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d216c3dbd2
This patch extracts out the relational operators in struct tombstone to a class capable of generating them from a tri-compare function. Signed-off-by: Duarte Nunes <duarte@scylladb.com>
105 lines
2.8 KiB
C++
105 lines
2.8 KiB
C++
/*
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* Copyright (C) 2015 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 <functional>
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#include "timestamp.hh"
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#include "gc_clock.hh"
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#include "hashing.hh"
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#include "utils/with_relational_operators.hh"
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/**
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* Represents deletion operation. Can be commuted with other tombstones via apply() method.
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* Can be empty.
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*/
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struct tombstone final : public with_relational_operators<tombstone> {
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api::timestamp_type timestamp;
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gc_clock::time_point deletion_time;
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tombstone(api::timestamp_type timestamp, gc_clock::time_point deletion_time)
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: timestamp(timestamp)
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, deletion_time(deletion_time)
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{ }
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tombstone()
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: tombstone(api::missing_timestamp, {})
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{ }
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int compare(const tombstone& t) const {
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if (timestamp < t.timestamp) {
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return -1;
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} else if (timestamp > t.timestamp) {
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return 1;
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} else if (deletion_time < t.deletion_time) {
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return -1;
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} else if (deletion_time > t.deletion_time) {
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return 1;
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} else {
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return 0;
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}
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}
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explicit operator bool() const {
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return timestamp != api::missing_timestamp;
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}
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void apply(const tombstone& t) noexcept {
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if (*this < t) {
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*this = t;
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}
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}
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// See reversibly_mergeable.hh
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void apply_reversibly(tombstone& t) noexcept {
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std::swap(*this, t);
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apply(t);
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}
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// See reversibly_mergeable.hh
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void revert(tombstone& t) noexcept {
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std::swap(*this, t);
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}
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friend std::ostream& operator<<(std::ostream& out, const tombstone& t) {
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if (t) {
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return out << "{tombstone: timestamp=" << t.timestamp << ", deletion_time=" << t.deletion_time.time_since_epoch().count() << "}";
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} else {
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return out << "{tombstone: none}";
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}
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}
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};
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template<>
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struct appending_hash<tombstone> {
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template<typename Hasher>
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void operator()(Hasher& h, const tombstone& t) const {
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feed_hash(h, t.timestamp);
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feed_hash(h, t.deletion_time);
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}
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};
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// Determines whether tombstone may be GC-ed.
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using can_gc_fn = std::function<bool(tombstone)>;
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static can_gc_fn always_gc = [] (tombstone) { return true; };
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