Question

我有一些按预期工作的代码。

public class PlayCommand: IPlayCommand {

    // this code works but `_userService.GetById()` and `_userService.Save()` lock the UI.
    public void Execute(object parameter) {
        var vm = (HomeFragmentViewModel) parameter;

        // first hit on the database 
        var user = _userService.GetById(Mvx.Resolve < UserModel > ().Id);

        user.PlayPositions.First(p = > p.ChapterId == vm.UserPlayPosition.ChapterId).PlayPosition = _audioPlayer.CurrentPosition;

        // second hit on the database.
        _userService.Save(user);
    }
}

我遇到的问题是，如果我尝试从UI层卸载工作以加快性能，则用户不会得到保存。

// Even though I can see all lines executing, the database doesn't get updated
// when using this approach.
public void Execute(object parameter) {

    var vm = (HomeFragmentViewModel)parameter;

    ThreadPool.QueueUserWorkItem(o = > UpdateUserPlayPosition(vm));

    // also tried
    // new Task(() => UpdateUsersCurrentChapter(vm)).Start();

}

private void UpdateUserPlayPosition(HomeFragmentViewModel vm)
{
    var user = _userService.GetById(Mvx.Resolve<UserModel>().Id);

    user.PlayPositions.First(p => p.ChapterId == vm.UserPlayPosition.ChapterId).PlayPosition = _audioPlayer.CurrentPosition;

    // execute a new task to save the user back to the local database
    _userService.Save(user);
}

下次我向数据库询问CurrentPosition时，它仍然设置为原始值（0）。

我还注意到调试输出中有很多以下内容。

01-13 13:31:57.242 E/SQLiteLog(16542): (1) statement aborts at 2: [ROLLBACK] cannot rollback - no transaction is active

我确实尝试在我的ConnectionProvider的构造函数中的配置中将SQLite设置为MultiThread，但是当我第一次尝试命中数据库时它会抛出一个不同的异常。

public class DbConnectionProvider : IDbConnectionProvider
{
    private readonly string _connectionString;

    public DbConnectionProvider(string sqliteDatabasePath)
    {
        _connectionString = "Data Source=" + sqliteDatabasePath;
        SqliteConnection.SetConfig(SQLiteConfig.MultiThread);
    }

    public SqliteConnection GetOpenConnection()
    {
        var connection = new SqliteConnection(_connectionString);
        if (connection == null) throw new Exception("Could not create a database connection.");

        connection.Open();

        return connection;
    }
}

01-18 13:33:31.278 E/mono    (21714): System.Reflection.TargetInvocationException: Exception has been thrown by the target of an invocation. ---> Mono.Data.Sqlite.SqliteException: Library used incorrectly
01-18 13:33:31.278 E/mono    (21714):   at Mono.Data.Sqlite.SqliteConnection.SetConfig (SQLiteConfig config) [0x00000] in <filename unknown>:0

我正在使用Mono.Data.Sqlite v2.0.5.0 作为我的DbProvider的后端。

无法从Thread更新SQLite数据

0 个答案: