c++ - SQLite SQLITE_BUSY[5] 击中析构函数并使用 :memory:

Question

我将 C++ 和 SQLite 与 CppSQLite 包装器一起使用 (http://www.codeproject.com/Articles/6343/CppSQLite-C-Wrapper-for-SQLite)，当我尝试关闭()。

我知道这有时是由于未对语句调用 finalize 或诸如此类的原因造成的，但 CppSQLite 应该会为我解决这个问题。为此只使用一个线程，所以它不应该是并发的事情。我正在使用大部分 CppSQLite 类，包括编译语句和缓冲区。

SQLManager::SQLManager()
{
    // ... other code

    m_pSqlDb = new CppSQLite3DB();

    const char* gszFile = ":memory:";

    m_pSqlDb->open(gszFile);

    // ... other code

}


SQLManager::~SQLManager() 
{
    if(m_pSqlDb != NULL)
    {   
        try
        {
            remove("C:\\sqldump.db");
            m_pSqlDb->loadOrSaveDb(m_pSqlDb->mpDB, "C:\\sqldump.db", 1);
            m_pSqlDb->close();
            delete m_pSqlDb;
        }
        catch(CppSQLite3Exception e)
        {
            ASSERT(false);
        }
    }
}

然后我使用此处 (http://www.sqlite.org/backup.html) 中的以下代码将表从内存写入文件。

/*
** This function is used to load the contents of a database file on disk 
** into the "main" database of open database connection pInMemory, or
** to save the current contents of the database opened by pInMemory into
** a database file on disk. pInMemory is probably an in-memory database, 
** but this function will also work fine if it is not.
**
** Parameter zFilename points to a nul-terminated string containing the
** name of the database file on disk to load from or save to. If parameter
** isSave is non-zero, then the contents of the file zFilename are 
** overwritten with the contents of the database opened by pInMemory. If
** parameter isSave is zero, then the contents of the database opened by
** pInMemory are replaced by data loaded from the file zFilename.
**
** If the operation is successful, SQLITE_OK is returned. Otherwise, if
** an error occurs, an SQLite error code is returned.
*/
int loadOrSaveDb(sqlite3 *pInMemory, const char *zFilename, int isSave){
  int rc;                   /* Function return code */
  sqlite3 *pFile;           /* Database connection opened on zFilename */
  sqlite3_backup *pBackup;  /* Backup object used to copy data */
  sqlite3 *pTo;             /* Database to copy to (pFile or pInMemory) */
  sqlite3 *pFrom;           /* Database to copy from (pFile or pInMemory) */

  /* Open the database file identified by zFilename. Exit early if this fails
  ** for any reason. */
  rc = sqlite3_open(zFilename, &pFile);
  if( rc==SQLITE_OK ){

    /* If this is a 'load' operation (isSave==0), then data is copied
    ** from the database file just opened to database pInMemory. 
    ** Otherwise, if this is a 'save' operation (isSave==1), then data
    ** is copied from pInMemory to pFile.  Set the variables pFrom and
    ** pTo accordingly. */
    pFrom = (isSave ? pInMemory : pFile);
    pTo   = (isSave ? pFile     : pInMemory);

    /* Set up the backup procedure to copy from the "main" database of 
    ** connection pFile to the main database of connection pInMemory.
    ** If something goes wrong, pBackup will be set to NULL and an error
    ** code and  message left in connection pTo.
    **
    ** If the backup object is successfully created, call backup_step()
    ** to copy data from pFile to pInMemory. Then call backup_finish()
    ** to release resources associated with the pBackup object.  If an
    ** error occurred, then  an error code and message will be left in
    ** connection pTo. If no error occurred, then the error code belonging
    ** to pTo is set to SQLITE_OK.
    */
    pBackup = sqlite3_backup_init(pTo, "main", pFrom, "main");
    if( pBackup ){
      (void)sqlite3_backup_step(pBackup, -1);
      (void)sqlite3_backup_finish(pBackup);
    }
    rc = sqlite3_errcode(pTo);
  }

  /* Close the database connection opened on database file zFilename
  ** and return the result of this function. */
  (void)sqlite3_close(pFile);
  return rc;
}

我真的不确定为什么会出现忙错误，除非写出尚未完成或保持锁定状态或其他原因。任何建议将不胜感激。谢谢!

编辑:

我认为这可能是我的编译语句，但我确保对所有这些语句都调用了 finalize()，并且编译语句的析构函数无论如何都调用了 finalize()。还是卡住了:(

它似乎也与 loadOrSaveDb() 函数无关，也与写入 :memory: 无关。

Answer 1

事实证明这是编译语句，但我仍然不确定为什么。不过我把它们拿出来了，效果很好。