MyShaarli/application/bookmark/BookmarkIO.php
ArthurHoaro 8a6b7e96b7 Fix: soft fail if the mutex is not working
And display the error in server admin page

Fixes #1650
2020-11-24 13:39:35 +01:00

147 lines
4.1 KiB
PHP

<?php
declare(strict_types=1);
namespace Shaarli\Bookmark;
use malkusch\lock\exception\LockAcquireException;
use malkusch\lock\mutex\Mutex;
use malkusch\lock\mutex\NoMutex;
use Shaarli\Bookmark\Exception\DatastoreNotInitializedException;
use Shaarli\Bookmark\Exception\EmptyDataStoreException;
use Shaarli\Bookmark\Exception\NotWritableDataStoreException;
use Shaarli\Config\ConfigManager;
/**
* Class BookmarkIO
*
* This class performs read/write operation to the file data store.
* Used by BookmarkFileService.
*
* @package Shaarli\Bookmark
*/
class BookmarkIO
{
/**
* @var string Datastore file path
*/
protected $datastore;
/**
* @var ConfigManager instance
*/
protected $conf;
/** @var Mutex */
protected $mutex;
/**
* string Datastore PHP prefix
*/
protected static $phpPrefix = '<?php /* ';
/**
* string Datastore PHP suffix
*/
protected static $phpSuffix = ' */ ?>';
/**
* LinksIO constructor.
*
* @param ConfigManager $conf instance
*/
public function __construct(ConfigManager $conf, Mutex $mutex = null)
{
if ($mutex === null) {
// This should only happen with legacy classes
$mutex = new NoMutex();
}
$this->conf = $conf;
$this->datastore = $conf->get('resource.datastore');
$this->mutex = $mutex;
}
/**
* Reads database from disk to memory
*
* @return Bookmark[]
*
* @throws NotWritableDataStoreException Data couldn't be loaded
* @throws EmptyDataStoreException Datastore file exists but does not contain any bookmark
* @throws DatastoreNotInitializedException File does not exists
*/
public function read()
{
if (! file_exists($this->datastore)) {
throw new DatastoreNotInitializedException();
}
if (!is_writable($this->datastore)) {
throw new NotWritableDataStoreException($this->datastore);
}
$content = null;
$this->synchronized(function () use (&$content) {
$content = file_get_contents($this->datastore);
});
// Note that gzinflate is faster than gzuncompress.
// See: http://www.php.net/manual/en/function.gzdeflate.php#96439
$links = unserialize(gzinflate(base64_decode(
substr($content, strlen(self::$phpPrefix), -strlen(self::$phpSuffix))
)));
if (empty($links)) {
if (filesize($this->datastore) > 100) {
throw new NotWritableDataStoreException($this->datastore);
}
throw new EmptyDataStoreException();
}
return $links;
}
/**
* Saves the database from memory to disk
*
* @param Bookmark[] $links
*
* @throws NotWritableDataStoreException the datastore is not writable
*/
public function write($links)
{
if (is_file($this->datastore) && !is_writeable($this->datastore)) {
// The datastore exists but is not writeable
throw new NotWritableDataStoreException($this->datastore);
} elseif (!is_file($this->datastore) && !is_writeable(dirname($this->datastore))) {
// The datastore does not exist and its parent directory is not writeable
throw new NotWritableDataStoreException(dirname($this->datastore));
}
$data = self::$phpPrefix . base64_encode(gzdeflate(serialize($links))) . self::$phpSuffix;
$this->synchronized(function () use ($data) {
file_put_contents(
$this->datastore,
$data
);
});
}
/**
* Wrapper applying mutex to provided function.
* If the lock can't be acquired (e.g. some shared hosting provider), we execute the function without mutex.
*
* @see https://github.com/shaarli/Shaarli/issues/1650
*
* @param callable $function
*/
protected function synchronized(callable $function): void
{
try {
$this->mutex->synchronized($function);
} catch (LockAcquireException $exception) {
$function();
}
}
}