State
Magento\Indexer\Model\ResourceModel\Indexer\State
What it does
This resource model manages database operations for indexer states in Magento 2.
It handles saving, loading, and updating the status of indexers (like catalog search, price, etc.) in the indexer_state table.
Developers use this indirectly through the indexer state model when checking or updating indexer statuses, with special logic to ensure status transitions to 'valid' only occur from specific states.