Question

我有一个使用Entity Framework和MySQL数据库的ASP.NET Web应用程序。我正在使用动态表做一些工作，所以已经使用编写原始SQL。有什么我需要添加，以使这个代码线程安全吗？对于我的系统的每个用户，可以并且将非常频繁地调用此代码。它始终是针对INFORMATION_SCHEMA的错误调用。

以下是我经常尝试拨打AddMessageAction但不是每次都会收到的错误：

UserActionModel:CheckTableExists ex: The underlying provider failed on Open..
4/23/2013 9:00:24 AM: UserActionModel:CheckTableExists inner ex: System.NotSupportedException: Multiple simultaneous connections or connections with different connection strings inside the same transaction are not currently supported.
   at MySql.Data.MySqlClient.ExceptionInterceptor.Throw(Exception exception)
   at MySql.Data.MySqlClient.MySqlConnection.Throw(Exception ex)
   at MySql.Data.MySqlClient.MySqlConnection.Open()
   at System.Data.EntityClient.EntityConnection.OpenStoreConnectionIf(Boolean openCondition, DbConnection storeConnectionToOpen, DbConnection originalConnection, String exceptionCode, String attemptedOperation, Boolean& closeStoreConnectionOnFailure).

代码：

public static class UserActionModel
{

private const string databaseName = "chat";

public static string CheckTableExists(long _userId)
{
    string tableName = null;
    List<long> tableExists;

    try
    {
        string date = DateTime.Now.ToUniversalTime().Year.ToString() + DateTime.Now.ToUniversalTime().Month.ToString("D2") + DateTime.Now.ToUniversalTime().Day.ToString("D2");

        tableName = "user_actions_" + date + "_" + _userId;

        string sql = "SELECT COUNT(*) FROM information_schema.TABLES WHERE TABLE_NAME = '" + tableName + "' AND TABLE_SCHEMA = 'archive'";

        using (var readContext = new ArchiveConnector())
        {
            tableExists = readContext.Database.SqlQuery<long>(sql).ToList();
            readContext.Database.Connection.Close();
        }

        if (tableExists.Any(tableExist => tableExist == 0))
        {
            sql = "CREATE TABLE IF NOT EXISTS `" + tableName + "` ("
                  + "`id` bigint(20) NOT NULL AUTO_INCREMENT, "
                  + "`user_id` bigint(20) NOT NULL, "
                  + "`user_device_id` bigint(20) NOT NULL, "
                  + "`coordinate_address_id` bigint(20) NOT NULL, "
                  + "`message_id` bigint(20) DEFAULT NULL, "
                  + "`created` datetime NOT NULL, "
                  + "PRIMARY KEY (`id`), "
                  + "KEY `user_id` (`user_id`), "
                  + "KEY `user_device_id` (`user_device_id`), "
                  + "KEY `coordinate_address_id` (`coordinate_address_id`), "
                  + "KEY `message_id` (`message_id`); "

            using (var writeContext = new ArchiveConnector())
            {
                writeContext.Database.ExecuteSqlCommand(sql);
                writeContext.SaveChanges();
                writeContext.Database.Connection.Close();

            }
        }
    }
    catch (Exception ex)
    {
        Logger.LogMessage("UserActionModel:CheckTableExists ex: " + ex.Message);

        if (ex.InnerException != null)
            Logger.LogMessage("UserActionModel:CheckTableExists inner ex: " + ex.InnerException);

        tableName = null;
    }

    return tableName;
}

public static void AddMessageAction(long _messageId, long _userId, long _userDeviceId, long _coordinateAddressId)
{
    try
    {
        string tableName = CheckTableExists(_userId);

        if (String.IsNullOrEmpty(tableName)) return;

        using (var dataContext = new ArchiveConnector())
        {
            string sql = "INSERT INTO " + tableName + " "
                + "(user_id, user_device_id, coordinate_address_id, message_id, created) "
                + "VALUES "
                + "(" + _userId + ", " + _userDeviceId + ", " + _coordinateAddressId + ", " + _messageId + ", NOW());";

            dataContext.Database.ExecuteSqlCommand(sql);
            dataContext.SaveChanges();
        }
    }
    catch (Exception ex)
    {
        Logger.LogMessage("UserActionModel:AddMessageAction (" + _messageId + ") ex: " + ex.Message);
    }
}
}

从我的web.config连接字符串中删除persist security info=True没有任何区别（我读到这是一个可能的解决方案）。

UDPATE：从连接器6.6.4更新到6.6.5。没变。 UDPATE：从连接器6.6.5更新到6.7.1 Alpha。没有变化。

Answer 1

ArchiveConnector的{{1}}方法未关闭其MySQL连接。当你：

Dispose

连接：

using (var writeContext = new ArchiveConnector())

仍处于打开状态，MySQL不支持同一事务上的多个连接。确保您的连接已在using (var readContext = new ArchiveConnector())上关闭。

祝你好运。

Answer 2

我是在AddMessageAction()内的另一个连接器上呼叫我的using。不要这样做。

零星的“目前不支持多个同时连接”

2 个答案: