73 lines
2.3 KiB
C++
73 lines
2.3 KiB
C++
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/// @file
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#pragma once
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#include "raft/config.hpp"
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#include "raft/coordination.hpp"
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#include "storage/common/kvstore/kvstore.hpp"
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namespace raft {
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enum class Mode { FOLLOWER, CANDIDATE, LEADER };
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/**
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* Class which models the behaviour of a single server within the Raft
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* cluster. The class is responsible for storing both volatile and
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* persistent internal state of the corresponding state machine as well
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* as performing operations that comply with the Raft protocol.
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*/
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class RaftServer {
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public:
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RaftServer() = delete;
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/**
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* The implementation assumes that server IDs are unique integers between
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* ranging from 1 to cluster_size.
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*
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* @param server_id ID of the current server.
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* @param config Configurable Raft parameters (e.g. timeout interval)
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* @param coordination Abstraction for coordination between Raft servers.
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*/
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RaftServer(uint16_t server_id, const raft::Config &config,
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raft::Coordination *coordination);
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private:
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/** volatile state on all servers **/
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raft::Mode mode_; ///< Server's current mode.
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raft::Config config_; ///< Raft config.
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uint16_t server_id_; ///< ID of the current server.
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uint64_t commit_index_; ///< Index of the highest known commited entry.
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uint64_t last_applied_; ///< Index of the highest applied entry to SM.
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/** volatile state on leaders **/
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std::vector<uint16_t> next_index_; ///< for each server, index of the next
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///< log entry to send to that server.
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std::vector<uint16_t> match_index_; ///< for each server, index of the
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///< highest log entry known to be
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///< replicated on server.
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/** persistent state on all servers
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*
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* Persistent data consists of:
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* - uint64_t current_term -- latest term server has seen.
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* - uint16_t voted_for -- candidate_id that received vote in current
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* term (null if none).
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* - vector<LogEntry> log -- log entries.
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*/
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storage::KVStore disk_storage_;
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/**
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* Makes a transition to a new `raft::Mode`.
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*
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* @throws InvalidTransitionException when transitioning between uncompatible
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* `raft::Mode`s.
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*/
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void Transition(const raft::Mode &new_mode);
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};
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} // namespace raft
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