--- /dev/null
+<?php
+
+namespace Wikimedia\Rdbms;
+
+use InvalidArgumentException;
+
+/**
+ * DBMasterPos class for MySQL/MariaDB
+ *
+ * Note that master positions and sync logic here make some assumptions:
+ * - Binlog-based usage assumes single-source replication and non-hierarchical replication.
+ * - GTID-based usage allows getting/syncing with multi-source replication. It is assumed
+ * that GTID sets are complete (e.g. include all domains on the server).
+ */
+class MySQLMasterPos implements DBMasterPos {
+ /** @var string Binlog file */
+ public $file;
+ /** @var int Binglog file position */
+ public $pos;
+ /** @var string[] GTID list */
+ public $gtids = [];
+ /** @var float UNIX timestamp */
+ public $asOfTime = 0.0;
+
+ /**
+ * @param string $file Binlog file name
+ * @param int $pos Binlog position
+ * @param string $gtid Comma separated GTID set [optional]
+ */
+ function __construct( $file, $pos, $gtid = '' ) {
+ $this->file = $file;
+ $this->pos = $pos;
+ $this->gtids = array_map( 'trim', explode( ',', $gtid ) );
+ $this->asOfTime = microtime( true );
+ }
+
+ /**
+ * @return string <binlog file>/<position>, e.g db1034-bin.000976/843431247
+ */
+ function __toString() {
+ return "{$this->file}/{$this->pos}";
+ }
+
+ function asOfTime() {
+ return $this->asOfTime;
+ }
+
+ function hasReached( DBMasterPos $pos ) {
+ if ( !( $pos instanceof self ) ) {
+ throw new InvalidArgumentException( "Position not an instance of " . __CLASS__ );
+ }
+
+ // Prefer GTID comparisons, which work with multi-tier replication
+ $thisPosByDomain = $this->getGtidCoordinates();
+ $thatPosByDomain = $pos->getGtidCoordinates();
+ if ( $thisPosByDomain && $thatPosByDomain ) {
+ $reached = true;
+ // Check that this has positions GTE all of those in $pos for all domains in $pos
+ foreach ( $thatPosByDomain as $domain => $thatPos ) {
+ $thisPos = isset( $thisPosByDomain[$domain] ) ? $thisPosByDomain[$domain] : -1;
+ $reached = $reached && ( $thatPos <= $thisPos );
+ }
+
+ return $reached;
+ }
+
+ // Fallback to the binlog file comparisons
+ $thisBinPos = $this->getBinlogCoordinates();
+ $thatBinPos = $pos->getBinlogCoordinates();
+ if ( $thisBinPos && $thatBinPos && $thisBinPos['binlog'] === $thatBinPos['binlog'] ) {
+ return ( $thisBinPos['pos'] >= $thatBinPos['pos'] );
+ }
+
+ // Comparing totally different binlogs does not make sense
+ return false;
+ }
+
+ function channelsMatch( DBMasterPos $pos ) {
+ if ( !( $pos instanceof self ) ) {
+ throw new InvalidArgumentException( "Position not an instance of " . __CLASS__ );
+ }
+
+ // Prefer GTID comparisons, which work with multi-tier replication
+ $thisPosDomains = array_keys( $this->getGtidCoordinates() );
+ $thatPosDomains = array_keys( $pos->getGtidCoordinates() );
+ if ( $thisPosDomains && $thatPosDomains ) {
+ // Check that this has GTIDs for all domains in $pos
+ return !array_diff( $thatPosDomains, $thisPosDomains );
+ }
+
+ // Fallback to the binlog file comparisons
+ $thisBinPos = $this->getBinlogCoordinates();
+ $thatBinPos = $pos->getBinlogCoordinates();
+
+ return ( $thisBinPos && $thatBinPos && $thisBinPos['binlog'] === $thatBinPos['binlog'] );
+ }
+
+ /**
+ * @note: this returns false for multi-source replication GTID sets
+ * @see https://mariadb.com/kb/en/mariadb/gtid
+ * @see https://dev.mysql.com/doc/refman/5.6/en/replication-gtids-concepts.html
+ * @return array Map of (domain => integer position) or false
+ */
+ protected function getGtidCoordinates() {
+ $gtidInfos = [];
+ foreach ( $this->gtids as $gtid ) {
+ $m = [];
+ // MariaDB style: <domain>-<server id>-<sequence number>
+ if ( preg_match( '!^(\d+)-\d+-(\d+)$!', $gtid, $m ) ) {
+ $gtidInfos[(int)$m[1]] = (int)$m[2];
+ // MySQL style: <UUID domain>:<sequence number>
+ } elseif ( preg_match( '!^(\w{8}-\w{4}-\w{4}-\w{4}-\w{12}):(\d+)$!', $gtid, $m ) ) {
+ $gtidInfos[$m[1]] = (int)$m[2];
+ } else {
+ $gtidInfos = [];
+ break; // unrecognized GTID
+ }
+
+ }
+
+ return $gtidInfos;
+ }
+
+ /**
+ * @see https://dev.mysql.com/doc/refman/5.7/en/show-master-status.html
+ * @see https://dev.mysql.com/doc/refman/5.7/en/show-slave-status.html
+ * @return array|bool (binlog, (integer file number, integer position)) or false
+ */
+ protected function getBinlogCoordinates() {
+ $m = [];
+ if ( preg_match( '!^(.+)\.(\d+)/(\d+)$!', (string)$this, $m ) ) {
+ return [ 'binlog' => $m[1], 'pos' => [ (int)$m[2], (int)$m[3] ] ];
+ }
+
+ return false;
+ }
+}