Unhandled NullReferenceException when closing FbRemoteEvent
-----------------------------------------------------------
Key: DNET-541
URL: http://tracker.firebirdsql.org/browse/DNET-541
Project: .NET Data provider
Issue Type: Bug
Components: ADO.NET Provider
Affects Versions: 4.1.0.0
Environment: WPF application, .Net 4.5 (c#) , Firebird Server
2.5.2.26536 accessed via 127.0.0.1, VS2012 on Win7 x64 Prof.
Reporter: G. Krug
Assignee: Jiri Cincura
Priority: Blocker
I have opened an event registration like shown in example at
http://www.firebirdsql.org/en/net-examples-of-use/ .
CreateConnection creates a new unpooled connection which is only used for this
event (beside other connections with Pooling=true) :
FbRemoteEventEventHandler handler = new
FbRemoteEventEventHandler(this.Update_Event);
FbConnection conn = CreateConnection();
FbRemoteEvent rv = new FbRemoteEvent(conn, dbEventNames);
rv.RemoteEventCounts += new FbRemoteEventEventHandler(handler);
rv.QueueEvents();
private void Update_Event(object sender, FbRemoteEventEventArgs e)
{
// do something
}
The registered event(s) are working fine then. If I want to stop event
processing with
fbEvent.RemoteEventCounts -= handler;
// In most cases an unhandled NullReferenceException is thrown, we can not
catch it here
try
{
fbEvent.CancelEvents();
}
catch (NullReferenceException nre)
{
// ignore, but log to debug output
}
if (conn .State != ConnectionState.Closed)
{
conn .Close();
}
conn.Dispose();
// hereafter
an unhandled exception is thrown as follows:
Exception: System.NullReferenceException: Der Objektverweis wurde nicht auf
eine Objektinstanz festgelegt.
bei FirebirdSql.Data.Common.RemoteEvent.EventCounts(Byte[] buffer) in
c:\Users\Jiri\Documents\devel\NETProvider\working\NETProvider\source\FirebirdSql\Data\Common\RemoteEvent.cs:Zeile
179.
bei
FirebirdSql.Data.Client.Managed.Version10.GdsEventManager.<>c__DisplayClassa.<ThreadHandler>b__7(Object
param0) in
c:\Users\Jiri\Documents\devel\NETProvider\working\NETProvider\source\FirebirdSql\Data\Client\Managed\Version10\GdsEventManager.cs:Zeile
201.
bei System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate
callback, Object args, Int32 numArgs)
bei MS.Internal.Threading.ExceptionFilterHelper.TryCatchWhen(Object source,
Delegate method, Object args, Int32 numArgs, Delegate catchHandler)
When stepping through the code inside my application there is a method in
RemoteEvent.cs which is called after cancelling events, closing and disposing
connection of that event (see code above):
public void EventCounts(byte[] buffer)
{
int pos = 1;
Charset charset = this.db.Charset;
....
and this Charset is already null which will lead to the reported exception. As
it is thrown asynchronously on the internal worker thread the exception gets
not catched by the main thread.
Both parts of code are getting called from main thread in an WPF application.
This problem is not reproducible with 4.0.0.0 but I had to update to the newest
version due to other bugs in there.
If there is any way to resolve this immediately, please post here,
Thank you in advance.
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