lithium\storage\cache\adapter\File::key()

Overrides lithium\storage\cache\Adapter::key()
public method

Generates safe cache keys.

Keys should be safe to be used as filename. So we conservatively disallalow any non alphanumeric characters with the exception of dash und underscore.

We also limit to max. 255 characters. The limit is actually lowered to 255 minus the length of an crc32b hash minus separator (246) minus scope length minus separator (246 - x).

255 was chosen as most commonly used filesystems (ext2-4, HFS+, NTFS, XFS, FAT32, btrfs) limit filename characters to a length of 255.

Parameters

  • array $keys

    The original keys.

Returns

array

Keys modified and safe to use with adapter.

Source

	public function key(array $keys) {
		$length = 246 - ($this->_config['scope'] ? strlen($this->_config['scope']) + 1 : 0);

		return array_map(
			function($key) use ($length) {
				$result = substr(preg_replace('/[^a-z0-9_\-]/iu', '_', $key), 0, $length);
				return $result !== $key ? $result . '_' . hash('crc32b', $key) : $result;
			},
			$keys
		);
	}