Cache.php

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<?php
 
namespace Rsi\Fred;
 
/**
 *  Wrapper for the Doctrine cache.
 */
class Cache extends Component{
 
  const TYPE_ARRAY = 'array';
  const TYPE_CHAIN = 'chain';
 
  public $busyPlaceholder = null; //!< Placeholder for preventing cache slam.
  public $defaultTtl = null; //!< Default lifetime.
  public $ttlVariation = null; //!< Variation (plus and minus; percentage) of input value.
  public $statPrefix = null; //!< Set to something to stat all cache requests (hit/miss).
 
  protected $_type = self::TYPE_ARRAY; //!< Cache type to use.
  protected $_params = null; //!< Parameters (arguments) for this type of cache.
  protected $_altType = self::TYPE_CHAIN;
  protected $_altParams = [self::TYPE_ARRAY => null,null => null];
  protected $_busyTtl = null; //!< Lifetime for cache slam prevention (default = current timeout).
 
  protected $_provider = null;
  protected $_altProvider = null;
  protected $_useAlt = false;
  protected $_refresh = false;
  protected $_refreshed = [];
  protected $_duploCount = [];
 
  protected function init(){
    parent::init();
    $this->publish(['type','refresh']);
  }
 
  public function createProvider($type,$params = null){
    if($type == self::TYPE_CHAIN){
      $providers = [];
      foreach($params as $sub_type => $sub_params)
        $providers[] = $sub_type ? $this->createProvider($sub_type,$sub_params) : $this->_provider;
      $params = [$providers];
    }
    $reflect = new \ReflectionClass('\\Doctrine\\Common\\Cache\\' . ucfirst($type) . 'Cache');
    return $reflect->newInstanceArgs($params ?: []);
  }
  /**
   * Save data to the cache.
   * @param string $id  Cache id.
   * @param mixed $data
   * @param int $ttl  Cache lifetime (null = use default, 0 = never expire).
   * @return bool  Provider response (true = OK).
   */
  public function save($id,$data,$ttl = null){
    $log = $this->component('log');
    $log->debug(__CLASS__ . "::save('$id',...,$ttl)",__FILE__,__LINE__);
    if($data === false) $log->warning("Saving false in cache for id '$id' (means 'no cache found')",__FILE__,__LINE__);
    if($this->_refresh) $this->_refreshed[] = $id;
    if($ttl === null) $ttl = $this->defaultTtl;
    if($this->ttlVariation) $ttl *= 1 + rand(-1000,1000) * $this->ttlVariation / 100000;
    try{
      return $this->provider->save($id,$data,$ttl);
    }
    catch(\Exception $e){
      $log->error($e,compact('id','data'));
    }
    return false;
  }
  /**
   * Fetch with callback function in case cache fails.
   * @param string $id  Cache id.
   * @param int $ttl  Cache lifetime (null = use default, 0 = never expire).
   * @param callable $callback  Function to get data if cache fails (parameters: $id; returns data).
   * @return mixed  Data (false on fail).
   */
  public function fetch($id,$ttl = null,$callback = null){
    $log = $this->component('log');
    $time = $this->statPrefix ? microtime(true) : null;
    try{
      do{
        $data = $this->_refresh && !in_array($id,$this->_refreshed) ? false : $this->provider->fetch($id);
        if($busy = $this->busyPlaceholder && ($data === $this->busyPlaceholder)) sleep(1);
      }
      while($busy);
    }
    catch(\Exception $e){
      $data = $busy = false;
      $log->error($e,compact('id'));
    }
    $log->debug(__CLASS__ . "::fetch('$id',$ttl,...)",__FILE__,__LINE__,['cache' => $id,'found' => $data !== false]);
    if($data !== false) $time = false;
    elseif($callback){
      if($this->busyPlaceholder) $this->save($id,$this->busyPlaceholder,$this->_busyTtl ?: ini_get('max_execution_time'));
      $this->save($id,$data = call_user_func($callback,$id),$ttl);
    }
    if($this->statPrefix) $this->component('stats')->inc(
      $this->statPrefix . ':' . $id . ':' . ($time ? 'miss' : 'hit'),
      $time && $callback ? microtime(true) - $time : null
    );
    if($this->_fred->debug){
      if(array_key_exists($id,$this->_duploCount))
        $log->info('Duplicate fetch' . ($this->_duploCount[$id]++ ? ' (' . $this->_duploCount[$id] . ')' : ''),__FILE__,__LINE__,compact('id','ttl'));
      else $this->_duploCount[$id] = 0;
    }
    return $data;
  }
  /**
   * Remove expired items from the cache.
   * @param array $errors  Returns any errors.
   * @return array  Statistics about the purge.
   */
  public function purge(&$errors = null){
    $type = null;
    $stats = $errors = [];
    if($this->provider instanceof \Doctrine\Common\Cache\FilesystemCache) $type = 'file';
    elseif($this->provider instanceof \Doctrine\Common\Cache\PhpFileCache) $type = 'php';
    if($type){
      set_time_limit(300);
      $files = new \RegexIterator(
        new \RecursiveIteratorIterator(new \RecursiveDirectoryIterator($this->getDirectory())),
        '/^.+' . preg_quote($this->getExtension(),'/') . '$/i'
      );
      $time = time();
      $count = $purged = $total = $largest = $dirs = 0;
      foreach($files as $path => $file) try{
        set_time_limit(10);
        $count++;
        if(($size = filesize($path)) > $largest) $largest = $size;
        switch($type){
          case 'file':
            $resource = fopen($path,'r');
            $purge = (int)fgets($resource) < $time;
            fclose($resource);
            break;
          case 'php':
            $purge = !is_array($data = include($path)) || !array_key_exists('lifetime',$data) || ($data['lifetime'] < $time);
            break;
        }
        if($purge){
          $total += $size;
          $purged += unlink($path);
          if(!(new \FilesystemIterator($dir = dirname($path)))->valid()) $dirs += rmdir($dir);
        }
      }
      catch(Exception $e){
        $errors[] = "Could not purge $path: " . $e->getMessage();
      }
      $stats = compact('type','count','purged','total','largest','dirs');
    }
    else $errors[] = 'Cache type not supported';
    return $stats;
  }
 
  protected function getProvider(){
    if(!$this->_provider) $this->_provider = $this->createProvider($this->_type,$this->_params);
    if(!$this->_useAlt) return $this->_provider;
    if(!$this->_altProvider) $this->_altProvider = $this->createProvider($this->_altType,$this->_altParams);
    return $this->_altProvider;
  }
 
  protected function setRefresh($value){
    $this->_refresh = $value;
    $this->_refreshed = [];
  }
  /**
   * See vendor/doctrine/cache/lib/Doctrine/Common/Cache/Cache.php for the available functions (save, contains, fetch, delete,
   * flushAll, getStats) and more explanation.
   */
  public function __call($func_name,$params){
    if($this->_useAlt = substr($func_name,0,1) == '_'){
      $result = call_user_func_array([$this,substr($func_name,1)],$params);
      $this->_useAlt = false;
      return $result;
    }
    if(in_array($func_name,['save','contains','fetch','delete']))
      $this->component('log')->debug(__CLASS__ . "::$func_name('$params[0]')",__FILE__,__LINE__);
    return call_user_func_array([$this->provider,$func_name],$params);
  }
 
  public function __invoke($id){
    return $this->provider->fetch($id);
  }
 
}