Not sure what I'm doing wrong:
class MyClass
{
private EventInfo eventInfo;
public void OnGenerateEvent(object sender, EventArgs e)
{
// Called from *main* thread
// Load assembly and set eventInfo here
eventInfo = ....GetEvent(...);
eventInfo.AddEventHandler(source, handler);
// Call to a static method in another assembly
someMethodInfo.Invoke(null, null);
}
public void OnEventChanged(object sender, 开发者_如何学编程EventArgs args)
{
// Called from a *worker* thread created
// by that static method in the other assembly
eventInfo is null here !
// Trying to remove handler
eventInfo.RemoveEventHandler(.....);
}
// But...
protected override void Dispose(bool disposing)
{
// Called from *main* thread when program closes
eventInfo is *not* null here
}
}
I think we'd need to see reproducible code, but I can see 4 scenarios:
- you are talking to a different
MyClass
instance in the two cases - my bet is here - you have a variable called
eventInfo
in one of the methods (try usingthis.eventInfo
when you mean the field if there is any ambiguity) - the write or read is cached (try marking the field
volatile
; again unlikely) - a thread-specific field (thread-local storage) - very unlikely
The first two are much more likely.
You'll need to do at least one of the following:
make
eventInfo
volatile to ensure thatOnGenerateEvent()
writes it all the way out to memory before callingsomeMethodInfo.Invoke()
use something like a mutex/lock to protect access to
eventInfo
. This will also provide the proper memory barriers (this is what really should be done in my opinion)
Oh, and I'm assuming that there aren't really 2 different MyClass
instances involved - that can't be verified by the code you've shown.
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