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Diffstat (limited to 'src/ck_ht.c')
| -rw-r--r-- | src/ck_ht.c | 1036 |
1 files changed, 1036 insertions, 0 deletions
diff --git a/src/ck_ht.c b/src/ck_ht.c new file mode 100644 index 0000000..2c864c5 --- /dev/null +++ b/src/ck_ht.c @@ -0,0 +1,1036 @@ +/* + * Copyright 2012-2015 Samy Al Bahra. + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + */ + +#define CK_HT_IM +#include <ck_ht.h> + +/* + * This implementation borrows several techniques from Josh Dybnis's + * nbds library which can be found at http://code.google.com/p/nbds + * + * This release currently only includes support for 64-bit platforms. + * We can address 32-bit platforms in a future release. + */ +#include <ck_cc.h> +#include <ck_md.h> +#include <ck_pr.h> +#include <ck_stdint.h> +#include <ck_stdbool.h> +#include <ck_string.h> + +#include "ck_ht_hash.h" +#include "ck_internal.h" + +#ifndef CK_HT_BUCKET_LENGTH + +#ifdef CK_HT_PP +#define CK_HT_BUCKET_SHIFT 2ULL +#else +#define CK_HT_BUCKET_SHIFT 1ULL +#endif + +#define CK_HT_BUCKET_LENGTH (1U << CK_HT_BUCKET_SHIFT) +#define CK_HT_BUCKET_MASK (CK_HT_BUCKET_LENGTH - 1) +#endif + +#ifndef CK_HT_PROBE_DEFAULT +#define CK_HT_PROBE_DEFAULT 64ULL +#endif + +#if defined(CK_F_PR_LOAD_8) && defined(CK_F_PR_STORE_8) +#define CK_HT_WORD uint8_t +#define CK_HT_WORD_MAX UINT8_MAX +#define CK_HT_STORE(x, y) ck_pr_store_8(x, y) +#define CK_HT_LOAD(x) ck_pr_load_8(x) +#elif defined(CK_F_PR_LOAD_16) && defined(CK_F_PR_STORE_16) +#define CK_HT_WORD uint16_t +#define CK_HT_WORD_MAX UINT16_MAX +#define CK_HT_STORE(x, y) ck_pr_store_16(x, y) +#define CK_HT_LOAD(x) ck_pr_load_16(x) +#elif defined(CK_F_PR_LOAD_32) && defined(CK_F_PR_STORE_32) +#define CK_HT_WORD uint32_t +#define CK_HT_WORD_MAX UINT32_MAX +#define CK_HT_STORE(x, y) ck_pr_store_32(x, y) +#define CK_HT_LOAD(x) ck_pr_load_32(x) +#else +#error "ck_ht is not supported on your platform." +#endif + +struct ck_ht_map { + unsigned int mode; + CK_HT_TYPE deletions; + CK_HT_TYPE probe_maximum; + CK_HT_TYPE probe_length; + CK_HT_TYPE probe_limit; + CK_HT_TYPE size; + CK_HT_TYPE n_entries; + CK_HT_TYPE mask; + CK_HT_TYPE capacity; + CK_HT_TYPE step; + CK_HT_WORD *probe_bound; + struct ck_ht_entry *entries; +}; + +void +ck_ht_stat(struct ck_ht *table, + struct ck_ht_stat *st) +{ + struct ck_ht_map *map = table->map; + + st->n_entries = map->n_entries; + st->probe_maximum = map->probe_maximum; + return; +} + +void +ck_ht_hash(struct ck_ht_hash *h, + struct ck_ht *table, + const void *key, + uint16_t key_length) +{ + + table->h(h, key, key_length, table->seed); + return; +} + +void +ck_ht_hash_direct(struct ck_ht_hash *h, + struct ck_ht *table, + uintptr_t key) +{ + + ck_ht_hash(h, table, &key, sizeof(key)); + return; +} + +static void +ck_ht_hash_wrapper(struct ck_ht_hash *h, + const void *key, + size_t length, + uint64_t seed) +{ + + h->value = (unsigned long)MurmurHash64A(key, length, seed); + return; +} + +static struct ck_ht_map * +ck_ht_map_create(struct ck_ht *table, CK_HT_TYPE entries) +{ + struct ck_ht_map *map; + CK_HT_TYPE size; + uintptr_t prefix; + uint32_t n_entries; + + n_entries = ck_internal_power_2(entries); + if (n_entries < CK_HT_BUCKET_LENGTH) + n_entries = CK_HT_BUCKET_LENGTH; + + size = sizeof(struct ck_ht_map) + + (sizeof(struct ck_ht_entry) * n_entries + CK_MD_CACHELINE - 1); + + if (table->mode & CK_HT_WORKLOAD_DELETE) { + prefix = sizeof(CK_HT_WORD) * n_entries; + size += prefix; + } else { + prefix = 0; + } + + map = table->m->malloc(size); + if (map == NULL) + return NULL; + + map->mode = table->mode; + map->size = size; + map->probe_limit = ck_internal_max_64(n_entries >> + (CK_HT_BUCKET_SHIFT + 2), CK_HT_PROBE_DEFAULT); + + map->deletions = 0; + map->probe_maximum = 0; + map->capacity = n_entries; + map->step = ck_internal_bsf_64(map->capacity); + map->mask = map->capacity - 1; + map->n_entries = 0; + map->entries = (struct ck_ht_entry *)(((uintptr_t)&map[1] + prefix + + CK_MD_CACHELINE - 1) & ~(CK_MD_CACHELINE - 1)); + + if (table->mode & CK_HT_WORKLOAD_DELETE) { + map->probe_bound = (CK_HT_WORD *)&map[1]; + memset(map->probe_bound, 0, prefix); + } else { + map->probe_bound = NULL; + } + + memset(map->entries, 0, sizeof(struct ck_ht_entry) * n_entries); + ck_pr_fence_store(); + return map; +} + +static inline void +ck_ht_map_bound_set(struct ck_ht_map *m, + struct ck_ht_hash h, + CK_HT_TYPE n_probes) +{ + CK_HT_TYPE offset = h.value & m->mask; + + if (n_probes > m->probe_maximum) + CK_HT_TYPE_STORE(&m->probe_maximum, n_probes); + + if (m->probe_bound != NULL && m->probe_bound[offset] < n_probes) { + if (n_probes >= CK_HT_WORD_MAX) + n_probes = CK_HT_WORD_MAX; + + CK_HT_STORE(&m->probe_bound[offset], n_probes); + ck_pr_fence_store(); + } + + return; +} + +static inline CK_HT_TYPE +ck_ht_map_bound_get(struct ck_ht_map *m, struct ck_ht_hash h) +{ + CK_HT_TYPE offset = h.value & m->mask; + CK_HT_TYPE r = CK_HT_WORD_MAX; + + if (m->probe_bound != NULL) { + r = CK_HT_LOAD(&m->probe_bound[offset]); + if (r == CK_HT_WORD_MAX) + r = CK_HT_TYPE_LOAD(&m->probe_maximum); + } else { + r = CK_HT_TYPE_LOAD(&m->probe_maximum); + } + + return r; +} + +static void +ck_ht_map_destroy(struct ck_malloc *m, struct ck_ht_map *map, bool defer) +{ + + m->free(map, map->size, defer); + return; +} + +static inline size_t +ck_ht_map_probe_next(struct ck_ht_map *map, size_t offset, ck_ht_hash_t h, size_t probes) +{ + ck_ht_hash_t r; + size_t stride; + unsigned long level = (unsigned long)probes >> CK_HT_BUCKET_SHIFT; + + r.value = (h.value >> map->step) >> level; + stride = (r.value & ~CK_HT_BUCKET_MASK) << 1 + | (r.value & CK_HT_BUCKET_MASK); + + return (offset + level + + (stride | CK_HT_BUCKET_LENGTH)) & map->mask; +} + +bool +ck_ht_init(struct ck_ht *table, + unsigned int mode, + ck_ht_hash_cb_t *h, + struct ck_malloc *m, + CK_HT_TYPE entries, + uint64_t seed) +{ + + if (m == NULL || m->malloc == NULL || m->free == NULL) + return false; + + table->m = m; + table->mode = mode; + table->seed = seed; + + if (h == NULL) { + table->h = ck_ht_hash_wrapper; + } else { + table->h = h; + } + + table->map = ck_ht_map_create(table, entries); + return table->map != NULL; +} + +static struct ck_ht_entry * +ck_ht_map_probe_wr(struct ck_ht_map *map, + ck_ht_hash_t h, + ck_ht_entry_t *snapshot, + ck_ht_entry_t **available, + const void *key, + uint16_t key_length, + CK_HT_TYPE *probe_limit, + CK_HT_TYPE *probe_wr) +{ + struct ck_ht_entry *bucket, *cursor; + struct ck_ht_entry *first = NULL; + size_t offset, i, j; + CK_HT_TYPE probes = 0; + CK_HT_TYPE limit; + + if (probe_limit == NULL) { + limit = ck_ht_map_bound_get(map, h); + } else { + limit = CK_HT_TYPE_MAX; + } + + offset = h.value & map->mask; + for (i = 0; i < map->probe_limit; i++) { + /* + * Probe on a complete cache line first. Scan forward and wrap around to + * the beginning of the cache line. Only when the complete cache line has + * been scanned do we move on to the next row. + */ + bucket = (void *)((uintptr_t)(map->entries + offset) & + ~(CK_MD_CACHELINE - 1)); + + for (j = 0; j < CK_HT_BUCKET_LENGTH; j++) { + uint16_t k; + + if (probes++ > limit) + break; + + cursor = bucket + ((j + offset) & (CK_HT_BUCKET_LENGTH - 1)); + + /* + * It is probably worth it to encapsulate probe state + * in order to prevent a complete reprobe sequence in + * the case of intermittent writers. + */ + if (cursor->key == CK_HT_KEY_TOMBSTONE) { + if (first == NULL) { + first = cursor; + *probe_wr = probes; + } + + continue; + } + + if (cursor->key == CK_HT_KEY_EMPTY) + goto leave; + + if (cursor->key == (uintptr_t)key) + goto leave; + + if (map->mode & CK_HT_MODE_BYTESTRING) { + void *pointer; + + /* + * Check memoized portion of hash value before + * expensive full-length comparison. + */ + k = ck_ht_entry_key_length(cursor); + if (k != key_length) + continue; + +#ifdef CK_HT_PP + if ((cursor->value >> CK_MD_VMA_BITS) != ((h.value >> 32) & CK_HT_KEY_MASK)) + continue; +#else + if (cursor->hash != h.value) + continue; +#endif + + pointer = ck_ht_entry_key(cursor); + if (memcmp(pointer, key, key_length) == 0) + goto leave; + } + } + + offset = ck_ht_map_probe_next(map, offset, h, probes); + } + + cursor = NULL; + +leave: + if (probe_limit != NULL) { + *probe_limit = probes; + } else if (first == NULL) { + *probe_wr = probes; + } + + *available = first; + + if (cursor != NULL) { + *snapshot = *cursor; + } + + return cursor; +} + +bool +ck_ht_gc(struct ck_ht *ht, unsigned long cycles, unsigned long seed) +{ + CK_HT_WORD *bounds = NULL; + struct ck_ht_map *map = ht->map; + CK_HT_TYPE maximum, i; + CK_HT_TYPE size = 0; + + if (map->n_entries == 0) { + CK_HT_TYPE_STORE(&map->probe_maximum, 0); + if (map->probe_bound != NULL) + memset(map->probe_bound, 0, sizeof(CK_HT_WORD) * map->capacity); + + return true; + } + + if (cycles == 0) { + maximum = 0; + + if (map->probe_bound != NULL) { + size = sizeof(CK_HT_WORD) * map->capacity; + bounds = ht->m->malloc(size); + if (bounds == NULL) + return false; + + memset(bounds, 0, size); + } + } else { + maximum = map->probe_maximum; + } + + for (i = 0; i < map->capacity; i++) { + struct ck_ht_entry *entry, *priority, snapshot; + struct ck_ht_hash h; + CK_HT_TYPE probes_wr; + CK_HT_TYPE offset; + + entry = &map->entries[(i + seed) & map->mask]; + if (entry->key == CK_HT_KEY_EMPTY || + entry->key == CK_HT_KEY_TOMBSTONE) { + continue; + } + + if (ht->mode & CK_HT_MODE_BYTESTRING) { +#ifndef CK_HT_PP + h.value = entry->hash; +#else + ht->h(&h, ck_ht_entry_key(entry), ck_ht_entry_key_length(entry), + ht->seed); +#endif + entry = ck_ht_map_probe_wr(map, h, &snapshot, &priority, + ck_ht_entry_key(entry), + ck_ht_entry_key_length(entry), + NULL, &probes_wr); + } else { +#ifndef CK_HT_PP + h.value = entry->hash; +#else + ht->h(&h, &entry->key, sizeof(entry->key), ht->seed); +#endif + entry = ck_ht_map_probe_wr(map, h, &snapshot, &priority, + (void *)entry->key, + sizeof(entry->key), + NULL, &probes_wr); + } + + offset = h.value & map->mask; + + if (priority != NULL) { + CK_HT_TYPE_STORE(&map->deletions, map->deletions + 1); + ck_pr_fence_store(); +#ifndef CK_HT_PP + CK_HT_TYPE_STORE(&priority->key_length, entry->key_length); + CK_HT_TYPE_STORE(&priority->hash, entry->hash); +#endif + ck_pr_store_ptr_unsafe(&priority->value, (void *)entry->value); + ck_pr_fence_store(); + ck_pr_store_ptr_unsafe(&priority->key, (void *)entry->key); + ck_pr_fence_store(); + CK_HT_TYPE_STORE(&map->deletions, map->deletions + 1); + ck_pr_fence_store(); + ck_pr_store_ptr_unsafe(&entry->key, (void *)CK_HT_KEY_TOMBSTONE); + ck_pr_fence_store(); + } + + if (cycles == 0) { + if (probes_wr > maximum) + maximum = probes_wr; + + if (probes_wr >= CK_HT_WORD_MAX) + probes_wr = CK_HT_WORD_MAX; + + if (bounds != NULL && probes_wr > bounds[offset]) + bounds[offset] = probes_wr; + } else if (--cycles == 0) + break; + } + + if (maximum != map->probe_maximum) + CK_HT_TYPE_STORE(&map->probe_maximum, maximum); + + if (bounds != NULL) { + for (i = 0; i < map->capacity; i++) + CK_HT_STORE(&map->probe_bound[i], bounds[i]); + + ht->m->free(bounds, size, false); + } + + return true; +} + +static struct ck_ht_entry * +ck_ht_map_probe_rd(struct ck_ht_map *map, + ck_ht_hash_t h, + ck_ht_entry_t *snapshot, + const void *key, + uint16_t key_length) +{ + struct ck_ht_entry *bucket, *cursor; + size_t offset, i, j; + CK_HT_TYPE probes = 0; + CK_HT_TYPE probe_maximum; + +#ifndef CK_HT_PP + CK_HT_TYPE d = 0; + CK_HT_TYPE d_prime = 0; +retry: +#endif + + probe_maximum = ck_ht_map_bound_get(map, h); + offset = h.value & map->mask; + + for (i = 0; i < map->probe_limit; i++) { + /* + * Probe on a complete cache line first. Scan forward and wrap around to + * the beginning of the cache line. Only when the complete cache line has + * been scanned do we move on to the next row. + */ + bucket = (void *)((uintptr_t)(map->entries + offset) & + ~(CK_MD_CACHELINE - 1)); + + for (j = 0; j < CK_HT_BUCKET_LENGTH; j++) { + uint16_t k; + + if (probes++ > probe_maximum) + return NULL; + + cursor = bucket + ((j + offset) & (CK_HT_BUCKET_LENGTH - 1)); + +#ifdef CK_HT_PP + snapshot->key = (uintptr_t)ck_pr_load_ptr(&cursor->key); + ck_pr_fence_load(); + snapshot->value = (uintptr_t)ck_pr_load_ptr(&cursor->value); +#else + d = CK_HT_TYPE_LOAD(&map->deletions); + snapshot->key = (uintptr_t)ck_pr_load_ptr(&cursor->key); + ck_pr_fence_load(); + snapshot->key_length = CK_HT_TYPE_LOAD(&cursor->key_length); + snapshot->hash = CK_HT_TYPE_LOAD(&cursor->hash); + snapshot->value = (uintptr_t)ck_pr_load_ptr(&cursor->value); +#endif + + /* + * It is probably worth it to encapsulate probe state + * in order to prevent a complete reprobe sequence in + * the case of intermittent writers. + */ + if (snapshot->key == CK_HT_KEY_TOMBSTONE) + continue; + + if (snapshot->key == CK_HT_KEY_EMPTY) + goto leave; + + if (snapshot->key == (uintptr_t)key) + goto leave; + + if (map->mode & CK_HT_MODE_BYTESTRING) { + void *pointer; + + /* + * Check memoized portion of hash value before + * expensive full-length comparison. + */ + k = ck_ht_entry_key_length(snapshot); + if (k != key_length) + continue; +#ifdef CK_HT_PP + if ((snapshot->value >> CK_MD_VMA_BITS) != ((h.value >> 32) & CK_HT_KEY_MASK)) + continue; +#else + if (snapshot->hash != h.value) + continue; + + d_prime = CK_HT_TYPE_LOAD(&map->deletions); + + /* + * It is possible that the slot was + * replaced, initiate a re-probe. + */ + if (d != d_prime) + goto retry; +#endif + + pointer = ck_ht_entry_key(snapshot); + if (memcmp(pointer, key, key_length) == 0) + goto leave; + } + } + + offset = ck_ht_map_probe_next(map, offset, h, probes); + } + + return NULL; + +leave: + return cursor; +} + +CK_HT_TYPE +ck_ht_count(struct ck_ht *table) +{ + struct ck_ht_map *map = ck_pr_load_ptr(&table->map); + + return CK_HT_TYPE_LOAD(&map->n_entries); +} + +bool +ck_ht_next(struct ck_ht *table, + struct ck_ht_iterator *i, + struct ck_ht_entry **entry) +{ + struct ck_ht_map *map = table->map; + uintptr_t key; + + if (i->offset >= map->capacity) + return false; + + do { + key = map->entries[i->offset].key; + if (key != CK_HT_KEY_EMPTY && key != CK_HT_KEY_TOMBSTONE) + break; + } while (++i->offset < map->capacity); + + if (i->offset >= map->capacity) + return false; + + *entry = map->entries + i->offset++; + return true; +} + +bool +ck_ht_reset_size_spmc(struct ck_ht *table, CK_HT_TYPE size) +{ + struct ck_ht_map *map, *update; + + map = table->map; + update = ck_ht_map_create(table, size); + if (update == NULL) + return false; + + ck_pr_store_ptr_unsafe(&table->map, update); + ck_ht_map_destroy(table->m, map, true); + return true; +} + +bool +ck_ht_reset_spmc(struct ck_ht *table) +{ + struct ck_ht_map *map = table->map; + + return ck_ht_reset_size_spmc(table, map->capacity); +} + +bool +ck_ht_grow_spmc(struct ck_ht *table, CK_HT_TYPE capacity) +{ + struct ck_ht_map *map, *update; + struct ck_ht_entry *bucket, *previous; + struct ck_ht_hash h; + size_t k, i, j, offset; + CK_HT_TYPE probes; + +restart: + map = table->map; + + if (map->capacity >= capacity) + return false; + + update = ck_ht_map_create(table, capacity); + if (update == NULL) + return false; + + for (k = 0; k < map->capacity; k++) { + previous = &map->entries[k]; + + if (previous->key == CK_HT_KEY_EMPTY || previous->key == CK_HT_KEY_TOMBSTONE) + continue; + + if (table->mode & CK_HT_MODE_BYTESTRING) { +#ifdef CK_HT_PP + void *key; + uint16_t key_length; + + key = ck_ht_entry_key(previous); + key_length = ck_ht_entry_key_length(previous); +#endif + +#ifndef CK_HT_PP + h.value = previous->hash; +#else + table->h(&h, key, key_length, table->seed); +#endif + } else { +#ifndef CK_HT_PP + h.value = previous->hash; +#else + table->h(&h, &previous->key, sizeof(previous->key), table->seed); +#endif + } + + offset = h.value & update->mask; + probes = 0; + + for (i = 0; i < update->probe_limit; i++) { + bucket = (void *)((uintptr_t)(update->entries + offset) & ~(CK_MD_CACHELINE - 1)); + + for (j = 0; j < CK_HT_BUCKET_LENGTH; j++) { + struct ck_ht_entry *cursor = bucket + ((j + offset) & (CK_HT_BUCKET_LENGTH - 1)); + + probes++; + if (CK_CC_LIKELY(cursor->key == CK_HT_KEY_EMPTY)) { + *cursor = *previous; + update->n_entries++; + ck_ht_map_bound_set(update, h, probes); + break; + } + } + + if (j < CK_HT_BUCKET_LENGTH) + break; + + offset = ck_ht_map_probe_next(update, offset, h, probes); + } + + if (i == update->probe_limit) { + /* + * We have hit the probe limit, the map needs to be even + * larger. + */ + ck_ht_map_destroy(table->m, update, false); + capacity <<= 1; + goto restart; + } + } + + ck_pr_fence_store(); + ck_pr_store_ptr_unsafe(&table->map, update); + ck_ht_map_destroy(table->m, map, true); + return true; +} + +bool +ck_ht_remove_spmc(struct ck_ht *table, + ck_ht_hash_t h, + ck_ht_entry_t *entry) +{ + struct ck_ht_map *map; + struct ck_ht_entry *candidate, snapshot; + + map = table->map; + + if (table->mode & CK_HT_MODE_BYTESTRING) { + candidate = ck_ht_map_probe_rd(map, h, &snapshot, + ck_ht_entry_key(entry), + ck_ht_entry_key_length(entry)); + } else { + candidate = ck_ht_map_probe_rd(map, h, &snapshot, + (void *)entry->key, + sizeof(entry->key)); + } + + /* No matching entry was found. */ + if (candidate == NULL || snapshot.key == CK_HT_KEY_EMPTY) + return false; + + *entry = snapshot; + + ck_pr_store_ptr_unsafe(&candidate->key, (void *)CK_HT_KEY_TOMBSTONE); + ck_pr_fence_store(); + CK_HT_TYPE_STORE(&map->n_entries, map->n_entries - 1); + return true; +} + +bool +ck_ht_get_spmc(struct ck_ht *table, + ck_ht_hash_t h, + ck_ht_entry_t *entry) +{ + struct ck_ht_entry *candidate, snapshot; + struct ck_ht_map *map; + CK_HT_TYPE d, d_prime; + +restart: + map = ck_pr_load_ptr(&table->map); + + /* + * Platforms that cannot read key and key_length atomically must reprobe + * on the scan of any single entry. + */ + d = CK_HT_TYPE_LOAD(&map->deletions); + + if (table->mode & CK_HT_MODE_BYTESTRING) { + candidate = ck_ht_map_probe_rd(map, h, &snapshot, + ck_ht_entry_key(entry), ck_ht_entry_key_length(entry)); + } else { + candidate = ck_ht_map_probe_rd(map, h, &snapshot, + (void *)entry->key, sizeof(entry->key)); + } + + d_prime = CK_HT_TYPE_LOAD(&map->deletions); + if (d != d_prime) { + /* + * It is possible we have read (K, V'). Only valid states are + * (K, V), (K', V') and (T, V). Restart load operation in face + * of concurrent deletions or replacements. + */ + goto restart; + } + + if (candidate == NULL || snapshot.key == CK_HT_KEY_EMPTY) + return false; + + *entry = snapshot; + return true; +} + +bool +ck_ht_set_spmc(struct ck_ht *table, + ck_ht_hash_t h, + ck_ht_entry_t *entry) +{ + struct ck_ht_entry snapshot, *candidate, *priority; + struct ck_ht_map *map; + CK_HT_TYPE probes, probes_wr; + bool empty = false; + + for (;;) { + map = table->map; + + if (table->mode & CK_HT_MODE_BYTESTRING) { + candidate = ck_ht_map_probe_wr(map, h, &snapshot, &priority, + ck_ht_entry_key(entry), + ck_ht_entry_key_length(entry), + &probes, &probes_wr); + } else { + candidate = ck_ht_map_probe_wr(map, h, &snapshot, &priority, + (void *)entry->key, + sizeof(entry->key), + &probes, &probes_wr); + } + + if (priority != NULL) { + probes = probes_wr; + break; + } + + if (candidate != NULL) + break; + + if (ck_ht_grow_spmc(table, map->capacity << 1) == false) + return false; + } + + if (candidate == NULL) { + candidate = priority; + empty = true; + } + + if (candidate->key != CK_HT_KEY_EMPTY && + priority != NULL && candidate != priority) { + /* + * Entry is moved into another position in probe sequence. + * We avoid a state of (K, B) (where [K, B] -> [K', B]) by + * guaranteeing a forced reprobe before transitioning from K to + * T. (K, B) implies (K, B, D') so we will reprobe successfully + * from this transient state. + */ + probes = probes_wr; + +#ifndef CK_HT_PP + CK_HT_TYPE_STORE(&priority->key_length, entry->key_length); + CK_HT_TYPE_STORE(&priority->hash, entry->hash); +#endif + + /* + * Readers must observe version counter change before they + * observe re-use. If they observe re-use, it is at most + * a tombstone. + */ + if (priority->value == CK_HT_KEY_TOMBSTONE) { + CK_HT_TYPE_STORE(&map->deletions, map->deletions + 1); + ck_pr_fence_store(); + } + + ck_pr_store_ptr_unsafe(&priority->value, (void *)entry->value); + ck_pr_fence_store(); + ck_pr_store_ptr_unsafe(&priority->key, (void *)entry->key); + ck_pr_fence_store(); + + /* + * Make sure that readers who observe the tombstone would + * also observe counter change. + */ + CK_HT_TYPE_STORE(&map->deletions, map->deletions + 1); + ck_pr_fence_store(); + + ck_pr_store_ptr_unsafe(&candidate->key, (void *)CK_HT_KEY_TOMBSTONE); + ck_pr_fence_store(); + } else { + /* + * In this case we are inserting a new entry or replacing + * an existing entry. Yes, this can be combined into above branch, + * but isn't because you are actually looking at dying code + * (ck_ht is effectively deprecated and is being replaced soon). + */ + bool replace = candidate->key != CK_HT_KEY_EMPTY && + candidate->key != CK_HT_KEY_TOMBSTONE; + + if (priority != NULL) { + if (priority->key == CK_HT_KEY_TOMBSTONE) { + CK_HT_TYPE_STORE(&map->deletions, map->deletions + 1); + ck_pr_fence_store(); + } + + candidate = priority; + probes = probes_wr; + } + +#ifdef CK_HT_PP + ck_pr_store_ptr_unsafe(&candidate->value, (void *)entry->value); + ck_pr_fence_store(); + ck_pr_store_ptr_unsafe(&candidate->key, (void *)entry->key); +#else + CK_HT_TYPE_STORE(&candidate->key_length, entry->key_length); + CK_HT_TYPE_STORE(&candidate->hash, entry->hash); + ck_pr_store_ptr_unsafe(&candidate->value, (void *)entry->value); + ck_pr_fence_store(); + ck_pr_store_ptr_unsafe(&candidate->key, (void *)entry->key); +#endif + + /* + * If we are insert a new entry then increment number + * of entries associated with map. + */ + if (replace == false) + CK_HT_TYPE_STORE(&map->n_entries, map->n_entries + 1); + } + + ck_ht_map_bound_set(map, h, probes); + + /* Enforce a load factor of 0.5. */ + if (map->n_entries * 2 > map->capacity) + ck_ht_grow_spmc(table, map->capacity << 1); + + if (empty == true) { + entry->key = CK_HT_KEY_EMPTY; + } else { + *entry = snapshot; + } + + return true; +} + +bool +ck_ht_put_spmc(struct ck_ht *table, + ck_ht_hash_t h, + ck_ht_entry_t *entry) +{ + struct ck_ht_entry snapshot, *candidate, *priority; + struct ck_ht_map *map; + CK_HT_TYPE probes, probes_wr; + + for (;;) { + map = table->map; + + if (table->mode & CK_HT_MODE_BYTESTRING) { + candidate = ck_ht_map_probe_wr(map, h, &snapshot, &priority, + ck_ht_entry_key(entry), + ck_ht_entry_key_length(entry), + &probes, &probes_wr); + } else { + candidate = ck_ht_map_probe_wr(map, h, &snapshot, &priority, + (void *)entry->key, + sizeof(entry->key), + &probes, &probes_wr); + } + + if (candidate != NULL || priority != NULL) + break; + + if (ck_ht_grow_spmc(table, map->capacity << 1) == false) + return false; + } + + if (priority != NULL) { + /* Version counter is updated before re-use. */ + CK_HT_TYPE_STORE(&map->deletions, map->deletions + 1); + ck_pr_fence_store(); + + /* Re-use tombstone if one was found. */ + candidate = priority; + probes = probes_wr; + } else if (candidate->key != CK_HT_KEY_EMPTY && + candidate->key != CK_HT_KEY_TOMBSTONE) { + /* + * If the snapshot key is non-empty and the value field is not + * a tombstone then an identical key was found. As store does + * not implement replacement, we will fail. + */ + return false; + } + + ck_ht_map_bound_set(map, h, probes); + +#ifdef CK_HT_PP + ck_pr_store_ptr_unsafe(&candidate->value, (void *)entry->value); + ck_pr_fence_store(); + ck_pr_store_ptr_unsafe(&candidate->key, (void *)entry->key); +#else + CK_HT_TYPE_STORE(&candidate->key_length, entry->key_length); + CK_HT_TYPE_STORE(&candidate->hash, entry->hash); + ck_pr_store_ptr_unsafe(&candidate->value, (void *)entry->value); + ck_pr_fence_store(); + ck_pr_store_ptr_unsafe(&candidate->key, (void *)entry->key); +#endif + + CK_HT_TYPE_STORE(&map->n_entries, map->n_entries + 1); + + /* Enforce a load factor of 0.5. */ + if (map->n_entries * 2 > map->capacity) + ck_ht_grow_spmc(table, map->capacity << 1); + + return true; +} + +void +ck_ht_destroy(struct ck_ht *table) +{ + + ck_ht_map_destroy(table->m, table->map, false); + return; +} |