens */

        || n_in_flight == 0

        || pacer->pa_next_sched > pacer->pa_now + tx_time / 2;

}





void

lsquic_pacer_tick_in (struct pacer *pacer, lsquic_time_t now)

{

    assert(now >= pacer->pa_now);

    pacer->pa_now = now;

    if (pacer->pa_flags & PA_LAST_SCHED_DELAYED)

        pacer->pa_flags |= PA_DELAYED_ON_TICK_IN;

    pacer->pa_n_scheduled = 0;

}





void

lsquic_pacer_tick_out (struct pacer *pacer)

{

    if ((pacer->pa_flags & PA_DELAYED_ON_TICK_IN)

            && pacer->pa_n_scheduled == 0

                && pacer->pa_now > pacer->pa_next_sched)

    {

        LSQ_DEBUG("tick passed without scheduled packets: reset delayed flag");

        pacer->pa_flags &= ~PA_LAST_SCHED_DELAYED;

    }

    pacer->pa_flags &= ~PA_DELAYED_ON_TICK_IN;

}