<?php

namespace common\components\caching;

use yii\caching\Cache;
use yii\base\InvalidConfigException;

class ShmCache extends Cache
{

    //memory size bytes,default 10MB
    public $memSize = 10485760;
    
    protected $shm;

    /**
     * Initializes this application component.
     * It checks if extension required is loaded.
     */
    public function init()
    {
        parent::init();
        if (!extension_loaded('sysvshm')) {
            throw new InvalidConfigException("ShmCache requires PHP sysvshm extension to be loaded.");
        }
        
        $key = ftok(__FILE__, 'p');
        $this->shm = shm_attach($key,10000);
    }
    
    public function exists($key)
    {
        $key = $this->buildKey($key);

        return shm_has_var($this->shm,$key);
    }
    
    protected function getValue($key)
    {
        return @shm_get_var($this->shm,$key);
    }
    
    protected function getValues($keys)
    {
        $results = [];
        foreach ($keys as $key) {
            $results[$key] = @shm_get_var($this->shm,$key);
        }
        return $results;
    }
    
    protected function setValue($key, $value, $duration)
    {
        return shm_put_var($this->shm,$key,$value);
    }
    
    protected function addValue($key, $value, $duration)
    {
        return shm_has_var($this->shm,$key) ? false : shm_put_var($this->shm,$key,$value);
    }
    
    protected function deleteValue($key)
    {
        return @shm_remove_var($this->shm,$key);
    }
    
    protected function flushValues()
    {
        return shm_remove($this->shm);
    }
    
    public function buildKey($key)
    {
        return crc32(parent::buildKey($key));
    }
}