CheckpointStorageInterface.php

<?php

declare (strict_types=1);
namespace Drupal\Core\Config\Checkpoint;

use Drupal\Core\Config\StorageInterface;

/**
 * Provides an interface for checkpoint storages.
 *
 * @internal
 *   This API is experimental.
 */
interface CheckpointStorageInterface extends StorageInterface {
    
    /**
     * Creates a checkpoint, if required, and returns the active checkpoint.
     *
     * If the storage determines that the current active checkpoint would contain
     * the same information, it does not have to create a new checkpoint.
     *
     * @param string|\Stringable $label
     *   The checkpoint label to use if a new checkpoint is created.
     *
     * @return \Drupal\Core\Config\Checkpoint\Checkpoint
     *   The currently active checkpoint.
     */
    public function checkpoint(string|\Stringable $label) : Checkpoint;
    
    /**
     * Sets the checkpoint to read from.
     *
     * Calling read() or readMultiple() will return the configuration data at the
     * time of the checkpoint that was set here. If none is set, then the
     * configuration from the initial checkpoint will be returned.
     *
     * @param string|\Drupal\Core\Config\Checkpoint\Checkpoint $checkpoint_id
     *   The checkpoint ID to read from.
     *
     * @return $this
     *
     * @throws \Drupal\Core\Config\Checkpoint\UnknownCheckpointException
     *   Thrown when the provided checkpoint does not exist.
     */
    public function setCheckpointToReadFrom(string|Checkpoint $checkpoint_id) : static;

}