RTC Hybrid: Table with awareness in object cache when available.

[peterwilsoncc]

This combines to two best performing approaches following feedback from various stakeholders.

• Single table for collaboration updates
• Awareness stored in object cache only when a persistent cache is available, no attempt at DB writes is made.
• Awareness stored in table when a persistent cache is not available, writes to DB.

The awareness approach is taken from that used by transients but uses the new table as the fallback rather than storing the data in the object cache. This is to allow for the table optimized for collaboration to be used.

Forked from #11256
Trac ticket: https://core.trac.wordpress.org/ticket/64696

Props

The following WP.org accounts should be included in the props list in addition to any added by the bot below.

jorbin, czarate, desrosj, zieladam, joefusco, paulkevan, mindctrl, mukesh27, dmonad, westonruter

Use of AI Tools

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This Pull Request is for code review only. Please keep all other discussion in the Trac ticket. Do not merge this Pull Request. See GitHub Pull Requests for Code Review in the Core Handbook for more details.

[westonruter]

There are redundant is_numeric() checks and what's more, it is not checking for zero or negative numbers. This was accounted for previously by wrapping with an is_int( $object_id ) conditional. Why change that?

[westonruter]

Problem: $existing['type'] is not guaranteed to exist because ::get_updates_after_cursor() returns array<int, mixed>. So $existing here is mixed. It should be updated to account for that somehow.

[westonruter]

for example:

					if ( is_array( $existing ) && isset( $existing['type'] ) && self::UPDATE_TYPE_COMPACTION === $existing['type'] ) {

[westonruter]

Suggested change

	$exists = $wpdb->get_row(
	/** @var object{ collaboration_id: string, date_gmt: string, data: string }|null $exists */
	$exists = $wpdb->get_row(

(Even though collaboration_id is a bigint(20) in the database, it is a string here.)

[westonruter]

I was wrong to suggest these were int:

Suggested change

	/** @var object{ max_id: int, total: int } $snapshot */
	/** @var object{ max_id: string, total: string } $snapshot */

[westonruter]

Very minor, but in \WP_Collaboration_Table_Storage::get_awareness_state() it is supposed to return a list of AwarenessState arrays, but it doesn't validate in any way the shape of state. It just ensures it is an array. Therefore, to not mislead any callers, this is more truthful:

Suggested change

	* @phpstan-type AwarenessState array{client_id: string, state: array<string, mixed>, user_id: int, timestamp: int}
	* @phpstan-type AwarenessState array{client_id: string, state: array<mixed, mixed>, user_id: int, timestamp: int}

I chose array<mixed, mixed> as opposed to just array because the latter is flagged by PHPStan with a strict configuration:

phpstan: Class WP_Collaboration_Table_Storage has type alias AwarenessState with no value type specified in iterable type array.

This is because PHPStan is trying to get the code to be as explicit as possible.

[westonruter]

Since ::get_updates_after_cursor() returns array<int, mixed> we should verify that we only get the updates with the expected types.

Suggested change

	$updates_after_cursor = $this->storage->get_updates_after_cursor( $room, $cursor );
	$updates_after_cursor = array_filter(
	$this->storage->get_updates_after_cursor( $room, $cursor ),
	static function ( $update ): bool {
	return (
	is_array( $update )
	&&
	isset( $update['client_id'], $update['type'], $update['data'] )
	&&
	is_string( $update['type'] )
	&&
	is_string( $update['data'] )
	);
	}
	);