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/*
* Copyright © 2019 Intel Corporation
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice (including the next
* paragraph) shall be included in all copies or substantial portions of the
* Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
* IN THE SOFTWARE.
*/
#include "sparse_array.h"
struct util_sparse_array_node {
uint32_t level;
uint32_t _pad;
uint64_t max_idx;
};
void
util_sparse_array_init(struct util_sparse_array *arr,
size_t elem_size, size_t node_size)
{
memset(arr, 0, sizeof(*arr));
arr->elem_size = elem_size;
arr->node_size_log2 = util_logbase2_64(node_size);
assert(node_size >= 2 && node_size == (1ull << arr->node_size_log2));
}
static inline void *
_util_sparse_array_node_data(struct util_sparse_array_node *node)
{
return node + 1;
}
static inline void
_util_sparse_array_node_finish(struct util_sparse_array *arr,
struct util_sparse_array_node *node)
{
if (node->level > 0) {
struct util_sparse_array_node **children =
_util_sparse_array_node_data(node);
size_t node_size = 1ull << arr->node_size_log2;
for (size_t i = 0; i < node_size; i++) {
if (children[i] != NULL)
_util_sparse_array_node_finish(arr, children[i]);
}
}
free(node);
}
void
util_sparse_array_finish(struct util_sparse_array *arr)
{
if (arr->root)
_util_sparse_array_node_finish(arr, arr->root);
}
static inline struct util_sparse_array_node *
_util_sparse_array_alloc_node(struct util_sparse_array *arr,
unsigned level)
{
size_t size = sizeof(struct util_sparse_array_node);
if (level == 0) {
size += arr->elem_size << arr->node_size_log2;
} else {
size += sizeof(struct util_sparse_array_node *) << arr->node_size_log2;
}
struct util_sparse_array_node *node = calloc(1, size);
node->level = level;
return node;
}
static inline struct util_sparse_array_node *
_util_sparse_array_set_or_free_node(struct util_sparse_array_node **node_ptr,
struct util_sparse_array_node *cmp_node,
struct util_sparse_array_node *node)
{
struct util_sparse_array_node *prev_node =
p_atomic_cmpxchg(node_ptr, cmp_node, node);
if (prev_node != cmp_node) {
/* We lost the race. Free this one and return the one that was already
* allocated.
*/
free(node);
return prev_node;
} else {
return node;
}
}
void *
util_sparse_array_get(struct util_sparse_array *arr, uint64_t idx)
{
struct util_sparse_array_node *root = p_atomic_read(&arr->root);
if (unlikely(root == NULL)) {
unsigned root_level = 0;
uint64_t idx_iter = idx >> arr->node_size_log2;
while (idx_iter) {
idx_iter >>= arr->node_size_log2;
root_level++;
}
struct util_sparse_array_node *new_root =
_util_sparse_array_alloc_node(arr, root_level);
root = _util_sparse_array_set_or_free_node(&arr->root, NULL, new_root);
}
while (1) {
uint64_t root_idx = idx >> (root->level * arr->node_size_log2);
if (likely(root_idx < (1ull << arr->node_size_log2)))
break;
/* In this case, we have a root but its level is low enough that the
* requested index is out-of-bounds.
*/
struct util_sparse_array_node *new_root =
_util_sparse_array_alloc_node(arr, root->level + 1);
struct util_sparse_array_node **new_root_children =
_util_sparse_array_node_data(new_root);
new_root_children[0] = root;
/* We only add one at a time instead of the whole tree because it's
* easier to ensure correctness of both the tree building and the
* clean-up path. Because we're only adding one node we never have to
* worry about trying to free multiple things without freeing the old
* things.
*/
root = _util_sparse_array_set_or_free_node(&arr->root, root, new_root);
}
struct util_sparse_array_node *node = root;
while (node->level > 0) {
uint64_t child_idx = (idx >> (node->level * arr->node_size_log2)) &
((1ull << arr->node_size_log2) - 1);
struct util_sparse_array_node **children =
_util_sparse_array_node_data(node);
struct util_sparse_array_node *child =
p_atomic_read(&children[child_idx]);
if (unlikely(child == NULL)) {
child = _util_sparse_array_alloc_node(arr, node->level - 1);
child = _util_sparse_array_set_or_free_node(&children[child_idx],
NULL, child);
}
node = child;
}
uint64_t elem_idx = idx & ((1ull << arr->node_size_log2) - 1);
return (void *)((char *)_util_sparse_array_node_data(node) +
(elem_idx * arr->elem_size));
}
static void
validate_node_level(struct util_sparse_array *arr,
struct util_sparse_array_node *node,
unsigned level)
{
assert(node->level == level);
if (node->level > 0) {
struct util_sparse_array_node **children =
_util_sparse_array_node_data(node);
size_t node_size = 1ull << arr->node_size_log2;
for (size_t i = 0; i < node_size; i++) {
if (children[i] != NULL)
validate_node_level(arr, children[i], level - 1);
}
}
}
void
util_sparse_array_validate(struct util_sparse_array *arr)
{
validate_node_level(arr, arr->root, arr->root->level);
}
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