[ProgressBar] Empty iterable throws Exception on "maximum number of steps is not set" #47259

freimair · 2022-08-12T08:22:17Z

Q	A
Branch?	6.2
Bug fix?	yes
New feature?	no
Deprecations?	no
Tickets	Fix #47244
License	MIT
Doc PR

Bug Description
When using the progress bar with an empty input and time estimates, an error has been thrown which stopped the execution:

            $bar = new ProgressBar($output = $this->getOutputStream());
            $bar->setFormat("%elapsed%/%estimated%");

            $input = [];
            foreach ($bar->iterate($input) as $item)
                var_dump($item);

I dug around in the code and found a semantically incorrect check for getMaxSteps() that evaluated a maxSteps of 0 (because of an empty input) to be interpreted like maxSteps has not been set at all und thus, triggering

                if (!$bar->getMaxSteps())) {
                    throw new LogicException('Unable to display the .* time if the maximum number of steps is not set.');
                }

Fix Proposal

I propose to change the check to be semantically correct as in "0 is a valid value of maxSteps, null is not".

More details and a bit of discussion in #47244.

carsonbot · 2022-08-12T08:22:21Z

Hey!

I see that this is your first PR. That is great! Welcome!

Symfony has a contribution guide which I suggest you to read.

In short:

Always add tests
Keep backward compatibility (see https://symfony.com/bc).
Bug fixes must be submitted against the lowest maintained branch where they apply (see https://symfony.com/releases)
Features and deprecations must be submitted against the 6.2 branch.

Review the GitHub status checks of your pull request and try to solve the reported issues. If some tests are failing, try to see if they are failing because of this change.

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I am going to sit back now and wait for the reviews.

Cheers!

Carsonbot

freimair · 2022-08-12T08:48:15Z

well, the issues seems to be there since the creation of the progress bar #10356 back in 2014.

Has been merged into the 2.5-dev branch 554b28d.

Please let me know if I should PR against 2.8? I would opt for including it in v6, because stirring up code that old seems not reasonable to me. plus, nobody encountered the issue since then or people made sure not to iterate over emtpy arrays.

src/Symfony/Component/Console/Helper/ProgressBar.php

`max` value has been prepared to contain a `null` value, however, the constructor with its default value of `max = 0` prevents `$max` to ever be `null`. Hence, declare `$max` as `int` instead of `?int`.

Up until now, it has been very hard to determin whether a progressbar has a known maximum value or not, because the property `max` is an integer. Up until now, `max == 0` has been treated like we do _not_ know the `max` value. However, `max == 0` _is_ a valid `max` value when iterating over an empty but countable array for example. We cannot simply keep `max == null` if unknown, because that would break rendering mechanics and fixing those would require interface changes. Hence, enter `isMaxKnown` - a property which keeps track of whether the `max` value is known or not.

fabpot · 2022-08-26T16:12:28Z

src/Symfony/Component/Console/Helper/ProgressBar.php

@@ -50,7 +50,8 @@ final class ProgressBar
    private OutputInterface $output;
    private int $step = 0;
    private int $startingStep = 0;
-    private ?int $max = null;
+    private int $max = 0;
+    private bool $isMaxKnown = false;


Do we need this new variable? I suppose 0 is not a valid max, so having max at 0 probably means that it is not known?

the whole point of this PR and the issue I found with Progessbars is that max = 0 IS a valid max value but it is treated like it is not.

we stumbled over that behavior because we need to do a lot of import/sync operations, nasty but necessary. Once in a while, one of our imports/sync iterables is empty and thus max value = 0. foreach([] as ...) does not throw errors in vanilla PHP. Using the progressbar with foreach($bar->iterate([]) as ...) does.

jwilson-ind · 2023-10-11T14:10:54Z

I see this PR is in milestone 6.4 - does that mean that this fix will be in the 6.4 release?

jwilson-ind · 2023-10-11T14:43:20Z

I'd like to note that I believe this fix isn't going to help if you just use start():

$progressBar = new ProgressBar( $output, 0 );
$progressBar->start();

This only helps when you trigger the bar with $progressBar->iterate([]) as the isMaxKnown is only set it the iterate method.

GromNaN · 2023-11-15T23:18:31Z

I submitted an alternative patch, using $max = null to indicate when the value is unknown. #52605

fabpot · 2023-11-16T18:04:47Z

Closing in favor of #52605

…ray (GromNaN) This PR was merged into the 7.1 branch. Discussion ---------- [Console] Support `ProgressBar::iterate()` on empty array | Q | A | ------------- | --- | Branch? | 6.4 | Bug fix? | yes | New feature? | no | Deprecations? | no | Issues | Fix #47244 | License | MIT Alternative to #47259 Use `$max = null` to indicate that the value is unknown. This allows `0` to be displayed by directly setting the progress bar to 100%. Zero is only supported for `iterate()`. When passed to the constructor or `setMaxSteps`, it means "unknown max". Commits ------- 574b8a3 Fix ProgressBar::iterate on empty iterator

freimair added 2 commits August 12, 2022 09:58

Fix: ProgressBar does not fail on emtpy Iterable

010af2a

Fix: divide by Zero chance in ProgressBar

50d6cd1

freimair requested a review from chalasr as a code owner August 12, 2022 08:22

carsonbot added Status: Needs Review Bug labels Aug 12, 2022

carsonbot added this to the 6.2 milestone Aug 12, 2022

fabpot requested changes Aug 19, 2022

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src/Symfony/Component/Console/Helper/ProgressBar.php Outdated Show resolved Hide resolved

carsonbot added Status: Needs Work and removed Status: Needs Review labels Aug 19, 2022

freimair added 3 commits August 23, 2022 10:08

Set max to int since it cannot be null

eac82fc

`max` value has been prepared to contain a `null` value, however, the constructor with its default value of `max = 0` prevents `$max` to ever be `null`. Hence, declare `$max` as `int` instead of `?int`.

Ui work

d0cc3bd

freimair requested review from fabpot and removed request for chalasr August 24, 2022 06:52

carsonbot added Status: Needs Review and removed Status: Needs Work labels Aug 24, 2022

fabpot reviewed Aug 26, 2022

View reviewed changes

nicolas-grekas modified the milestones: 6.2, 6.3 Nov 5, 2022

freimair mentioned this pull request Mar 2, 2023

[ProgressBar] Empty iterable throws Exception on "maximum number of steps is not set" #47244

Closed

nicolas-grekas modified the milestones: 6.3, 6.4 May 23, 2023

Set maxKnown also in start function

42a0884

nicolas-grekas modified the milestones: 6.4, 7.1 Nov 15, 2023

nicolas-grekas added this to the 6.4 milestone Nov 15, 2023

GromNaN mentioned this pull request Nov 15, 2023

[Console] Support ProgressBar::iterate() on empty array #52605

Merged

fabpot closed this Nov 16, 2023

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[ProgressBar] Empty iterable throws Exception on "maximum number of steps is not set" #47259

[ProgressBar] Empty iterable throws Exception on "maximum number of steps is not set" #47259

freimair commented Aug 12, 2022

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fabpot commented Nov 16, 2023

[ProgressBar] Empty iterable throws Exception on "maximum number of steps is not set" #47259

[ProgressBar] Empty iterable throws Exception on "maximum number of steps is not set" #47259

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