Support local filesystems with a large number of directories or files (using Flysystem)

LocalSpread.php

<?php

namespace Acme\Adapter;

use League\Flysystem\Adapter\Local;

/**
 * A local adapter that works around filesystems' limit of subdirectories in a
 * directory.
 *
 * For files or directories in the root of the filesystem, we SHA1-hash their
 * name and use the first 4 chars of the hash as four levels of subdirs. The file
 * or directory is then placed inside the last level.
 *
 * Thus, a directory with name 'foo' will be interpreted as "0/b/e/e/foo", where
 * "0bee" are the first four characters of sha1('foo')
 */
class LocalSpread extends Local
{
    public function applyPathPrefix($path)
    {
        // Only apply the prefix if it's not already present
        if (empty($path) || preg_match('/^([a-fA-F0-9]\/){4}/', $path)) {
            return parent::applyPathPrefix($path);
        }

        // We're only interested in prefixing the first level, imediately under
        // the filesystem root
        $pos = strpos($path, DIRECTORY_SEPARATOR);
        if (false === $pos) {
            $prefix = $this->getPrefix($path);
        } else {
            $prefix = $this->getPrefix(substr($path, 0, $pos));
        }

        return parent::applyPathPrefix($prefix.DIRECTORY_SEPARATOR.$path);
    }

    private function getPrefix($path)
    {
        return implode(DIRECTORY_SEPARATOR, str_split(substr(hash('sha1', $path), 0, 4)));
    }
}

LocalSpreadTest.php

<?php

namespace Acme\Tests\Adapter;

use Memeoirs\StorageBundle\Adapter\LocalSpread;

class LocalSpreadTest extends \PHPUnit_Framework_TestCase
{
    const ROOT = '/tmp';

    public function setUp()
    {
        $this->adapter = new LocalSpread(self::ROOT);
    }

    public function testApplyPathPrefix()
    {
        $this->doTestApplyPathPrefix('', '');
        $this->doTestApplyPathPrefix('foo', '0/b/e/e/foo');
        $this->doTestApplyPathPrefix('foo/bar', '0/b/e/e/foo/bar');
        $this->doTestApplyPathPrefix('0/b/e/e/foo/bar', '0/b/e/e/foo/bar');
    }

    private function doTestApplyPathPrefix($path, $realPath)
    {
        $this->assertEquals(
            $this->adapter->applyPathPrefix($path),
            self::ROOT.DIRECTORY_SEPARATOR.$realPath
        );
    }
}