HashBagOStuff.php

Go to the documentation of this file.

<?php
namespace Wikimedia\ObjectCache;
 
use InvalidArgumentException;
 
class HashBagOStuff extends MediumSpecificBagOStuff {
    protected $bag = [];
    protected $maxCacheKeys;
 
    private $token;
 
    private static $casCounter = 0;
 
    public const KEY_VAL = 0;
    public const KEY_EXP = 1;
    public const KEY_CAS = 2;
 
    public function __construct( $params = [] ) {
        $params['segmentationSize'] ??= INF;
        parent::__construct( $params );
 
        $this->token = microtime( true ) . ':' . mt_rand();
        $maxKeys = $params['maxKeys'] ?? INF;
        if ( $maxKeys !== INF && ( !is_int( $maxKeys ) || $maxKeys <= 0 ) ) {
            throw new InvalidArgumentException( '$maxKeys parameter must be above zero' );
        }
        $this->maxCacheKeys = $maxKeys;
 
        $this->attrMap[self::ATTR_DURABILITY] = self::QOS_DURABILITY_SCRIPT;
    }
 
    protected function doGet( $key, $flags = 0, &$casToken = null ) {
        $getToken = ( $casToken === self::PASS_BY_REF );
        $casToken = null;
 
        if ( !$this->hasKey( $key ) || $this->expire( $key ) ) {
            return false;
        }
 
        // Refresh key position for maxCacheKeys eviction
        $temp = $this->bag[$key];
        unset( $this->bag[$key] );
        $this->bag[$key] = $temp;
 
        $value = $this->bag[$key][self::KEY_VAL];
        if ( $getToken && $value !== false ) {
            $casToken = $this->bag[$key][self::KEY_CAS];
        }
 
        return $value;
    }
 
    protected function doSet( $key, $value, $exptime = 0, $flags = 0 ) {
        // Refresh key position for maxCacheKeys eviction
        unset( $this->bag[$key] );
        $this->bag[$key] = [
            self::KEY_VAL => $value,
            self::KEY_EXP => $this->getExpirationAsTimestamp( $exptime ),
            self::KEY_CAS => $this->token . ':' . ++self::$casCounter
        ];
 
        if ( count( $this->bag ) > $this->maxCacheKeys ) {
            $evictKey = array_key_first( $this->bag );
            unset( $this->bag[$evictKey] );
        }
 
        return true;
    }
 
    protected function doAdd( $key, $value, $exptime = 0, $flags = 0 ) {
        if ( $this->hasKey( $key ) && !$this->expire( $key ) ) {
            // key already set
            return false;
        }
 
        return $this->doSet( $key, $value, $exptime, $flags );
    }
 
    protected function doDelete( $key, $flags = 0 ) {
        unset( $this->bag[$key] );
 
        return true;
    }
 
    protected function doIncrWithInit( $key, $exptime, $step, $init, $flags ) {
        $curValue = $this->doGet( $key );
        if ( $curValue === false ) {
            $newValue = $this->doSet( $key, $init, $exptime ) ? $init : false;
        } elseif ( $this->isInteger( $curValue ) ) {
            $newValue = max( $curValue + $step, 0 );
            $this->bag[$key][self::KEY_VAL] = $newValue;
        } else {
            $newValue = false;
        }
 
        return $newValue;
    }
 
    public function clear() {
        $this->bag = [];
    }
 
    protected function expire( $key ) {
        $et = $this->bag[$key][self::KEY_EXP];
        if ( $et == self::TTL_INDEFINITE || $et > $this->getCurrentTime() ) {
            return false;
        }
 
        $this->doDelete( $key );
 
        return true;
    }
 
    public function hasKey( $key ) {
        return isset( $this->bag[$key] );
    }
}
 
class_alias( HashBagOStuff::class, 'HashBagOStuff' );