* Note: This is code uses synchronous atomic operations because that is all that x86 provides.
* Every atomic operation is also an implicit full memory barrier. The upshot is that it simplifies
* the code a bit, but it won't be as fast as it could be on platforms that provide weaker
- * operations like and unfenced CAS which would still do the job.
+ * operations like unfenced CAS which would still do the job.
+ *
+ * 11FebO9 - Bug fix in ht_iter_next() from Rui Ueyama
*/
#include <stdio.h>
volatile entry_t *table;
hashtable_t *ht; // parent ht;
struct hti *next;
+#ifdef USE_SYSTEM_MALLOC
+ void *unaligned_table_ptr; // system malloc doesn't guarentee cache-line alignment
+#endif
unsigned scale;
int max_probe;
int ref_count;
const datatype_t *key_type;
};
-static const map_val_t COPIED_VALUE = TAG_VALUE(DOES_NOT_EXIST, TAG1);
-static const map_val_t TOMBSTONE = STRIP_TAG(-1, TAG1);
+static const map_val_t COPIED_VALUE = TAG_VALUE(DOES_NOT_EXIST, TAG1);
+static const map_val_t TOMBSTONE = STRIP_TAG(-1, TAG1);
static const unsigned ENTRIES_PER_BUCKET = CACHE_LINE_SIZE/sizeof(entry_t);
static const unsigned ENTRIES_PER_COPY_CHUNK = CACHE_LINE_SIZE/sizeof(entry_t)*2;
map_key_t ent_key = ent->key;
if (ent_key == DOES_NOT_EXIST) {
TRACE("h1", "hti_lookup: entry %p for key %p is empty", ent,
- (hti->ht->key_type == NULL) ? (void *)ent_key : GET_PTR(ent_key));
+ (hti->ht->key_type == NULL) ? (void *)key : GET_PTR(key));
*is_empty = 1; // indicate an empty so the caller avoids an expensive key compare
return ent;
}
static hti_t *hti_alloc (hashtable_t *parent, int scale) {
hti_t *hti = (hti_t *)nbd_malloc(sizeof(hti_t));
memset(hti, 0, sizeof(hti_t));
-
- size_t sz = sizeof(entry_t) * (1 << scale);
- entry_t *table = nbd_malloc(sz);
- memset(table, 0, sz);
- hti->table = table;
-
hti->scale = scale;
+ size_t sz = sizeof(entry_t) * (1ULL << scale);
+#ifdef USE_SYSTEM_MALLOC
+ hti->unaligned_table_ptr = nbd_malloc(sz + CACHE_LINE_SIZE - 1);
+ hti->table = (void *)(((size_t)hti->unaligned_table_ptr + CACHE_LINE_SIZE - 1) & ~(CACHE_LINE_SIZE - 1));
+#else
+ hti->table = nbd_malloc(sz);
+#endif
+ memset((void *)hti->table, 0, sz);
+
// When searching for a key probe a maximum of 1/4 of the buckets up to 1000 buckets.
- hti->max_probe = ((1 << (hti->scale - 2)) / ENTRIES_PER_BUCKET) + 4;
+ hti->max_probe = ((1ULL << (hti->scale - 2)) / ENTRIES_PER_BUCKET) + 4;
if (hti->max_probe > MAX_BUCKETS_TO_PROBE) {
hti->max_probe = MAX_BUCKETS_TO_PROBE;
}
// heuristics to determine the size of the new table
size_t count = ht_count(hti->ht);
unsigned int new_scale = hti->scale;
- new_scale += (count > (1 << (new_scale - 2))); // double size if more than 1/4 full
- new_scale += (count > (1 << (new_scale - 2))); // double size again if more than 1/2 full
+ new_scale += (count > (1ULL << (new_scale - 2))); // double size if more than 1/4 full
+ new_scale += (count > (1ULL << (new_scale - 2))); // double size again if more than 1/2 full
// Allocate the new table and attempt to install it.
hti_t *next = hti_alloc(hti->ht, new_scale);
if (old_next != NULL) {
// Another thread beat us to it.
TRACE("h0", "hti_start_copy: lost race to install new hti; found %p", old_next, 0);
- nbd_free(next);
+#ifdef USE_SYSTEM_MALLOC
+ nbd_free(next->unaligned_table_ptr);
+#else
+ nbd_free((void *)next->table);
+#endif
return;
}
TRACE("h0", "hti_start_copy: new hti %p scale %llu", next, next->scale);
assert(ht1);
assert(ht1->next);
assert(ht2);
- assert(ht1_ent >= ht1->table && ht1_ent < ht1->table + (1 << ht1->scale));
+ assert(ht1_ent >= ht1->table && ht1_ent < ht1->table + (1ULL << ht1->scale));
#ifndef NBD32
assert(key_hash == 0 || ht1->ht->key_type == NULL || (key_hash >> 16) == (ht1_ent->key >> 48));
#endif
// We use 0 to indicate that <key_hash> is uninitiallized. Occasionally the key's hash will really be 0 and we
// waste time recomputing it every time. It is rare enough that it won't hurt performance.
if (key_hash == 0) {
- key_hash = (ht1->ht->key_type == NULL)
- ? murmur32_8b(ht1_ent_key)
- : ht1->ht->key_type->hash((void *)key);
+#ifdef NBD32
+ key_hash = (ht1->ht->key_type == NULL) ? murmur32_4b(ht1_ent_key) : ht1->ht->key_type->hash((void *)key);
+#else
+ key_hash = (ht1->ht->key_type == NULL) ? murmur32_8b(ht1_ent_key) : ht1->ht->key_type->hash((void *)key);
+#endif
}
int ht2_ent_is_empty;
// Update the count if we were the one that completed the copy.
if (old_ht2_ent_val == DOES_NOT_EXIST) {
TRACE("h0", "hti_copy_entry: key %p value %p copied to new entry", key, ht1_ent_val);
- SYNC_ADD(&ht1->count, -1);
- SYNC_ADD(&ht2->count, 1);
+ (void)SYNC_ADD(&ht1->count, -1);
+ (void)SYNC_ADD(&ht2->count, 1);
return TRUE;
}
map_val_t ent_val = ent->val;
if (EXPECT_FALSE(IS_TAGGED(ent_val, TAG1))) {
if (ent_val != COPIED_VALUE && ent_val != TAG_VALUE(TOMBSTONE, TAG1)) {
- int did_copy = hti_copy_entry(hti, ent, key_hash, ((volatile hti_t *)hti)->next);
+ int did_copy = hti_copy_entry(hti, ent, key_hash, VOLATILE_DEREF(hti).next);
if (did_copy) {
- SYNC_ADD(&hti->num_entries_copied, 1);
+ (void)SYNC_ADD(&hti->num_entries_copied, 1);
}
TRACE("h0", "hti_cas: value in the middle of a copy, copy completed by %s",
(did_copy ? "self" : "other"), 0);
// The set succeeded. Adjust the value count.
if (old_existed && new == DOES_NOT_EXIST) {
- SYNC_ADD(&hti->count, -1);
+ (void)SYNC_ADD(&hti->count, -1);
} else if (!old_existed && new != DOES_NOT_EXIST) {
- SYNC_ADD(&hti->count, 1);
+ (void)SYNC_ADD(&hti->count, 1);
}
// Return the previous value.
// searching the table. In that case, if a copy is in progress the key
// might exist in the copy.
if (EXPECT_FALSE(ent == NULL)) {
- if (((volatile hti_t *)hti)->next != NULL)
+ if (VOLATILE_DEREF(hti).next != NULL)
return hti_get(hti->next, key, key_hash); // recursive tail-call
return DOES_NOT_EXIST;
}
map_val_t ent_val = ent->val;
if (EXPECT_FALSE(IS_TAGGED(ent_val, TAG1))) {
if (EXPECT_FALSE(ent_val != COPIED_VALUE && ent_val != TAG_VALUE(TOMBSTONE, TAG1))) {
- int did_copy = hti_copy_entry(hti, ent, key_hash, ((volatile hti_t *)hti)->next);
+ int did_copy = hti_copy_entry(hti, ent, key_hash, VOLATILE_DEREF(hti).next);
if (did_copy) {
- SYNC_ADD(&hti->num_entries_copied, 1);
+ (void)SYNC_ADD(&hti->num_entries_copied, 1);
}
}
- return hti_get(((volatile hti_t *)hti)->next, key, key_hash); // tail-call
+ return hti_get(VOLATILE_DEREF(hti).next, key, key_hash); // tail-call
}
return (ent_val == TOMBSTONE) ? DOES_NOT_EXIST : ent_val;
//
map_val_t ht_get (hashtable_t *ht, map_key_t key) {
+#ifdef NBD32
+ uint32_t hash = (ht->key_type == NULL) ? murmur32_4b((uint64_t)key) : ht->key_type->hash((void *)key);
+#else
uint32_t hash = (ht->key_type == NULL) ? murmur32_8b((uint64_t)key) : ht->key_type->hash((void *)key);
+#endif
return hti_get(ht->hti, key, hash);
}
size_t x = hti->copy_scan;
TRACE("h1", "ht_cas: help copy. scan is %llu, size is %llu", x, 1<<hti->scale);
- if (total_copied != (1 << hti->scale)) {
+ if (total_copied != (1ULL << hti->scale)) {
// Panic if we've been around the array twice and still haven't finished the copy.
- int panic = (x >= (1 << (hti->scale + 1)));
+ int panic = (x >= (1ULL << (hti->scale + 1)));
if (!panic) {
limit = ENTRIES_PER_COPY_CHUNK;
TRACE("h1", "ht_cas: help copy panic", 0, 0);
// scan the whole table
ent = hti->table;
- limit = (1 << hti->scale);
+ limit = (1ULL << hti->scale);
}
// Copy the entries
for (int i = 0; i < limit; ++i) {
num_copied += hti_copy_entry(hti, ent++, 0, hti->next);
- assert(ent <= hti->table + (1 << hti->scale));
+ assert(ent <= hti->table + (1ULL << hti->scale));
}
if (num_copied != 0) {
total_copied = SYNC_ADD(&hti->num_entries_copied, num_copied);
}
}
- return (total_copied == (1 << hti->scale));
+ return (total_copied == (1ULL << hti->scale));
}
static void hti_defer_free (hti_t *hti) {
assert(hti->ref_count == 0);
- for (uint32_t i = 0; i < (1 << hti->scale); ++i) {
+ for (uint32_t i = 0; i < (1ULL << hti->scale); ++i) {
map_key_t key = hti->table[i].key;
map_val_t val = hti->table[i].val;
if (val == COPIED_VALUE)
rcu_defer_free(GET_PTR(key));
}
}
+#ifdef USE_SYSTEM_MALLOC
+ rcu_defer_free(hti->unaligned_table_ptr);
+#else
rcu_defer_free((void *)hti->table);
+#endif
rcu_defer_free(hti);
}
}
map_val_t old_val;
+#ifdef NBD32
+ uint32_t key_hash = (ht->key_type == NULL) ? murmur32_4b((uint64_t)key) : ht->key_type->hash((void *)key);
+#else
uint32_t key_hash = (ht->key_type == NULL) ? murmur32_8b((uint64_t)key) : ht->key_type->hash((void *)key);
+#endif
while ((old_val = hti_cas(hti, key, key_hash, expected_val, new_val)) == COPIED_VALUE) {
assert(hti->next);
hti = hti->next;
map_val_t ht_remove (hashtable_t *ht, map_key_t key) {
hti_t *hti = ht->hti;
map_val_t val;
+#ifdef NBD32
+ uint32_t key_hash = (ht->key_type == NULL) ? murmur32_4b((uint64_t)key) : ht->key_type->hash((void *)key);
+#else
uint32_t key_hash = (ht->key_type == NULL) ? murmur32_8b((uint64_t)key) : ht->key_type->hash((void *)key);
+#endif
do {
val = hti_cas(hti, key, key_hash, CAS_EXPECT_WHATEVER, DOES_NOT_EXIST);
if (val != COPIED_VALUE)
hti_t *hti = ht->hti;
while (hti) {
printf("hti:%p scale:%u count:%d copied:%d\n", hti, hti->scale, hti->count, hti->num_entries_copied);
- for (int i = 0; i < (1 << hti->scale); ++i) {
+ for (int i = 0; i < (1ULL << hti->scale); ++i) {
volatile entry_t *ent = hti->table + i;
printf("[0x%x] 0x%llx:0x%llx\n", i, (uint64_t)ent->key, (uint64_t)ent->val);
if (i > 30) {
volatile entry_t *ent;
map_key_t key;
map_val_t val;
- size_t table_size = (1 << iter->hti->scale);
+ size_t table_size = (1ULL << iter->hti->scale);
do {
iter->idx++;
if (iter->idx == table_size) {
} while (key == DOES_NOT_EXIST || val == DOES_NOT_EXIST || val == TOMBSTONE);
- if (key_ptr) {
- *key_ptr = key;
- }
if (val == COPIED_VALUE) {
- uint32_t hash = (iter->hti->ht->key_type == NULL)
- ? murmur32_8b((uint64_t)key)
- : iter->hti->ht->key_type->hash((void *)key);
+ const datatype_t *key_type = iter->hti->ht->key_type;
+#ifdef NBD32
+ uint32_t hash = (key_type == NULL) ? murmur32_4b((uint64_t)key) : key_type->hash((void *)key);
+#else
+ uint32_t hash = (key_type == NULL) ? murmur32_8b((uint64_t)key) : key_type->hash((void *)key);
+#endif
val = hti_get(iter->hti->next, (map_key_t)ent->key, hash);
+
+ // Go to the next entry if key is already deleted.
+ if (val == DOES_NOT_EXIST)
+ return ht_iter_next(iter, key_ptr); // recursive tail-call
}
+ if (key_ptr) {
+ *key_ptr = key;
+ }
return val;
}
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