APCUBagOStuff.php

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<?php
namespace Wikimedia\ObjectCache;
 
class APCUBagOStuff extends MediumSpecificBagOStuff {
    private const KEY_SUFFIX = ':5';
 
    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 ) {
            $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;
    }
}
 
class_alias( APCUBagOStuff::class, 'APCUBagOStuff' );