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/*
* nghttp2 - HTTP/2 C Library
*
* 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 "nghttp2_ratelim.h"
#include "nghttp2_helper.h"
void nghttp2_ratelim_init(nghttp2_ratelim *rl, uint64_t burst, uint64_t rate) {
rl->val = rl->burst = burst;
rl->rate = rate;
rl->tstamp = 0;
}
void nghttp2_ratelim_update(nghttp2_ratelim *rl, uint64_t tstamp) {
uint64_t d, gain;
if (tstamp == rl->tstamp) {
return;
}
if (tstamp > rl->tstamp) {
d = tstamp - rl->tstamp;
} else {
d = 1;
}
rl->tstamp = tstamp;
if (UINT64_MAX / d < rl->rate) {
rl->val = rl->burst;
return;
}
gain = rl->rate * d;
if (UINT64_MAX - gain < rl->val) {
rl->val = rl->burst;
return;
}
rl->val += gain;
rl->val = nghttp2_min(rl->val, rl->burst);
}
int nghttp2_ratelim_drain(nghttp2_ratelim *rl, uint64_t n) {
if (rl->val < n) {
return -1;
}
rl->val -= n;
return 0;
}
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