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/*
* ngtcp2
*
* Copyright (c) 2025 ngtcp2 contributors
* Copyright (c) 2023 nghttp2 contributors
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sublicense, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
* LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
* OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
* WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
#include "ngtcp2_ratelim.h"
#include <assert.h>
#include "ngtcp2_macro.h"
void ngtcp2_ratelim_init(ngtcp2_ratelim *rlim, uint64_t burst, uint64_t rate,
ngtcp2_tstamp ts) {
*rlim = (ngtcp2_ratelim){
.burst = burst,
.rate = rate,
.tokens = burst,
.ts = ts,
};
}
/* ratelim_update updates rlim->tokens with the current |ts|. */
static void ratelim_update(ngtcp2_ratelim *rlim, ngtcp2_tstamp ts) {
uint64_t d, gain;
assert(ts >= rlim->ts);
if (ts == rlim->ts) {
return;
}
d = ts - rlim->ts;
rlim->ts = ts;
gain = rlim->rate * d + rlim->carry;
rlim->tokens += gain / NGTCP2_SECONDS;
if (rlim->tokens < rlim->burst) {
rlim->carry = gain % NGTCP2_SECONDS;
} else {
rlim->tokens = rlim->burst;
rlim->carry = 0;
}
}
int ngtcp2_ratelim_drain(ngtcp2_ratelim *rlim, uint64_t n, ngtcp2_tstamp ts) {
ratelim_update(rlim, ts);
if (rlim->tokens < n) {
return -1;
}
rlim->tokens -= n;
return 0;
}
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