class Redis_CacheCompressed in Redis 7.3

This typically brings 80..85% compression in ~20ms/mb write, 5ms/mb read.

Hierarchy

• class \Redis_Cache implements DrupalCacheInterface
  • class \Redis_CacheCompressed implements DrupalCacheInterface

File

lib/Redis/CacheCompressed.php, line 6

class Redis_CacheCompressed extends Redis_Cache implements DrupalCacheInterface {
  private $compressionSizeThreshold = 100;
  private $compressionRatio = 1;

  /**
   * {@inheritdoc}
   */
  public function __construct($bin) {
    parent::__construct($bin);
    $this->compressionSizeThreshold = (int) variable_get('cache_compression_size_threshold', 100);
    if ($this->compressionSizeThreshold < 0) {
      trigger_error('cache_compression_size_threshold must be 0 or a positive integer, negative value found, switching back to default 100', E_USER_WARNING);
      $this->compressionSizeThreshold = 100;
    }

    // Minimum compression level (1) has good ratio in low time.
    $this->compressionRatio = (int) variable_get('cache_compression_ratio', 1);
    if ($this->compressionRatio < 1 || 9 < $this->compressionRatio) {
      trigger_error('cache_compression_ratio must be between 1 and 9, out of bounds value found, switching back to default 1', E_USER_WARNING);
      $this->compressionRatio = 1;
    }
  }

  /**
   * {@inheritdoc}
   */
  protected function createEntryHash($cid, $data, $expire = CACHE_PERMANENT) {
    $hash = parent::createEntryHash($cid, $data, $expire);

    // Empiric level when compression makes sense.
    if (!$this->compressionSizeThreshold || strlen($hash['data']) > $this->compressionSizeThreshold) {
      $hash['data'] = gzcompress($hash['data'], $this->compressionRatio);
      $hash['compressed'] = true;
    }
    return $hash;
  }

  /**
   * {@inheritdoc}
   */
  protected function expandEntry(array $values, $flushPerm, $flushVolatile) {
    if (!empty($values['data']) && !empty($values['compressed'])) {

      // Uncompress, suppress warnings e.g. for broken CRC32.
      $values['data'] = @gzuncompress($values['data']);

      // In such cases, void the cache entry.
      if ($values['data'] === false) {
        return false;
      }
    }
    return parent::expandEntry($values, $flushPerm, $flushVolatile);
  }

}

Members

Name	Modifiers	Type	Description	Overrides
Redis_Cache::$allowPipeline	protected	property	When in shard mode, the proxy may or may not support pipelining, Twemproxy is known to support it.
Redis_Cache::$allowTemporaryFlush	protected	property	When the global 'cache_lifetime' Drupal variable is set to a value, the cache backends should not expire temporary entries by themselves per Drupal signature. Volatile items will be dropped accordingly to their set lifetime.
Redis_Cache::$backend	protected	property
Redis_Cache::$bin	protected	property
Redis_Cache::$flushCache	protected	property	Flush permanent and volatile cached values
Redis_Cache::$isSharded	protected	property	When in shard mode, the backend cannot proceed to multiple keys operations, and won't delete keys on flush calls.
Redis_Cache::$maxTtl	protected	property	Maximum TTL for this bin from Drupal configuration.
Redis_Cache::$permTtl	protected	property	Default TTL for CACHE_PERMANENT items.
Redis_Cache::allowPipeline	public	function	Does this bin allow pipelining through sharded environment
Redis_Cache::allowTemporaryFlush	public	function	Does this bin allow temporary item flush
Redis_Cache::clear	public	function	Expires data from the cache. Overrides DrupalCacheInterface::clear
Redis_Cache::FLUSH_NORMAL		constant	Uses EVAL scripts to flush data when called
Redis_Cache::FLUSH_SHARD		constant	This mode is tailored for sharded Redis servers instances usage: it will never delete entries but only mark the latest flush timestamp into one of the servers in the shard. It will proceed to delete on read single entries when invalid entries are…
Redis_Cache::FLUSH_SHARD_WITH_PIPELINING		constant	Same as the one above, plus attempt to do pipelining when possible.
Redis_Cache::get	public	function	Returns data from the persistent cache. Overrides DrupalCacheInterface::get
Redis_Cache::getLastFlushTime	public	function	Get latest flush time
Redis_Cache::getMaxTtl	public	function	Get maximum TTL for all items.
Redis_Cache::getMultiple	public	function	Returns data from the persistent cache when given an array of cache IDs. Overrides DrupalCacheInterface::getMultiple
Redis_Cache::getNextIncrement	public	function	From the given timestamp build an incremental safe time-based identifier.
Redis_Cache::getPermTtl	public	function	Get TTL for CACHE_PERMANENT items.
Redis_Cache::getValidChecksum	public	function	Get valid checksum
Redis_Cache::isEmpty	public	function	Checks if a cache bin is empty. Overrides DrupalCacheInterface::isEmpty
Redis_Cache::isSharded	public	function	Is this bin in shard mode
Redis_Cache::KEY_THRESHOLD		constant	Computed keys are let's say arround 60 characters length due to key prefixing, which makes 1,000 keys DEL command to be something arround 50,000 bytes length: this is huge and may not pass into Redis, let's split this off. Some recommend to…
Redis_Cache::LIFETIME_PERM_DEFAULT		constant	Default lifetime for permanent items. Approximatively 1 year.
Redis_Cache::refreshCapabilities	public	function	Find from Drupal variables the clear mode.
Redis_Cache::refreshMaxTtl	public	function	Find from Drupal variables the maximum cache lifetime.
Redis_Cache::refreshPermTtl	protected	function	Find from Drupal variables the right permanent items TTL.
Redis_Cache::set	public	function	Stores data in the persistent cache. Overrides DrupalCacheInterface::set
Redis_Cache::setLastFlushTime	public	function	Set last flush time
Redis_CacheCompressed::$compressionRatio	private	property
Redis_CacheCompressed::$compressionSizeThreshold	private	property
Redis_CacheCompressed::createEntryHash	protected	function	Create cache entry Overrides Redis_Cache::createEntryHash
Redis_CacheCompressed::expandEntry	protected	function	Expand cache entry from fetched data Overrides Redis_Cache::expandEntry
Redis_CacheCompressed::__construct	public	function	Overrides Redis_Cache::__construct