223910 - Mid-air collision should be hidden from users

Status: RESOLVED INVALID

(Bugzilla :: Creating/Changing Bugs, defect)

Description

[Tom Schneider]

User-Agent:       Mozilla/5.0 (Macintosh; U; PPC Mac OS X Mach-O; en-US; rv:1.5) Gecko/20031007
Build Identifier: Mozilla/5.0 (Macintosh; U; PPC Mac OS X Mach-O; en-US; rv:1.5) Gecko/20031007

I just got a collision:
------
Mid-air collision!
                
Mid-air collision detected!

Someone else has made changes to this bug at the same time you were trying to. T
he changes made were:

Added comments:


    ------- Additional Comment #60 From Eugene Pizzetta 2003-10-27 20:08 -------

I haven't seen the .html+.html problem, but it does .shtml.html and jhtml.html

This release shouldn't have been made, since the bug was reported on the release
candidates.

I've gone back to 1.4.1, which does not mess with .jpg files.

You have the following choices:

    *
      This will cause all of the above changes to be overwritten, except for the
 added comment(s).
    * Throw away my changes, and revisit bug 163254

-----

Apparently this happened because I submitted a bug within exactly the same
moment as someone else.

To deal with it, I backed up several pages, cut the text I had written,
moved forward, moved to the bug and reinserted.  That went in fine.

I should never have had to do this.

There is a trivial solution: if there is a collision, increment the
time of submission by 1 second (and handle the minutes and so on properly!!).
Then test for collision again.  These events are so rare that it should
be clear and the bug processed.  One COULD have an upper cap, say
60 seconds.  That would mean that 60 people had submitted simultanenously,
which is hard to imagine without it being caused by another bug ...



Reproducible: Didn't try

Steps to Reproduce:
1. submit bugs
2. submit bugs simultaneously?
3.

Actual Results:  
Mid-air collision!


Expected Results:  
It should have been totally invisible to me.

I don't care if my bug is submitted 2 seconds later!!

Comment 1

[Myk Melez [:myk] [@mykmelez]]

Sorry, but a mid-air collision is not a simultaneous submission, it's submission
of changes after someone else already submitted changes that you weren't privy
to (because you loaded the bug before the first set of changes went through). 
In this situation, it's vital for you to know what happened, because your
changes might not be valid anymore (or might override the changes the other
person made).

In other words, in the following situation:

person A loads bug
person B loads bug
person A submits changes to bug
person B submits changes to bug

... person B should know that the bug she is changing is not the same as it was
when she loaded it.  It now reflects person A's changes, and those changes
should not be arbitrarily undone (which submission of person B's changes will
cause), nor should person B submit her changes without knowing what person A has
just done.

Of course, there are many things to improve about mid-air collisions (f.e. more
intelligent merging of changes), but this feature is definitely needed and not
merely an artifact of a technical limitation.

Comment 2

[Tom Schneider]

Thanks for explaining, Myk!

So now I have a suggestion.  You have written up a very nice description
of the basic problem.  Could you please take that and add it to
the Mid-air collision page?  Then the next person will understand
it better.

Also, perhaps my scheme is not entirely useless.  I was simply putting
in a comment.  I had not changed code at all.  Under this circumstance,
my comments and the other persons were parallel.  So is there a way
to distinguish this case?  That is, "Additional Comments" would not
collide.  (Note:  I have not worked on code, so I don't know how that
works.)

Comment 3

[Myk Melez [:myk] [@mykmelez]]

Yes, I can add it to that page.  Where is it?

Yes, we could disable mid-air collisions for comments, but then people couldn't
edit their comments to take the other person's comments into account.  With the
mid-air collision (which allows you to edit your comments, then submit them),
you can do that (although since it doesn't allow you to isolate the comment
change, any other changes on your or the other person's part makes this feature
less useful).

Comment 4

[Tom Schneider]

Oh gee, sorry, I forgot to record the page.
I suppose one should be able to grep through the sources though,
as I did paste the exact text there.

It seems to me that being hit over the head with this collision
is not a good thing for comments.  In comments people are discussing
the situation and there well may be

One danger:  the message in comment #
says that I could OVERWRITE the other person's comment, and this
seemed totally unreasonable to me.  What right do I have to stop
this person from saying that?

Also, I did not go forward (for fear of overwriting the other person)
and so never got to a page where the Additional Comments were prefilled.
Instead, to be safe, I went back (using the Back button) and copied
them.  Then I went to the bug and pasted.  Does it really give you
the option?  I think there is another thread where that is discussed.

Yes, a related discussion is bug 53452.
It refers to bug 31117.
You may want to try to merge these lines ...
For some reson I did not pick up bug 31117 when I searched for 
'Mid-air collision'!  Oh, they are using "midair" and mine was following
the exact message ...  I suggest changing the name of bug 31117
so that it can be FOUND by a search with the defacto standard!