[Mono-dev] StackOverflow on System.Delegate.Equals

[Alan]

Hey,

Well the other thing is that the delegate class is supposed to be
immutable. Therefore it should be impossible to produce a corrupt
delegate through multithreaded access as any modification to a
delegate instance results in a new copy of the delegate (with
modification) being created, just like for string operations. If what
we're seeing is truly a corrupt delegate instance then it's a bug in
mono that this is able to occur.

Alan

On Mon, Apr 4, 2011 at 10:54 PM,  <kralu at poczta.onet.pl> wrote:
> On Mon, 2011-04-04 22:41:47 nekresh <nekresh at gmail.com> wrote:
>> On Mon, Apr 4, 2011 at 10:37 PM,  <kralu at poczta.onet.pl> wrote:
>> > On Mon, 2011-04-04 22:03:47 Gonzalo Paniagua Javier <gonzalo.mono at gmail.com> wrote:
>> >> On Mon, 2011-04-04 at 20:48 +0100, Alan wrote:
>> >> > Aren't event handler methods emitted with a [synchronized] attribute
>> >> > by default which would prevent this issue? You can check by
>> >> > disassembling the IL and seeing if its there.
>> >>
>> >> They are synchronized as long as you don't replace the default
>> >> add/remove with your own code.
>> >
>> > AFAIK you cannot inherit from the Delegate/MulticastDelegate class. So how can I replace the default add/remove code? Anyway I'm almost sure that case has no place in my code but I have to take a look on 3rd part libraries.  Thanks in advance for any help.
>> >
>> public event MyType MyEvent {
>>   add { }
>>   remove { }
>> }
>
> Ok, thanks. I found in Telerik's code a few places where code looks like:
>                public event XmlHttpPanelEventHandler ServiceRequest
>                {
>                        add
>                        {
>                                base.Events.AddHandler(WebServiceRequestEvent, value);
>                        }
>                        remove
>                        {
>                                base.Events.RemoveHandler(WebServiceRequestEvent, value);
>                        }
>                }
>
> The base.Events is a property of the WebControl class. Maybe that's the problem?
> I've also took a look on a code generated for a "default" event handler (from my class):
>
> internal event EventHandler<MenuItemClickedEventArgs> ItemClicked
> {
>    add
>    {
>        EventHandler<MenuItemClickedEventArgs> handler2;
>        EventHandler<MenuItemClickedEventArgs> itemClicked = this.ItemClicked;
>        do
>        {
>            handler2 = itemClicked;
>            EventHandler<MenuItemClickedEventArgs> handler3 = (EventHandler<MenuItemClickedEventArgs>) Delegate.Combine(handler2, value);
>            itemClicked = Interlocked.CompareExchange<EventHandler<MenuItemClickedEventArgs>>(ref this.ItemClicked, handler3, handler2);
>        }
>        while (itemClicked != handler2);
>    }
>    remove
>    {
>        EventHandler<MenuItemClickedEventArgs> handler2;
>        EventHandler<MenuItemClickedEventArgs> itemClicked = this.ItemClicked;
>        do
>        {
>            handler2 = itemClicked;
>            EventHandler<MenuItemClickedEventArgs> handler3 = (EventHandler<MenuItemClickedEventArgs>) Delegate.Remove(handler2, value);
>            itemClicked = Interlocked.CompareExchange<EventHandler<MenuItemClickedEventArgs>>(ref this.ItemClicked, handler3, handler2);
>        }
>        while (itemClicked != handler2);
>    }
> }
>
>
> Kind regards,
> Marcin
>
>
>
>
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