struct node *next;
} node_t;
-typedef struct list {
+struct ll {
node_t *head;
- node_t *last;
-} list_t;
+};
-node_t *node_alloc (uint64_t key, uint64_t value) {
+static node_t *node_alloc (uint64_t key, uint64_t value) {
node_t *item = (node_t *)nbd_malloc(sizeof(node_t));
memset(item, 0, sizeof(node_t));
item->key = key;
return item;
}
-list_t *list_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;
- return list;
+list_t *ll_alloc (void) {
+ list_t *ll = (list_t *)nbd_malloc(sizeof(list_t));
+ ll->head = node_alloc((uint64_t)-1, 0);
+ ll->head->next = NULL;
+ return ll;
}
-static node_t *find_pred (node_t **pred_ptr, list_t *list, uint64_t key, int help_remove) {
- node_t *pred = list->head;
+static node_t *find_pred (node_t **pred_ptr, list_t *ll, uint64_t key, int help_remove) {
+ node_t *pred = ll->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
+ TRACE("l3", "find_pred: searching for key %p in ll (head is %p)", key, pred);
- 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;
}
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
+ return find_pred(pred_ptr, ll, 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);
+ }
+
+ // <key> is not in <ll>.
+ 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);
- node_t *item = find_pred(NULL, list, key, FALSE);
+uint64_t ll_lookup (list_t *ll, uint64_t key) {
+ TRACE("l3", "ll_lookup: searching for key %p in ll %p", key, ll);
+ node_t *item = find_pred(NULL, ll, key, FALSE);
// If we found an <item> matching the <key> return its value.
- return (item->key == key) ? item->value : DOES_NOT_EXIST;
+ return (item && item->key == key) ? item->value : DOES_NOT_EXIST;
}
-// Insert the <key>, if it doesn't already exist in the <list>
-uint64_t list_add (list_t *list, uint64_t key, uint64_t value) {
- TRACE("l3", "list_add: inserting key %p value %p", key, value);
+// Insert the <key>, if it doesn't already exist in <ll>
+uint64_t ll_add (list_t *ll, 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);
+ node_t *next = find_pred(&pred, ll, key, TRUE);
- // If a node matching <key> 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 a node matching <key> already exists in <ll>, return its 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 *ll, uint64_t key) {
+ TRACE("l3", "ll_remove: removing item with key %p from ll %p", key, ll);
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);
+ node_t *item = find_pred(&pred, ll, key, TRUE);
+ if (item == NULL || item->key != key) {
+ TRACE("l3", "ll_remove: remove failed, an item with a matching key does not exist in the ll", 0, 0);
return DOES_NOT_EXIST;
}
// Mark <item> 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 <item> from the list.
- TRACE("l3", "list_remove: link item's pred %p to it's successor %p", pred, next);
+ // Unlink <item> from <ll>.
+ 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 ll.
return value;
}
return value;
}
-void list_print (list_t *list) {
+void ll_print (list_t *ll) {
node_t *item;
- item = list->head;
+ item = ll->head->next;
while (item) {
printf("0x%llx ", item->key);
fflush(stdout);
}
printf("\n");
}
-
-#ifdef MAKE_list_test
-#include <errno.h>
-#include <pthread.h>
-#include <sys/time.h>
-
-#include "runtime.h"
-
-#define NUM_ITERATIONS 10000000
-
-static volatile int wait_;
-static long num_threads_;
-static list_t *list_;
-
-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);
- } else {
- list_remove(list_, key);
- }
-
- rcu_update();
- }
-
- return NULL;
-}
-
-int main (int argc, char **argv) {
- nbd_init();
- //lwt_set_trace_level("m0l0");
-
- char* program_name = argv[0];
- pthread_t thread[MAX_NUM_THREADS];
-
- if (argc > 2) {
- fprintf(stderr, "Usage: %s num_threads\n", program_name);
- return -1;
- }
-
- num_threads_ = 2;
- if (argc == 2)
- {
- errno = 0;
- num_threads_ = strtol(argv[1], NULL, 10);
- if (errno) {
- fprintf(stderr, "%s: Invalid argument for number of threads\n", program_name);
- return -1;
- }
- if (num_threads_ <= 0) {
- fprintf(stderr, "%s: Number of threads must be at least 1\n", program_name);
- return -1;
- }
- if (num_threads_ > MAX_NUM_THREADS) {
- fprintf(stderr, "%s: Number of threads cannot be more than %d\n", program_name, MAX_NUM_THREADS);
- return -1;
- }
- }
-
- list_ = list_alloc();
-
- struct timeval tv1, tv2;
- gettimeofday(&tv1, NULL);
-
- __asm__ __volatile__("sfence");
- wait_ = num_threads_;
-
- for (int i = 0; i < num_threads_; ++i) {
- int rc = nbd_thread_create(thread + i, i, worker, (void*)(size_t)i);
- if (rc != 0) { perror("pthread_create"); return rc; }
- }
-
- for (int i = 0; i < num_threads_; ++i) {
- pthread_join(thread[i], NULL);
- }
-
- gettimeofday(&tv2, NULL);
- int ms = (int)(1000000*(tv2.tv_sec - tv1.tv_sec) + tv2.tv_usec - tv1.tv_usec) / 1000;
- printf("Th:%ld Time:%dms\n", num_threads_, ms);
- list_print(list_);
- lwt_dump("lwt.out");
-
- return 0;
-}
-#endif//list_test
projects / nbds / blobdiff