RepeatedField: unset by index

[Leprechaunz]

Instead of using array_pop() to remove last element use unset() to remove by index

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[haberman]

Looks like the change is failing in CI.

[Leprechaunz]

@haberman I think it fixed it. Could you please run CI tests again?

[haberman]

Looks like it is still failing:

==5074== Memcheck, a memory error detector
==5074== Copyright (C) 2002-2017, and GNU GPL'd, by Julian Seward et al.
==5074== Using Valgrind-3.14.0 and LibVEX; rerun with -h for copyright info
==5074== Command: php -dextension=ext/google/protobuf/modules/protobuf.so vendor/bin/phpunit --bootstrap tests/force_c_ext.php tests
==5074==
PHPUnit 8.5.26 #StandWithUkraine

....WW....E.S..................................................  63 / 399 ( 15%)
............................................................... 126 / 399 ( 31%)
.............................WW................................ 189 / 399 ( 47%)
.....SS...WWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWW..WW.WWWW.....WW..... 252 / 399 ( 63%)
..SSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSS............... 315 / 399 ( 78%)
............................................................... 378 / 399 ( 94%)
.....................                                           399 / 399 (100%)

Time: 10.54 seconds, Memory: 0 bytes

There was 1 error:

1) ArrayTest::testInsertRemoval
Element at 3 doesn't exist.

[Leprechaunz]

@haberman Thanks for logs. Should be fixed now.

Replaced unset with array_splice to reindex keys. But I'm sure this behaviour is correct for PHP.

If initial array was [0 => "a", 1 => "b", 2 => "c"] and we unset index 1 then we will result in [0 => "a", 1 => "c"]. But normal PHP unset should result in [0 => "a", 2 => "c"].

WDYT?

[bshaffer]

@Leprechaunz we should remain consistent with how PHP treats unset, and not reindex the array. Why not just use unset instead of array_splice?

[Leprechaunz]

@bshaffer It's easy to do it for PHP. But extension written in C works differently.

RepeatedField uses upb_Array structure (basically array) and converts it into map later. We can set NULL, but not remove specific key. I'm not a huge C expert, but only solution I see is to replace upb_Array with upb_Map in RepeatedField in extension implementation. Sounds like a huge change for small bug like this.

Maybe someone more experienced has better ideas?

[bshaffer]

@Leprechaunz thank you for the explanation, that makes sense! It's also probably why the original implementation was written like it is (only unsetting the last element).

Since this is new behavior, I think the way you've implemented it makes sense (given that it isn't a breaking change and is consistent between the extension and the native implementation).

I'm not the maintainer of this library though, so it'll be up to them. Thanks for your work on this!

[Leprechaunz]

@haberman Could you please re-run tests?

[haberman]

The approach in this PR makes sense to me. Protobuf repeated fields are always dense: there is no way to have gaps or missing indices in the middle. So we definitely don't want a repeated field to use upb_Map.

[Leprechaunz]

@haberman Sorry to bother you, but I updated my branch and re-run tests. Everything works localy. Could you please re-run tests?

[Leprechaunz]

Merge of this PR is blocked because of "Tests / Check for Safety". Is there something I can do about it? Or maintainers will handle it?

[fowles]

I think you need to rebase this onto our latest head. We have had a bunch of updates to our CI recently.