/* Copyright (c) 2017 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. */ /* * cuckoo hash implementation based on paper * 'Algorithmic Improvements for Fast Concurrent Cuckoo Hashing' * by Xiaozhou Li, David G. Andersen, Michael Kaminsky, Michael J. Freedman * and their libcuckoo implementation (https://github.com/efficient/libcuckoo) */ /* * Note: to instantiate the template multiple times in a single file, * #undef __included_cuckoo_template_h__... */ #ifndef __included_cuckoo_template_h__ #define __included_cuckoo_template_h__ #include <vppinfra/heap.h> #include <vppinfra/format.h> #include <vppinfra/pool.h> #include <vppinfra/lock.h> #include <vppinfra/error.h> #include <vppinfra/hash.h> #include <vppinfra/cache.h> #include <vppinfra/cuckoo_8_8.h> #ifndef CLIB_CUCKOO_TYPE #error CLIB_CUCKOO_TYPE not defined #endif #ifndef CLIB_CUCKOO_BFS_MAX_STEPS #error CLIB_CUCKOO_BFS_MAX_STEPS not defined #endif #ifndef CLIB_CUCKOO_KVP_PER_BUCKET #error CLIB_CUCKOO_KVP_PER_BUCKET not defined #endif #ifndef CLIB_CUCKOO_LOG2_KVP_PER_BUCKET #error CLIB_CUCKOO_LOG2_KVP_PER_BUCKET not defined #endif #ifndef CLIB_CUCKOO_BFS_MAX_PATH_LENGTH #error CLIB_CUCKOO_BFS_MAX_PATH_LENGTH not defined #endif STATIC_ASSERT (CLIB_CUCKOO_KVP_PER_BUCKET == (1 << CLIB_CUCKOO_LOG2_KVP_PER_BUCKET), "CLIB_CUCKOO_KVP_PER_BUCKET != (1 << CLIB_CUCKOO_LOG2_KVP_PER_BUCKET"); #define _cv(a, b) a##b #define __cv(a, b) _cv (a, b) #define CV(a) __cv (a, CLIB_CUCKOO_TYPE) #define _cvt(a, b) a##b##_t #define __cvt(a, b) _cvt (a, b) #define CVT(a) __cvt (a, CLIB_CUCKOO_TYPE) typedef u64 clib_cuckoo_bucket_aux_t; #define CLIB_CUCKOO_USE_COUNT_BIT_WIDTH (1 + CLIB_CUCKOO_LOG2_KVP_PER_BUCKET) always_inline u64 clib_cuckoo_bucket_aux_get_version (clib_cuckoo_bucket_aux_t aux) { return aux >> (1 + CLIB_CUCKOO_USE_COUNT_BIT_WIDTH); } always_inline int clib_cuckoo_bucket_aux_get_use_count (clib_cuckoo_bucket_aux_t aux) { u64 use_count_mask = (1 << CLIB_CUCKOO_USE_COUNT_BIT_WIDTH) - 1; return (aux >> 1) & use_count_mask; } always_inline int clib_cuckoo_bucket_aux_get_writer_flag (clib_cuckoo_bucket_aux_t aux) { return aux & 1; } always_inline clib_cuckoo_bucket_aux_t clib_cuckoo_bucket_aux_pack (u64 version, int use_count, int writer_flag) { return (version << (1 + CLIB_CUCKOO_USE_COUNT_BIT_WIDTH)) + (use_count << 1) + writer_flag; } always_inline clib_cuckoo_bucket_aux_t clib_cuckoo_bucket_aux_set_version (clib_cuckoo_bucket_aux_t aux, u64 version) { int use_count = clib_cuckoo_bucket_aux_get_use_count (aux); int writer_flag = clib_cuckoo_bucket_aux_get_writer_flag (aux); return clib_cuckoo_bucket_aux_pack (version, use_count, writer_flag); } always_inline clib_cuckoo_bucket_aux_t clib_cuckoo_bucket_aux_set_use_count (clib_cuckoo_bucket_aux_t aux, int use_count) { u64 version = clib_cuckoo_bucket_aux_get_version (aux); int writer_flag = clib_cuckoo_bucket_aux_get_writer_flag (aux); return clib_cuckoo_bucket_aux_pack (version, use_count, writer_flag); } always_inline clib_cuckoo_bucket_aux_t clib_cuckoo_bucket_aux_set_writer_flag (clib_cuckoo_bucket_aux_t aux, int writer_flag) { u64 version = clib_cuckoo_bucket_aux_get_version (aux); int use_count = clib_cuckoo_bucket_aux_get_use_count (aux); return clib_cuckoo_bucket_aux_pack (version, use_count, writer_flag); } #define PATH_BITS_REQ \ (CLIB_CUCKOO_BFS_MAX_PATH_LENGTH * CLIB_CUCKOO_LOG2_KVP_PER_BUCKET) #if PATH_BITS_REQ <= 8 typedef u8 path_data_t; #elif PATH_BITS_REQ <= 16 typedef u16 path_data_t; #elif PATH_BITS_REQ <= 32 typedef u32 path_data_t; #elif PATH_BITS_REQ <= 64 typedef u64 path_data_t; #else #error no suitable datatype for path storage... #endif typedef struct { /** bucket where this path begins */ u64 start; /** bucket at end of path */ u64 bucket; /** length of the path */ u8 length; /** holds compressed offsets in buckets along path */ path_data_t data; } clib_cuckoo_path_t; typedef struct { CLIB_CACHE_LINE_ALIGN_MARK (cacheline0); /** reduced hashes corresponding to elements */ u8 reduced_hashes[CLIB_CUCKOO_KVP_PER_BUCKET]; /** auxiliary data - version, writer flag and used count */ volatile clib_cuckoo_bucket_aux_t aux; /** cuckoo elements in this bucket */ CVT (clib_cuckoo_kv) elts[CLIB_CUCKOO_KVP_PER_BUCKET]; } CVT (clib_cuckoo_bucket); #define clib_cuckoo_bucket_foreach_idx(var) \ for (var = 0; var < CLIB_CUCKOO_KVP_PER_BUCKET; var++) #if CLIB_CUCKOO_OPTIMIZE_UNROLL #if CLIB_CUCKOO_KVP_PER_BUCKET == 2 #define clib_cuckoo_bucket_foreach_idx_unrolled(var, body) \ do \ { \ var = 0; \ body; \ var = 1; \ body; \ } \ while (0); #elif CLIB_CUCKOO_KVP_PER_BUCKET == 4 #define clib_cuckoo_bucket_foreach_idx_unrolled(var, body) \ do \ { \ var = 0; \ body; \ var = 1; \ body; \ var = 2; \ body; \ var = 3; \ body; \ } \ while (0); #elif CLIB_CUCKOO_KVP_PER_BUCKET == 8 #define clib_cuckoo_bucket_foreach_idx_unrolled(var, body) \ do \ { \ var = 0; \ body; \ var = 1; \ body; \ var = 2; \ body; \ var = 3; \ body; \ var = 4; \ body; \ var = 5; \ body; \ var = 6; \ body; \ var = 7; \ body; \ } \ while (0); #else #define clib_cuckoo_bucket_foreach_idx_unrolled(var, body) \ clib_cuckoo_bucket_foreach_idx (var) \ { \ body; \ } #endif #else /* CLIB_CUCKOO_OPTIMIZE_UNROLL */ #define clib_cuckoo_bucket_foreach_idx_unrolled(var, body) \ clib_cuckoo_bucket_foreach_idx (var) \ { \ body; \ } #endif /* CLIB_CUCKOO_OPTIMIZE_UNROLL */ #define clib_cuckoo_bucket_foreach_elt_index(var, bucket) \ for (var = 0; var < CLIB_CUCKOO_KVP_PER_BUCKET; ++i) #define clib_cuckoo_foreach_bucket(var, h, body) \ do \ { \ CVT (clib_cuckoo_bucket) *__buckets = h->buckets; \ vec_foreach (var, __buckets) \ { \ body; \ } \ } \ while (0) typedef struct CV (clib_cuckoo) { /** vector of elements containing key-value pairs and auxiliary data */ CVT (clib_cuckoo_bucket) * volatile buckets; /** garbage to be freed once its safe to do so .. */ CVT (clib_cuckoo_bucket) * *to_be_freed; /** hash table name */ const char *name; /** pool of cuckoo paths (reused when doing bfd search) */ clib_cuckoo_path_t *paths; /** * vector used as queue when doing cuckoo path searches - holds offsets * in paths pool */ uword *bfs_search_queue; /** * writer lock - whether this lock is taken or not has zero effect on * readers */ clib_spinlock_t writer_lock; /** caller context passed to callback with garbage notification */ void *garbage_ctx; /** * garbage notify function - called when some garbage needs to be collected * in main thread while other threads are stopped */ void (*garbage_callback) (struct CV (clib_cuckoo) * h, void *garbage_ctx); #if CLIB_CUCKOO_DEBUG_COUNTERS u64 steps_exceeded; u64 bfs_queue_emptied; u64 fast_adds; u64 slow_adds; u64 rehashes; #endif } CVT (clib_cuckoo); void CV (clib_cuckoo_init) (CVT (clib_cuckoo) * h, const char *name, u64 nbuckets, void (*garbage_callback) (CVT (clib_cuckoo) *, void *), void *garbage_ctx); void CV (clib_cuckoo_garbage_collect) (CVT (clib_cuckoo) * h); void CV (clib_cuckoo_free) (CVT (clib_cuckoo) * h); int CV (clib_cuckoo_add_del) (CVT (clib_cuckoo) * h, CVT (clib_cuckoo_kv) * add_v, int is_add); int CV (clib_cuckoo_search) (CVT (clib_cuckoo) * h, CVT (clib_cuckoo_kv) * search_v, CVT (clib_cuckoo_kv) * return_v); void CV (clib_cuckoo_foreach_key_value_pair) (CVT (clib_cuckoo) * h, void *callback, void *arg); float CV (clib_cuckoo_calc_load) (CVT (clib_cuckoo) * h); format_function_t CV (format_cuckoo); format_function_t CV (format_cuckoo_kvp); always_inline u8 clib_cuckoo_reduce_hash (u64 hash) { u32 v32 = ((u32) hash) ^ ((u32) (hash >> 32)); u16 v16 = ((u16) v32) ^ ((u16) (v32 >> 16)); u8 v8 = ((u8) v16) ^ ((u8) (v16 >> 8)); return v8; } always_inline u64 clib_cuckoo_get_other_bucket (u64 nbuckets, u64 bucket, u8 reduced_hash) { u64 mask = (nbuckets - 1); return (bucket ^ ((reduced_hash + 1) * 0xc6a4a7935bd1e995)) & mask; } always_inline clib_cuckoo_lookup_info_t CV (clib_cuckoo_calc_lookup) (CVT (clib_cuckoo_bucket) * buckets, u64 hash) { clib_cuckoo_lookup_info_t lookup; u64 nbuckets = vec_len (buckets); u64 mask = (nbuckets - 1); lookup.bucket1 = hash & mask; #if CLIB_CUCKOO_OPTIMIZE_PREFETCH CLIB_PREFETCH (vec_elt_at_index (buckets, lookup.bucket1), sizeof (*buckets), LOAD); #endif u8 reduced_hash = clib_cuckoo_reduce_hash (hash); lookup.bucket2 = clib_cuckoo_get_other_bucket (nbuckets, lookup.bucket1, reduced_hash); #if CLIB_CUCKOO_OPTIMIZE_PREFETCH CLIB_PREFETCH (vec_elt_at_index (buckets, lookup.bucket2), sizeof (*buckets), LOAD); #endif lookup.reduced_hash = reduced_hash; ASSERT (lookup.bucket1 < nbuckets); ASSERT (lookup.bucket2 < nbuckets); return lookup; } /** * search for key within bucket */ always_inline int CV (clib_cuckoo_bucket_search) (CVT (clib_cuckoo_bucket) * b, CVT (clib_cuckoo_kv) * kvp, u8 reduced_hash) { clib_cuckoo_bucket_aux_t bucket_aux; u8 writer_flag; do { bucket_aux = b->aux; writer_flag = clib_cuckoo_bucket_aux_get_writer_flag (bucket_aux); } while (PREDICT_FALSE (writer_flag)); /* loop while writer flag is set */ int i; #if CLIB_CUCKOO_OPTIMIZE_USE_COUNT_LIMITS_SEARCH const int use_count = clib_cuckoo_bucket_aux_get_use_count (bucket_aux); #endif /* *INDENT-OFF* */ clib_cuckoo_bucket_foreach_idx_unrolled (i, { #if CLIB_CUCKOO_OPTIMIZE_USE_COUNT_LIMITS_SEARCH if (i > use_count) { break; } #endif if ( #if CLIB_CUCKOO_OPTIMIZE_CMP_REDUCED_HASH reduced_hash == b->reduced_hashes[i] && #endif 0 == memcmp (&kvp->key, &b->elts[i].key, sizeof (kvp->key))) { kvp->value = b->elts[i].value; clib_cuckoo_bucket_aux_t bucket_aux2 = b->aux; if (PREDICT_TRUE (clib_cuckoo_bucket_aux_get_version (bucket_aux) == clib_cuckoo_bucket_aux_get_version (bucket_aux2))) { /* yay, fresh data */ return CLIB_CUCKOO_ERROR_SUCCESS; } else { /* oops, modification detected */ return CLIB_CUCKOO_ERROR_AGAIN; } } }); /* *INDENT-ON* */ return CLIB_CUCKOO_ERROR_NOT_FOUND; } always_inline int CV (clib_cuckoo_search_inline) (CVT (clib_cuckoo) * h, CVT (clib_cuckoo_kv) * kvp) { clib_cuckoo_lookup_info_t lookup; int rv; u64 hash = CV (clib_cuckoo_hash) (kvp); CVT (clib_cuckoo_bucket) * buckets; again: buckets = h->buckets; lookup = CV (clib_cuckoo_calc_lookup) (buckets, hash); do { rv = CV (clib_cuckoo_bucket_search) (vec_elt_at_index (buckets, lookup.bucket1), kvp, lookup.reduced_hash); } while (PREDICT_FALSE (CLIB_CUCKOO_ERROR_AGAIN == rv)); if (CLIB_CUCKOO_ERROR_SUCCESS == rv) { return CLIB_CUCKOO_ERROR_SUCCESS; } rv = CV (clib_cuckoo_bucket_search) (vec_elt_at_index (buckets, lookup.bucket2), kvp, lookup.reduced_hash); if (PREDICT_FALSE (CLIB_CUCKOO_ERROR_AGAIN == rv)) { /* * change to 2nd bucket could bump the item to 1st bucket and the bucket * indexes might not even be valid anymore - restart the search */ goto again; } return rv; } #endif /* __included_cuckoo_template_h__ */ /** @endcond */ /* * fd.io coding-style-patch-verification: ON * * Local Variables: * eval: (c-set-style "gnu") * End: */