X-Git-Url: https://pd.if.org/git/?p=nbds;a=blobdiff_plain;f=map%2Flist.c;h=0d9c11f24f275254c238e9a538f5e8332b3b2729;hp=a0f52a57d573a7efb7ce74f32987ce22657a0d8e;hb=a03cf3b0c40e6c3b8b4877b49a64288cb3fcb919;hpb=025017478bb385da88a6b185849c8bcffeb2e2aa diff --git a/map/list.c b/map/list.c index a0f52a5..0d9c11f 100644 --- a/map/list.c +++ b/map/list.c @@ -5,73 +5,108 @@ * Harris-Michael lock-free list-based set * http://www.research.ibm.com/people/m/michael/spaa-2002.pdf */ + #include #include #include "common.h" -#include "mlocal.h" -#include "nstring.h" +#include "list.h" #include "mem.h" +#ifdef LIST_USE_HAZARD_POINTER +#include "hazard.h" +#else +#include "rcu.h" +#endif typedef struct node { - nstring_t *key; - uint64_t val; - struct node *next; + map_key_t key; + map_val_t val; + markable_t next; // next node } node_t; +struct ll_iter { + node_t *pred; +}; + struct ll { node_t *head; + const datatype_t *key_type; }; -static node_t *node_alloc (const void *key_data, uint32_t key_len, uint64_t val) { +// Marking the field of a node logically removes it from the list +#define MARK_NODE(x) TAG_VALUE((markable_t)(x), TAG1) +#define HAS_MARK(x) (IS_TAGGED((x), TAG1) == TAG1) +#define GET_NODE(x) ((node_t *)(x)) +#define STRIP_MARK(x) ((node_t *)STRIP_TAG((x), TAG1)) + +static node_t *node_alloc (map_key_t key, map_val_t val) { node_t *item = (node_t *)nbd_malloc(sizeof(node_t)); - memset(item, 0, sizeof(node_t)); - // If is -1 it indicates is an integer and not a pointer - item->key = (key_len == (unsigned)-1) - ? (void *)TAG_VALUE(key_data) - : ns_alloc(key_data, key_len); + item->key = key; item->val = val; return item; } -static void node_free (node_t *item) { - if (!IS_TAGGED(item->key)) { - nbd_free(item->key); - } - nbd_free(item); +list_t *ll_alloc (const datatype_t *key_type) { + list_t *ll = (list_t *)nbd_malloc(sizeof(list_t)); + ll->key_type = key_type; + ll->head = node_alloc(0, 0); + ll->head->next = DOES_NOT_EXIST; + return ll; } -static void node_defer_free (node_t *item) { - if (!IS_TAGGED(item->key)) { - nbd_defer_free(item->key); +void ll_free (list_t *ll) { + node_t *item = STRIP_MARK(ll->head->next); + while (item != NULL) { + node_t *next = STRIP_MARK(item->next); + if (ll->key_type != NULL) { + nbd_free((void *)item->key); + } + nbd_free(item); + item = next; } - nbd_defer_free(item); } -list_t *ll_alloc (void) { - list_t *ll = (list_t *)nbd_malloc(sizeof(list_t)); - ll->head = node_alloc(" ", 0, 0); - ll->head->next = NULL; - return ll; +size_t ll_count (list_t *ll) { + size_t count = 0; + node_t *item = STRIP_MARK(ll->head->next); + while (item) { + if (!HAS_MARK(item->next)) { + count++; + } + item = STRIP_MARK(item->next); + } + return count; } -void ll_free (list_t *ll) { +#ifdef LIST_USE_HAZARD_POINTER +static void nbd_free_node (node_t *x) { + nbd_free((void *)x->key); + nbd_free(x); } +#endif -static int find_pred (node_t **pred_ptr, node_t **item_ptr, list_t *ll, const void *key_data, uint32_t key_len, int help_remove) { +static int find_pred (node_t **pred_ptr, node_t **item_ptr, list_t *ll, map_key_t key, int help_remove) { node_t *pred = ll->head; - node_t *item = pred->next; - TRACE("l2", "find_pred: searching for key %p in ll (head is %p)", key_data, pred); + node_t *item = GET_NODE(pred->next); + TRACE("l2", "find_pred: searching for key %p in list (head is %p)", key, pred); +#ifdef LIST_USE_HAZARD_POINTER + haz_t *temp, *hp0 = haz_get_static(0), *hp1 = haz_get_static(1); +#endif while (item != NULL) { - node_t *next = item->next; +#ifdef LIST_USE_HAZARD_POINTER + haz_set(hp0, item); + if (STRIP_MARK(pred->next) != item) + return find_pred(pred_ptr, item_ptr, ll, key, help_remove); // retry +#endif + markable_t next = item->next; - // A tag means an item is logically removed but not physically unlinked yet. - while (EXPECT_FALSE(IS_TAGGED(next))) { + // A mark means the node is logically removed but not physically unlinked yet. + while (EXPECT_FALSE(HAS_MARK(next))) { // Skip over logically removed items. if (!help_remove) { - item = (node_t *)STRIP_TAG(item->next); + item = STRIP_MARK(item->next); if (EXPECT_FALSE(item == NULL)) break; TRACE("l3", "find_pred: skipping marked item %p (next is %p)", item, next); @@ -80,27 +115,32 @@ static int find_pred (node_t **pred_ptr, node_t **item_ptr, list_t *ll, const vo } // Unlink logically removed items. - node_t *other; TRACE("l3", "find_pred: unlinking marked item %p next is %p", item, next); - if ((other = SYNC_CAS(&pred->next, item, STRIP_TAG(next))) == item) { + + markable_t other = SYNC_CAS(&pred->next, item, STRIP_MARK(next)); + if (other == (markable_t)item) { TRACE("l2", "find_pred: unlinked item %p from pred %p", item, pred); - item = (node_t *)STRIP_TAG(next); - if (EXPECT_FALSE(item == NULL)) - break; - next = item->next; + item = STRIP_MARK(next); + next = (item != NULL) ? item->next : DOES_NOT_EXIST; TRACE("l3", "find_pred: now current item is %p next is %p", item, next); // The thread that completes the unlink should free the memory. - node_defer_free(other); +#ifdef LIST_USE_HAZARD_POINTER + free_t free_ = (ll->key_type != NULL ? (free_t)nbd_free_node : nbd_free); + haz_defer_free(GET_NODE(other), free_); +#else + if (ll->key_type != NULL) { + rcu_defer_free((void *)GET_NODE(other)->key); + } + rcu_defer_free(GET_NODE(other)); +#endif } else { TRACE("l2", "find_pred: lost a race to unlink item %p from pred %p", item, pred); TRACE("l2", "find_pred: pred's link changed to %p", other, 0); - if (IS_TAGGED(other)) - return find_pred(pred_ptr, item_ptr, ll, key_data, key_len, help_remove); // retry - item = other; - if (EXPECT_FALSE(item == NULL)) - break; - next = item->next; + if (HAS_MARK(other)) + return find_pred(pred_ptr, item_ptr, ll, key, help_remove); // retry + item = GET_NODE(other); + next = (item != NULL) ? item->next : DOES_NOT_EXIST; } } @@ -108,17 +148,13 @@ static int find_pred (node_t **pred_ptr, node_t **item_ptr, list_t *ll, const vo break; TRACE("l3", "find_pred: visiting item %p (next is %p)", item, next); - TRACE("l4", "find_pred: key %p val %p", STRIP_TAG(item->key), item->val); + TRACE("l4", "find_pred: key %p val %p", item->key, item->val); - // A tagged key is an integer, otherwise it is a pointer to a string int d; - if (IS_TAGGED(item->key)) { - d = (STRIP_TAG(item->key) - (uint64_t)key_data); + if (EXPECT_TRUE(ll->key_type == NULL)) { + d = item->key - key; } else { - int item_key_len = item->key->len; - int len = (key_len < item_key_len) ? key_len : item_key_len; - d = memcmp(item->key->data, key_data, len); - if (d == 0) { d = item_key_len - key_len; } + d = ll->key_type->cmp((void *)item->key, (void *)key); } // If we reached the key (or passed where it should be), we found the right predesssor @@ -126,17 +162,22 @@ static int find_pred (node_t **pred_ptr, node_t **item_ptr, list_t *ll, const vo if (pred_ptr != NULL) { *pred_ptr = pred; } - *item_ptr = item; + if (item_ptr != NULL) { + *item_ptr = item; + } if (d == 0) { TRACE("l2", "find_pred: found matching item %p in list, pred is %p", item, pred); return TRUE; } - TRACE("l2", "find_pred: found proper place for key %p in list, pred is %p", key_data, pred); + TRACE("l2", "find_pred: found proper place for key %p in list, pred is %p", key, pred); return FALSE; } pred = item; - item = next; +#ifdef LIST_USE_HAZARD_POINTER + temp = hp0; hp0 = hp1; hp1 = temp; +#endif + item = GET_NODE(next); } // is not in . @@ -149,14 +190,14 @@ static int find_pred (node_t **pred_ptr, node_t **item_ptr, list_t *ll, const vo } // Fast find. Do not help unlink partially removed nodes and do not return the found item's predecessor. -uint64_t ll_lookup (list_t *ll, const void *key_data, uint32_t key_len) { - TRACE("l1", "ll_lookup: searching for key %p in list %p", key_data, ll); +map_val_t ll_lookup (list_t *ll, map_key_t key) { + TRACE("l1", "ll_lookup: searching for key %p in list %p", key, ll); node_t *item; - int found = find_pred(NULL, &item, ll, key_data, key_len, FALSE); + int found = find_pred(NULL, &item, ll, key, FALSE); // If we found an matching the key return its value. if (found) { - uint64_t val = item->val; + map_val_t val = item->val; if (val != DOES_NOT_EXIST) { TRACE("l1", "ll_lookup: found item %p. val %p. returning item", item, item->val); return val; @@ -167,28 +208,28 @@ uint64_t ll_lookup (list_t *ll, const void *key_data, uint32_t key_len) { return DOES_NOT_EXIST; } -uint64_t ll_cas (list_t *ll, const void *key_data, uint32_t key_len, uint64_t expectation, uint64_t new_val) { - TRACE("l1", "ll_cas: key %p list %p", key_data, ll); +map_val_t ll_cas (list_t *ll, map_key_t key, map_val_t expectation, map_val_t new_val) { + TRACE("l1", "ll_cas: key %p list %p", key, ll); TRACE("l1", "ll_cas: expectation %p new value %p", expectation, new_val); ASSERT((int64_t)new_val > 0); do { node_t *pred, *old_item; - if (!find_pred(&pred, &old_item, ll, key_data, key_len, TRUE)) { + int found = find_pred(&pred, &old_item, ll, key, TRUE); + if (!found) { // There was not an item in the list that matches the key. - if (EXPECT_FALSE((int64_t)expectation > 0 || expectation == CAS_EXPECT_EXISTS)) { + if (EXPECT_FALSE(expectation != CAS_EXPECT_DOES_NOT_EXIST && expectation != CAS_EXPECT_WHATEVER)) { TRACE("l1", "ll_cas: the expectation was not met, the list was not changed", 0, 0); return DOES_NOT_EXIST; // failure } - ASSERT(expectation == CAS_EXPECT_DOES_NOT_EXIST || expectation == CAS_EXPECT_WHATEVER); - // Create a new item and insert it into the list. TRACE("l2", "ll_cas: attempting to insert item between %p and %p", pred, pred->next); - node_t *new_item = node_alloc(key_data, key_len, new_val); - node_t *next = new_item->next = old_item; - node_t *other = SYNC_CAS(&pred->next, next, new_item); + map_key_t new_key = ll->key_type == NULL ? key : (map_key_t)ll->key_type->clone((void *)key); + node_t *new_item = node_alloc(new_key, new_val); + markable_t next = new_item->next = (markable_t)old_item; + markable_t other = SYNC_CAS(&pred->next, next, new_item); if (other == next) { TRACE("l1", "ll_cas: successfully inserted new item %p", new_item, 0); return DOES_NOT_EXIST; // success @@ -196,12 +237,15 @@ uint64_t ll_cas (list_t *ll, const void *key_data, uint32_t key_len, uint64_t ex // Lost a race. Failed to insert the new item into the list. TRACE("l1", "ll_cas: lost a race. CAS failed. expected pred's link to be %p but found %p", next, other); - node_free(new_item); + if (ll->key_type != NULL) { + nbd_free((void *)new_key); + } + nbd_free(new_item); continue; // retry } // Found an item in the list that matches the key. - uint64_t old_item_val = old_item->val; + map_val_t old_item_val = old_item->val; do { // If the item's value is DOES_NOT_EXIST it means another thread removed the node out from under us. if (EXPECT_FALSE(old_item_val == DOES_NOT_EXIST)) { @@ -219,7 +263,7 @@ uint64_t ll_cas (list_t *ll, const void *key_data, uint32_t key_len, uint64_t ex // replace DOES_NOT_EXIST with our value. Then another thread that is updating the value could think it // succeeded and return our value even though we indicated that the node has been removed. If the CAS // fails it means another thread either removed the node or updated its value. - uint64_t ret_val = SYNC_CAS(&old_item->val, old_item_val, new_val); + map_val_t ret_val = SYNC_CAS(&old_item->val, old_item_val, new_val); if (ret_val == old_item_val) { TRACE("l1", "ll_cas: the CAS succeeded. updated the value of the item", 0, 0); return ret_val; // success @@ -231,67 +275,123 @@ uint64_t ll_cas (list_t *ll, const void *key_data, uint32_t key_len, uint64_t ex } while (1); } -uint64_t ll_remove (list_t *ll, const void *key_data, uint32_t key_len) { - TRACE("l1", "ll_remove: removing item with key %p from list %p", key_data, ll); +map_val_t ll_remove (list_t *ll, map_key_t key) { + TRACE("l1", "ll_remove: removing item with key %p from list %p", key, ll); node_t *pred; node_t *item; - int found = find_pred(&pred, &item, ll, key_data, key_len, TRUE); + int found = find_pred(&pred, &item, ll, key, TRUE); if (!found) { TRACE("l1", "ll_remove: remove failed, an item with a matching key does not exist in the list", 0, 0); return DOES_NOT_EXIST; } - // Mark removed. This must be atomic. If multiple threads try to remove the same item - // only one of them should succeed. - node_t *next; - node_t *old_next = item->next; + // Mark removed. If multiple threads try to remove the same item only one of them should succeed. + markable_t next; + markable_t old_next = item->next; do { - next = old_next; - old_next = SYNC_CAS(&item->next, next, TAG_VALUE(next)); - if (IS_TAGGED(old_next)) { + next = old_next; + old_next = SYNC_CAS(&item->next, next, MARK_NODE(STRIP_MARK(next))); + if (HAS_MARK(old_next)) { TRACE("l1", "ll_remove: lost a race -- %p is already marked for removal by another thread", item, 0); return DOES_NOT_EXIST; } } while (next != old_next); TRACE("l2", "ll_remove: logically removed item %p", item, 0); - ASSERT(IS_TAGGED(item->next)); + ASSERT(HAS_MARK(((volatile node_t *)item)->next)); - // This has to be an atomic swap in case another thread is updating the item while we are removing it. - uint64_t val = SYNC_SWAP(&item->val, DOES_NOT_EXIST); + // Atomically swap out the item's value in case another thread is updating the item while we are + // removing it. This establishes which operation occurs first logically, the update or the remove. + map_val_t val = SYNC_SWAP(&item->val, DOES_NOT_EXIST); TRACE("l2", "ll_remove: replaced item's val %p with DOES_NOT_EXIT", val, 0); // Unlink from . If we lose a race to another thread just back off. It is safe to leave the // item logically removed for a later call (or some other thread) to physically unlink. By marking the // item earlier, we logically removed it. TRACE("l2", "ll_remove: unlink the item by linking its pred %p to its successor %p", pred, next); - node_t *other; - if ((other = SYNC_CAS(&pred->next, item, next)) != item) { + markable_t other; + if ((other = SYNC_CAS(&pred->next, item, next)) != (markable_t)item) { TRACE("l1", "ll_remove: unlink failed; pred's link changed from %p to %p", item, other); return val; } // The thread that completes the unlink should free the memory. - node_defer_free(item); +#ifdef LIST_USE_HAZARD_POINTER + free_t free_ = (ll->key_type != NULL ? (free_t)nbd_free_node : nbd_free); + haz_defer_free(GET_NODE(item), free_); +#else + if (ll->key_type != NULL) { + rcu_defer_free((void *)item->key); + } + rcu_defer_free(item); +#endif TRACE("l1", "ll_remove: successfully unlinked item %p from the list", item, 0); return val; } void ll_print (list_t *ll) { - node_t *item; - item = ll->head->next; - while (item) { - node_t *next = item->next; - if (IS_TAGGED(item)) { - printf("*"); - } - printf("%p:", item); - if (IS_TAGGED(item->key)) { - printf("0x%llx ", STRIP_TAG(item->key)); - } else { - printf("%s ", (char *)item->key->data); - } + markable_t next = ll->head->next; + int i = 0; + while (next != DOES_NOT_EXIST) { + node_t *item = STRIP_MARK(next); + if (item == NULL) + break; + printf("%s%p:0x%llx ", HAS_MARK(item->next) ? "*" : "", item, (uint64_t)item->key); fflush(stdout); - item = (node_t *)STRIP_TAG(next); + if (i++ > 30) { + printf("..."); + break; + } + next = item->next; } printf("\n"); } + +ll_iter_t *ll_iter_begin (list_t *ll, map_key_t key) { + ll_iter_t *iter = (ll_iter_t *)nbd_malloc(sizeof(ll_iter_t)); + if (key != DOES_NOT_EXIST) { + find_pred(&iter->pred, NULL, ll, key, FALSE); + } else { + iter->pred = ll->head; + } +#ifdef LIST_USE_HAZARD_POINTER + haz_register_dynamic((void **)&iter->pred); +#endif + return iter; +} + +map_val_t ll_iter_next (ll_iter_t *iter, map_key_t *key_ptr) { + assert(iter); + if (iter->pred == NULL) + return DOES_NOT_EXIST; + + // advance iterator to next item; skip items that have been removed + markable_t item; +#ifdef LIST_USE_HAZARD_POINTER + haz_t *hp0 = haz_get_static(0); +#endif + do { +#ifndef LIST_USE_HAZARD_POINTER + item = iter->pred->next; +#else //LIST_USE_HAZARD_POINTER + do { + item = iter->pred->next; + haz_set(hp0, STRIP_MARK(item)); + } while (item != ((volatile node_t *)iter->pred)->next); +#endif//LIST_USE_HAZARD_POINTER + iter->pred = STRIP_MARK(item); + if (iter->pred == NULL) + return DOES_NOT_EXIST; + } while (HAS_MARK(item)); + + if (key_ptr != NULL) { + *key_ptr = GET_NODE(item)->key; + } + return GET_NODE(item)->val; +} + +void ll_iter_free (ll_iter_t *iter) { +#ifdef LIST_USE_HAZARD_POINTER + haz_unregister_dynamic((void **)&iter->pred); +#endif + nbd_free(iter); +}