Question

我有一个具有以下结构的交叉线程操作。

异常是当我在记录查询操作上放置断点时，记录不为空。但是，当我删除断点并让程序执行时，记录始终为null。我确保记录检索过程是正确的。这是某种跨线程操作异常吗？

这是调用程序

    Invoke(new Action(() =>
    {
        var filters = new KeyValuePair<string, object>[]
          {
            new KeyValuePair<string, object>("from_userid", ParentMessage.from_userid),
            new KeyValuePair<string, object>("to_userid", this.SourceUser.id),
            new KeyValuePair<string, object>("group_header_id", ParentMessage.group_header_id),
            new KeyValuePair<string, object>("message", ParentMessage.message),
            new KeyValuePair<string, object>("is_read", 0)
          };

            MessagerLogModel MessageLog = null;

            MessageLog = MessagerLogs.CustomFilter(filters).FirstOrDefault();


            if (MessageLog == null)
            {
                MessageBox.Show("message log model not found in database.");
                return;
            }
}));

并且，这是检索数据库记录的操作。

public static List<MessagerLogModel> CustomFilter(KeyValuePair<string, object>[] _params)
{
    var result = new List<MessagerLogModel>();

    string Query = @"SELECT * FROM messager_logs";

    List<MySqlParameter> commandParams = new List<MySqlParameter>();

    foreach (KeyValuePair<string, object> param in _params)
    {
        if (commandParams.Count == 0)
            Query += " WHERE ";
        else
            Query += " AND ";

        if (param.Value == DBNull.Value)
            Query += param.Key + " IS @" + param.Key;

        else
            Query += param.Key + " = @" + param.Key;


        commandParams.Add(new MySqlParameter("@" + param.Key, param.Value));
    }

    MySqlDataReader r =
        MySqlHelper.ExecuteReader(Shared.getConnectionString(),
        Query, commandParams.ToArray());

    while (r.Read())
        result.Add(dataToModel(r));

    r.Close();

    return result;
}

Answer 1

问题是＆＃34; lambda＆＃34;在你的行动中。在那里包含一些值：在定义lambda时，它们不会被复制到lambda表达式中，但是在执行lambda时。像ParentMessage.from_userid这样的成员变量可能同时发生了变化。

跨线程操作的异常行为

1 个答案: