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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
57 lines
1.8 KiB
C++
57 lines
1.8 KiB
C++
/*
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*
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*
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*/
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/*
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* Copyright (C) 2019-present ScyllaDB
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*
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* Modified by ScyllaDB
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*/
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/*
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* SPDX-License-Identifier: (AGPL-3.0-or-later and Apache-2.0)
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*/
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#pragma once
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#include "utils/UUID_gen.hh"
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#include "frozen_mutation.hh"
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namespace service {
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namespace paxos {
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// Proposal represents replica's value associated with a given ballot. The origin uses the term
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// "commit" for this object, however, Scylla follows the terminology as set by Paxos Made Simple
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// paper.
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// Each replica persists the proposals it receives in the system.paxos table. A proposal may be
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// new, accepted by a replica, or accepted by a majority. When a proposal is accepted by majority it
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// is considered "chosen" by Paxos, and we call such a proposal "decision". A decision is
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// saved in the paxos table in an own column and applied to the base table during "learn" phase of
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// the protocol. After a decision is applied it is considered "committed".
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class proposal {
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public:
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// The ballot for the update.
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utils::UUID ballot;
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// The mutation representing the update that is being applied.
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frozen_mutation update;
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proposal(utils::UUID ballot_arg, frozen_mutation update_arg)
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: ballot(ballot_arg)
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, update(std::move(update_arg)) {}
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};
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// Proposals are ordered by their ballot's timestamp.
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// A proposer uses it to find the newest proposal accepted
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// by some replica among the responses to its own one.
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inline bool operator<(const proposal& lhs, const proposal& rhs) {
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return lhs.ballot.timestamp() < rhs.ballot.timestamp();
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}
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inline bool operator>(const proposal& lhs, const proposal& rhs) {
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return lhs.ballot.timestamp() > rhs.ballot.timestamp();
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}
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// Used for logging and debugging.
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std::ostream& operator<<(std::ostream& os, const proposal& proposal);
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} // end of namespace "paxos"
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} // end of namespace "service"
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