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/**
* @file Backup.h
* @ingroup SQLiteCpp
* @brief Backup is used to backup a database file in a safe and online way.
*
* Copyright (c) 2015 Shibao HONG (shibaohong@outlook.com)
* Copyright (c) 2015-2025 Sebastien Rombauts (sebastien.rombauts@gmail.com)
*
* Distributed under the MIT License (MIT) (See accompanying file LICENSE.txt
* or copy at http://opensource.org/licenses/MIT)
*/
#pragma once
#include <SQLiteCpp/SQLiteCppExport.h>
#include <SQLiteCpp/Database.h>
#include <string>
#include <memory>
// Forward declaration to avoid inclusion of <sqlite3.h> in a header
struct sqlite3_backup;
namespace SQLite
{
/**
* @brief RAII encapsulation of a SQLite Database Backup process.
*
* A Backup object is used to backup a source database file to a destination database file
* in a safe and online way.
*
* See also the a reference implementation of live backup taken from the official site:
* https://www.sqlite.org/backup.html
*/
class SQLITECPP_API Backup
{
public:
/**
* @brief Initialize a SQLite Backup object.
*
* Initialize a SQLite Backup object for the source database and destination database.
* The database name is "main" for the main database, "temp" for the temporary database,
* or the name specified after the AS keyword in an ATTACH statement for an attached database.
*
* Exception is thrown in case of error, then the Backup object is NOT constructed.
*
* @param[in] aDestDatabase Destination database connection
* @param[in] apDestDatabaseName Destination database name
* @param[in] aSrcDatabase Source database connection
* @param[in] apSrcDatabaseName Source database name
*
* @throw SQLite::Exception in case of error
*/
Backup(Database& aDestDatabase,
const char* apDestDatabaseName,
Database& aSrcDatabase,
const char* apSrcDatabaseName);
/**
* @brief Initialize a SQLite Backup object.
*
* Initialize a SQLite Backup object for source database and destination database.
* The database name is "main" for the main database, "temp" for the temporary database,
* or the name specified after the AS keyword in an ATTACH statement for an attached database.
*
* Exception is thrown in case of error, then the Backup object is NOT constructed.
*
* @param[in] aDestDatabase Destination database connection
* @param[in] aDestDatabaseName Destination database name
* @param[in] aSrcDatabase Source database connection
* @param[in] aSrcDatabaseName Source database name
*
* @throw SQLite::Exception in case of error
*/
Backup(Database& aDestDatabase,
const std::string& aDestDatabaseName,
Database& aSrcDatabase,
const std::string& aSrcDatabaseName);
/**
* @brief Initialize a SQLite Backup object for main databases.
*
* Initialize a SQLite Backup object for source database and destination database.
* Backup the main databases between the source and the destination.
*
* Exception is thrown in case of error, then the Backup object is NOT constructed.
*
* @param[in] aDestDatabase Destination database connection
* @param[in] aSrcDatabase Source database connection
*
* @throw SQLite::Exception in case of error
*/
Backup(Database& aDestDatabase,
Database& aSrcDatabase);
// Backup is non-copyable
Backup(const Backup&) = delete;
Backup& operator=(const Backup&) = delete;
/**
* @brief Execute a step of backup with a given number of source pages to be copied
*
* Exception is thrown when SQLITE_IOERR_XXX, SQLITE_NOMEM, or SQLITE_READONLY is returned
* in sqlite3_backup_step(). These errors are considered fatal, so there is no point
* in retrying the call to executeStep().
*
* @param[in] aNumPage The number of source pages to be copied, with a negative value meaning all remaining source pages
*
* @return SQLITE_OK/SQLITE_DONE/SQLITE_BUSY/SQLITE_LOCKED
*
* @throw SQLite::Exception in case of error
*/
int executeStep(const int aNumPage = -1);
/// Return the number of source pages still to be backed up as of the most recent call to executeStep().
int getRemainingPageCount() const;
/// Return the total number of pages in the source database as of the most recent call to executeStep().
int getTotalPageCount() const;
private:
// Deleter functor to use with smart pointers to close the SQLite database backup in an RAII fashion.
struct Deleter
{
void operator()(sqlite3_backup* apBackup);
};
std::unique_ptr<sqlite3_backup, Deleter> mpSQLiteBackup; ///< Pointer to SQLite Database Backup Handle
};
} // namespace SQLite
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