X-Git-Url: https://pd.if.org/git/?p=nbds;a=blobdiff_plain;f=struct%2Flist.c;h=124043d2b4363222c711c644a15a599869b86c51;hp=aa28b85190ddcdc330bd3bb38ac35d36721e6b45;hb=052506ff082f134f00834f666653819e18d9bddf;hpb=269f52d6f8cd031692c83afaa05c389115d05bd0 diff --git a/struct/list.c b/struct/list.c index aa28b85..124043d 100644 --- a/struct/list.c +++ b/struct/list.c @@ -20,7 +20,6 @@ typedef struct node { typedef struct list { node_t *head; - node_t *last; } list_t; node_t *node_alloc (uint64_t key, uint64_t value) { @@ -31,11 +30,10 @@ node_t *node_alloc (uint64_t key, uint64_t value) { return item; } -list_t *list_alloc (void) { +list_t *ll_alloc (void) { list_t *list = (list_t *)nbd_malloc(sizeof(list_t)); - list->head = node_alloc(0, 0); - list->last = node_alloc((uint64_t)-1, 0); - list->head->next = list->last; + list->head = node_alloc((uint64_t)-1, 0); + list->head->next = NULL; return list; } @@ -43,21 +41,20 @@ static node_t *find_pred (node_t **pred_ptr, list_t *list, uint64_t key, int hel node_t *pred = list->head; node_t *item = pred->next; TRACE("l3", "find_pred: searching for key %p in list (head is %p)", key, pred); -#ifndef NDEBUG - int count = 0; -#endif - do { + while (item != NULL) { node_t *next = item->next; TRACE("l3", "find_pred: visiting item %p (next %p)", item, next); - TRACE("l3", "find_pred: key %p value %p", item->key, item->value); + TRACE("l3", "find_pred: key %p", item->key, item->value); - // Marked items are partially removed. + // Marked items are logically removed, but not unlinked yet. while (EXPECT_FALSE(IS_TAGGED(next))) { // Skip over partially removed items. if (!help_remove) { item = (node_t *)STRIP_TAG(item->next); + if (EXPECT_FALSE(item == NULL)) + break; next = item->next; continue; } @@ -66,101 +63,116 @@ static node_t *find_pred (node_t **pred_ptr, list_t *list, uint64_t key, int hel node_t *other; if ((other = SYNC_CAS(&pred->next, item, STRIP_TAG(next))) == item) { item = (node_t *)STRIP_TAG(next); + if (EXPECT_FALSE(item == NULL)) + break; next = item->next; - TRACE("l3", "find_pred: unlinked item; %p is the new item (next is %p)", item, next); + TRACE("l3", "find_pred: unlinked item %p from pred %p", item, pred); + TRACE("l3", "find_pred: now item is %p next is %p", item, next); + + // The thread that completes the unlink should free the memory. nbd_defer_free(other); } else { - TRACE("l3", "find_pred: lost race to unlink item from pred %p; its link changed to %p", pred, other); + TRACE("l3", "find_pred: lost race to unlink from pred %p; its link changed to %p", pred, other); if (IS_TAGGED(other)) return find_pred(pred_ptr, list, key, help_remove); // retry item = other; + if (EXPECT_FALSE(item == NULL)) + break; next = item->next; } } + if (EXPECT_FALSE(item == NULL)) + break; + // If we reached the key (or passed where it should be), we found the right predesssor if (item->key >= key) { - TRACE("l3", "find_pred: returning pred %p and item %p", pred, item); + TRACE("l3", "find_pred: found pred %p item %p", pred, item); if (pred_ptr != NULL) { *pred_ptr = pred; } return item; } - assert(count++ < 18); pred = item; item = next; - } while (1); + } + + // is not in the list. + if (pred_ptr != NULL) { + *pred_ptr = pred; + } + return NULL; } // Fast find. Do not help unlink partially removed nodes and do not return the found item's predecessor. -uint64_t list_lookup (list_t *list, uint64_t key) { - TRACE("l3", "list_lookup: searching for key %p in list %p", key, list); +uint64_t ll_lookup (list_t *list, uint64_t key) { + TRACE("l3", "ll_lookup: searching for key %p in list %p", key, list); node_t *item = find_pred(NULL, list, key, FALSE); // If we found an matching the return its value. - return (item->key == key) ? item->value : DOES_NOT_EXIST; + return (item && item->key == key) ? item->value : DOES_NOT_EXIST; } // Insert the , if it doesn't already exist in the -uint64_t list_add (list_t *list, uint64_t key, uint64_t value) { - TRACE("l3", "list_add: inserting key %p value %p", key, value); +uint64_t ll_add (list_t *list, uint64_t key, uint64_t value) { + TRACE("l3", "ll_add: inserting key %p value %p", key, value); node_t *pred; node_t *item = NULL; do { node_t *next = find_pred(&pred, list, key, TRUE); // If a node matching already exists in the list, return its value. - if (next->key == key) { - TRACE("l3", "list_add: there is already an item %p (value %p) with the same key", next, next->value); + if (next != NULL && next->key == key) { + TRACE("l3", "ll_add: there is already an item %p (value %p) with the same key", next, next->value); if (EXPECT_FALSE(item != NULL)) { nbd_free(item); } return next->value; } - TRACE("l3", "list_add: attempting to insert item between %p and %p", pred, next); + TRACE("l3", "ll_add: attempting to insert item between %p and %p", pred, next); if (EXPECT_TRUE(item == NULL)) { item = node_alloc(key, value); } item->next = next; node_t *other = SYNC_CAS(&pred->next, next, item); if (other == next) { - TRACE("l3", "list_add: insert was successful", 0, 0); + TRACE("l3", "ll_add: successfully inserted item %p", item, 0); return DOES_NOT_EXIST; // success } - TRACE("l3", "list_add: failed to change pred's link: expected %p found %p", next, other); + TRACE("l3", "ll_add: failed to change pred's link: expected %p found %p", next, other); } while (1); } -uint64_t list_remove (list_t *list, uint64_t key) { - TRACE("l3", "list_remove: removing item with key %p from list %p", key, list); +uint64_t ll_remove (list_t *list, uint64_t key) { + TRACE("l3", "ll_remove: removing item with key %p from list %p", key, list); node_t *pred; node_t *item = find_pred(&pred, list, key, TRUE); - if (item->key != key) { - TRACE("l3", "list_remove: remove failed, an item with a matching key does not exist in the list", 0, 0); + if (item == NULL || item->key != key) { + TRACE("l3", "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. if (EXPECT_FALSE(IS_TAGGED(item->next))) { - TRACE("l3", "list_remove: %p is already marked for removal by another thread", item, 0); + TRACE("l3", "ll_remove: %p is already marked for removal by another thread", item, 0); return DOES_NOT_EXIST; } node_t *next = SYNC_FETCH_AND_OR(&item->next, TAG); if (EXPECT_FALSE(IS_TAGGED(next))) { - TRACE("l3", "list_remove: lost race -- %p is already marked for removal by another thread", item, 0); + TRACE("l3", "ll_remove: lost race -- %p is already marked for removal by another thread", item, 0); return DOES_NOT_EXIST; } uint64_t value = item->value; // Unlink from the list. - TRACE("l3", "list_remove: link item's pred %p to it's successor %p", pred, next); + TRACE("l3", "ll_remove: link item's pred %p to it's successor %p", pred, next); node_t *other; if ((other = SYNC_CAS(&pred->next, item, next)) != item) { - TRACE("l3", "list_remove: unlink failed; pred's link changed from %p to %p", item, other); - // By being marked, the item was logically removed. It is safe to leave it for - // another thread to finish physically removing it from the skiplist. + TRACE("l3", "ll_remove: unlink failed; pred's link changed from %p to %p", item, other); + // By marking the item earlier, we logically removed it. It is safe to leave the item. + // Another thread will finish physically removing it from the list. return value; } @@ -169,9 +181,9 @@ uint64_t list_remove (list_t *list, uint64_t key) { return value; } -void list_print (list_t *list) { +void ll_print (list_t *list) { node_t *item; - item = list->head; + item = list->head->next; while (item) { printf("0x%llx ", item->key); fflush(stdout); @@ -191,25 +203,21 @@ void list_print (list_t *list) { static volatile int wait_; static long num_threads_; -static list_t *list_; +static list_t *ll_; void *worker (void *arg) { - int id = (int)(size_t)arg; - - unsigned int rand_seed = id+1;//rdtsc_l(); // Wait for all the worker threads to be ready. SYNC_ADD(&wait_, -1); do {} while (wait_); - __asm__ __volatile__("lfence"); for (int i = 0; i < NUM_ITERATIONS/num_threads_; ++i) { - int n = rand_r(&rand_seed); - int key = (n & 0xF) + 1; - if (n & (1 << 8)) { - list_add(list_, key, 1); + unsigned r = nbd_rand(); + int key = (r & 0xF); + if (r & (1 << 8)) { + ll_add(ll_, key, 1); } else { - list_remove(list_, key); + ll_remove(ll_, key); } rcu_update(); @@ -249,12 +257,11 @@ int main (int argc, char **argv) { } } - list_ = list_alloc(); + ll_ = ll_alloc(); struct timeval tv1, tv2; gettimeofday(&tv1, NULL); - __asm__ __volatile__("sfence"); wait_ = num_threads_; for (int i = 0; i < num_threads_; ++i) { @@ -268,9 +275,8 @@ int main (int argc, char **argv) { gettimeofday(&tv2, NULL); int ms = (int)(1000000*(tv2.tv_sec - tv1.tv_sec) + tv2.tv_usec - tv1.tv_usec) / 1000; + ll_print(ll_); printf("Th:%ld Time:%dms\n", num_threads_, ms); - list_print(list_); - lwt_dump("lwt.out"); return 0; }