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