FileBackendStoreShardListIterator.php

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<?php
abstract class FileBackendStoreShardListIterator extends FilterIterator {
    protected $backend;
 
    protected $params;
 
    protected $container;
 
    protected $directory;
 
    protected $multiShardPaths = []; // (rel path => 1)
 
    public function __construct(
        FileBackendStore $backend, $container, $dir, array $suffixes, array $params
    ) {
        $this->backend = $backend;
        $this->container = $container;
        $this->directory = $dir;
        $this->params = $params;
 
        $iter = new AppendIterator();
        foreach ( $suffixes as $suffix ) {
            $iter->append( $this->listFromShard( $this->container . $suffix ) );
        }
 
        parent::__construct( $iter );
    }
 
    public function accept(): bool {
        $rel = $this->getInnerIterator()->current(); // path relative to given directory
        $path = $this->params['dir'] . "/{$rel}"; // full storage path
        if ( $this->backend->isSingleShardPathInternal( $path ) ) {
            return true; // path is only on one shard; no issue with duplicates
        } elseif ( isset( $this->multiShardPaths[$rel] ) ) {
            // Don't keep listing paths that are on multiple shards
            return false;
        } else {
            $this->multiShardPaths[$rel] = 1;
 
            return true;
        }
    }
 
    public function rewind(): void {
        parent::rewind();
        $this->multiShardPaths = [];
    }
 
    abstract protected function listFromShard( $container );
}