From: Mathieu Desnoyers Date: Sun, 19 Aug 2012 01:16:34 +0000 (-0400) Subject: rcuja: implement add X-Git-Url: https://git.lttng.org./?a=commitdiff_plain;h=5a9a87dd2a194207a0d98ee999d69b7db7183dea;p=urcu.git rcuja: implement add Signed-off-by: Mathieu Desnoyers --- diff --git a/rcuja/rcuja.c b/rcuja/rcuja.c index a58e609..1c1d6e4 100644 --- a/rcuja/rcuja.c +++ b/rcuja/rcuja.c @@ -72,6 +72,8 @@ struct cds_ja_type { #define JA_ENTRY_PER_NODE 256UL #define JA_BITS_PER_BYTE 3 +#define JA_MAX_INTERNAL_DEPTH 5 /* Maximum depth, excluding leafs */ + /* * Entry for NULL node is at index 8 of the table. It is never encoded * in flags. @@ -314,6 +316,7 @@ uint8_t ja_linear_node_get_nr_child(const struct cds_ja_type *type, static struct cds_ja_inode_flag *ja_linear_node_get_nth(const struct cds_ja_type *type, struct cds_ja_inode *node, + struct cds_ja_inode_flag ***child_node_flag_ptr, uint8_t n) { uint8_t nr_child; @@ -337,13 +340,15 @@ struct cds_ja_inode_flag *ja_linear_node_get_nth(const struct cds_ja_type *type, if (i >= nr_child) return NULL; pointers = (struct cds_ja_inode_flag **) align_ptr_size(&values[type->max_linear_child]); + if (caa_unlikely(child_node_flag_ptr)) + *child_node_flag_ptr = &pointers[i]; ptr = rcu_dereference(pointers[i]); assert(ja_node_ptr(ptr) != NULL); return ptr; } static -struct cds_ja_inode_flag *ja_linear_node_get_ith_pos(const struct cds_ja_type *type, +void ja_linear_node_get_ith_pos(const struct cds_ja_type *type, struct cds_ja_inode *node, uint8_t i, uint8_t *v, @@ -364,6 +369,7 @@ struct cds_ja_inode_flag *ja_linear_node_get_ith_pos(const struct cds_ja_type *t static struct cds_ja_inode_flag *ja_pool_node_get_nth(const struct cds_ja_type *type, struct cds_ja_inode *node, + struct cds_ja_inode_flag ***child_node_flag_ptr, uint8_t n) { struct cds_ja_inode *linear; @@ -375,7 +381,7 @@ struct cds_ja_inode_flag *ja_pool_node_get_nth(const struct cds_ja_type *type, */ linear = (struct cds_ja_inode *) &node->u.data[((unsigned long) n >> (CHAR_BIT - type->nr_pool_order)) << type->pool_size_order]; - return ja_linear_node_get_nth(type, linear, n); + return ja_linear_node_get_nth(type, linear, child_node_flag_ptr, n); } static @@ -391,10 +397,16 @@ struct cds_ja_inode *ja_pool_node_get_ith_pool(const struct cds_ja_type *type, static struct cds_ja_inode_flag *ja_pigeon_node_get_nth(const struct cds_ja_type *type, struct cds_ja_inode *node, + struct cds_ja_inode_flag ***child_node_flag_ptr, uint8_t n) { + struct cds_ja_inode_flag **child_node_flag; + assert(type->type_class == RCU_JA_PIGEON); - return rcu_dereference(((struct cds_ja_inode_flag **) node->u.data)[n]); + child_node_flag = &((struct cds_ja_inode_flag **) node->u.data)[n]; + if (caa_unlikely(child_node_flag_ptr)) + *child_node_flag_ptr = child_node_flag; + return rcu_dereference(*child_node_flag); } /* @@ -403,6 +415,7 @@ struct cds_ja_inode_flag *ja_pigeon_node_get_nth(const struct cds_ja_type *type, */ static struct cds_ja_inode_flag * ja_node_get_nth(struct cds_ja_inode_flag *node_flag, + struct cds_ja_inode_flag ***child_node_flag_ptr, uint8_t n) { unsigned int type_index; @@ -410,18 +423,20 @@ struct cds_ja_inode_flag * ja_node_get_nth(struct cds_ja_inode_flag *node_flag, const struct cds_ja_type *type; node = ja_node_ptr(node_flag); - if (caa_unlikely(node == NULL)) - return NULL; + assert(node != NULL); type_index = ja_node_type(node_flag); type = &ja_types[type_index]; switch (type->type_class) { case RCU_JA_LINEAR: - return ja_linear_node_get_nth(type, node, n); + return ja_linear_node_get_nth(type, node, + child_node_flag_ptr, n); case RCU_JA_POOL: - return ja_pool_node_get_nth(type, node, n); + return ja_pool_node_get_nth(type, node, + child_node_flag_ptr, n); case RCU_JA_PIGEON: - return ja_pigeon_node_get_nth(type, node, n); + return ja_pigeon_node_get_nth(type, node, + child_node_flag_ptr, n); default: assert(0); return (void *) -1UL; @@ -505,7 +520,7 @@ int ja_pigeon_node_set_nth(const struct cds_ja_type *type, assert(type->type_class == RCU_JA_PIGEON); ptr = &((struct cds_ja_inode_flag **) node->u.data)[n]; - if (*ptr != NULL) + if (*ptr) return -EEXIST; rcu_assign_pointer(*ptr, child_node_flag); shadow_node->nr_child++; @@ -547,13 +562,15 @@ int _ja_node_set_nth(const struct cds_ja_type *type, /* * ja_node_recompact_add: recompact a node, adding a new child. * TODO: for pool type, take selection bit(s) into account. + * Return 0 on success, -ENOENT if need to retry, or other negative + * error value otherwise. */ static int ja_node_recompact_add(struct cds_ja *ja, unsigned int old_type_index, const struct cds_ja_type *old_type, struct cds_ja_inode *old_node, - struct cds_ja_shadow_node **shadow_node, + struct cds_ja_shadow_node *shadow_node, struct cds_ja_inode_flag **old_node_flag, uint8_t n, struct cds_ja_inode_flag *child_node_flag) { @@ -561,9 +578,10 @@ int ja_node_recompact_add(struct cds_ja *ja, struct cds_ja_inode *new_node; const struct cds_ja_type *new_type; struct cds_ja_inode_flag *new_node_flag; + int new_shadow = 0; int ret; - if (*shadow_node == NULL) { + if (!shadow_node) { new_type_index = 0; } else { new_type_index = old_type_index + 1; @@ -574,20 +592,23 @@ int ja_node_recompact_add(struct cds_ja *ja, return -ENOMEM; new_node_flag = ja_node_flag(new_node, new_type_index); - ret = rcuja_shadow_set(ja->ht, new_node, *shadow_node); - if (ret) + ret = rcuja_shadow_set(ja->ht, new_node, shadow_node); + if (ret) { + free(new_node); return ret; + } - if (*shadow_node == NULL) { - *shadow_node = rcuja_shadow_lookup_lock(ja->ht, new_node); - assert(*shadow_node); + if (!shadow_node) { + shadow_node = rcuja_shadow_lookup_lock(ja->ht, new_node); + assert(shadow_node); + new_shadow = 1; } /* * We need to clear nr_child, because it will be re-incremented * by _ja_node_set_nth(). */ - (*shadow_node)->nr_child = 0; + shadow_node->nr_child = 0; assert(old_type->type_class != RCU_JA_PIGEON); switch (old_type->type_class) { @@ -604,7 +625,7 @@ int ja_node_recompact_add(struct cds_ja *ja, ja_linear_node_get_ith_pos(old_type, old_node, i, &v, &iter); if (!iter) continue; - ret = _ja_node_set_nth(new_type, new_node, *shadow_node, + ret = _ja_node_set_nth(new_type, new_node, shadow_node, v, iter); assert(!ret); } @@ -630,7 +651,7 @@ int ja_node_recompact_add(struct cds_ja *ja, j, &v, &iter); if (!iter) continue; - ret = _ja_node_set_nth(new_type, new_node, *shadow_node, + ret = _ja_node_set_nth(new_type, new_node, shadow_node, v, iter); assert(!ret); } @@ -640,52 +661,57 @@ int ja_node_recompact_add(struct cds_ja *ja, case RCU_JA_PIGEON: default: assert(0); - return -EINVAL; + ret = -EINVAL; + goto unlock_new_shadow; } /* add node */ - ret = _ja_node_set_nth(new_type, new_node, *shadow_node, + ret = _ja_node_set_nth(new_type, new_node, shadow_node, n, child_node_flag); assert(!ret); - /* Replace the old node with the new recompacted one */ - rcu_assign_pointer(*old_node_flag, new_node_flag); + /* Return pointer to new recompacted new through old_node_flag */ + *old_node_flag = new_node_flag; ret = rcuja_shadow_clear(ja->ht, old_node, RCUJA_SHADOW_CLEAR_FREE_NODE); assert(!ret); - return 0; + + ret = 0; + +unlock_new_shadow: + if (new_shadow) + rcuja_shadow_unlock(shadow_node); + return ret; } +/* + * Return 0 on success, -ENOENT if need to retry, or other negative + * error value otherwise. + */ static int ja_node_set_nth(struct cds_ja *ja, struct cds_ja_inode_flag **node_flag, uint8_t n, - struct cds_ja_inode_flag *child_node_flag) + struct cds_ja_inode_flag *child_node_flag, + struct cds_ja_shadow_node *shadow_node) { int ret; unsigned int type_index; const struct cds_ja_type *type; struct cds_ja_inode *node; - struct cds_ja_shadow_node *shadow_node = NULL; node = ja_node_ptr(*node_flag); type_index = ja_node_type(*node_flag); type = &ja_types[type_index]; - if (node != NULL) { - shadow_node = rcuja_shadow_lookup_lock(ja->ht, node); - assert(shadow_node); - } ret = _ja_node_set_nth(type, node, shadow_node, n, child_node_flag); if (ret == -ENOSPC) { /* Not enough space in node, need to recompact. */ ret = ja_node_recompact_add(ja, type_index, type, node, - &shadow_node, node_flag, n, child_node_flag); - /* recompact always leave shadow_node locked */ + shadow_node, node_flag, n, child_node_flag); } - rcuja_shadow_unlock(shadow_node); return ret; } -struct cds_ja_node *cds_ja_lookup(struct cds_ja *ja, uint64_t key) +struct cds_hlist_head *cds_ja_lookup(struct cds_ja *ja, uint64_t key) { unsigned int tree_depth, i; struct cds_ja_inode_flag *node_flag; @@ -693,18 +719,202 @@ struct cds_ja_node *cds_ja_lookup(struct cds_ja *ja, uint64_t key) if (caa_unlikely(key > ja->key_max)) return NULL; tree_depth = ja->tree_depth; - node_flag = ja->root; + node_flag = rcu_dereference(ja->root); - for (i = 0; i < tree_depth; i++) { - node_flag = ja_node_get_nth(node_flag, + /* level 0: root node */ + if (!ja_node_ptr(node_flag)) + return NULL; + + for (i = 1; i < tree_depth; i++) { + node_flag = ja_node_get_nth(node_flag, NULL, (unsigned char) key); if (!ja_node_ptr(node_flag)) return NULL; key >>= JA_BITS_PER_BYTE; } - /* Last level lookup succeded. We got an actual node. */ - return (struct cds_ja_node *) node_flag; + /* Last level lookup succeded. We got an actual match. */ + return (struct cds_hlist_head *) node_flag; +} + +/* + * We reached an unpopulated node. Create it and the children we need, + * and then attach the entire branch to the current node. This may + * trigger recompaction of the current node. Locks needed: node lock + * (for add), and, possibly, parent node lock (to update pointer due to + * node recompaction). + * + * First take node lock, check if recompaction is needed, then take + * parent lock (if needed). Then we can proceed to create the new + * branch. Publish the new branch, and release locks. + * TODO: we currently always take the parent lock even when not needed. + */ +static +int ja_attach_node(struct cds_ja *ja, + struct cds_ja_inode_flag **node_flag_ptr, + struct cds_ja_inode_flag *node_flag, + struct cds_ja_inode_flag *parent_node_flag, + uint64_t key, + unsigned int depth, + struct cds_ja_node *child_node) +{ + struct cds_ja_shadow_node *shadow_node = NULL, + *parent_shadow_node = NULL; + struct cds_ja_inode *node = ja_node_ptr(node_flag); + struct cds_ja_inode *parent_node = ja_node_ptr(parent_node_flag); + struct cds_hlist_head head; + struct cds_ja_inode_flag *iter_node_flag, *iter_dest_node_flag; + int ret, i; + struct cds_ja_inode_flag *created_nodes[JA_MAX_INTERNAL_DEPTH]; + int nr_created_nodes = 0; + + assert(node); + shadow_node = rcuja_shadow_lookup_lock(ja->ht, node); + if (!shadow_node) { + ret = -ENOENT; + goto end; + } + if (parent_node) { + parent_shadow_node = rcuja_shadow_lookup_lock(ja->ht, + parent_node); + if (!parent_shadow_node) { + ret = -ENOENT; + goto unlock_shadow; + } + } + + CDS_INIT_HLIST_HEAD(&head); + cds_hlist_add_head_rcu(&child_node->list, &head); + + iter_dest_node_flag = NULL; + ret = ja_node_set_nth(ja, &iter_dest_node_flag, + key >> (JA_BITS_PER_BYTE * (ja->tree_depth - 2)), + (struct cds_ja_inode_flag *) head.next, + NULL); + if (ret) + goto unlock_parent; + created_nodes[nr_created_nodes++] = iter_dest_node_flag; + iter_node_flag = iter_dest_node_flag; + + /* Create new branch, starting from bottom */ + for (i = ja->tree_depth - 2; i >= (int) depth; i--) { + iter_dest_node_flag = NULL; + ret = ja_node_set_nth(ja, &iter_dest_node_flag, + key >> (JA_BITS_PER_BYTE * (i - 1)), + iter_node_flag, + NULL); + if (ret) + goto check_error; + created_nodes[nr_created_nodes++] = iter_dest_node_flag; + iter_node_flag = iter_dest_node_flag; + } + + /* Publish new branch */ + rcu_assign_pointer(*node_flag_ptr, iter_node_flag); + + /* Success */ + ret = 0; + +check_error: + if (ret) { + for (i = 0; i < nr_created_nodes; i++) { + int tmpret; + tmpret = rcuja_shadow_clear(ja->ht, + ja_node_ptr(created_nodes[i]), + RCUJA_SHADOW_CLEAR_FREE_NODE + | RCUJA_SHADOW_CLEAR_FREE_LOCK); + assert(!tmpret); + } + } +unlock_parent: + if (parent_shadow_node) + rcuja_shadow_unlock(parent_shadow_node); +unlock_shadow: + if (shadow_node) + rcuja_shadow_unlock(shadow_node); +end: + return ret; +} + +/* + * Lock the hlist head shadow node mutex, and add node to list of + * duplicates. Failure can happen if concurrent removal removes the last + * node with same key before we get the lock. + * Return 0 on success, negative error value on failure. + */ +static +int ja_chain_node(struct cds_ja *ja, + struct cds_hlist_head *head, + struct cds_ja_node *node) +{ + struct cds_ja_shadow_node *shadow_node; + + shadow_node = rcuja_shadow_lookup_lock(ja->ht, + (struct cds_ja_inode *) head); + if (!shadow_node) + return -ENOENT; + cds_hlist_add_head_rcu(&node->list, head); + rcuja_shadow_unlock(shadow_node); + return 0; +} + +int cds_ja_add(struct cds_ja *ja, uint64_t key, + struct cds_ja_node *new_node) +{ + unsigned int tree_depth, i; + uint64_t iter_key; + struct cds_ja_inode_flag **node_flag_ptr; /* in parent */ + struct cds_ja_inode_flag *node_flag, + *parent_node_flag, + *parent2_node_flag; + int ret; + + if (caa_unlikely(key > ja->key_max)) + return -EINVAL; + tree_depth = ja->tree_depth; + +retry: + iter_key = key; + parent2_node_flag = NULL; + parent_node_flag = NULL; + node_flag_ptr = &ja->root; + node_flag = rcu_dereference(*node_flag_ptr); + + /* Iterate on all internal levels */ + for (i = 0; i < tree_depth - 1; i++) { + if (!ja_node_ptr(node_flag)) { + ret = ja_attach_node(ja, node_flag_ptr, + parent_node_flag, parent2_node_flag, + key, i, new_node); + if (ret == -ENOENT || ret == -EEXIST) + goto retry; + else + goto end; + } + parent2_node_flag = parent_node_flag; + parent_node_flag = node_flag; + node_flag = ja_node_get_nth(node_flag, + &node_flag_ptr, + (unsigned char) iter_key); + iter_key >>= JA_BITS_PER_BYTE; + } + + /* + * We reached bottom of tree, simply add node to last internal + * level, or chain it if key is already present. + */ + if (!ja_node_ptr(node_flag)) { + ret = ja_attach_node(ja, node_flag_ptr, parent_node_flag, + parent2_node_flag, key, i, new_node); + } else { + ret = ja_chain_node(ja, + (struct cds_hlist_head *) ja_node_ptr(node_flag), + new_node); + } + if (ret == -ENOENT) + goto retry; +end: + return ret; } struct cds_ja *_cds_ja_new(unsigned int key_bits, @@ -712,7 +922,6 @@ struct cds_ja *_cds_ja_new(unsigned int key_bits, { struct cds_ja *ja; - ja = calloc(sizeof(*ja), 1); if (!ja) goto ja_error; @@ -735,7 +944,9 @@ struct cds_ja *_cds_ja_new(unsigned int key_bits, } /* ja->root is NULL */ - ja->tree_depth = key_bits >> JA_BITS_PER_BYTE; + /* tree_depth 0 is for pointer to root node */ + ja->tree_depth = (key_bits >> JA_BITS_PER_BYTE) + 1; + assert(ja->tree_depth <= JA_MAX_INTERNAL_DEPTH + 1); ja->ht = rcuja_create_ht(flavor); if (!ja->ht) goto ht_error;