参考代码
#include <sqlite3.h>
#include <iostream>
/*
** Perform an online backup of database pDb to the database file named
** by zFilename. This function copies 5 database pages from pDb to
** zFilename, then unlocks pDb and sleeps for 250 ms, then repeats the
** process until the entire database is backed up.
**
** The third argument passed to this function must be a pointer to a progress
** function. After each set of 5 pages is backed up, the progress function
** is invoked with two integer parameters: the number of pages left to
** copy, and the total number of pages in the source file. This information
** may be used, for example, to update a GUI progress bar.
**
** While this function is running, another thread may use the database pDb, or
** another process may access the underlying database file via a separate
** connection.
**
** If the backup process is successfully completed, SQLITE_OK is returned.
** Otherwise, if an error occurs, an SQLite error code is returned.
** 官网地址：https://sqlite.org/backup.html
*/int backupDb(sqlite3 *pDb, /* Database to back up */const char *zFilename /* Name of file to back up to */
// void(*xProgress)(int, int) /* Progress function to invoke */
){int rc; /* Function return code */sqlite3 *pFile; /* Database connection opened on zFilename */sqlite3_backup *pBackup; /* Backup handle used to copy data *//* Open the database file identified by zFilename. */rc = sqlite3_open(zFilename, &pFile);if( rc==SQLITE_OK ){/* Open the sqlite3_backup object used to accomplish the transfer */pBackup = sqlite3_backup_init(pFile, "main", pDb, "main");if( pBackup ){/* Each iteration of this loop copies 5 database pages from database** pDb to the backup database. If the return value of backup_step()** indicates that there are still further pages to copy, sleep for** 250 ms before repeating. */do {rc = sqlite3_backup_step(pBackup, 5);
// xProgress(sqlite3_backup_remaining(pBackup);sqlite3_backup_pagecount(pBackup);
// );if( rc==SQLITE_OK || rc==SQLITE_BUSY || rc==SQLITE_LOCKED ){sqlite3_sleep(250);}} while( rc==SQLITE_OK || rc==SQLITE_BUSY || rc==SQLITE_LOCKED );/* Release resources allocated by backup_init(). */(void)sqlite3_backup_finish(pBackup);}rc = sqlite3_errcode(pFile);}/* Close the database connection opened on database file zFilename** and return the result of this function. */(void)sqlite3_close(pFile);return rc;
}
#pragma once#include <sqlite3.h>
namespace hsm {
namespace common {/*** @brief 备份和恢复数据库数据* @param pInMemory 指向内存数据库的指针* @param zFilename 指向文件数据库目录的字符串指针* @param isSave 0：从文件数据库恢复到内存数据库* 1：从内存数据库备份到文件数据库* @return 状态码*/
int backup_or_restore(sqlite3 *pInMemory,const char* zFilename,int isSave){int rc;sqlite3 *pFile;sqlite3_backup *pBackup;sqlite3 *pTo;sqlite3 *pFrom;rc = sqlite3_open(zFilename,&pFile);if (rc == SQLITE_OK){pFrom = (isSave?pInMemory:pFile);pTo = (isSave?pFile:pInMemory);pBackup = sqlite3_backup_init(pTo,"main",pFrom,"main");if (pBackup){(void)sqlite3_backup_step(pBackup,-1);(void)sqlite3_backup_finish(pBackup);}rc = sqlite3_close(pFile);}return rc;
}
} // namespace common
} // namespace hsm
对于backup函数的调用例子
void KeyStorage::backup(const std::string &filename) {sqlite3 *pDB;int rc = sqlite3_open(MGMT_KEY_STORAGE_FILE, &pDB);if( rc==SQLITE_OK ){printf("open test.db OK!\n");rc = backupDb(pDB, MGMT_KEY_STORAGE_FILE);if( rc==SQLITE_OK ){printf("backupDb new.db OK!\n");} else {printf("backupDb new.db error!\n");}} else {printf("open test.db error!\n");}
}
参考链接
-
https://sqlite.org/backup.html
