serval-dna/limit.c
2014-05-12 13:44:50 +09:30

76 lines
2.2 KiB
C

/*
Copyright (C) 2014 Serval Project Inc.
This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*/
#include <unistd.h>
#include "os.h"
#include "limit.h"
#define MIN_BURST_LENGTH 5000
static void update_limit_state(struct limit_state *state, time_ms_t now){
if (state->next_interval > now || state->burst_size==0){
return;
}
if (state->next_interval + state->burst_length>now)
state->next_interval+=state->burst_length;
else
state->next_interval=now + state->burst_length;
state->sent = 0;
}
/* When should we next allow this thing to occur? */
time_ms_t limit_next_allowed(struct limit_state *state){
time_ms_t now = gettime_ms();
if (!state->burst_size)
return now;
update_limit_state(state, now);
if (state->sent < state->burst_size)
return now;
return state->next_interval;
}
/* Can we do this now? if so, track it */
int limit_is_allowed(struct limit_state *state){
time_ms_t now = gettime_ms();
if (!state->burst_size)
return 0;
update_limit_state(state, now);
if (state->sent >= state->burst_size){
return -1;
}
state->sent ++;
return 0;
}
/* Initialise burst size and length based on the number we can do in one MIN_BURST */
int limit_init(struct limit_state *state, uint32_t rate_micro_seconds){
state->rate_micro_seconds = rate_micro_seconds;
if (rate_micro_seconds==0){
state->burst_size=0;
state->burst_length=0;
}else{
state->burst_size = (MIN_BURST_LENGTH / rate_micro_seconds)+1;
state->burst_length = (state->burst_size * rate_micro_seconds) / 1000.0;
}
return 0;
}