Bug 5815 - Cross-Thread Check would be more tolerant within the UIDocument
Summary: Cross-Thread Check would be more tolerant within the UIDocument
Status: RESOLVED FIXED
Alias: None
Product: iOS
Classification: Xamarin
Component: Xamarin.iOS.dll ()
Version: 5.3.x
Hardware: Macintosh Mac OS
: --- normal
Target Milestone: Untriaged
Assignee: Bugzilla
URL:
Depends on:
Blocks:
 
Reported: 2012-06-22 04:34 UTC by tome
Modified: 2012-09-04 10:04 UTC (History)
2 users (show)

Tags:
Is this bug a regression?: ---
Last known good build:

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Status:
RESOLVED FIXED

Description tome 2012-06-22 04:34:20 UTC
The feature on MonoTouch 5.3.x's "Cross-Thread Check" is very useful.
But I met a minor trouble around the sub-class of UIDocument.
As you know, the some of the UIDocument's methods are called from background thread,
and if you would override the method as like;

public override bool Save (NSUrl url, out NSError outError)
{
    return base.Save (url, out outError);  // raises UIKitThreadAccessException here
}

however, it just invoke the method of the base, this would be an illegal call.
To avoid this,

public override bool Save (NSUrl url, out NSError outError)
{
  UIApplication.CheckForIllegalCrossThreadCalls = false;
  try {
    return base.Save (url, out outError);
  }
  finally {
    UIApplication.CheckForIllegalCrossThreadCalls = true;
  }
}

I have to write this kind of code every overridden methods though not so smart.
So, could you provide a solution about that, like an Attribute to mark the method
as no-check or something. Or set a flag to the specific background thread somehow.

[DisableIllegalCrossThreadCalls] // something like this
public override bool Save ...


Thanks, I dig Mono and MonoTouch also MonoDevelop
Comment 1 tome 2012-06-23 18:43:47 UTC
As far as I know this kind of system built-in async-calls in UIKit are UIDocument only (e.g. AutoSave)
So, this title of report has changed as 'within UIDocument', and it could be treated about UIDocument only in this time.
But, I suppose that is needed which the way to avoid the check by context.
Comment 2 Sebastien Pouliot 2012-09-04 10:04:51 UTC
There's a [ThreadSafe] attribute for this - but it's used when creating bindings (i.e. at build time) and  not for user code (which would be very costly, reflection, to check at runtime).

Fixed in:
master: 3db56f90647fabb6845374a6bf196f60c8ccb901
monotouch-5.4-series: 48c016c64c607dc11931b61b56ebbdec96a26d7b