SubhashUpdater.php

Go to the documentation of this file.

<?php

 
namespace Depage\XmlDb\Helpers;

class SubhashUpdater
{
    protected $pdo;

    public function __construct(
        $pdo,
        protected string $table,
        protected $docId,
        protected int $pad,
        protected int $batchSize = CaseUpdate::DEFAULT_SIZE
    ) {
        $this->pdo = $pdo;
    }

    public function refresh(): void
    {
        $query = $this->pdo->prepare(
            TreeSql::descendants($this->table, "id_doc = :doc_id AND id_parent IS NULL", $this->pad) . "
            SELECT xml.id, xml.id_parent, xml.type, xml.name, xml.value, xml.subhash
            FROM tree JOIN {$this->table} AS xml ON tree.id = xml.id
            ORDER BY tree.lvl DESC, xml.id_parent ASC, xml.pos ASC;",
            \Depage\Db\Pdo::unbuffered(),
        );
        $query->execute([
            'doc_id' => $this->docId,
        ]);
 
        // deepest level first, so a node is only reached after all of its
        // children contributed their hash
        $childHashes = [];
 
        // the recalculated hashes are only written after the cursor is
        // closed (no statement may run on the connection while the
        // unbuffered result is open), so they are collected in the update
        // buffer first
        $subhashes = new CaseUpdate($this->pdo, $this->table, $this->batchSize);
 
        while ($row = $query->fetchObject()) {
            $hash = NodeContent::hash($row->type, $row->name, $row->value, $childHashes[$row->id] ?? []);
 
            if ($row->subhash !== $hash) {
                $subhashes->add($row->id, $hash);
            }
 
            if ($row->id_parent !== null) {
                $childHashes[$row->id_parent][] = $hash;
            }
            unset($childHashes[$row->id]);
        }
        // no statements may run while the unbuffered result is open
        $query->closeCursor();
 
        // subhash takes part in no unique index, so the case updates
        // cannot collide
        $subhashes->write('subhash', ['id_doc' => $this->docId]);
    }
}
 
/* vim:set ft=php sw=4 sts=4 fdm=marker et : */