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/* SPDX-License-Identifier: GPL-3.0-only */
#include <errno.h>
#include <bwlimit.h>
#include <platform.h>
#define timespeczerorize(ts) \
do { \
ts.tv_sec = 0; \
ts.tv_nsec = 0; \
} while (0)
int bwlimit_init(struct bwlimit *bw, uint64_t bps, uint64_t win)
{
if (!(bw->sem = sem_create(1)))
return -1;
bw->bps = bps;
bw->win = win; /* msec window */
bw->amt = (double)bps / 8 / 1000 * win; /* bytes in a window (msec) */
bw->credit = bw->amt;
timespeczerorize(bw->wstart);
timespeczerorize(bw->wend);
return 0;
}
#define timespecisset(ts) ((ts).tv_sec || (ts).tv_nsec)
#define timespecmsadd(a, msec, r) \
do { \
(r).tv_sec = (a).tv_sec; \
(r).tv_nsec = (a).tv_nsec + (msec * 1000000); \
if ((r).tv_nsec > 1000000000) { \
(r).tv_sec += (r.tv_nsec) / 1000000000L; \
(r).tv_nsec = (r.tv_nsec) % 1000000000L; \
} \
} while (0)
#define timespecsub(a, b, r) \
do { \
(r).tv_sec = (a).tv_sec - (b).tv_sec; \
(r).tv_nsec = (a).tv_nsec - (b).tv_nsec; \
if ((r).tv_nsec < 0) { \
(r).tv_sec -= 1; \
(r).tv_nsec += 1000000000; \
} \
} while (0)
#define timespeccmp(a, b, expr) \
((a.tv_sec * 1000000000 + a.tv_nsec) expr(b.tv_sec * 1000000000 + b.tv_nsec))
#include <stdio.h>
int bwlimit_wait(struct bwlimit *bw, size_t nr_bytes)
{
struct timespec now, end, rq, rm;
if (bw->bps == 0)
return 0; /* no bandwidth limit */
if (sem_wait(bw->sem) < 0)
return -1;
clock_gettime(CLOCK_MONOTONIC, &now);
if (!timespecisset(bw->wstart)) {
bw->wstart = now;
timespecmsadd(bw->wstart, bw->win, bw->wend);
}
bw->credit -= nr_bytes;
if (bw->credit < 0) {
/* no more credit on this window. sleep until the end
* of this window + additional time for the remaining
* bytes. */
uint64_t addition = (double)(bw->credit * -1) / (bw->bps / 8);
timespecmsadd(bw->wend, addition * 1000, end);
if (timespeccmp(end, now, >)) {
timespecsub(end, now, rq);
while (nanosleep(&rq, &rm) == -1) {
if (errno != EINTR)
break;
rq = rm;
}
}
bw->credit = bw->amt;
timespeczerorize(bw->wstart);
}
sem_post(bw->sem);
return 0;
}
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