MediaWiki REL1_39
purgeParserCache.php
Go to the documentation of this file.
1<?php
25require_once __DIR__ . '/Maintenance.php';
26
29use Wikimedia\Timestamp\ConvertibleTimestamp;
30
37
39 private $lastProgress;
40
42 private $lastTimestamp;
43
44 private $tmpCount = 0;
45 private $usleep = 0;
46
47 public function __construct() {
48 parent::__construct();
49 $this->addDescription( "Remove old objects from the parser cache. " .
50 "This only works when the parser cache is in an SQL database." );
51 $this->addOption( 'expiredate', 'Delete objects expiring before this date.', false, true );
52 $this->addOption(
53 'age',
54 'Delete objects created more than this many seconds ago, assuming ' .
55 '$wgParserCacheExpireTime has remained consistent.',
56 false,
57 true );
58 $this->addOption( 'dry-run', 'Perform a dry run, to verify age and date calculation.' );
59 $this->addOption( 'msleep', 'Milliseconds to sleep between purge chunks of $wgUpdateRowsPerQuery.',
60 false,
61 true );
62 $this->addOption(
63 'tag',
64 'Purge a single server only. This feature is designed for use by large wiki farms where ' .
65 'one has to purge multiple servers concurrently in order to keep up with new writes. ' .
66 'This requires using the SqlBagOStuff "servers" option in $wgObjectCaches.',
67 false,
68 true );
69 }
70
71 public function execute() {
72 $inputDate = $this->getOption( 'expiredate' );
73 $inputAge = $this->getOption( 'age' );
74
75 if ( $inputDate !== null ) {
76 $timestamp = strtotime( $inputDate );
77 } elseif ( $inputAge !== null ) {
78 $expireTime = (int)$this->getConfig()->get( MainConfigNames::ParserCacheExpireTime );
79 $timestamp = time() + $expireTime - intval( $inputAge );
80 } else {
81 $this->fatalError( "Must specify either --expiredate or --age" );
82 }
83 $this->usleep = 1e3 * $this->getOption( 'msleep', 0 );
84 $this->lastTimestamp = microtime( true );
85
86 $humanDate = ConvertibleTimestamp::convert( TS_RFC2822, $timestamp );
87 if ( $this->hasOption( 'dry-run' ) ) {
88 $this->fatalError( "\nDry run mode, would delete objects having an expiry before " . $humanDate . "\n" );
89 }
90
91 $this->output( "Deleting objects expiring before " . $humanDate . "\n" );
92
93 $pc = MediaWikiServices::getInstance()->getParserCache()->getCacheStorage();
94 $success = $pc->deleteObjectsExpiringBefore(
95 $timestamp,
96 [ $this, 'showProgressAndWait' ],
97 INF,
98 // Note that "0" can be a valid server tag, and must not be discarded or changed to null.
99 $this->getOption( 'tag', null )
100 );
101 if ( !$success ) {
102 $this->fatalError( "\nCannot purge this kind of parser cache." );
103 }
104 $this->showProgressAndWait( 100 );
105 $this->output( "\nDone\n" );
106 }
107
108 public function showProgressAndWait( $percent ) {
109 // Parser caches involve mostly-unthrottled writes of large blobs. This is sometimes prone
110 // to replication lag. As such, while our purge queries are simple primary key deletes,
111 // we want to avoid adding significant load to the replication stream, by being
112 // proactively graceful with these sleeps between each batch.
113 // The reason we don't explicitly wait for replication is that that would require the script
114 // to be aware of cross-dc replicas, which we prefer not to, and waiting for replication
115 // and confirmation latency might actually be *too* graceful and take so long that the
116 // purge script would not be able to finish within 24 hours for large wiki farms.
117 // (T150124).
118 usleep( $this->usleep );
119 $this->tmpCount++;
120
121 $percentString = sprintf( "%.1f", $percent );
122 if ( $percentString === $this->lastProgress ) {
123 // Only print a line if we've progressed >= 0.1% since the last printed line.
124 // This does not mean every 0.1% step is printed since we only run this callback
125 // once after a deletion batch. How often and how many lines we print depends on the
126 // batch size (SqlBagOStuff::deleteObjectsExpiringBefore, $wgUpdateRowsPerQuery),
127 // and on how many table rows there are.
128 return;
129 }
130 $now = microtime( true );
131 $sec = sprintf( "%.1f", $now - $this->lastTimestamp );
132
133 // Give a sense of how much time is spent in the delete operations vs the sleep time,
134 // by recording the number of iterations we've completed since the last progress update.
135 $this->output( "... {$percentString}% done (+{$this->tmpCount} iterations in {$sec}s)\n" );
136
137 $this->lastProgress = $percentString;
138 $this->tmpCount = 0;
139 $this->lastTimestamp = $now;
140 }
141}
142
143$maintClass = PurgeParserCache::class;
144require_once RUN_MAINTENANCE_IF_MAIN;
Abstract maintenance class for quickly writing and churning out maintenance scripts with minimal effo...
output( $out, $channel=null)
Throw some output to the user.
hasOption( $name)
Checks to see if a particular option was set.
addDescription( $text)
Set the description text.
addOption( $name, $description, $required=false, $withArg=false, $shortName=false, $multiOccurrence=false)
Add a parameter to the script.
getOption( $name, $default=null)
Get an option, or return the default.
fatalError( $msg, $exitCode=1)
Output a message and terminate the current script.
A class containing constants representing the names of configuration variables.
Service locator for MediaWiki core services.
Maintenance script to remove old objects from the parser cache.
execute()
Do the actual work.
__construct()
Default constructor.
showProgressAndWait( $percent)