» flock() Alternative mkdir() optimiert

function mkfile($filename, $data='', $chmod=0644) {
	$h = @fopen($filename, 'w');
	@fwrite($h, $data);
	@fclose($h);
	@umask(0000);
	@chmod($filename, $chmod);
	return $data;
}

1. der Cache wird immer nur von einem Besucher aktualisiert z.B. wenn der Administrator die Seite nutzt.
2. man sperrt die Datei, solange der Schreibprozess stattfindet

function mkfile($filename, $data='', $chmod=0644) {
	if (($h = @fopen($filename, 'w')) && flock($h, LOCK_EX | LOCK_NB, $wouldblock) && !$wouldblock) {
		@fwrite($h, $data);
		@fclose($h);
		@umask(0000);
		@chmod($filename, $chmod);
		flock($h, LOCK_UN); 
		return $data;
	}
}

function mkfile($filename, $data='', $chmod=0644, $flock=false) {
	if (($h = @fopen($filename, 'w')) && (!$flock || (!file_exists($filename . '_lock') && @mkdir($filename . '_lock')))) {
		@fwrite($h, $data);
		@fclose($h);
		@umask(0000);
		@chmod($filename, $chmod);
		if ($flock) rmdir($filename . '_lock');
		return $data;
	}
	return false;
}

error_reporting(-1);
set_error_handler(function($errno, $errstr, $errfile, $errline, array $errcontext) {
	// error was suppressed with the @-operator
	if (0 === error_reporting()) {
		return false;
	}
	throw new ErrorException($errstr, 0, $errno, $errfile, $errline);
});
try {
	$filename = 'cache3/atomic6.txt';
	if (!file_exists($filename . '_lock')) {
		if (mkdir($filename . '_lock')) {
			if ($h = fopen($filename, 'w')) {
				// $wouldblock makes only sense for flock() with LOCK_NB flag: http://stackoverflow.com/a/24823415/318765
				// LOCK_NB is not supported in windows (our machine uses debian)
				if (flock($h, LOCK_EX | LOCK_NB, $wouldblock)) {
					if (!$wouldblock) {
						// used from file_rand()
						$filesize = 102400;
						if ($filesize > 1024) {
							for ($i = 0; $i < floor($filesize / 1024); $i++) {
								fwrite($h, bin2hex(openssl_random_pseudo_bytes(511)) . "\r\n");
							}
							$filesize = $filesize - (1024 * $i);
						}
						$mod = $filesize % 2;
						fwrite($h, bin2hex(openssl_random_pseudo_bytes(($filesize - $mod) / 2)));
						if ($mod) {
							fwrite($h, substr(uniqid(), 0, 1));
						}
						flock($h, LOCK_UN);
						fclose($h);
						umask(0000);
						chmod($filename, 0644);
					}
					else {
						trigger_error('$wouldblock is true = mkdir() is not atomic');
					}
				}
				else {
					trigger_error('flock() failed');
				}
				if (!rmdir($filename . '_lock')) {
					trigger_error('rmdir() failed');
				}
			}
			else {
				trigger_error('fopen() failed');
			}
		}
		else {
			trigger_error('mkdir() failed');
		}
	}
}
catch (ErrorException $e) {
	mail('webmaster@example.org', 'mkdir() test6 failed', print_r($e, true));
}

$GLOBALS['webmaster_email'] = 'mail@example.org';
$filename = 'atomic.txt';

register_shutdown_function(function(){
	$error = error_get_last();
	if ($error && $error["type"] == E_ERROR) {
		mail($GLOBALS['webmaster_email'], 'Fatal error', print_r($error, true));
	}
});
error_reporting(-1);
set_error_handler(function($errno, $errstr, $errfile, $errline, array $errcontext) {
	// error was suppressed with the @-operator
	if (0 === error_reporting()) {
		return false;
	}
	mail($GLOBALS['webmaster_email'], print_r($errstr, true), print_r($errno, true) . print_r($errfile, true) . print_r($errline, true) . print_r($errcontext, true));
	if ($errno == E_USER_ERROR) {
		exit;
	}
	return true;
});

if (!file_exists($filename . '_lock')) {
	if (@mkdir($filename . '_lock')) {
		if ($h = fopen($filename, 'w')) {
			// $wouldblock makes only sense for flock() with LOCK_NB flag: http://stackoverflow.com/a/24823415/318765
			// LOCK_NB is not supported in windows (our machine uses debian)
			if (flock($h, LOCK_EX | LOCK_NB, $wouldblock)) {
				if (!$wouldblock) {
					// used from file_rand()
					$filesize = 102400;
					if ($filesize > 1024) {
						for ($i = 0; $i < floor($filesize / 1024); $i++) {
							fwrite($h, bin2hex(openssl_random_pseudo_bytes(511)) . "\r\n");
						}
						$filesize = $filesize - (1024 * $i);
					}
					$mod = $filesize % 2;
					fwrite($h, bin2hex(openssl_random_pseudo_bytes(($filesize - $mod) / 2)));
					if ($mod) {
						fwrite($h, substr(uniqid(), 0, 1));
					}
					flock($h, LOCK_UN);
					fclose($h);
					umask(0000);
					chmod($filename, 0644);
				}
				else {
					trigger_error('$wouldblock is true = mkdir() is not atomic');
				}
			}
			else {
				trigger_error('flock() failed');
			}
			if (!rmdir($filename . '_lock')) {
				trigger_error('rmdir() failed');
			}
		}
		else {
			trigger_error('fopen() failed');
		}
	}
	else {
		//trigger_error('mkdir() failed');
	}
}

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