75 lines
2.1 KiB
C++
75 lines
2.1 KiB
C++
#pragma once
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#include <mutex>
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#include <unordered_map>
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#include "logging/default.hpp"
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#include "storage/indexes/index_definition.hpp"
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#include "transactions/transaction.hpp"
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class SnapshotEncoder;
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class SnapshotDecoder;
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class Db;
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class DbTransaction;
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class DbAccessor;
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// Captures snapshots. Only one per database should exist.
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class SnapshotEngine
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{
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public:
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SnapshotEngine(Db &db);
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~SnapshotEngine() = default;
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// Returns number of succesffuly created snapshots.
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size_t snapshoted_no() { return snapshoted_no_v.load(); }
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// Imports latest snapshot into the databse. Blocks until other calls don't
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// end.
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bool import();
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// Makes snapshot of given type. Blocks until other calls don't end.
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bool make_snapshot();
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private:
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// Removes excess of snapshots starting with oldest one.
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void clean_snapshots();
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// Makes snapshot of given type
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bool make_snapshot(std::time_t now, const char *type);
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// Makes snapshot. It only saves records which have changed since old_trans.
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void snapshot(DbTransaction const &dt, SnapshotEncoder &snap,
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tx::TransactionRead const &old_trans);
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// Loads snapshot. True if success. Returns indexes which were in snapshot.
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std::vector<IndexDefinition> snapshot_load(DbAccessor &t,
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SnapshotDecoder &snap);
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// Adds indexes. Should be called outside transactions.
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void add_indexes(std::vector<IndexDefinition> &v);
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// Will return different name on every call.
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std::string snapshot_file(std::time_t const &now, const char *type);
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// Returns name of snapshot commit file.
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std::string snapshot_commit_file();
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// Path to directory of database. Ensures that all necessary directorys
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// exist.
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std::string snapshot_db_dir();
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Logger logger;
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Db &db;
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std::mutex guard;
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const std::string snapshot_folder;
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// Determines how many newest snapshot will be preserved, while the other
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// ones will be deleted.
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const size_t max_retained_snapshots;
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std::atomic<size_t> snapshoted_no_v = {0};
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};
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