如何在ADO.NET对象上调用Dispose？ [英] How is Dispose called on ADO.NET objects?

问题描述

实现 IDbConnection ， IDbCommand 和 IDataReader 都实现了 IDisposable ，但是命令和读取器显然取决于Connection。我的问题是，我是否必须分别对每个这些对象都进行Dispose（）处理，还是将Connection对象的处理也对其他对象进行处理？

The database access classes that implement IDbConnection, IDbCommand and IDataReader all implement IDisposable, but obviously the Command and the Reader are dependent on the Connection. My question is, do I have to Dispose() of each these objects individually or will disposing of the Connection object dispose of the others too ?

也就是说，我可以这样做并保证我不会冒任何未托管资源未被释放的风险：

That is, can I do this and guarantee I'm not risking leaving any unmanaged resources not being freed:

using (IDbConnection conn = GetConnection())
{
      IDbCommand cmd = conn.CreateCommand();
      cmd.CommandText = " ..... ";
      IDataReader rdr = cmd.ExecuteReader();
      while (rdr.Read())
      {

      }
}

还是我必须这样做：

using (IDbConnection conn = GetConnection())
{
    using (IDbCommand cmd = conn.CreateCommand())
    {
        cmd.CommandText = " ..... ";
        using (IDataReader rdr = cmd.ExecuteReader())
        {
            while (rdr.Read())
            {

            }
        }
    }
}

或者此实现取决于它，所以它可能

Or is this implementation dependent, so it would potentially work using one database's provider but not for another's ?

推荐答案

最好的策略是在使用块时使用所有ADO.NET对象。

Best policy is to use all ADO.NET objects in using blocks- full stop.

在各种ADO.NET对象上进行一点反射，即会发现，如果未关闭/处置，事物或多或少会掉在地上。这样做的效果在很大程度上取决于您使用的提供程序-如果您使用的是下面带有非托管句柄的内容（ODBC，OleDb等），则可能会泄漏内存，因为我什么也没看到以终结器的方式。如果它是一个全托管的提供程序（例如SqlClient），它将最终得到清理，但是根据您持有的对象，最终可能会使数据库服务器上的资源使用时间比您想要的长得多

A little Reflector-ing on various ADO.NET objects shows that things will more or less be dropped on the floor if not Closed/Disposed. The effect of that will depend a lot on which providers you're using- if you're using something with unmanaged handles underneath (ODBC, OleDb, etc), you're probably going to leak memory, as I didn't see anything in the way of finalizers. If it's an all-managed provider (eg, SqlClient), it'll eventually get cleaned up, but depending on which objects you're holding onto, you could end up keeping resources in use on the DB server a lot longer than you want.

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