fcb8d040e8
Instead of lengthy blurbs, switch to single-line, machine-readable standardized (https://spdx.dev) license identifiers. The Linux kernel switched long ago, so there is strong precedent. Three cases are handled: AGPL-only, Apache-only, and dual licensed. For the latter case, I chose (AGPL-3.0-or-later and Apache-2.0), reasoning that our changes are extensive enough to apply our license. The changes we applied mechanically with a script, except to licenses/README.md. Closes #9937
79 lines
2.1 KiB
C++
79 lines
2.1 KiB
C++
/*
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* Copyright (C) 2018-present ScyllaDB
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*/
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/*
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* SPDX-License-Identifier: AGPL-3.0-or-later
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*/
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#pragma once
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#include "partition_version.hh"
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// Double-ended chained list of partition_version objects
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// utilizing partition_version's intrinsic anchorless_list_base_hook.
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class partition_version_list {
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partition_version_ref _head;
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partition_version_ref _tail; // nullptr means _tail == _head.
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public:
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// Appends v to the tail of this deque.
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// The version must not be already referenced.
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void push_back(partition_version& v) noexcept {
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if (!_tail) {
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if (_head) {
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v.insert_before(*_head);
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_tail = std::move(_head);
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}
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_head = partition_version_ref(v);
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} else {
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v.insert_after(*_tail);
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_tail = partition_version_ref(v);
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}
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}
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// Returns a reference to the first version in this deque.
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// Call only if !empty().
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partition_version& front() noexcept {
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return *_head;
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}
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// Returns true iff contains any versions.
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bool empty() const noexcept {
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return !_head;
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}
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// Detaches the first version from the list.
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// Assumes !empty().
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void pop_front() noexcept {
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if (_tail && _head->next() == &*_tail) {
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_tail = {};
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}
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partition_version* next = _head->next();
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_head->erase();
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_head.release();
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if (next) {
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_head = partition_version_ref(*next);
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}
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}
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// Appends other to the tail of this deque.
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// The other deque will be left empty.
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void splice(partition_version_list& other) noexcept {
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if (!other._head) {
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return;
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}
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if (!_head) {
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_head = std::move(other._head);
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_tail = std::move(other._tail);
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} else {
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(_tail ? _tail : _head)->splice(*other._head);
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if (other._tail) {
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_tail = std::move(other._tail);
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other._head = {};
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} else {
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_tail = std::move(other._head);
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}
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}
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}
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};
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