diff options
Diffstat (limited to 'absl/container')
| -rw-r--r-- | absl/container/internal/btree.h | 151 |
1 files changed, 61 insertions, 90 deletions
diff --git a/absl/container/internal/btree.h b/absl/container/internal/btree.h index b23138f0..f52fe235 100644 --- a/absl/container/internal/btree.h +++ b/absl/container/internal/btree.h @@ -817,33 +817,52 @@ class btree_node { absl::container_internal::SanitizerPoisonObject(slot(i)); } - // Transfers value from slot `src_i` in `src` to slot `dest_i` in `this`. - void transfer(const size_type dest_i, const size_type src_i, btree_node *src, - allocator_type *alloc) { + // Transfers value from slot `src_i` in `src_node` to slot `dest_i` in `this`. + void transfer(const size_type dest_i, const size_type src_i, + btree_node *src_node, allocator_type *alloc) { absl::container_internal::SanitizerUnpoisonObject(slot(dest_i)); - params_type::transfer(alloc, slot(dest_i), src->slot(src_i)); - absl::container_internal::SanitizerPoisonObject(src->slot(src_i)); + params_type::transfer(alloc, slot(dest_i), src_node->slot(src_i)); + absl::container_internal::SanitizerPoisonObject(src_node->slot(src_i)); } - // Move n values starting at value i in this node into the values starting at - // value j in dest_node. - void uninitialized_move_n(const size_type n, const size_type i, - const size_type j, btree_node *dest_node, - allocator_type *alloc) { + // Transfers `n` values starting at value `src_i` in `src_node` into the + // values starting at value `dest_i` in `this`. + void transfer_n(const size_type n, const size_type dest_i, + const size_type src_i, btree_node *src_node, + allocator_type *alloc) { absl::container_internal::SanitizerUnpoisonMemoryRegion( - dest_node->slot(j), n * sizeof(slot_type)); - for (slot_type *src = slot(i), *end = src + n, *dest = dest_node->slot(j); + slot(dest_i), n * sizeof(slot_type)); + for (slot_type *src = src_node->slot(src_i), *end = src + n, + *dest = slot(dest_i); src != end; ++src, ++dest) { - params_type::construct(alloc, dest, src); + params_type::transfer(alloc, dest, src); } + // We take care to avoid poisoning transferred-to nodes in case of overlap. + const size_type overlap = + this == src_node ? (std::max)(src_i, dest_i + n) - src_i : 0; + assert(n >= overlap); + absl::container_internal::SanitizerPoisonMemoryRegion( + src_node->slot(src_i + overlap), (n - overlap) * sizeof(slot_type)); } - // Destroys a range of n values, starting at index i. - void value_destroy_n(const size_type i, const size_type n, - allocator_type *alloc) { - for (int j = 0; j < n; ++j) { - value_destroy(i + j, alloc); + // Same as above, except that we start at the end and work our way to the + // beginning. + void transfer_n_backward(const size_type n, const size_type dest_i, + const size_type src_i, btree_node *src_node, + allocator_type *alloc) { + absl::container_internal::SanitizerUnpoisonMemoryRegion( + slot(dest_i), n * sizeof(slot_type)); + for (slot_type *src = src_node->slot(src_i + n - 1), *end = src - n, + *dest = slot(dest_i + n - 1); + src != end; --src, --dest) { + params_type::transfer(alloc, dest, src); } + // We take care to avoid poisoning transferred-to nodes in case of overlap. + assert(this != src_node || dest_i >= src_i); + const size_type num_to_poison = + this == src_node ? (std::min)(n, dest_i - src_i) : n; + absl::container_internal::SanitizerPoisonMemoryRegion( + src_node->slot(src_i), num_to_poison * sizeof(slot_type)); } template <typename P> @@ -1531,10 +1550,8 @@ inline void btree_node<P>::emplace_value(const size_type i, // Shift old values to create space for new value and then construct it in // place. if (i < finish()) { - value_init(finish(), alloc, slot(finish() - 1)); - for (size_type j = finish() - 1; j > i; --j) - params_type::move(alloc, slot(j - 1), slot(j)); - value_destroy(i, alloc); + transfer_n_backward(finish() - i, /*dest_i=*/i + 1, /*src_i=*/i, this, + alloc); } value_init(i, alloc, std::forward<Args>(args)...); set_finish(finish() + 1); @@ -1564,7 +1581,9 @@ template <typename P> inline void btree_node<P>::remove_values_ignore_children( const int i, const int to_erase, allocator_type *alloc) { params_type::move(alloc, slot(i + to_erase), finish_slot(), slot(i)); - value_destroy_n(finish() - to_erase, to_erase, alloc); + for (int j = finish() - to_erase; j < finish(); ++j) { + value_destroy(j, alloc); + } set_finish(finish() - to_erase); } @@ -1579,22 +1598,17 @@ void btree_node<P>::rebalance_right_to_left(const int to_move, assert(to_move <= right->count()); // 1) Move the delimiting value in the parent to the left node. - value_init(finish(), alloc, parent()->slot(position())); + transfer(finish(), position(), parent(), alloc); // 2) Move the (to_move - 1) values from the right node to the left node. - right->uninitialized_move_n(to_move - 1, right->start(), finish() + 1, this, - alloc); + transfer_n(to_move - 1, finish() + 1, right->start(), right, alloc); // 3) Move the new delimiting value to the parent from the right node. - params_type::move(alloc, right->slot(to_move - 1), - parent()->slot(position())); - - // 4) Shift the values in the right node to their correct position. - params_type::move(alloc, right->slot(to_move), right->finish_slot(), - right->start_slot()); + parent()->transfer(position(), right->start() + to_move - 1, right, alloc); - // 5) Destroy the now-empty to_move entries in the right node. - right->value_destroy_n(right->finish() - to_move, to_move, alloc); + // 4) Shift the values in the right node to their correct positions. + right->transfer_n(right->count() - to_move, right->start(), + right->start() + to_move, right, alloc); if (!leaf()) { // Move the child pointers from the right to the left node. @@ -1629,54 +1643,19 @@ void btree_node<P>::rebalance_left_to_right(const int to_move, // Lastly, a new delimiting value is moved from the left node into the // parent, and the remaining empty left node entries are destroyed. - if (right->count() >= to_move) { - // The original location of the right->count() values are sufficient to hold - // the new to_move entries from the parent and left node. - - // 1) Shift existing values in the right node to their correct positions. - right->uninitialized_move_n(to_move, right->finish() - to_move, - right->finish(), right, alloc); - for (slot_type *src = right->slot(right->finish() - to_move - 1), - *dest = right->slot(right->finish() - 1), - *end = right->start_slot(); - src >= end; --src, --dest) { - params_type::move(alloc, src, dest); - } - - // 2) Move the delimiting value in the parent to the right node. - params_type::move(alloc, parent()->slot(position()), - right->slot(to_move - 1)); + // 1) Shift existing values in the right node to their correct positions. + right->transfer_n_backward(right->count(), right->start() + to_move, + right->start(), right, alloc); - // 3) Move the (to_move - 1) values from the left node to the right node. - params_type::move(alloc, slot(finish() - (to_move - 1)), finish_slot(), - right->start_slot()); - } else { - // The right node does not have enough initialized space to hold the new - // to_move entries, so part of them will move to uninitialized space. - - // 1) Shift existing values in the right node to their correct positions. - right->uninitialized_move_n(right->count(), right->start(), - right->start() + to_move, right, alloc); + // 2) Move the delimiting value in the parent to the right node. + right->transfer(right->start() + to_move - 1, position(), parent(), alloc); - // 2) Move the delimiting value in the parent to the right node. - right->value_init(to_move - 1, alloc, parent()->slot(position())); - - // 3) Move the (to_move - 1) values from the left node to the right node. - const size_type uninitialized_remaining = to_move - right->count() - 1; - uninitialized_move_n(uninitialized_remaining, - finish() - uninitialized_remaining, right->finish(), - right, alloc); - params_type::move(alloc, slot(finish() - (to_move - 1)), - slot(finish() - uninitialized_remaining), - right->start_slot()); - } + // 3) Move the (to_move - 1) values from the left node to the right node. + right->transfer_n(to_move - 1, right->start(), finish() - (to_move - 1), this, + alloc); // 4) Move the new delimiting value to the parent from the left node. - params_type::move(alloc, slot(finish() - to_move), - parent()->slot(position())); - - // 5) Destroy the now-empty to_move entries in the left node. - value_destroy_n(finish() - to_move, to_move, alloc); + parent()->transfer(position(), finish() - to_move, this, alloc); if (!leaf()) { // Move the child pointers from the left to the right node. @@ -1716,10 +1695,7 @@ void btree_node<P>::split(const int insert_position, btree_node *dest, assert(count() >= 1); // Move values from the left sibling to the right sibling. - uninitialized_move_n(dest->count(), finish(), dest->start(), dest, alloc); - - // Destroy the now-empty entries in the left node. - value_destroy_n(finish(), dest->count(), alloc); + dest->transfer_n(dest->count(), dest->start(), finish(), this, alloc); // The split key is the largest value in the left sibling. --mutable_finish(); @@ -1746,11 +1722,7 @@ void btree_node<P>::merge(btree_node *src, allocator_type *alloc) { value_init(finish(), alloc, parent()->slot(position())); // Move the values from the right to the left node. - src->uninitialized_move_n(src->count(), src->start(), finish() + 1, this, - alloc); - - // Destroy the now-empty entries in the right node. - src->value_destroy_n(src->start(), src->count(), alloc); + transfer_n(src->count(), finish() + 1, src->start(), src, alloc); if (!leaf()) { // Move the child pointers from the right to the left node. @@ -2474,9 +2446,8 @@ inline auto btree<P>::internal_emplace(iterator iter, Args &&... args) // Transfer the values from the old root to the new root. node_type *old_root = root(); node_type *new_root = iter.node; - for (int i = old_root->start(), f = old_root->finish(); i < f; ++i) { - new_root->transfer(i, i, old_root, alloc); - } + new_root->transfer_n(old_root->count(), new_root->start(), + old_root->start(), old_root, alloc); new_root->set_finish(old_root->finish()); old_root->set_finish(old_root->start()); delete_leaf_node(old_root); |