2021-01-14 16:20:33 +00:00
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#pragma once
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2021-10-27 23:10:39 +00:00
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#include <libnuraft/nuraft.hxx>
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2021-01-14 16:20:33 +00:00
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#include <Core/Types.h>
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#include <atomic>
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#include <map>
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#include <mutex>
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namespace DB
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{
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2021-01-25 14:47:03 +00:00
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/// Example trivial state machine.
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class SummingStateMachine : public nuraft::state_machine
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{
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public:
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SummingStateMachine();
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2021-04-08 14:17:57 +00:00
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nuraft::ptr<nuraft::buffer> pre_commit(const uint64_t /*log_idx*/, nuraft::buffer & /*data*/) override { return nullptr; }
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2021-04-08 14:17:57 +00:00
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nuraft::ptr<nuraft::buffer> commit(const uint64_t log_idx, nuraft::buffer & data) override;
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2021-04-08 14:17:57 +00:00
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void rollback(const uint64_t /*log_idx*/, nuraft::buffer & /*data*/) override {}
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2021-04-08 14:17:57 +00:00
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uint64_t last_commit_index() override { return last_committed_idx; }
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bool apply_snapshot(nuraft::snapshot & s) override;
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nuraft::ptr<nuraft::snapshot> last_snapshot() override;
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void create_snapshot(
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nuraft::snapshot & s,
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nuraft::async_result<bool>::handler_type & when_done) override;
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void save_logical_snp_obj(
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nuraft::snapshot & s,
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uint64_t & obj_id,
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nuraft::buffer & data,
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bool is_first_obj,
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bool is_last_obj) override;
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int read_logical_snp_obj(
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nuraft::snapshot & s,
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void* & user_snp_ctx,
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uint64_t obj_id,
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nuraft::ptr<nuraft::buffer> & data_out,
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bool & is_last_obj) override;
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int64_t getValue() const { return value; }
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private:
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struct SingleValueSnapshotContext
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{
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SingleValueSnapshotContext(nuraft::ptr<nuraft::snapshot> & s, int64_t v)
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: snapshot(s)
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, value(v)
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{}
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nuraft::ptr<nuraft::snapshot> snapshot;
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int64_t value;
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};
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void createSnapshotInternal(nuraft::snapshot & s);
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// State machine's current value.
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std::atomic<int64_t> value;
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// Last committed Raft log number.
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std::atomic<uint64_t> last_committed_idx;
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// Keeps the last 3 snapshots, by their Raft log numbers.
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std::map<uint64_t, nuraft::ptr<SingleValueSnapshotContext>> snapshots;
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// Mutex for `snapshots_`.
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std::mutex snapshots_lock;
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};
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}
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