Optimize WeakDelegateReference by introducing TargetEquals, which tak…

[hermestobias]

…es 60% less time than comparing with Target if it's still alive, and makes WeakDelegateManager.RemoveListener take 90% less time in normal usage.

### Description of Change ###

In our application, we saw a lot of time being spent inside WeakDelegateManager.RemoveListener when injecting a view with many subviews (around 100 in total). This was due to WeakDelegateManager creating temporary Delegates for each DelegateReference in the list just to do comparisions. By introducing TargetEquals method, you can now test equality without actually using. Testing the fix locally showed that time spent in WeakDelegateManager.RemoveListener got reduced with 90% and made our view injection almost 3 seconds faster!

Bugs Fixed

#1796

API Changes

List all API changes here (or just put None), example:

Added:

• bool DelegateReference.TargetEquals(Delegate);

Behavioral Changes

None

PR Checklist

• Has tests (if omitted, state reason in description)
• Rebased on top of master at time of PR
• Changes adhere to coding standard

[dnfclas]

All CLA requirements met.

[brianlagunas]

Thank you for the PR, but I wish you would have submitted an issue first. These percentages need to be verified before I can merge this PR. Do you have any sample/test apps to confirm your statements? Specifically, I need to see the perf before the change was made, and then again after the changes are made. Then we can look at the numbers and calculate the exact percentage of improvement, if any exists.

[hermestobias]

I have only profiled our full closed source application (which is using Prism 6.3, so did the change there initially and rebased later).

I guess I can make a test application (in 7.X) to show the performance gains this optimization provides. Do you want me to provide that in form of an issue, and then refer to it from this?

[brianlagunas]

Yes please create a new issue, provide your findings, and link back to this PR. Thanks.

[hermestobias]

But it replaces expensive calls to CreateDelegate with GetMethodInfo, which it then can avoid for most cases where operands do not have the same target (which you can see are the majority of cases in WeakDelegateManager). But seeing is believing I guess...

[hermestobias]

This PR is a fix for #1796

[lock]

This thread has been automatically locked since there has not been any recent activity after it was closed. Please open a new issue for related bugs.