TranslationCorporaStore.php

<?php
/**
 * @copyright See AUTHORS.txt
 * @license GPL-2.0-or-later
 */
declare( strict_types = 1 );

namespace ContentTranslation\Store;

use ContentTranslation\Entity\TranslationUnit;
use ContentTranslation\LoadBalancer;
use LogicException;
use stdClass;
use Wikimedia\Rdbms\IDatabase;
use Wikimedia\Rdbms\IExpression;
use Wikimedia\Rdbms\LBFactory;
use Wikimedia\Rdbms\LikeValue;
use Wikimedia\Rdbms\Platform\ISQLPlatform;
use Wikimedia\Rdbms\SelectQueryBuilder;

/**
 * The TranslationCorporaStore service represents the Data Access Layer for the parallel corpora. More
 * specifically, this service relies on the database load balancer to interact with the "cx_corpora"
 * table, to insert, update, delete or fetch data to this table. This class exposes methods that
 * usually accepts TranslationUnit entity objects as arguments (when it's an insert/update query),
 * or return TranslationUnit entity objects (for read operations). This service is mostly used inside
 * TranslationCorporaManager service to interact with the database.
 */
class TranslationCorporaStore {

	/** @var LoadBalancer */
	private $lb;

	/** @var LBFactory */
	private $lbFactory;
	public const TABLE_NAME = 'cx_corpora';

	public function __construct( LoadBalancer $lb, LBFactory $lbFactory ) {
		$this->lb = $lb;
		$this->lbFactory = $lbFactory;
	}

	/**
	 * Update a translation unit.
	 *
	 * @param TranslationUnit $translationUnit
	 * @param string $timestamp
	 */
	private function updateTranslationUnit( TranslationUnit $translationUnit, string $timestamp ): void {
		$dbw = $this->lb->getConnection( DB_PRIMARY );

		$dbw->newUpdateQueryBuilder()
			->update( self::TABLE_NAME )
			->set( [
				'cxc_sequence_id' => $translationUnit->getSequenceId(),
				'cxc_timestamp' => $dbw->timestamp(),
				'cxc_content' => $translationUnit->getContent()
			] )
			->where( [
				'cxc_translation_id' => $translationUnit->getTranslationId(),
				'cxc_section_id' => $translationUnit->getSectionId(),
				'cxc_origin' => $translationUnit->getOrigin(),
				// Sometimes we get "duplicates" entries which differ in timestamp.
				// Then any updates to those sections would fail (duplicate key for
				// a unique index), if we did not limit this call to only one of them.
				'cxc_timestamp' => $dbw->timestamp( $timestamp ),
			] )
			->caller( __METHOD__ )
			->execute();

		if ( $dbw->affectedRows() < 1 ) {
			// Possible reasons:
			// * concurrent request has already updated the row with new timestamp
			// * no change (saving same thing twice in the same second)
			// * translation has been deleted
			throw new LogicException( 'Failed to update a translation section' );
		}
	}

	/**
	 * Insert a translation unit.
	 *
	 * @param TranslationUnit $translationUnit
	 */
	private function insertTranslationUnit( TranslationUnit $translationUnit ): void {
		$dbw = $this->lb->getConnection( DB_PRIMARY );

		$dbw->newInsertQueryBuilder()
			->insertInto( self::TABLE_NAME )
			->row( [
				'cxc_translation_id' => $translationUnit->getTranslationId(),
				'cxc_section_id' => $translationUnit->getSectionId(),
				'cxc_origin' => $translationUnit->getOrigin(),
				'cxc_sequence_id' => $translationUnit->getSequenceId(),
				'cxc_timestamp' => $dbw->timestamp(),
				'cxc_content' => $translationUnit->getContent()
			] )
			->caller( __METHOD__ )
			->execute();
	}

	/**
	 * Delete translation units and categories associated with the given translation identifier.
	 *
	 * @param int|int[] $translationId
	 */
	public function deleteTranslationData( $translationId ): void {
		$dbw = $this->lb->getConnection( DB_PRIMARY );

		$dbw->newDeleteQueryBuilder()
			->deleteFrom( self::TABLE_NAME )
			->where( [ 'cxc_translation_id' => $translationId ] )
			->caller( __METHOD__ )
			->execute();
	}

	/**
	 * Given the "parent" translation id and the base section id (in the "${revision}_${sectionNumber}"
	 * form), this method deletes all the translation units that belong to that section translation,
	 * from the "cx_corpora" table.
	 *
	 * NOTE: The "cxc_section_id" field inside "cx_corpora" table is in the following form for
	 * section translation parallel corpora units: "${baseSectionId}_${subSectionId}", where
	 * "subSectionId" is given by the cxserver as the section HTML element id (e.g. "cxSourceSection4").
	 * This is why we use a "LIKE" query in the following form, here: "${baseSectionId}_%"
	 *
	 * @param int $translationId the id of the "parent" translation inside "cx_translations" table
	 * @param string $baseSectionId the "cxsx_section_id" as stored inside "cx_section_translations" table
	 * @return void
	 */
	public function deleteTranslationDataBySectionId( int $translationId, string $baseSectionId ): void {
		$dbw = $this->lb->getConnection( DB_PRIMARY );

		$dbw->newDeleteQueryBuilder()
			->deleteFrom( self::TABLE_NAME )
			->where( [
				'cxc_translation_id' => $translationId,
				$dbw->expr( 'cxc_section_id', IExpression::LIKE,
					new LikeValue( $baseSectionId, '_', $dbw->anyString() ) ),
			] )
			->caller( __METHOD__ )
			->execute();
	}

	/**
	 * Given a translation id, this method returns the count of the parallel corpora
	 * translation units, associated with this translation id.
	 *
	 * @param int $translationId the id of the translation inside "cx_translations" table
	 * @return int
	 */
	public function countByTranslationId( int $translationId ): int {
		$dbr = $this->lb->getConnection( DB_REPLICA );

		return $dbr->newSelectQueryBuilder()
			->select( ISQLPlatform::ALL_ROWS )
			->from( self::TABLE_NAME )
			->where( [ 'cxc_translation_id' => $translationId ] )
			->caller( __METHOD__ )
			->fetchRowCount();
	}

	/**
	 * Delete translation units and categories associated with the given translation identifier
	 * in a manner that avoids creating excessive database lag.
	 *
	 * @param int|int[] $ids
	 * @param int $batchSize
	 */
	public function deleteTranslationDataGently( $ids, int $batchSize = 1000 ): void {
		$dbw = $this->lb->getConnection( DB_PRIMARY );

		while ( true ) {
			$rowsToDelete = $dbw->newSelectQueryBuilder()
				->select( 'cxc_id' )
				->from( self::TABLE_NAME )
				->where( [ 'cxc_translation_id' => $ids ] )
				->limit( $batchSize )
				->caller( __METHOD__ )
				->fetchFieldValues();

			if ( !$rowsToDelete ) {
				break;
			}

			$dbw->newDeleteQueryBuilder()
				->deleteFrom( self::TABLE_NAME )
				->where( [ 'cxc_id' => $rowsToDelete ] )
				->caller( __METHOD__ )
				->execute();
			$this->lbFactory->waitForReplication();
		}
	}

	/**
	 * @param int $translationId
	 * @return TranslationUnit[]
	 */
	public function findByTranslationId( int $translationId ): array {
		$dbr = $this->lb->getConnection( DB_REPLICA );

		$resultSet = $dbr->newSelectQueryBuilder()
			->select( [
				'cxc_translation_id',
				'cxc_origin',
				'cxc_section_id',
				'cxc_timestamp',
				'cxc_sequence_id',
				'cxc_content',
			] )
			->from( self::TABLE_NAME )
			->where( [ 'cxc_translation_id' => $translationId ] )
			->caller( __METHOD__ )
			->fetchResultSet();

		$units = [];
		foreach ( $resultSet as $row ) {
			$units[] = $this->createTranslationUnitFromRow( $row );
		}

		return $units;
	}

	/**
	 * Given a translation id, this method returns an integer, indicating
	 * the count of the translated subsections (paragraphs) for that translation.
	 *
	 * @param int $translationId
	 * @return int count of translated subsections
	 */
	public function countTranslatedSubSectionsByTranslationId( int $translationId ): int {
		$dbr = $this->lb->getConnection( DB_REPLICA );

		$row = $dbr->newSelectQueryBuilder()
			->select( [
				'cxc_translation_id',
				'cxc_section_id',
				'count' => 'COUNT(DISTINCT cxc_section_id)',
			] )
			->from( self::TABLE_NAME )
			->where( [ 'cxc_translation_id' => $translationId ] )
			->groupBy( [ 'cxc_translation_id' ] )
			->caller( __METHOD__ )
			->fetchRow();

		return (int)$row->count;
	}

	/**
	 * Saves the translation unit. If the record exists, updates it, otherwise creates it.
	 *
	 * @param TranslationUnit $translationUnit
	 * @param bool $isNewTranslation Whether these are for a brand-new Translation record
	 */
	public function save( TranslationUnit $translationUnit, bool $isNewTranslation ): void {
		$fname = __METHOD__;
		// Update the latest row if there is one instead of making a new one
		$conditions = [
			'cxc_translation_id' => $translationUnit->getTranslationId(),
			'cxc_section_id' => $translationUnit->getSectionId(),
			'cxc_origin' => $translationUnit->getOrigin()
		];
		if ( $isNewTranslation ) {
			// T134245: brand new translations can also insert corpora data in the same
			// request. The doFind() query uses only a subset of a unique cx_corpora index,
			// causing SH gap locks. Worse, is that the leftmost values comes from the
			// auto-incrementing translation_id. This puts gap locks on the range of
			// (MAX(cxc_translation_id),+infinity), which could make the whole API prone
			// to deadlocks and timeouts. Bypass this problem by remembering if the parent
			// translation row is brand new and skipping doFind() in such cases.
			$existing = false;
		} else {
			// Note that the only caller of this method will have already locked the
			// parent Translation row, serializing simultaneous duplicate submissions at
			// this point. Without that row lock, the two transaction might both acquire
			// SH gap locks in doFind() and then deadlock in create() trying to get IX gap
			// locks (if no duplicate rows were found).
			$options = [];
			$dbr = $this->lb->getConnection( DB_REPLICA );
			$existing = $this->doFind( $dbr, $conditions, $options, $fname );
		}

		if ( $existing ) {
			$dbw = $this->lb->getConnection( DB_PRIMARY );
			$dbw->doAtomicSection(
				__METHOD__,
				function ( IDatabase $dbw ) use ( $translationUnit, $conditions, $fname ) {
					// Lock the record for updating it. This time we use $dbw - primary db.
					// This is to avoid the unnecessary gap locking with 'for update' query
					// when the record does not exist.
					$options = [ 'FOR UPDATE' ];
					$existing = $this->doFind( $dbw, $conditions, $options, $fname );
					$this->updateTranslationUnit( $translationUnit, $existing->getTimestamp() );
				}
			);
		} else {
			$this->insertTranslationUnit( $translationUnit );
		}
	}

	private function doFind( IDatabase $db, $conditions, $options, $method ): ?TranslationUnit {
		$row = $db->newSelectQueryBuilder()
			->select( [
				'cxc_translation_id',
				'cxc_section_id',
				'cxc_origin',
				'cxc_timestamp',
				'cxc_sequence_id',
				'cxc_content'
			] )
			->from( self::TABLE_NAME )
			->where( $conditions )
			->orderBy( 'cxc_timestamp', SelectQueryBuilder::SORT_DESC )
			->options( $options )
			->caller( $method )
			->fetchRow();
		if ( $row ) {
			return $this->createTranslationUnitFromRow( $row );
		}

		return null;
	}

	private function createTranslationUnitFromRow( stdClass $row ): TranslationUnit {
		return new TranslationUnit(
			$row->cxc_section_id,
			$row->cxc_origin,
			(int)$row->cxc_sequence_id, // cxc_sequence_id can be null
			(string)$row->cxc_content, // cxc_content can be null
			(int)$row->cxc_translation_id,
			$row->cxc_timestamp
		);
	}
}