1a9c6d9fd3
This patch implements a simple variation of LFRU eviction policy:
* We define 2 dynamic cache sections which total size should not exceed the maximum cache size.
* New cache entry is always added to the "unprivileged" section.
* After a cache entry is read more than SectionHitThreshold times it moves to the second cache section.
* Both sections' entries obey expiration and reload rules in the same way as before this patch.
* When cache entries need to be evicted due to a size restriction "unprivileged" section's
least recently used entries are evicted first.
Note:
With a 2 sections cache it's not enough for a new entry to have the latest timestamp
in order not be evicted right after insertion: e.g. if all all other entries
are from the privileged section.
And obviously we want to allow new cache entries to be added to a cache.
Therefore we can no longer first add a new entry and then shrink the cache.
Switching the order of these two operations resolves the culprit.
Fixes #8674
Signed-off-by: Vlad Zolotarov <vladz@scylladb.com>
90 lines
2.2 KiB
C++
90 lines
2.2 KiB
C++
/*
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* Copyright (C) 2017-present ScyllaDB
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*/
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/*
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* This file is part of Scylla.
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*
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* Scylla is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Affero General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* Scylla is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with Scylla. If not, see <http://www.gnu.org/licenses/>.
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*/
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#pragma once
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#include <chrono>
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#include <string_view>
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#include <functional>
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#include <iostream>
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#include <optional>
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#include <utility>
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#include <seastar/core/future.hh>
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#include <seastar/core/shared_ptr.hh>
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#include <seastar/core/sstring.hh>
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#include "auth/authenticated_user.hh"
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#include "auth/permission.hh"
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#include "auth/resource.hh"
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#include "auth/role_or_anonymous.hh"
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#include "log.hh"
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#include "utils/hash.hh"
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#include "utils/loading_cache.hh"
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namespace std {
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inline std::ostream& operator<<(std::ostream& os, const pair<auth::role_or_anonymous, auth::resource>& p) {
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os << "{role: " << p.first << ", resource: " << p.second << "}";
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return os;
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}
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}
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namespace db {
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class config;
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}
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namespace auth {
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class service;
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struct permissions_cache_config final {
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std::size_t max_entries;
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std::chrono::milliseconds validity_period;
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std::chrono::milliseconds update_period;
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};
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class permissions_cache final {
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using cache_type = utils::loading_cache<
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std::pair<role_or_anonymous, resource>,
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permission_set,
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1,
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utils::loading_cache_reload_enabled::yes,
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utils::simple_entry_size<permission_set>,
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utils::tuple_hash>;
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using key_type = typename cache_type::key_type;
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cache_type _cache;
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public:
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explicit permissions_cache(const permissions_cache_config&, service&, logging::logger&);
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future <> stop() {
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return _cache.stop();
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}
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future<permission_set> get(const role_or_anonymous&, const resource&);
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};
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}
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