HashBagOStuff.php

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<?php
class HashBagOStuff extends BagOStuff {
    protected $bag = [];
    protected $maxCacheKeys;

    private $token;

    private static $casCounter = 0;

    const KEY_VAL = 0;
    const KEY_EXP = 1;
    const KEY_CAS = 2;

    function __construct( $params = [] ) {
        parent::__construct( $params );

        $this->token = microtime( true ) . ':' . mt_rand();
        $this->maxCacheKeys = $params['maxKeys'] ?? INF;
        if ( $this->maxCacheKeys <= 0 ) {
            throw new InvalidArgumentException( '$maxKeys parameter must be above zero' );
        }
    }

    protected function doGet( $key, $flags = 0, &$casToken = null ) {
        $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;

        $casToken = $this->bag[$key][self::KEY_CAS];

        return $this->bag[$key][self::KEY_VAL];
    }

    public function set( $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->convertToExpiry( $exptime ),
            self::KEY_CAS => $this->token . ':' . ++self::$casCounter
        ];

        if ( count( $this->bag ) > $this->maxCacheKeys ) {
            reset( $this->bag );
            $evictKey = key( $this->bag );
            unset( $this->bag[$evictKey] );
        }

        return true;
    }

    public function add( $key, $value, $exptime = 0, $flags = 0 ) {
        if ( $this->get( $key ) === false ) {
            return $this->set( $key, $value, $exptime, $flags );
        }

        return false; // key already set
    }

    public function delete( $key, $flags = 0 ) {
        unset( $this->bag[$key] );

        return true;
    }

    public function incr( $key, $value = 1 ) {
        $n = $this->get( $key );
        if ( $this->isInteger( $n ) ) {
            $n = max( $n + intval( $value ), 0 );
            $this->bag[$key][self::KEY_VAL] = $n;

            return $n;
        }

        return false;
    }

    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->delete( $key );

        return true;
    }

    protected function hasKey( $key ) {
        return isset( $this->bag[$key] );
    }
}