Question

I’m using C++ and SQLite with the CppSQLite wrapper (http://www.codeproject.com/Articles/6343/CppSQLite-C-Wrapper-for-SQLite) and I keep getting the SQLITE_BUSY error when I try to close().

I know that it’s sometimes caused by not calling finalize on statements or whatnot, but CppSQLite should take care of that for me. Only one thread is being used for this, so it shouldn’t be a concurrency thing. I AM making use of most of the CppSQLite classes, including the compiled statements and the buffer.

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);
        }
    }
}

And then I’m using the following code from here (http://www.sqlite.org/backup.html) to write the tables from memory out to a file.

/*
** 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;
}

I’m really not sure why I’m getting a busy error, unless the writing out hasn’t finished or keeps a lock or something. Any suggestions would be greatly appreciated. Thanks!

Edit:

I thought it might have been my compiled statements, but I made sure to call finalize() on all of them, and the destructors for the compiled statements call finalize() anyway. Still stuck 🙁

It also doesn’t appear to have anyhting to do with the loadOrSaveDb() function, nor does it appear to have to do with writing to :memory:.

Answer 1

Turns out that it WAS the compiled statements, but I’m still not sure why. I took them out though and it works fine.