/* Copyright (c) 2017 LiteSpeed Technologies Inc.  See LICENSE. */
/*
 * lsquic_conn_flow.h -- Connection flow control-related functions
 */

#ifndef LSQUIC_CONN_FLOW_H
#define LSQUIC_CONN_FLOW_H 1

struct lsquic_conn_public;

typedef struct lsquic_cfcw {
    struct lsquic_conn_public
                 *cf_conn_pub;
    uint64_t      cf_max_recv_off;  /* Largest offset observed (cumulative) */
    uint64_t      cf_recv_off;      /* Flow control receive offset */
    uint64_t      cf_read_off;      /* Number of bytes consumed (cumulative) */
    lsquic_time_t cf_last_updated;
    unsigned      cf_max_recv_win;  /* Maximum receive window */
} lsquic_cfcw_t;

struct lsquic_conn_cap {
    uint64_t cc_sent;           /* Number of bytes sent on connection */
    uint64_t cc_max;            /* Maximum cumulative number of bytes allowed
                                 * to be sent on this connection.
                                 */
    uint64_t cc_tosend;         /* Number of bytes scheduled to be sent
                                 * accross all streams.
                                 */
    uint64_t cc_blocked;        /* Last blocked offset used */
};


#define lsquic_conn_cap_init(cc, max) do {                          \
    (cc)->cc_sent = 0;                                              \
    (cc)->cc_tosend = 0;                                            \
    (cc)->cc_max = max;                                             \
} while (0)


#define lsquic_conn_cap_avail(cap) (                                \
    ((cap)->cc_sent + (cap)->cc_tosend <= (cap)->cc_max)            \
    ?                                                               \
        ((cap)->cc_max - (cap)->cc_sent - (cap)->cc_tosend)         \
    :                                                               \
        0                                                           \
)


void
lsquic_cfcw_init (lsquic_cfcw_t *, struct lsquic_conn_public *,
                                        unsigned initial_max_recv_window);

/* If update is to be sent, updates max_recv_off and returns true.  Note
 * that if you call this function twice, the second call will return false.
 */
int
lsquic_cfcw_fc_offsets_changed (lsquic_cfcw_t *);

#define lsquic_cfcw_get_fc_recv_off(fc) (+(fc)->cf_recv_off)

#define lsquic_cfcw_get_max_recv_off(fc) (+(fc)->cf_max_recv_off)

#define lsquic_cfcw_get_max_recv_window(fc) (+(fc)->cf_max_recv_win)

/* Returns false if flow control violation is encountered */
int
lsquic_cfcw_incr_max_recv_off (lsquic_cfcw_t *, uint64_t);

/* Void because we do not expect the caller to make a mistake.
 */
void
lsquic_cfcw_incr_read_off (lsquic_cfcw_t *, uint64_t);

#endif