1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138
|
<?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
*/
namespace Wikimedia\ObjectCache;
/**
* Store data in the local server memory via APCu (php-apcu)
*
* Past issues of note:
* - Memory corruption when `apc.serializer=default` in INI:
* https://phabricator.wikimedia.org/T120267
* - We used to recommend `apc.serializer=php` as non-default setting, and if not set,
* applied serialize() manually to workaround bugs and to create values we can use
* as CAS tokens. Upstream defaults to serializer=php since php-apcu 5.1.15 (2018).
* https://gerrit.wikimedia.org/r/671634
*
* @see https://www.php.net/apcu
* @ingroup Cache
*/
class APCUBagOStuff extends MediumSpecificBagOStuff {
/**
* @var string String to append to each APC key. This may be changed
* whenever the handling of values is changed, to prevent existing code
* from encountering older values which it cannot handle.
*/
private const KEY_SUFFIX = ':5';
/** @var int Max attempts for implicit CAS operations */
private static $CAS_MAX_ATTEMPTS = 100;
public function __construct( array $params = [] ) {
// No use in segmenting values
$params['segmentationSize'] = INF;
parent::__construct( $params );
// Versions of apcu < 5.1.19 use apc.use_request_time=1 by default, causing new keys
// to be assigned timestamps based on the start of the PHP request/script. The longer
// the request has been running, the more likely that newly stored keys will instantly
// be seen as expired by other requests. Disable apc.use_request_time.
ini_set( 'apc.use_request_time', '0' );
if ( PHP_SAPI === 'cli' ) {
$this->attrMap[self::ATTR_DURABILITY] = ini_get( 'apc.enable_cli' )
? self::QOS_DURABILITY_SCRIPT
: self::QOS_DURABILITY_NONE;
} else {
$this->attrMap[self::ATTR_DURABILITY] = self::QOS_DURABILITY_SERVICE;
}
}
protected function doGet( $key, $flags = 0, &$casToken = null ) {
$getToken = ( $casToken === self::PASS_BY_REF );
$casToken = null;
$value = apcu_fetch( $key . self::KEY_SUFFIX );
if ( $getToken && $value !== false ) {
// Note that if the driver handles serialization then this uses the PHP value
// as the token. This might require inspection or re-serialization in doCas().
$casToken = $value;
}
return $value;
}
protected function doSet( $key, $value, $exptime = 0, $flags = 0 ) {
$ttl = $this->getExpirationAsTTL( $exptime );
return apcu_store( $key . self::KEY_SUFFIX, $value, $ttl );
}
protected function doAdd( $key, $value, $exptime = 0, $flags = 0 ) {
if ( apcu_exists( $key . self::KEY_SUFFIX ) ) {
// Avoid global write locks for high contention keys
return false;
}
$ttl = $this->getExpirationAsTTL( $exptime );
return apcu_add( $key . self::KEY_SUFFIX, $value, $ttl );
}
protected function doDelete( $key, $flags = 0 ) {
apcu_delete( $key . self::KEY_SUFFIX );
return true;
}
protected function doIncrWithInit( $key, $exptime, $step, $init, $flags ) {
// Use apcu 5.1.12 $ttl argument if apcu_inc() will initialize to $init:
// https://www.php.net/manual/en/function.apcu-inc.php
if ( $step === $init ) {
/** @noinspection PhpMethodParametersCountMismatchInspection */
$ttl = $this->getExpirationAsTTL( $exptime );
$result = apcu_inc( $key . self::KEY_SUFFIX, $step, $success, $ttl );
} else {
$result = false;
for ( $i = 0; $i < self::$CAS_MAX_ATTEMPTS; ++$i ) {
$oldCount = apcu_fetch( $key . self::KEY_SUFFIX );
if ( $oldCount === false ) {
$count = $init;
$ttl = $this->getExpirationAsTTL( $exptime );
if ( apcu_add( $key . self::KEY_SUFFIX, $count, $ttl ) ) {
$result = $count;
break;
}
} elseif ( is_int( $oldCount ) ) {
$count = $oldCount + $step;
if ( apcu_cas( $key . self::KEY_SUFFIX, $oldCount, $count ) ) {
$result = $count;
break;
}
} else {
break;
}
}
}
return $result;
}
}
/** @deprecated class alias since 1.43 */
class_alias( APCUBagOStuff::class, 'APCUBagOStuff' );
|