uhs/twophase/coordinator/state_machine.hpp

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// Copyright (c) 2021 MIT Digital Currency Initiative,
//                    Federal Reserve Bank of Boston
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
#ifndef OPENCBDC_TX_SRC_COORDINATOR_STATE_MACHINE_H_
#define OPENCBDC_TX_SRC_COORDINATOR_STATE_MACHINE_H_
 
#include "util/common/hashmap.hpp"
#include "util/common/logging.hpp"
 
#include <libnuraft/nuraft.hxx>
#include <unordered_map>
#include <unordered_set>
 
namespace cbdc::coordinator {
    class state_machine final : public nuraft::state_machine {
      public:
        explicit state_machine(std::shared_ptr<logging::log> logger);
 
        enum class command : uint8_t {
            prepare = 0, 
            commit = 1,  
            discard = 2, 
            done = 3,    
            get = 4      
        };
 
        struct coordinator_state {
            std::unordered_map<hash_t,
                               nuraft::ptr<nuraft::buffer>,
                               cbdc::hashing::const_sip_hash<hash_t>>
                m_prepare_txs{};
            std::unordered_map<hash_t,
                               nuraft::ptr<nuraft::buffer>,
                               cbdc::hashing::const_sip_hash<hash_t>>
                m_commit_txs{};
            std::unordered_set<hash_t, cbdc::hashing::const_sip_hash<hash_t>>
                m_discard_txs{};
        };
 
        auto commit(uint64_t log_idx, nuraft::buffer& data)
            -> nuraft::ptr<nuraft::buffer> override;
 
        void commit_config(
            nuraft::ulong log_idx,
            nuraft::ptr<nuraft::cluster_config>& /*new_conf*/) override;
 
        auto apply_snapshot(nuraft::snapshot& /* s */) -> bool override;
 
        auto last_snapshot() -> nuraft::ptr<nuraft::snapshot> override;
 
        auto last_commit_index() -> uint64_t override;
 
        void create_snapshot(
            nuraft::snapshot& /* s */,
            nuraft::async_result<bool>::handler_type& when_done) override;
 
      private:
        std::atomic<uint64_t> m_last_committed_idx{0};
        coordinator_state m_state{};
        std::shared_ptr<logging::log> m_logger;
    };
}
 
#endif // OPENCBDC_TX_SRC_COORDINATOR_STATE_MACHINE_H_