Ensure new Revisions UI works reasonably well with hundreds of revisions

[adamsilverstein]

Description

Some WordPress sites may have hundreds or even thousands of revisions. Even though high numbers of revisions may be rare, we should still account and test for it, at the very least we should document the known limitations.

When we rewrote revisions to the current UI we maybe too clever approach to loading the revisions that kept retrying smaller batches down going one at a time.

Related: https://core.trac.wordpress.org/ticket/24958

Step-by-step reproduction instructions

1. create a post with several pages of text content (a large post)
2. generate hundreds of revisions of the post
3. open the revisions UI, try navigating revisions
4. compare to using the old UI

Screenshots, screen recording, code snippet

No response

Environment info

No response

Please confirm that you have searched existing issues in the repo.

• Yes

Please confirm that you have tested with all plugins deactivated except Gutenberg.

• Yes

Please confirm which theme type you used for testing.

• Block
• Classic
• Hybrid (e.g. classic with theme.json)
• Not sure

[adamsilverstein]

cc: @ellatrix

[Mamaduka]

We could fetch the last X revisions (10, 20 or 100) and use the response headers to render a slider or other UI. The older revisions can be fetched on demand.

[ellatrix]

Yes, we'll probably have to fetch them by 100 and if they're more display prev/next or arrow buttons. It's not pretty but that would be the fast fix. Additionally we'll also have a paginated timeline view at some point so the revisions can be browsed in two ways.

[adamsilverstein]

I did some testing with hundreds of revisions and the slider generally worked ok once all of the revisions loaded.

I'm using this script to quickly create the revisions:

wp eval '
$post_id = 2119;
$count   = 300;

$words = explode( " ", "lorem ipsum dolor sit amet consectetur adipiscing elit sed do eiusmod tempor incididunt ut labore et dolore magna aliqua enim ad minim veniam quis nostrud exercitation ullamco laboris nisi aliquip ex ea commodo consequat duis aute irure in reprehenderit voluptate velit esse cillum fugiat nulla pariatur excepteur sint occaecat cupidatat non proident sunt culpa qui officia deserunt mollit anim id est laborum" );

for ( $i = 1; $i <= $count; $i++ ) {
    $sentences = [];
    $num_sentences = wp_rand( 4, 8 );
    for ( $s = 0; $s < $num_sentences; $s++ ) {
        $len = wp_rand( 8, 18 );
        $picks = array_rand( $words, $len );
        $sentence = implode( " ", array_map( fn( $k ) => $words[ $k ], $picks ) );
        $sentences[] = ucfirst( $sentence ) . ".";
    }
    wp_update_post( [
        "ID"           => $post_id,
        "post_content" => implode( " ", $sentences ),
        "post_title"   => "Test Post (rev " . $i . ")",
    ] );
    if ( $i % 50 === 0 ) { WP_CLI::log( "Created $i revisions" ); }
}
WP_CLI::success( "Done." );
'

I tried ~300 first, which mostly looked fine:

then ~750. At that point the slider worked but the the ticks were not visible and occasionally got a spinner at the top:

---

on another note... one feature from the previous screen I noticed was missing @ellatrix - the ability to compare any two revisions (in the old UI, two handles would appear to let you select the revisions to compare). Is that something you intentinally dropped, or is it planned still?

[ellatrix]

I don't see much value in comparing two distinct revisions, but we can add it if it's missed. Would be good to check how many editors actually offer that.

Btw I fixed this issue through #77200, feel free to reopen if you encounter issues.