Effects: sync .stop/.finish with .tick to maintain proper queue (#3497)

[preethi26]

#3497

Summary

1.Whenever the .finish or the .stop functions modify the timers queue, we maintain all those indexes that are removed in a list ( i.e, lis[ ] ). Whenever the tick function iterates over the queue, we update the iterator based on the value of the indexes removed ( only when the indexes less than the current iterator value are removed there will be a skipping over the animations ).

2. Handled extra processing of the same animation by doing as mentioned below:
   All the new animations that are added to the timers queue in the middle of a particular iteration of the tick function are processed in the next iteration.

Checklist

• Handled the "skipping over multiple animations " of tick function.
• Handled extra processing.

[mention-bot]

@preethi26, thanks for your PR! By analyzing the history of the files in this pull request, we identified @jeresig, @gnarf and @timmywil to be potential reviewers.

[gibson042]

I'm hoping to avoid O(N²) operations and extra global variables, and was thinking we'd do this by checking/clearing timer.elem since that's already cleared in an always callback.

[preethi26]

ok ! not a problem.
I would like to know if the second bug about extra processing was handled?
As I wasn't sure about it I did not mark it in the checklist.

[gibson042]

Probably not, but we'll see. This PR will also require unit tests that don't pass without the updated code.

[preethi26]

hey @gibson042 ,

jQuery.timers = [];
jQuery.fx.tick = function() {

var timer,
	i = 0,
	timers = jQuery.timers;

fxNow = jQuery.now();
for ( ; i < timers.length; i++ ) {
	timer = timers[ i ];
	var x  = timers.indexOf(timer)
	
	if (  !timer()  ) {
		if( x > timers.indexOf(timer)) {
			i = i - ( x - timers.indexOf(timer) )
		}

		if( timers[ i ] === timer ) {
			timers.splice( i--, 1 );
		}
	}
}

if ( !timers.length ) {
	jQuery.fx.stop();
}
fxNow = undefined;

};
This is the edited [ jQuery.fx.tick()] https://github.com/jquery/jquery/blob/master/src/effects.js#L644) function.
I would like to know if this fixes the first part of the bug before proceeding further.

Thank you,
Preethi.

[preethi26]

@gibson042. Sorry, just realized that it wouldn't work. Coz we need to check the value of "timer" 's index in between consecutive iterations ( which is not done here ).

[preethi26]

@gibson042

In every iteration, making the value of the iterator equal to the value of the previous timer that successfully ran + 1.

[markelog]

@preethi26 friendly ping

[gibson042]

This is really not what I'm looking for; see my comment about O(N²) operations and extra global variables. And note that a functional change will absolutely not be accepted without unit tests.

[preethi26]

@gibson042 ,
Got it, and I am sorry for the previous mess. As I am less familiarised with the Source Code, I don't have much of clarity on what you meant in your first comment ( because of which I think I overlooked it and thought of some other solution that avoids O(N²) operations and new global variables, sorry for that ). Could you please brief me a little as I would like to fix and finish working on this issue ( if you didn't find the code that you were already working on ? )

[gibson042]

No problem. As I mentioned in the comment, I think we can mostly cover this by checking and deleting the elem property of items in jQuery.timers instead of manipulating the array itself, at least inside iterations over it (i.e., extending already existing logic so jQuery.timers can temporarily hold zombie entries). Outside the iterations, though, we may well need a global mutex variable.

[mgol]

Closing & re-opening the PR to trigger the EasyCLA check...

[linux-foundation-easycla]

• ❌ - Preethi Pravalika The commit (ae094b1 ,c6753d36283a66e57443f4b4d5693d21d189dae2) is not authorized under a signed CLA. Please click here to be authorized. For further assistance with EasyCLA, please submit a support request ticket.