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a459d9ab98
When the last non-dummy row is evicted from a partition, the partition entry is evicted as well. The existing logic in on_evicted() leaves the last dummy row in the partition version before evicting the partition entry. This row may still be attached to the LRU. Eviction of partition entry goes through mutation_cleaner::clear_gently(). If this is preempted, the destruction may proceed in the background. If evicition happens on the remaining row in that entry before it's destroyed, the code will hit undefined behavior. on_evicted() calls partition_version::is_referenced_from_entry(), which is unspecified when the version is enqueued in the mutation_cleaner. It returns incorrect value for the last item remaining in the LRU. In that case eviction will try to access non-existent containing partition_entry, causing undefined behavior. Caught by debug-mode cql_query_test.test_clustering_filtering with raft enabled. Where it manifested like this: partition_version.hh:328:16: runtime error: load of value 7, which is not a valid value for type 'bool' SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior partition_version.hh:328:16 in Aborting on shard 0. Instances of this issue outside of the unit test environment are not known as of yet. This change makes is_referenced_from_entry() return the correct value even for versions which are queued in the mutation cleaner. Fixes #11140
91 lines
2.5 KiB
C++
91 lines
2.5 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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// All references have unique_owner set to true
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// so that partition_version::is_referenced_from_entry() is false
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// so that versions owned here (by mutation_cleaner) are not evicted-from.
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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, true);
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#ifdef SEASTAR_DEBUG
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assert(!_head->is_referenced_from_entry());
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#endif
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} else {
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v.insert_after(*_tail);
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_tail = partition_version_ref(v, true);
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#ifdef SEASTAR_DEBUG
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assert(!_tail->is_referenced_from_entry());
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#endif
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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, true);
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#ifdef SEASTAR_DEBUG
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assert(!_head->is_referenced_from_entry());
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#endif
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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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