CacheCompressed.php in Redis 7.3

File

lib/Redis/CacheCompressed.php

<?php

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

}

Classes

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