From: jdybnis Date: Fri, 21 Nov 2008 07:26:49 +0000 (+0000) Subject: tweak list X-Git-Url: https://pd.if.org/git/?p=nbds;a=commitdiff_plain;h=269f52d6f8cd031692c83afaa05c389115d05bd0 tweak list --- diff --git a/include/common.h b/include/common.h index 5bc2a6f..d638fc9 100644 --- a/include/common.h +++ b/include/common.h @@ -32,16 +32,16 @@ #define SYNC_ADD __sync_add_and_fetch #define SYNC_FETCH_AND_OR __sync_fetch_and_or -#define MASK(n) ((1LL << (n)) - 1) - -#define TAG (1LL << 63) -#define IS_TAGGED(v) ((int64_t)(v) < 0) -#define TAG_VALUE(v) ((uint64_t)(v) | TAG) -#define STRIP_TAG(v) ((uint64_t)(v) & ~TAG) +#define MASK(n) ((1ULL << (n)) - 1) #define TRUE 1 #define FALSE 0 +#define TAG (1ULL << 63) +#define TAG_VALUE(v) ((uint64_t)(v) | TAG) +#define IS_TAGGED(v) ((uint64_t)(v) & TAG) +#define STRIP_TAG(v) ((uint64_t)(v) & ~TAG) + typedef unsigned long long uint64_t; typedef unsigned int uint32_t; typedef unsigned char uint8_t; diff --git a/include/ht.h b/include/ht.h index 965986e..49198bb 100644 --- a/include/ht.h +++ b/include/ht.h @@ -5,9 +5,7 @@ #ifndef HT_H #define HT_H -#include "common.h" - -#define DOES_NOT_EXIST 0 +#include "struct.h" #define HT_EXPECT_NOT_EXISTS ( 0) #define HT_EXPECT_EXISTS (-1) diff --git a/include/struct.h b/include/struct.h new file mode 100644 index 0000000..fa3f704 --- /dev/null +++ b/include/struct.h @@ -0,0 +1,6 @@ +#ifndef STRUCT_H +#define STRUCT_H + +#define DOES_NOT_EXIST 0 + +#endif//STRUCT_H diff --git a/makefile b/makefile index 8f50837..0a14c0e 100644 --- a/makefile +++ b/makefile @@ -6,15 +6,16 @@ # Makefile for building programs with whole-program interfile optimization ################################################################################################### OPT := -fwhole-program -combine -03 #-DNDEBUG -CFLAGS := -g -Wall -Werror -std=c99 -m64 -fnested-functions #$(OPT) #-DENABLE_TRACE +CFLAGS := -g -Wall -Werror -std=c99 -m64 -fnested-functions $(OPT) #-DENABLE_TRACE INCS := $(addprefix -I, include) -TESTS := output/rcu_test output/list_test output/ht_test output/txn_test +TESTS := output/rcu_test output/list_test output/skiplist_test output/ht_test output/txn_test EXES := $(TESTS) RUNTIME_SRCS := runtime/runtime.c runtime/rcu.c runtime/lwt.c runtime/mem.c TEST_SRCS := $(RUNTIME_SRCS) rcu_test_SRCS := $(TEST_SRCS) list_test_SRCS := $(TEST_SRCS) struct/list.c +#skiplist_test_SRCS := $(TEST_SRCS) struct/skiplist.c ht_test_SRCS := $(TEST_SRCS) struct/ht.c test/ht_test.c test/CuTest.c txn_test_SRCS := $(TEST_SRCS) struct/ht.c txn/txn.c diff --git a/struct/ht.c b/struct/ht.c index f444af0..953200d 100644 --- a/struct/ht.c +++ b/struct/ht.c @@ -16,6 +16,7 @@ #include "ht.h" #include "murmur.h" #include "mem.h" +#include "struct.h" #define GET_PTR(x) ((string_t *)((x) & MASK(48))) // low-order 48 bits is a pointer to a string_t diff --git a/struct/list.c b/struct/list.c index 2fad6ee..aa28b85 100644 --- a/struct/list.c +++ b/struct/list.c @@ -7,78 +7,84 @@ */ #include #include -#include #include "common.h" -#include "lwt.h" +#include "struct.h" #include "mem.h" -#define NUM_ITERATIONS 10000000 - -#define PLACE_MARK(x) (((size_t)(x))|1) -#define CLEAR_MARK(x) (((size_t)(x))&~(size_t)1) -#define IS_MARKED(x) ((size_t)(x))&1 - typedef struct node { + uint64_t key; + uint64_t value; struct node *next; - int key; } node_t; typedef struct list { - node_t head[1]; - node_t last; + node_t *head; + node_t *last; } list_t; -static void list_node_init (node_t *item, int key) { - memset(item, 0, sizeof(node_t)); - item->key = key; -} - -node_t *list_node_alloc (int key) { +node_t *node_alloc (uint64_t key, uint64_t value) { node_t *item = (node_t *)nbd_malloc(sizeof(node_t)); - list_node_init(item, key); + memset(item, 0, sizeof(node_t)); + item->key = key; + item->value = value; return item; } list_t *list_alloc (void) { list_t *list = (list_t *)nbd_malloc(sizeof(list_t)); - list_node_init(list->head, INT_MIN); - list_node_init(&list->last, INT_MAX); - list->head->next = &list->last; + list->head = node_alloc(0, 0); + list->last = node_alloc((uint64_t)-1, 0); + list->head->next = list->last; return list; } -static void find_pred_and_item (node_t **pred_ptr, node_t **item_ptr, list_t *list, int key) { +static node_t *find_pred (node_t **pred_ptr, list_t *list, uint64_t key, int help_remove) { node_t *pred = list->head; - node_t *item = list->head->next; // head is never removed - TRACE("l3", "find_pred_and_item: searching for key %llu in list (head is %p)", key, pred); + 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 { - // skip removed items - node_t *other, *next = item->next; - TRACE("l3", "find_pred_and_item: visiting item %p (next is %p)", item, next); - while (EXPECT_FALSE(IS_MARKED(next))) { - - // assist in unlinking partially removed items - if ((other = SYNC_CAS(&pred->next, item, CLEAR_MARK(next))) != item) - { - TRACE("l3", "find_pred_and_item: failed to unlink item from pred %p, pred's next pointer was changed to %p", pred, other); - return find_pred_and_item(pred_ptr, item_ptr, list, key); // retry + 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); + + // Marked items are partially removed. + while (EXPECT_FALSE(IS_TAGGED(next))) { + + // Skip over partially removed items. + if (!help_remove) { + item = (node_t *)STRIP_TAG(item->next); + next = item->next; + continue; } - assert(count++ < 18); - item = (node_t *)CLEAR_MARK(next); - next = item->next; - TRACE("l3", "find_pred_and_item: unlinked item, %p is the new item (next is %p)", item, next); + // Unlink partially removed items. + node_t *other; + if ((other = SYNC_CAS(&pred->next, item, STRIP_TAG(next))) == item) { + item = (node_t *)STRIP_TAG(next); + next = item->next; + TRACE("l3", "find_pred: unlinked item; %p is the new item (next is %p)", item, next); + nbd_defer_free(other); + } else { + TRACE("l3", "find_pred: lost race to unlink item 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; + next = item->next; + } } + // If we reached the key (or passed where it should be), we found the right predesssor if (item->key >= key) { - *pred_ptr = pred; - *item_ptr = item; - TRACE("l3", "find_pred_and_item: key found, returning pred %p and item %p", pred, item); - return; + TRACE("l3", "find_pred: returning pred %p and item %p", pred, item); + if (pred_ptr != NULL) { + *pred_ptr = pred; + } + return item; } assert(count++ < 18); @@ -88,77 +94,86 @@ static void find_pred_and_item (node_t **pred_ptr, node_t **item_ptr, list_t *li } while (1); } -int list_insert (list_t *list, node_t *item) { - TRACE("l3", "list_insert: inserting %p (with key %llu)", item, item->key); - node_t *pred, *next, *other = (node_t *)-1; +// 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); + + // If we found an matching the return its value. + return (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); + node_t *pred; + node_t *item = NULL; do { - if (other != (node_t *)-1) { - TRACE("l3", "list_insert: failed to swap item into list; pred's next was changed to %p", other, 0); - } - find_pred_and_item(&pred, &next, list, item->key); + node_t *next = find_pred(&pred, list, key, TRUE); - // fail if item already exists in list - if (next->key == item->key) - { - TRACE("l3", "list_insert: insert failed item with key already exists %p", next, 0); - return 0; + // 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 (EXPECT_FALSE(item != NULL)) { nbd_free(item); } + return next->value; } + TRACE("l3", "list_add: attempting to insert item between %p and %p", pred, next); + if (EXPECT_TRUE(item == NULL)) { item = node_alloc(key, value); } item->next = next; - TRACE("l3", "list_insert: attempting to insert item between %p and %p", pred, next); - - } while ((other = __sync_val_compare_and_swap(&pred->next, next, item)) != next); - - TRACE("l3", "list_insert: insert was successful", 0, 0); + node_t *other = SYNC_CAS(&pred->next, next, item); + if (other == next) { + TRACE("l3", "list_add: insert was successful", 0, 0); + return DOES_NOT_EXIST; // success + } + TRACE("l3", "list_add: failed to change pred's link: expected %p found %p", next, other); - // success - return 1; + } while (1); } -node_t *list_remove (list_t *list, int key) { - node_t *pred, *item, *next; - - TRACE("l3", "list_remove: removing item with key %llu", key, 0); - find_pred_and_item(&pred, &item, list, key); - if (item->key != key) - { - TRACE("l3", "list_remove: remove failed, key does not exist in list", 0, 0); - return NULL; +uint64_t list_remove (list_t *list, uint64_t key) { + TRACE("l3", "list_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); + return DOES_NOT_EXIST; } - // Mark removed, must be atomic. If multiple threads try to remove the - // same item only one of them should succeed - next = item->next; - node_t *other = (node_t *)-1; - if (IS_MARKED(next) || (other = __sync_val_compare_and_swap(&item->next, next, PLACE_MARK(next))) != next) { - if (other == (node_t *)-1) { - TRACE("l3", "list_remove: retry; %p is already marked for removal (it's next pointer is %p)", item, next); - } else { - TRACE("l3", "list_remove: retry; failed to mark %p for removal; it's next pointer was %p, but changed to %p", next, other); - } - return list_remove(list, key); // retry + // 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); + return DOES_NOT_EXIST; } - - // Remove from list - TRACE("l3", "list_remove: link item's pred %p to it's successor %p", pred, next); - if ((other = __sync_val_compare_and_swap(&pred->next, item, next)) != item) { - TRACE("l3", "list_remove: link failed; pred's link changed from %p to %p", item, other); - - // make sure item gets unlinked before returning it - node_t *d1, *d2; - find_pred_and_item(&d1, &d2, list, key); - } else { - TRACE("l3", "list_remove: link succeeded; pred's link changed from %p to %p", item, next); + 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); + return DOES_NOT_EXIST; } - return item; + 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); + 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. + return value; + } + + // The thread that completes the unlink should free the memory. + nbd_defer_free(item); + return value; } void list_print (list_t *list) { node_t *item; item = list->head; while (item) { - printf("%d ", item->key); + printf("0x%llx ", item->key); fflush(stdout); item = item->next; } @@ -168,8 +183,12 @@ void list_print (list_t *list) { #ifdef MAKE_list_test #include #include +#include + #include "runtime.h" +#define NUM_ITERATIONS 10000000 + static volatile int wait_; static long num_threads_; static list_t *list_; @@ -180,25 +199,17 @@ void *worker (void *arg) { unsigned int rand_seed = id+1;//rdtsc_l(); // Wait for all the worker threads to be ready. - __sync_fetch_and_add(&wait_, -1); + SYNC_ADD(&wait_, -1); do {} while (wait_); __asm__ __volatile__("lfence"); - int i; - for (i = 0; i < NUM_ITERATIONS/num_threads_; ++i) { + 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)) { - node_t *item = list_node_alloc(key); - int success = list_insert(list_, item); - if (!success) { - nbd_free(item); - } + list_add(list_, key, 1); } else { - node_t *item = list_remove(list_, key); - if (item) { - nbd_defer_free(item); - } + list_remove(list_, key); } rcu_update(); @@ -246,13 +257,12 @@ int main (int argc, char **argv) { __asm__ __volatile__("sfence"); wait_ = num_threads_; - int i; - for (i = 0; i < num_threads_; ++i) { + 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 (i = 0; i < num_threads_; ++i) { + for (int i = 0; i < num_threads_; ++i) { pthread_join(thread[i], NULL); }