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se"); * 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) */ #include <vppinfra/vec.h> int CV (clib_cuckoo_search) (CVT (clib_cuckoo) * h, CVT (clib_cuckoo_kv) * search_v, CVT (clib_cuckoo_kv) * return_v) { CVT (clib_cuckoo_kv) tmp = *search_v; int rv = CV (clib_cuckoo_search_inline) (h, &tmp); if (CLIB_CUCKOO_ERROR_SUCCESS == rv) { *return_v = tmp; } return rv; } static CVT (clib_cuckoo_bucket) * CV (clib_cuckoo_bucket_at_index) (CVT (clib_cuckoo) * h, uword bucket) { return vec_elt_at_index (h->buckets, bucket); } static uword CV (clib_cuckoo_get_nbuckets) (CVT (clib_cuckoo) * h) { return vec_len (h->buckets); } static inline uword CV (clib_cuckoo_elt_in_bucket_to_offset) (CVT (clib_cuckoo_bucket) * b, CVT (clib_cuckoo_kv) * e) { ASSERT (e >= b->elts); ASSERT (e <= &b->elts[sizeof (b->elts) / sizeof (b->elts[0]) - 1]); return e - b->elts; } u8 *CV (format_cuckoo_elt) (u8 * s, va_list * args) { CVT (clib_cuckoo_kv) * elt = va_arg (*args, CVT (clib_cuckoo_kv) *); unsigned reduced_hash = va_arg (*args, unsigned); if (CV (clib_cuckoo_kv_is_free) (elt)) { s = format (s, "[ -- empty -- ]"); } else { s = format (s, "[%U, reduced hash: %u]", CV (format_cuckoo_kvp), elt, reduced_hash); } return s; } u8 *CV (format_cuckoo_bucket) (u8 * s, va_list * args) { CVT (clib_cuckoo_bucket) * bucket = va_arg (*args, CVT (clib_cuckoo_bucket) *); int i = 0; /* *INDENT-OFF* */ clib_cuckoo_bucket_foreach_idx (i) { CVT (clib_cuckoo_kv) *elt = bucket->elts + i; s = format (s, "bucket %p, offset %d: %U\n", bucket, i, CV (format_cuckoo_elt), elt, bucket->reduced_hashes[i]); } /* *INDENT-ON* */ clib_cuckoo_bucket_aux_t aux = bucket->aux; s = format (s, "version: %lld, use count: %d\n", clib_cuckoo_bucket_aux_get_version (aux), clib_cuckoo_bucket_aux_get_use_count (aux)); return s; } #if CLIB_CUCKOO_DEBUG static void CV (clib_cuckoo_deep_self_check) (CVT (clib_cuckoo) * h) { CVT (clib_cuckoo_bucket) * bucket; uword bucket_idx = 0; /* *INDENT-OFF* */ clib_cuckoo_foreach_bucket (bucket, h, { int i = 0; int used = 0; clib_cuckoo_bucket_foreach_idx (i) { CVT (clib_cuckoo_kv) *elt = bucket->elts + i; if (!CV (clib_cuckoo_kv_is_free) (elt)) { u64 hash = CV (clib_cuckoo_hash) (elt); clib_cuckoo_lookup_info_t lookup = CV (clib_cuckoo_calc_lookup) (h->buckets, hash); CVT (clib_cuckoo_kv) kv = *elt; int rv = CV (clib_cuckoo_search) (h, &kv, &kv); if (CLIB_CUCKOO_ERROR_SUCCESS != rv) { CLIB_CUCKOO_DBG ("Search for elt `%U' failed!", CV (format_cuckoo_elt), elt, bucket->reduced_hashes[i]); CLIB_CUCKOO_DBG ("%U", CV (format_cuckoo), h, 1); } ASSERT (lookup.bucket1 == bucket_idx || lookup.bucket2 == bucket_idx); ASSERT (CLIB_CUCKOO_ERROR_SUCCESS == rv); ++used; } } clib_cuckoo_bucket_aux_t aux = bucket->aux; ASSERT (used == clib_cuckoo_bucket_aux_get_use_count (aux)); ++bucket_idx; }); /* *INDENT-ON* */ // CLIB_CUCKOO_DBG ("Deep self check passed: %U", CV (format_cuckoo), h); } #define CLIB_CUCKOO_DEEP_SELF_CHECK(h) CV (clib_cuckoo_deep_self_check) (h) #define CLIB_CUCKOO_ASSERT_BUCKET_SORTED(b) \ do \ { \ int i; \ int min_free = CLIB_CUCKOO_KVP_PER_BUCKET; \ int max_used = 0; \ clib_cuckoo_bucket_foreach_idx (i) \ { \ if (!CV (clib_cuckoo_kv_is_free) (b->elts + i)) \ { \ max_used = i; \ } \ if (CV (clib_cuckoo_kv_is_free) (b->elts + \ (CLIB_CUCKOO_KVP_PER_BUCKET - i))) \ { \ min_free = i; \ } \ } \ ASSERT (min_free > max_used); \ } \ while (0) #else #define CLIB_CUCKOO_DEEP_SELF_CHECK(h) #define CLIB_CUCKOO_ASSERT_BUCKET_SORTED(b) #endif void CV (clib_cuckoo_init) (CVT (clib_cuckoo) * h, const char *name, uword nbuckets, void (*garbage_callback) (CVT (clib_cuckoo) *, void *), void *garbage_ctx) { uword log2_nbuckets = max_log2 (nbuckets); nbuckets = 1ULL << (log2_nbuckets); CLIB_CUCKOO_DBG ("New cuckoo, adjusted nbuckets %wu", nbuckets); CVT (clib_cuckoo_bucket) * buckets = NULL; vec_validate_aligned (buckets, nbuckets - 1, CLIB_CACHE_LINE_BYTES); ASSERT (nbuckets == vec_len (buckets)); h->buckets = buckets; clib_spinlock_init (&h->writer_lock); /* mark all elements free ... */ CVT (clib_cuckoo_bucket) * bucket; /* *INDENT-OFF* */ clib_cuckoo_foreach_bucket ( bucket, h, { clib_memset (bucket->elts, 0xff, sizeof (bucket->elts)); }); /* *INDENT-ON* */ h->name = name; h->garbage_callback = garbage_callback; h->garbage_ctx = garbage_ctx; } void CV (clib_cuckoo_free) (CVT (clib_cuckoo) * h) { clib_memset (h, 0, sizeof (*h)); } static clib_cuckoo_bucket_aux_t CV (clib_cuckoo_bucket_version_bump_and_lock) (CVT (clib_cuckoo_bucket) * b) { clib_cuckoo_bucket_aux_t aux = b->aux; u64 version = clib_cuckoo_bucket_aux_get_version (aux); u8 use_count = clib_cuckoo_bucket_aux_get_use_count (aux); u8 writer_flag = clib_cuckoo_bucket_aux_get_writer_flag (aux); ASSERT (0 == writer_flag); aux = clib_cuckoo_bucket_aux_pack (version + 1, use_count, 1); b->aux = aux; return aux; } static void CV (clib_cuckoo_bucket_unlock) (CVT (clib_cuckoo_bucket) * b, clib_cuckoo_bucket_aux_t aux) { u64 version = clib_cuckoo_bucket_aux_get_version (aux); u8 use_count = clib_cuckoo_bucket_aux_get_use_count (aux); u8 writer_flag = clib_cuckoo_bucket_aux_get_writer_flag (aux); ASSERT (1 == writer_flag); aux = clib_cuckoo_bucket_aux_pack (version, use_count, 0); b->aux = aux; } #define CLIB_CUCKOO_DEBUG_PATH (1) #define CLIB_CUCKOO_DEBUG_PATH_DETAIL (0) #if CLIB_CUCKOO_DEBUG && CLIB_CUCKOO_DEBUG_PATH static u8 *CV (format_cuckoo_path) (u8 * s, va_list * args); #endif static clib_cuckoo_path_t *CV (clib_cuckoo_path_get) (CVT (clib_cuckoo) * h) { clib_cuckoo_path_t *path; pool_get (h->paths, path); clib_memset (path, 0, sizeof (*path)); #if CLIB_CUCKOO_DEBUG_PATH_DETAIL CLIB_CUCKOO_DBG ("Get path @%lu", (long unsigned) (path - h->paths)); #endif return path; } static void CV (clib_cuckoo_path_put) (CVT (clib_cuckoo) * h, uword path_idx) { clib_cuckoo_path_t *path = pool_elt_at_index (h->paths, path_idx); #if CLIB_CUCKOO_DEBUG_PATH_DETAIL CLIB_CUCKOO_DBG ("Put path @%lu", (long unsigned) (path - h->paths)); #endif pool_put (h->paths, path); } static clib_cuckoo_path_t *CV (clib_cuckoo_path_begin) (CVT (clib_cuckoo) * h, uword bucket, uword next_offset) { ASSERT (next_offset < CLIB_CUCKOO_KVP_PER_BUCKET); clib_cuckoo_path_t *new_path = CV (clib_cuckoo_path_get) (h); new_path->length = 1; new_path->data = next_offset; new_path->start = bucket; new_path->bucket = bucket; #if CLIB_CUCKOO_DEBUG_PATH CLIB_CUCKOO_DBG ("Create new path @%wu, length: %u data: %llu bucket: %wu " "next-offset: %wu", new_path - h->paths, new_path->length, (long long unsigned) new_path->data, new_path->bucket, next_offset); #endif return new_path; } /** * create a new path based on existing path extended by adding a bucket * and offset */ static uword CV (clib_cuckoo_path_extend) (CVT (clib_cuckoo) * h, uword path_idx, uword bucket, unsigned offset) { ASSERT (offset < CLIB_CUCKOO_KVP_PER_BUCKET); clib_cuckoo_path_t *new_path = CV (clib_cuckoo_path_get) (h); uword new_path_idx = new_path - h->paths; clib_cuckoo_path_t *path = pool_elt_at_index (h->paths, path_idx); new_path->start = path->start; new_path->length = path->length + 1; new_path->data = (path->data << CLIB_CUCKOO_LOG2_KVP_PER_BUCKET) + offset; new_path->bucket = bucket; #if CLIB_CUCKOO_DEBUG_PATH CLIB_CUCKOO_DBG ("Extend path @%wu, new path @%wu, %U", path_idx, new_path_idx, CV (format_cuckoo_path), h, new_path_idx); #endif return new_path_idx; } /** return the offset of the last element in the path */ static uword CV (clib_cuckoo_path_peek_offset) (const clib_cuckoo_path_t * path) { ASSERT (path->length > 0); uword mask = (1 << CLIB_CUCKOO_LOG2_KVP_PER_BUCKET) - 1; uword offset = path->data & mask; return offset; } static CVT (clib_cuckoo_kv) * CV (clib_cuckoo_bucket_find_empty) (CVT (clib_cuckoo_bucket) * bucket) { clib_cuckoo_bucket_aux_t aux = bucket->aux; u8 use_count = clib_cuckoo_bucket_aux_get_use_count (aux); if (use_count < CLIB_CUCKOO_KVP_PER_BUCKET) { return bucket->elts + use_count; } return NULL; } /** * walk the cuckoo path two ways, * first backwards, extracting offsets, * then forward, extracting buckets * * buckets and offsets are arrays filled with elements extracted from path * the arrays must be able to contain CLIB_CUCKOO_BFS_MAX_PATH_LENGTH elements */ static void clib_cuckoo_path_walk (CVT (clib_cuckoo) * h, uword path_idx, uword * buckets, uword * offsets) { clib_cuckoo_path_t *path = pool_elt_at_index (h->paths, path_idx); ASSERT (path->length > 0); u64 data = path->data; uword mask = (1 << CLIB_CUCKOO_LOG2_KVP_PER_BUCKET) - 1; uword i; for (i = path->length; i > 0; --i) { uword offset = data & mask; offsets[i - 1] = offset; data >>= CLIB_CUCKOO_LOG2_KVP_PER_BUCKET; } buckets[0] = path->start; for (i = 1; i < path->length; ++i) { CVT (clib_cuckoo_bucket) * b = CV (clib_cuckoo_bucket_at_index) (h, buckets[i - 1]); buckets[i] = clib_cuckoo_get_other_bucket (CV (clib_cuckoo_get_nbuckets) (h), buckets[i - 1], b->reduced_hashes[offsets[i - 1]]); } } #if CLIB_CUCKOO_DEBUG && CLIB_CUCKOO_DEBUG_PATH static u8 *CV (format_cuckoo_path) (u8 * s, va_list * args) { CVT (clib_cuckoo) * h = va_arg (*args, CVT (clib_cuckoo) *); uword path_idx = va_arg (*args, uword); clib_cuckoo_path_t *p = pool_elt_at_index (h->paths, path_idx); uword buckets[CLIB_CUCKOO_BFS_MAX_PATH_LENGTH]; uword offsets[CLIB_CUCKOO_BFS_MAX_PATH_LENGTH]; clib_cuckoo_path_walk (h, path_idx, buckets, offsets); s = format (s, "length %u: ", p->length); for (uword i = p->length - 1; i > 0; --i) { s = format (s, "%wu[%wu]->", buckets[i], offsets[i]); } if (p->length) { s = format (s, "%wu[%wu]", buckets[0], offsets[0]); } return s; } #endif /* * perform breadth-first search in the cuckoo hash, finding the closest * empty slot, i.e. one which requires minimum swaps to move it * to one of the buckets provided */ static int CV (clib_cuckoo_find_empty_slot_bfs) (CVT (clib_cuckoo) * h, clib_cuckoo_lookup_info_t * lookup, uword * path_idx_out, uword * found_bucket, CVT (clib_cuckoo_kv) * *found_elt) { uword *tail; ASSERT (!vec_len (h->bfs_search_queue)); clib_cuckoo_path_t *tmp; pool_flush (tmp, h->paths,); int rv = CLIB_CUCKOO_ERROR_AGAIN; int counter = 0; /* start by creating paths starting in each of the buckets ... */ vec_add2 (h->bfs_search_queue, tail, CLIB_CUCKOO_KVP_PER_BUCKET); int i; for (i = 0; i < CLIB_CUCKOO_KVP_PER_BUCKET; ++i) { clib_cuckoo_path_t *path = CV (clib_cuckoo_path_begin) (h, lookup->bucket1, i); tail[i] = path - h->paths; } if (lookup->bucket1 != lookup->bucket2) { vec_add2 (h->bfs_search_queue, tail, CLIB_CUCKOO_KVP_PER_BUCKET); for (i = 0; i < CLIB_CUCKOO_KVP_PER_BUCKET; ++i) { clib_cuckoo_path_t *path = CV (clib_cuckoo_path_begin) (h, lookup->bucket2, i); tail[i] = path - h->paths; } } while (1) { if (counter >= CLIB_CUCKOO_BFS_MAX_STEPS) { #if CLIB_CUCKOO_DEBUG_COUNTERS ++h->steps_exceeded; #endif break; } if (counter >= vec_len (h->bfs_search_queue)) { #if CLIB_CUCKOO_DEBUG_COUNTERS ++h->bfs_queue_emptied; #endif break; } const uword path_idx = vec_elt (h->bfs_search_queue, counter); const clib_cuckoo_path_t *path = pool_elt_at_index (h->paths, path_idx); #if CLIB_CUCKOO_DEBUG_PATH CLIB_CUCKOO_DBG ("Examine path @%wu: %U", path_idx, CV (format_cuckoo_path), h, path_idx); #endif /* TODO prefetch ? */ /* search the alternative bucket for free space */ int offset = CV (clib_cuckoo_path_peek_offset) (path); CVT (clib_cuckoo_bucket) * bucket = CV (clib_cuckoo_bucket_at_index) (h, path->bucket); uword other_bucket = clib_cuckoo_get_other_bucket (CV (clib_cuckoo_get_nbuckets) (h), path->bucket, bucket->reduced_hashes[offset]); CLIB_CUCKOO_DBG ("Path ends in bucket %wu, offset #%wu, other bucket is %wu", path->bucket, CV (clib_cuckoo_path_peek_offset) (path), other_bucket); if (path->bucket != other_bucket) { if ((*found_elt = CV (clib_cuckoo_bucket_find_empty) (CV (clib_cuckoo_bucket_at_index) (h, other_bucket)))) { /* found empty element */ *found_bucket = other_bucket; *path_idx_out = path_idx; rv = CLIB_CUCKOO_ERROR_SUCCESS; #if CLIB_CUCKOO_DEBUG_PATH CLIB_CUCKOO_DBG ("Bucket with empty slot:\n%U", CV (format_cuckoo_bucket), CV (clib_cuckoo_bucket_at_index) (h, other_bucket)); #endif goto out; } /* extend the current path with possible next buckets and add to * queue */ if (path->length < CLIB_CUCKOO_BFS_MAX_PATH_LENGTH && vec_len (h->bfs_search_queue) < CLIB_CUCKOO_BFS_MAX_STEPS) { uword *tail; vec_add2 (h->bfs_search_queue, tail, CLIB_CUCKOO_KVP_PER_BUCKET); for (i = 0; i < CLIB_CUCKOO_KVP_PER_BUCKET; ++i) { uword new_path_idx = CV (clib_cuckoo_path_extend) (h, path_idx, other_bucket, i); tail[i] = new_path_idx; } } } else { CLIB_CUCKOO_DBG ("Discard path @%wu, loop detected", path_idx); } /* done with this path - put back to pool for later reuse */ CV (clib_cuckoo_path_put) (h, path_idx); ++counter; } out: vec_reset_length (h->bfs_search_queue); return rv; } static void CV (clib_cuckoo_swap_elts_in_bucket) (CVT (clib_cuckoo_bucket) * b, uword e1, uword e2) { CVT (clib_cuckoo_kv) kv; clib_memcpy (&kv, b->elts + e1, sizeof (kv)); clib_memcpy (b->elts + e1, b->elts + e2, sizeof (kv)); clib_memcpy (b->elts + e2, &kv, sizeof (kv)); u8 reduced_hash = b->reduced_hashes[e1]; b->reduced_hashes[e1] = b->reduced_hashes[e2]; b->reduced_hashes[e2] = reduced_hash; } static void CV (clib_cuckoo_bucket_tidy) (CVT (clib_cuckoo_bucket) * b) { int i = 0; int j = CLIB_CUCKOO_KVP_PER_BUCKET - 1; while (i != j) { int min_free = i; int max_used = j; while (!CV (clib_cuckoo_kv_is_free) (&b->elts[min_free])) { ++min_free; } while (CV (clib_cuckoo_kv_is_free) (&b->elts[max_used])) { --max_used; } if (min_free < max_used) { CV (clib_cuckoo_swap_elts_in_bucket) (b, min_free, max_used); i = min_free + 1; j = max_used - 1; } else { break; } } } static void CV (clib_cuckoo_free_locked_elt) (CVT (clib_cuckoo_kv) * elt) { /* * FIXME - improve performance by getting rid of this clib_memset - make all * functions in this file not rely on clib_cuckoo_kv_is_free but instead * take use_count into account */ clib_memset (elt, 0xff, sizeof (*elt)); } static void CV (clib_cuckoo_free_elt_in_bucket) (CVT (clib_cuckoo_bucket) * b, CVT (clib_cuckoo_kv) * elt) { clib_cuckoo_bucket_aux_t aux = CV (clib_cuckoo_bucket_version_bump_and_lock) (b); int use_count = clib_cuckoo_bucket_aux_get_use_count (aux); int offset = elt - b->elts; ASSERT (offset < use_count); CV (clib_cuckoo_free_locked_elt) (elt); if (offset != use_count - 1) { CV (clib_cuckoo_bucket_tidy) (b); } aux = clib_cuckoo_bucket_aux_set_use_count (aux, use_count - 1); CV (clib_cuckoo_bucket_unlock) (b, aux); } static void CV (clib_cuckoo_set_locked_elt) (CVT (clib_cuckoo_bucket) * b, CVT (clib_cuckoo_kv) * elt, CVT (clib_cuckoo_kv) * kvp, u8 reduced_hash) { int offset = CV (clib_cuckoo_elt_in_bucket_to_offset) (b, elt); clib_memcpy (elt, kvp, sizeof (*elt)); b->reduced_hashes[offset] = reduced_hash; CLIB_CUCKOO_DBG ("Set bucket %p, offset %d, %U", b, offset, CV (format_cuckoo_elt), elt, b->reduced_hashes[offset]); } static void CV (clib_cuckoo_set_elt) (CVT (clib_cuckoo_bucket) * b, CVT (clib_cuckoo_kv) * elt, CVT (clib_cuckoo_kv) * kvp, u8 reduced_hash) { clib_cuckoo_bucket_aux_t aux = CV (clib_cuckoo_bucket_version_bump_and_lock) (b); CV (clib_cuckoo_set_locked_elt) (b, elt, kvp, reduced_hash); CV (clib_cuckoo_bucket_unlock) (b, aux); } static int CV (clib_cuckoo_add_slow) (CVT (clib_cuckoo) * h, CVT (clib_cuckoo_kv) * kvp, clib_cuckoo_lookup_info_t * lookup, u8 reduced_hash) { uword path_idx; uword empty_bucket_idx; CVT (clib_cuckoo_kv) * empty_elt; int rv = CV (clib_cuckoo_find_empty_slot_bfs) (h, lookup, &path_idx, &empty_bucket_idx, &empty_elt); if (CLIB_CUCKOO_ERROR_SUCCESS == rv) { uword buckets[CLIB_CUCKOO_BFS_MAX_PATH_LENGTH]; uword offsets[CLIB_CUCKOO_BFS_MAX_PATH_LENGTH]; clib_cuckoo_path_walk (h, path_idx, buckets, offsets); /* * walk back the path, moving the free element forward to one of our * buckets ... */ clib_cuckoo_path_t *path = pool_elt_at_index (h->paths, path_idx); CVT (clib_cuckoo_bucket) * empty_bucket = CV (clib_cuckoo_bucket_at_index) (h, empty_bucket_idx); int i; for (i = path->length - 1; i >= 0; --i) { /* copy the key-value in path to the bucket with empty element */ CVT (clib_cuckoo_bucket) * b = CV (clib_cuckoo_bucket_at_index) (h, buckets[i]); CVT (clib_cuckoo_kv) * elt = b->elts + offsets[i]; clib_cuckoo_bucket_aux_t empty_aux = CV (clib_cuckoo_bucket_version_bump_and_lock) (empty_bucket); CV (clib_cuckoo_set_locked_elt) (empty_bucket, empty_elt, elt, b->reduced_hashes[elt - b->elts]); if (i == path->length - 1) { /* we only need to increase the use count for the bucket with * free element - all other buckets' use counts won't change */ empty_aux = clib_cuckoo_bucket_aux_set_use_count (empty_aux, clib_cuckoo_bucket_aux_get_use_count (empty_aux) + 1); } CV (clib_cuckoo_bucket_unlock) (empty_bucket, empty_aux); /* * the element now exists in both places - in the previously empty * element and in its original bucket - we can now safely overwrite * the element in the original bucket with previous element in path * without loosing data (and we don't need to modify the use count) */ empty_bucket = b; empty_elt = elt; } /* now we have a place to put the kvp in ... */ CV (clib_cuckoo_set_elt) (empty_bucket, empty_elt, kvp, reduced_hash); CLIB_CUCKOO_DBG ("Slow insert success, bucket: %p\n%U", empty_bucket, CV (format_cuckoo_bucket), empty_bucket); #if CLIB_CUCKOO_DEBUG_COUNTERS ++h->slow_adds; #endif } return rv; } static int CV (clib_cuckoo_add_fast) (CVT (clib_cuckoo) * h, clib_cuckoo_lookup_info_t * lookup, CVT (clib_cuckoo_kv) * kvp, u8 reduced_hash) { CVT (clib_cuckoo_kv) * elt; CVT (clib_cuckoo_bucket) * bucket1 = CV (clib_cuckoo_bucket_at_index) (h, lookup->bucket1); if ((elt = CV (clib_cuckoo_bucket_find_empty) (bucket1))) { clib_cuckoo_bucket_aux_t aux = CV (clib_cuckoo_bucket_version_bump_and_lock) (bucket1); CV (clib_cuckoo_set_locked_elt) (bucket1, elt, kvp, reduced_hash); aux = clib_cuckoo_bucket_aux_set_use_count (aux, clib_cuckoo_bucket_aux_get_use_count (aux) + 1); CV (clib_cuckoo_bucket_unlock) (bucket1, aux); #if CLIB_CUCKOO_DEBUG_COUNTERS ++h->fast_adds; #endif return CLIB_CUCKOO_ERROR_SUCCESS; } CVT (clib_cuckoo_bucket) * bucket2 = CV (clib_cuckoo_bucket_at_index) (h, lookup->bucket2); if ((elt = CV (clib_cuckoo_bucket_find_empty) (CV (clib_cuckoo_bucket_at_index) (h, lookup->bucket2)))) { clib_cuckoo_bucket_aux_t aux = CV (clib_cuckoo_bucket_version_bump_and_lock) (bucket2); CV (clib_cuckoo_set_locked_elt) (bucket2, elt, kvp, reduced_hash); aux = clib_cuckoo_bucket_aux_set_use_count (aux, clib_cuckoo_bucket_aux_get_use_count (aux) + 1); CV (clib_cuckoo_bucket_unlock) (bucket2, aux); #if CLIB_CUCKOO_DEBUG_COUNTERS ++h->fast_adds; #endif return CLIB_CUCKOO_ERROR_SUCCESS; } return CLIB_CUCKOO_ERROR_AGAIN; } /** * perform garbage collection * * this function assumes there is no other thread touching the cuckoo hash, * not even a reader, it's meant to be called from main thread * in a stop-the-world situation */ void CV (clib_cuckoo_garbage_collect) (CVT (clib_cuckoo) * h) { CLIB_MEMORY_BARRIER (); CVT (clib_cuckoo_bucket) * *b; /* *INDENT-OFF* */ vec_foreach (b, h->to_be_freed) { if (*b == h->buckets) { continue; } #if CLIB_CUCKOO_DEBUG_GC fformat (stdout, "gc: free %p\n", *b); #endif vec_free (*b); } /* *INDENT-ON* */ vec_free (h->to_be_freed); CLIB_MEMORY_BARRIER (); } /** * expand and rehash a cuckoo hash * * 1. double the size of the hash table * 2. move items to new locations derived from the new size */ static void CV (clib_cuckoo_rehash) (CVT (clib_cuckoo) * h) { CVT (clib_cuckoo_bucket) * old = h->buckets; uword old_nbuckets = vec_len (old); uword new_nbuckets = 2 * old_nbuckets; CVT (clib_cuckoo_bucket) * new = vec_dup_aligned (old, CLIB_CACHE_LINE_BYTES); /* allocate space */ vec_validate_aligned (new, new_nbuckets - 1, CLIB_CACHE_LINE_BYTES); ASSERT (new_nbuckets == vec_len (new)); /* store old pointer in to-be-freed list */ vec_add1 (h->to_be_freed, old); /* mark new elements as free */ CVT (clib_cuckoo_bucket) * bucket; for (bucket = new + old_nbuckets; bucket < vec_end (new); ++bucket) { clib_memset (bucket->elts, 0xff, sizeof (bucket->elts)); } /* * this for loop manipulates the new (unseen) memory, so no locks * are required here */ uword old_bucket_idx; for (old_bucket_idx = 0; old_bucket_idx < old_nbuckets; ++old_bucket_idx) { /* items in old bucket might be moved to new bucket */ uword new_bucket_idx = old_bucket_idx + old_nbuckets; CVT (clib_cuckoo_bucket) * old_bucket = new + old_bucket_idx; CVT (clib_cuckoo_bucket) * new_bucket = new + new_bucket_idx; int i = 0; int moved = 0; clib_cuckoo_bucket_aux_t aux = old_bucket->aux; for (i = 0; i < clib_cuckoo_bucket_aux_get_use_count (aux); ++i) { CVT (clib_cuckoo_kv) * elt = old_bucket->elts + i; u64 hash = CV (clib_cuckoo_hash) (elt); clib_cuckoo_lookup_info_t old_lookup = CV (clib_cuckoo_calc_lookup) (old, hash); clib_cuckoo_lookup_info_t new_lookup = CV (clib_cuckoo_calc_lookup) (new, hash); if ((old_bucket_idx == old_lookup.bucket1 && new_bucket_idx == new_lookup.bucket1) || (old_bucket_idx == old_lookup.bucket2 && new_bucket_idx == new_lookup.bucket2)) { /* move the item to new bucket */ CVT (clib_cuckoo_kv) * empty_elt = new_bucket->elts + moved; ASSERT (empty_elt); CV (clib_cuckoo_set_locked_elt) (new_bucket, empty_elt, elt, old_bucket->reduced_hashes[i]); CV (clib_cuckoo_free_locked_elt) (elt); ++moved; } } if (moved) { CV (clib_cuckoo_bucket_tidy) (old_bucket); aux = clib_cuckoo_bucket_aux_set_use_count (aux, clib_cuckoo_bucket_aux_get_use_count (aux) - moved); old_bucket->aux = aux; aux = new_bucket->aux; aux = clib_cuckoo_bucket_aux_set_use_count (aux, clib_cuckoo_bucket_aux_get_use_count (aux) + moved); new_bucket->aux = aux; } } h->buckets = new; #if CLIB_CUCKOO_DEBUG_COUNTERS ++h->rehashes; #endif h->garbage_callback (h, h->garbage_ctx); } static int CV (clib_cuckoo_bucket_search_internal) (CVT (clib_cuckoo) * h, uword bucket, CVT (clib_cuckoo_kv) * kvp, CVT (clib_cuckoo_kv) * *found) { CVT (clib_cuckoo_bucket) * b = CV (clib_cuckoo_bucket_at_index) (h, bucket); int i; /* *INDENT-OFF* */ clib_cuckoo_bucket_foreach_idx_unrolled (i, { CVT (clib_cuckoo_kv) *elt = &b->elts[i]; if (CV (clib_cuckoo_key_compare) (elt->key, kvp->key)) { *found = elt; return CLIB_CUCKOO_ERROR_SUCCESS; } }); /* *INDENT-ON* */ return CLIB_CUCKOO_ERROR_NOT_FOUND; } int CV (clib_cuckoo_add_del) (CVT (clib_cuckoo) * h, CVT (clib_cuckoo_kv) * kvp, int is_add, int dont_overwrite) { CLIB_CUCKOO_DBG ("%s %U", is_add ? "Add" : "Del", CV (format_cuckoo_kvp), kvp); clib_cuckoo_lookup_info_t lookup; u64 hash = CV (clib_cuckoo_hash) (kvp); u8 reduced_hash = clib_cuckoo_reduce_hash (hash); clib_spinlock_lock (&h->writer_lock); restart: lookup = CV (clib_cuckoo_calc_lookup) (h->buckets, hash); CVT (clib_cuckoo_bucket) * b = CV (clib_cuckoo_bucket_at_index) (h, lookup.bucket1); CVT (clib_cuckoo_kv) * found; int rv = CV (clib_cuckoo_bucket_search_internal) (h, lookup.bucket1, kvp, &found); if (CLIB_CUCKOO_ERROR_SUCCESS != rv) { ASSERT (CLIB_CUCKOO_ERROR_NOT_FOUND == rv); b = CV (clib_cuckoo_bucket_at_index) (h, lookup.bucket2); rv = CV (clib_cuckoo_bucket_search_internal) (h, lookup.bucket2, kvp, &found); } if (CLIB_CUCKOO_ERROR_SUCCESS == rv) { if (is_add) { if (dont_overwrite) { CLIB_CUCKOO_DBG ("Refused replacing existing %U", CV (format_cuckoo_elt), found, b->reduced_hashes[found - b->elts]); rv = CLIB_CUCKOO_ERROR_AGAIN; } else { /* prevent readers reading this bucket while we switch the values */ clib_cuckoo_bucket_aux_t aux = CV (clib_cuckoo_bucket_version_bump_and_lock) (b); clib_memcpy (&found->value, &kvp->value, sizeof (found->value)); CLIB_CUCKOO_DBG ("Replaced existing %U", CV (format_cuckoo_elt), found, b->reduced_hashes[found - b->elts]); CV (clib_cuckoo_bucket_unlock) (b, aux); rv = CLIB_CUCKOO_ERROR_SUCCESS; } } else { CV (clib_cuckoo_free_elt_in_bucket) (b, found); rv = CLIB_CUCKOO_ERROR_SUCCESS; } CLIB_CUCKOO_DEEP_SELF_CHECK (h); goto unlock; } if (!is_add) { CLIB_CUCKOO_DBG ("%U not present in table", CV (format_cuckoo_kvp), kvp); rv = CLIB_CUCKOO_ERROR_NOT_FOUND; goto unlock; } /* from this point on, it's add code only */ ASSERT (CLIB_CUCKOO_ERROR_NOT_FOUND == rv); /* fast path: try to search for unoccupied slot in one of the buckets */ rv = CV (clib_cuckoo_add_fast) (h, &lookup, kvp, reduced_hash); CLIB_CUCKOO_DEEP_SELF_CHECK (h); if (CLIB_CUCKOO_ERROR_SUCCESS != rv) { CLIB_CUCKOO_DBG ("Fast insert failed, bucket 1: %wu, bucket 2: %wu\n%U%U", lookup.bucket1, lookup.bucket2, CV (format_cuckoo_bucket), CV (clib_cuckoo_bucket_at_index) (h, lookup.bucket1), CV (format_cuckoo_bucket), CV (clib_cuckoo_bucket_at_index) (h, lookup.bucket2)); /* slow path */ rv = CV (clib_cuckoo_add_slow) (h, kvp, &lookup, reduced_hash); CLIB_CUCKOO_DEEP_SELF_CHECK (h); if (CLIB_CUCKOO_ERROR_SUCCESS != rv) { CLIB_CUCKOO_DBG ("Slow insert failed, rehash required:\n%U", CV (format_cuckoo), h, 1); /* ultra slow path */ CV (clib_cuckoo_rehash) (h); CLIB_CUCKOO_DEEP_SELF_CHECK (h); CLIB_CUCKOO_DBG ("Restarting add after rehash..."); goto restart; } } unlock: clib_spinlock_unlock (&h->writer_lock); return rv; } u8 *CV (format_cuckoo) (u8 * s, va_list * args) { CVT (clib_cuckoo) * h = va_arg (*args, CVT (clib_cuckoo) *); int verbose = va_arg (*args, int); s = format (s, "Hash table %s\n", h->name ? h->name : "(unnamed)"); uword free = 0; uword used = 0; uword use_count_total = 0; float load_factor; CVT (clib_cuckoo_bucket) * b; /* *INDENT-OFF* */ clib_cuckoo_foreach_bucket (b, h, { if (verbose) { s = format (s, "%U", CV (format_cuckoo_bucket), b); } int i; clib_cuckoo_bucket_foreach_idx (i) { CVT (clib_cuckoo_kv) *elt = &b->elts[i]; if (CV (clib_cuckoo_kv_is_free) (elt)) { ++free; } else { ++used; } } clib_cuckoo_bucket_aux_t aux = b->aux; use_count_total += clib_cuckoo_bucket_aux_get_use_count (aux); }); /* *INDENT-ON* */ s = format (s, "Used slots: %wu\n", used); s = format (s, "Use count total: %wu\n", use_count_total); s = format (s, "Free slots: %wu\n", free); if (free + used != 0) load_factor = ((float) used) / ((float) (free + used)); else load_factor = 0.0; s = format (s, "Load factor: %.2f\n", load_factor); #if CLIB_CUCKOO_DEBUG_COUNTERS s = format (s, "BFS attempts limited by max steps: %lld\n", h->steps_exceeded); s = format (s, "BFS cutoffs due to empty queue: %lld\n", h->bfs_queue_emptied); s = format (s, "Fast adds: %lld\n", h->fast_adds); s = format (s, "Slow adds: %lld\n", h->slow_adds); s = format (s, "Rehashes: %lld\n", h->rehashes); #endif return s; } float CV (clib_cuckoo_calculate_load_factor) (CVT (clib_cuckoo) * h) { uword nonfree = 0; uword all = 0; CVT (clib_cuckoo_bucket) * bucket; /* *INDENT-OFF* */ clib_cuckoo_foreach_bucket (bucket, h, { int i; clib_cuckoo_bucket_foreach_idx (i) { CVT (clib_cuckoo_kv) *elt = bucket->elts + i; ++all; if (!CV (clib_cuckoo_kv_is_free) (elt)) { ++nonfree; } } }); /* *INDENT-ON* */ if (all) return (float) nonfree / (float) all; else return 0.0; } /** @endcond */ /* * fd.io coding-style-patch-verification: ON * * Local Variables: * eval: (c-set-style "gnu") * End: */