MediaWiki 1.30.2

[autoinstallsdev/mediawiki.git] / includes / utils / BatchRowUpdate.php

diff --git a/includes/utils/BatchRowUpdate.php b/includes/utils/BatchRowUpdate.php
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+<?php
+/*
+ * Ties together the batch update components to provide a composable
+ * method of batch updating rows in a database. To use create a class
+ * implementing the RowUpdateGenerator interface and configure the
+ * BatchRowIterator and BatchRowWriter for access to the correct table.
+ * The components will handle reading, writing, and waiting for replica DBs
+ * while the generator implementation handles generating update arrays
+ * for singular rows.
+ *
+ * Instantiate:
+ *   $updater = new BatchRowUpdate(
+ *       new BatchRowIterator( $dbr, 'some_table', 'primary_key_column', 500 ),
+ *       new BatchRowWriter( $dbw, 'some_table', 'clusterName' ),
+ *       new MyImplementationOfRowUpdateGenerator
+ *   );
+ *
+ * Run:
+ *   $updater->execute();
+ *
+ * An example maintenance script utilizing the BatchRowUpdate can be
+ * located in the Echo extension file maintenance/updateSchema.php
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ * http://www.gnu.org/copyleft/gpl.html
+ *
+ * @file
+ * @ingroup Maintenance
+ */
+class BatchRowUpdate {
+       /**
+        * @var BatchRowIterator $reader Iterator that returns an array of
+        *  database rows
+        */
+       protected $reader;
+
+       /**
+        * @var BatchRowWriter $writer Writer capable of pushing row updates
+        *  to the database
+        */
+       protected $writer;
+
+       /**
+        * @var RowUpdateGenerator $generator Generates single row updates
+        *  based on the rows content
+        */
+       protected $generator;
+
+       /**
+        * @var callable $output Output callback
+        */
+       protected $output;
+
+       /**
+        * @param BatchRowIterator $reader Iterator that returns an
+        *  array of database rows
+        * @param BatchRowWriter $writer Writer capable of pushing
+        *  row updates to the database
+        * @param RowUpdateGenerator $generator Generates single row updates
+        *  based on the rows content
+        */
+       public function __construct(
+               BatchRowIterator $reader, BatchRowWriter $writer, RowUpdateGenerator $generator
+       ) {
+               $this->reader = $reader;
+               $this->writer = $writer;
+               $this->generator = $generator;
+               $this->output = function () {
+               }; // nop
+       }
+
+       /**
+        * Runs the batch update process
+        */
+       public function execute() {
+               foreach ( $this->reader as $rows ) {
+                       $updates = [];
+                       foreach ( $rows as $row ) {
+                               $update = $this->generator->update( $row );
+                               if ( $update ) {
+                                       $updates[] = [
+                                               'primaryKey' => $this->reader->extractPrimaryKeys( $row ),
+                                               'changes' => $update,
+                                       ];
+                               }
+                       }
+
+                       if ( $updates ) {
+                               $this->output( "Processing " . count( $updates ) . " rows\n" );
+                               $this->writer->write( $updates );
+                       }
+               }
+
+               $this->output( "Completed\n" );
+       }
+
+       /**
+        * Accepts a callable which will receive a single parameter
+        * containing string status updates
+        *
+        * @param callable $output A callback taking a single string
+        *  parameter to output
+        */
+       public function setOutput( callable $output ) {
+               $this->output = $output;
+       }
+
+       /**
+        * Write out a status update
+        *
+        * @param string $text The value to print
+        */
+       protected function output( $text ) {
+               call_user_func( $this->output, $text );
+       }
+}