e955c94ed3
Listing the "Blender Foundation" as copyright holder implied the Blender Foundation holds copyright to files which may include work from many developers. While keeping copyright on headers makes sense for isolated libraries, Blender's own code may be refactored or moved between files in a way that makes the per file copyright holders less meaningful. Copyright references to the "Blender Foundation" have been replaced with "Blender Authors", with the exception of `./extern/` since these this contains libraries which are more isolated, any changed to license headers there can be handled on a case-by-case basis. Some directories in `./intern/` have also been excluded: - `./intern/cycles/` it's own `AUTHORS` file is planned. - `./intern/opensubdiv/`. An "AUTHORS" file has been added, using the chromium projects authors file as a template. Design task: #110784 Ref !110783.
111 lines
3.4 KiB
C++
111 lines
3.4 KiB
C++
/* SPDX-FileCopyrightText: 2023 Blender Authors
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*
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* SPDX-License-Identifier: GPL-2.0-or-later */
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#include "BLI_atomic_disjoint_set.hh"
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#include "BLI_enumerable_thread_specific.hh"
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#include "BLI_map.hh"
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#include "BLI_sort.hh"
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#include "BLI_task.hh"
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namespace blender {
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AtomicDisjointSet::AtomicDisjointSet(const int size) : items_(size)
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{
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threading::parallel_for(IndexRange(size), 4096, [&](const IndexRange range) {
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for (const int i : range) {
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items_[i].store(Item{i, 0}, relaxed);
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}
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});
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}
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static void update_first_occurrence(Map<int, int> &map, const int root, const int index)
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{
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map.add_or_modify(
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root,
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[&](int *first_occurrence) { *first_occurrence = index; },
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[&](int *first_occurrence) {
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if (index < *first_occurrence) {
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*first_occurrence = index;
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}
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});
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}
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void AtomicDisjointSet::calc_reduced_ids(MutableSpan<int> result) const
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{
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BLI_assert(result.size() == items_.size());
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const int size = result.size();
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/* Find the root for element. With multi-threading, this root is not deterministic. So
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* some postprocessing has to be done to make it deterministic. */
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threading::EnumerableThreadSpecific<Map<int, int>> first_occurrence_by_root_per_thread;
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threading::parallel_for(IndexRange(size), 1024, [&](const IndexRange range) {
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Map<int, int> &first_occurrence_by_root = first_occurrence_by_root_per_thread.local();
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for (const int i : range) {
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const int root = this->find_root(i);
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result[i] = root;
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update_first_occurrence(first_occurrence_by_root, root, i);
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}
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});
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/* Build a map that contains the first element index that has a certain root. */
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Map<int, int> &combined_map = first_occurrence_by_root_per_thread.local();
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for (const Map<int, int> &other_map : first_occurrence_by_root_per_thread) {
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if (&combined_map == &other_map) {
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continue;
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}
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for (const auto item : other_map.items()) {
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update_first_occurrence(combined_map, item.key, item.value);
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}
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}
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struct RootOccurence {
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int root;
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int first_occurrence;
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};
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/* Sort roots by first occurrence. This removes the non-determinism above. */
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Vector<RootOccurence, 16> root_occurrences;
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root_occurrences.reserve(combined_map.size());
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for (const auto item : combined_map.items()) {
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root_occurrences.append({item.key, item.value});
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}
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parallel_sort(root_occurrences.begin(),
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root_occurrences.end(),
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[](const RootOccurence &a, const RootOccurence &b) {
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return a.first_occurrence < b.first_occurrence;
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});
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/* Remap original root values with deterministic values. */
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Map<int, int> id_by_root;
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id_by_root.reserve(root_occurrences.size());
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for (const int i : root_occurrences.index_range()) {
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id_by_root.add_new(root_occurrences[i].root, i);
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}
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threading::parallel_for(IndexRange(size), 1024, [&](const IndexRange range) {
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for (const int i : range) {
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result[i] = id_by_root.lookup(result[i]);
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}
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});
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}
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int AtomicDisjointSet::count_sets() const
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{
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return threading::parallel_reduce<int>(
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items_.index_range(),
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1024,
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0,
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[&](const IndexRange range, int count) {
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for (const int i : range) {
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if (this->is_root(i)) {
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count++;
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}
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}
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return count;
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},
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[](const int a, const int b) { return a + b; });
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}
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} // namespace blender
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