85d5626d6c
This is a set of classes written for Echo to simplify writing maintenance scripts that iterate over an entire table and update some of those rows. This has shown to be reusable elsewhere, especially the BatchRowIterator class and will be useful to have generally avilable in core. The Echo classes are all prefixed with the Echo name so there wont be any conflict is both are installed. Change-Id: I64c1751106caf34f41af799dbaf8794115537f06
133 lines
3.8 KiB
PHP
133 lines
3.8 KiB
PHP
<?php
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/*
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* Ties together the batch update components to provide a composable
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* method of batch updating rows in a database. To use create a class
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* implementing the RowUpdateGenerator interface and configure the
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* BatchRowIterator and BatchRowWriter for access to the correct table.
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* The components will handle reading, writing, and waiting for slaves
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* while the generator implementation handles generating update arrays
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* for singular rows.
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*
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* Instantiate:
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* $updater = new BatchRowUpdate(
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* new BatchRowIterator( $dbr, 'some_table', 'primary_key_column', 500 ),
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* new BatchRowWriter( $dbw, 'some_table', 'clusterName' ),
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* new MyImplementationOfRowUpdateGenerator
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* );
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*
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* Run:
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* $updater->execute();
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*
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* An example maintenance script utilizing the BatchRowUpdate can be
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* located in the Echo extension file maintenance/updateSchema.php
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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* http://www.gnu.org/copyleft/gpl.html
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*
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* @file
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* @ingroup Maintenance
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*/
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class BatchRowUpdate {
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/**
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* @var BatchRowIterator $reader Iterator that returns an array of
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* database rows
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*/
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protected $reader;
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/**
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* @var BatchRowWriter $writer Writer capable of pushing row updates
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* to the database
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*/
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protected $writer;
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/**
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* @var RowUpdateGenerator $generator Generates single row updates
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* based on the rows content
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*/
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protected $generator;
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/**
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* @var callable $output Output callback
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*/
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protected $output;
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/**
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* @param BatchRowIterator $reader Iterator that returns an
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* array of database rows
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* @param BatchRowWriter $writer Writer capable of pushing
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* row updates to the database
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* @param RowUpdateGenerator $generator Generates single row updates
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* based on the rows content
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*/
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public function __construct( BatchRowIterator $reader, BatchRowWriter $writer, RowUpdateGenerator $generator ) {
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$this->reader = $reader;
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$this->writer = $writer;
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$this->generator = $generator;
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$this->output = function() {
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}; // nop
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}
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/**
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* Runs the batch update process
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*/
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public function execute() {
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foreach ( $this->reader as $rows ) {
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$updates = array();
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foreach ( $rows as $row ) {
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$update = $this->generator->update( $row );
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if ( $update ) {
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$updates[] = array(
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'primaryKey' => $this->reader->extractPrimaryKeys( $row ),
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'changes' => $update,
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);
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}
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}
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if ( $updates ) {
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$this->output( "Processing " . count( $updates ) . " rows\n" );
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$this->writer->write( $updates );
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}
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}
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$this->output( "Completed\n" );
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}
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/**
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* Accepts a callable which will receive a single parameter
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* containing string status updates
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*
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* @param callable $output A callback taking a single string
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* parameter to output
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*
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* @throws MWException
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*/
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public function setOutput( $output ) {
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if ( !is_callable( $output ) ) {
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throw new MWException(
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'Provided $output param is required to be callable.'
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);
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}
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$this->output = $output;
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}
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/**
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* Write out a status update
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*
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* @param string $text The value to print
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*/
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protected function output( $text ) {
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call_user_func( $this->output, $text );
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}
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}
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