| Bug #53097 | Connection.Ping() closes connection if executed on a connection with datareader | ||
|---|---|---|---|
| Submitted: | 23 Apr 2010 8:04 | Modified: | 30 Mar 2011 21:34 |
| Reporter: | Juergen Steinblock | Email Updates: | |
| Status: | Closed | Impact on me: | |
| Category: | Connector / NET | Severity: | S3 (Non-critical) |
| Version: | 6.1.3.0 | OS: | Microsoft Windows |
| Assigned to: | Iggy Galarza | CPU Architecture: | Any |
| Tags: | MySqlConnection DataReader Ping | ||
[26 Apr 2010 11:36]
Tonci Grgin
Hi Juergen and thanks for your report. Verified against trunk sources. Second reader.Read(); throws: "Object reference not set to an instance of an object." at MySql.Data.MySqlClient.NativeDriver.FetchDataRow(Int32 statementId, Int32 columns) in E:\bzr-repos\connectors\cNET\clones\trunk\MySql.Data\Provider\Source\NativeDriver.cs:line 845 at MySql.Data.MySqlClient.Driver.FetchDataRow(Int32 statementId, Int32 columns) in E:\bzr-repos\connectors\cNET\clones\trunk\MySql.Data\Provider\Source\Driver.cs:line 363 at MySql.Data.MySqlClient.ResultSet.GetNextRow() in E:\bzr-repos\connectors\cNET\clones\trunk\MySql.Data\Provider\Source\ResultSet.cs:line 173 at MySql.Data.MySqlClient.ResultSet.NextRow(CommandBehavior behavior) in E:\bzr-repos\connectors\cNET\clones\trunk\MySql.Data\Provider\Source\ResultSet.cs:line 196 at MySql.Data.MySqlClient.MySqlDataReader.Read() in E:\bzr-repos\connectors\cNET\clones\trunk\MySql.Data\Provider\Source\datareader.cs:line 875 at WindowsFormsApplication1.Form1.bnBug53097_Click(Object sender, EventArgs e) in C:\Users\Administrator\Documents\Visual Studio 2008\Projects\WindowsFormsApplication1\WindowsFormsApplication1\Form1.cs:line 1775
[26 Apr 2010 11:48]
Juergen Steinblock
Thanks for dealing with this. Please notice that the Exception isn't the initial problem but a result of closing a connection while the DataReader is still reading (you shouldn't do that). I just included it for demonstration. My problem is (I'm afraid I didn't highlight that sufficient) the behaviour of the Ping() method, which just closes my Connection even if everything's allright. Greetings from germany
[26 Apr 2010 11:51]
Tonci Grgin
Thanks for clarification Juergen. Let's see what Reggie has to say (my exception doesn't look quite ok either).
[26 Apr 2010 11:58]
Tonci Grgin
And yes, ConnectionState state4 = conn.State is *closed*.
[11 Jun 2010 1:30]
Bugs System
A patch for this bug has been committed. After review, it may be pushed to the relevant source trees for release in the next version. You can access the patch from: http://lists.mysql.com/commits/110777 815 iggy galarza 2010-06-10 Bug #53097 - Connection.Ping() closes connection if executed on a connection with datareader - Throw an exception if dataReader is present when Ping is called.
[11 Jun 2010 13:34]
Bugs System
A patch for this bug has been committed. After review, it may be pushed to the relevant source trees for release in the next version. You can access the patch from: http://lists.mysql.com/commits/110842 815 Iggy Galarza 2010-06-11 [merge] Bug #53097 Connection.Ping() closes connection if executed on a connection with datareader - Added check for existing DataReader to Ping().
[30 Mar 2011 21:34]
Reggie Burnett
Fixed in 6.1.5
Description: If I have an DataReader associated to a MySqlConnection and then execute Connection.Ping() the Connection is closed and Ping() returns false. I suspect that the Ping() closes the connection if the internal check fails, but the check uses a DataReader itself. And if there is already an open DataReader the Exception gets swallowed and the connection is closed. How to repeat: // this is a simple C# sample to reproduce the behaviour MySqlConnection conn = new MySqlConnection("server=localhost;database=mysql;userid=root;"); conn.Open(); MySqlCommand command = new MySqlCommand("SELECT * FROM help_topic", conn); ConnectionState state1 = conn.State; // open bool result1 = conn.Ping(); // true ConnectionState state2 = conn.State; // open MySqlDataReader reader = command.ExecuteReader(); reader.Read(); ConnectionState state3 = conn.State; // open bool result2 = conn.Ping(); // false ConnectionState state4 = conn.State; // close reader.Read(); // throws FormatException; Suggested fix: The Connection.Ping() method should either - Throw a MySqlException("There is already an open DataReader associated with this connection") (I would prefer that) - Do not close the Connection.