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/*
* Copyright (c) 2018 Cisco and/or its affiliates.
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at:
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#ifndef __THROTTLE_H__
#define __THROTTLE_H__
#include <vlib/vlib.h>
#include <vppinfra/xxhash.h>
/**
* @brief A throttle
* Used in the data plane to decide if a given hash should be throttled,
* i.e. that the hash has been seen already 'recently'. Recent is the time
* given in the throttle's initialisation.
*/
typedef struct throttle_t_
{
f64 time;
uword **bitmaps;
u64 *seeds;
f64 *last_seed_change_time;
} throttle_t;
#define THROTTLE_BITS (512)
extern void throttle_init (throttle_t * t, u32 n_threads, f64 time);
always_inline u64
throttle_seed (throttle_t * t, u32 thread_index, f64 time_now)
{
if (time_now - t->last_seed_change_time[thread_index] > t->time)
{
(void) random_u64 (&t->seeds[thread_index]);
clib_memset (t->bitmaps[thread_index], 0, THROTTLE_BITS / BITS (u8));
t->last_seed_change_time[thread_index] = time_now;
}
return t->seeds[thread_index];
}
always_inline int
throttle_check (throttle_t * t, u32 thread_index, u64 hash, u64 seed)
{
int drop;
uword m;
u32 w;
hash = clib_xxhash (hash ^ seed);
/* Select bit number */
hash &= THROTTLE_BITS - 1;
w = hash / BITS (uword);
m = (uword) 1 << (hash % BITS (uword));
drop = (t->bitmaps[thread_index][w] & m) != 0;
t->bitmaps[thread_index][w] |= m;
return (drop);
}
#endif
/*
* fd.io coding-style-patch-verification: ON
*
* Local Variables:
* eval: (c-set-style "gnu")
* End:
*/
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