cd35e53c92
Change-Id: I93c6b7bccd1a1ab71625ae29c99c974581186c4d Signed-off-by: Neale Ranns <nranns@cisco.com>
82 lines
2.0 KiB
C
82 lines
2.0 KiB
C
/*
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* Copyright (c) 2018 Cisco and/or its affiliates.
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at:
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#ifndef __THROTTLE_H__
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#define __THROTTLE_H__
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#include <vlib/vlib.h>
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#include <vppinfra/xxhash.h>
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/**
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* @brief A throttle
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* Used in the data plane to decide if a given hash should be throttled,
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* i.e. that the hash has been seen already 'recently'. Recent is the time
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* given in the throttle's initialisation.
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*/
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typedef struct throttle_t_
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{
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f64 time;
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uword **bitmaps;
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u64 *seeds;
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f64 *last_seed_change_time;
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} throttle_t;
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#define THROTTLE_BITS (512)
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extern void throttle_init (throttle_t * t, u32 n_threads, f64 time);
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always_inline u64
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throttle_seed (throttle_t * t, u32 thread_index, f64 time_now)
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{
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if (time_now - t->last_seed_change_time[thread_index] > t->time)
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{
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(void) random_u64 (&t->seeds[thread_index]);
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clib_memset (t->bitmaps[thread_index], 0, THROTTLE_BITS / BITS (u8));
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t->last_seed_change_time[thread_index] = time_now;
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}
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return t->seeds[thread_index];
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}
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always_inline int
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throttle_check (throttle_t * t, u32 thread_index, u64 hash, u64 seed)
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{
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int drop;
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uword m;
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u32 w;
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hash = clib_xxhash (hash ^ seed);
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/* Select bit number */
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hash &= THROTTLE_BITS - 1;
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w = hash / BITS (uword);
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m = (uword) 1 << (hash % BITS (uword));
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drop = (t->bitmaps[thread_index][w] & m) != 0;
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t->bitmaps[thread_index][w] |= m;
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return (drop);
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}
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#endif
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/*
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* fd.io coding-style-patch-verification: ON
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*
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* Local Variables:
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* eval: (c-set-style "gnu")
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* End:
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*/
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