/* * 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: */