异步的SqlCommand和CCR
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21-08-2019 - |
题
我一直在玩的演示代码从这个MSDN文章由杰弗里里希特。
我添加了一个新功能,他ApmToCcrAdapters处理SqlCommand.BeginExecuteReader。只有它被关闭之前读者我可以读取它。
下面的代码用于提供一个FromIteratorHandler:
private static IEnumerator<ITask> AsyncReaderDemoHandler()
{
SqlDataReader reader = null;
SqlConnection connection = new SqlConnection(@"Data Source=.\SQLEXPRESS;Initial Catalog=BizData;Integrated Security=True;Async=True;");
string query = "SELECT * FROM Account;";
SqlCommand command = new SqlCommand(query,connection);
connection.Open();
yield return Arbiter.Choice(ApmToCcrAdapters.GetReader(command),
delegate(SqlDataReader r) { Msg("Got SQL data"); reader = r; },
delegate(Exception e) { Msg("Failed to get SQL data"); });
connection.Close();
if (reader == null) yield break;
//This is where the code fails: Reader is Closed!
while (reader.Read())
{
Console.WriteLine(reader["Account"]);
}
}
,后者又调用以下代码:
/// <summary>
/// Gets the Reader, requires connection to be managed
/// </summary>
public static PortSet<SqlDataReader, Exception> GetReader(SqlCommand sqlCommand)
{
Port<SqlDataReader> portResponse = null;
Port<Exception> portException = null;
GetReaderResponse(sqlCommand, ref portResponse, ref portException);
return new PortSet<SqlDataReader, Exception>(portResponse, portException);
}
// Wrapper for SqlCommand's GetResponse
public static void GetReaderResponse(SqlCommand sqlCom,
ref Port<SqlDataReader> portResponse, ref Port<Exception> portException)
{
EnsurePortsExist(ref portResponse, ref portException);
sqlCom.BeginExecuteReader(ApmResultToCcrResultFactory.Create(
portResponse, portException,
delegate(IAsyncResult ar) { return sqlCom.EndExecuteReader(ar); }), null);
}
解决方案
在连接必须保持开放为读者工作。我相信,关闭连接是你的问题。离开连接打开并调用Dispose读者做,我认为应该清理连接时。
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