146 lines
4.5 KiB
PHP
146 lines
4.5 KiB
PHP
<?php
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/**
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* Object caching using PHP's APCU accelerator.
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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 Cache
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*/
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/**
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* This is a wrapper for APCU's shared memory functions
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*
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* Use PHP serialization to avoid bugs and easily create CAS tokens.
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* APCu has a memory corruption bug when the serializer is set to 'default'.
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* See T120267, and upstream bug reports:
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* - https://github.com/krakjoe/apcu/issues/38
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* - https://github.com/krakjoe/apcu/issues/35
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* - https://github.com/krakjoe/apcu/issues/111
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*
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* @ingroup Cache
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*/
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class APCUBagOStuff extends MediumSpecificBagOStuff {
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/** @var bool Whether to trust the APC implementation to serialization */
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private $nativeSerialize;
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/** @var bool */
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private $useIncrTTLArg;
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/**
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* @var string String to append to each APC key. This may be changed
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* whenever the handling of values is changed, to prevent existing code
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* from encountering older values which it cannot handle.
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*/
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const KEY_SUFFIX = ':4';
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/** @var int Max attempts for implicit CAS operations */
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private static $CAS_MAX_ATTEMPTS = 100;
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public function __construct( array $params = [] ) {
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$params['segmentationSize'] = $params['segmentationSize'] ?? INF;
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parent::__construct( $params );
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// The extension serializer is still buggy, unlike "php" and "igbinary"
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$this->nativeSerialize = ( ini_get( 'apc.serializer' ) !== 'default' );
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$this->useIncrTTLArg = version_compare( phpversion( 'apcu' ), '5.1.12', '>=' );
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}
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protected function doGet( $key, $flags = 0, &$casToken = null ) {
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$casToken = null;
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$blob = apcu_fetch( $key . self::KEY_SUFFIX );
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$value = $this->nativeSerialize ? $blob : $this->unserialize( $blob );
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if ( $value !== false ) {
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$casToken = $blob; // don't bother hashing this
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}
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return $value;
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}
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protected function doSet( $key, $value, $exptime = 0, $flags = 0 ) {
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return apcu_store(
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$key . self::KEY_SUFFIX,
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$this->nativeSerialize ? $value : $this->serialize( $value ),
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$exptime
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);
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}
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protected function doAdd( $key, $value, $exptime = 0, $flags = 0 ) {
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return apcu_add(
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$key . self::KEY_SUFFIX,
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$this->nativeSerialize ? $value : $this->serialize( $value ),
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$exptime
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);
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}
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protected function doDelete( $key, $flags = 0 ) {
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apcu_delete( $key . self::KEY_SUFFIX );
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return true;
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}
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public function incr( $key, $value = 1, $flags = 0 ) {
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// https://github.com/krakjoe/apcu/issues/166
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for ( $i = 0; $i < self::$CAS_MAX_ATTEMPTS; ++$i ) {
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$oldCount = apcu_fetch( $key . self::KEY_SUFFIX );
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if ( !is_int( $oldCount ) ) {
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return false;
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}
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$count = $oldCount + (int)$value;
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if ( apcu_cas( $key . self::KEY_SUFFIX, $oldCount, $count ) ) {
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return $count;
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}
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}
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return false;
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}
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public function decr( $key, $value = 1, $flags = 0 ) {
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// https://github.com/krakjoe/apcu/issues/166
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if ( apcu_exists( $key . self::KEY_SUFFIX ) ) {
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return apcu_dec( $key . self::KEY_SUFFIX, $value );
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} else {
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return false;
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}
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}
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public function incrWithInit( $key, $exptime, $value = 1, $init = null, $flags = 0 ) {
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// Use apcu 5.1.12 $ttl argument if apcu_inc() will initialize to $init:
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// https://www.php.net/manual/en/function.apcu-inc.php
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if ( $value === $init && $this->useIncrTTLArg ) {
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/** @noinspection PhpMethodParametersCountMismatchInspection */
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return apcu_inc( $key . self::KEY_SUFFIX, $value, $success, $exptime );
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}
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for ( $i = 0; $i < self::$CAS_MAX_ATTEMPTS; ++$i ) {
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$oldCount = apcu_fetch( $key . self::KEY_SUFFIX );
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if ( $oldCount === false ) {
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$count = (int)$init;
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if ( apcu_add( $key . self::KEY_SUFFIX, $count, $exptime ) ) {
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return $count;
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}
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} elseif ( !is_int( $oldCount ) ) {
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return false;
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} else {
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$count = $oldCount + (int)$value;
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if ( apcu_cas( $key . self::KEY_SUFFIX, $oldCount, $count ) ) {
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return $count;
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}
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}
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}
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return false;
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}
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}
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