PHP Global Error Handler
06 Jul 2017When it comes to handling uncaught Throwables in PHP 7, there are a few things to consider:
- It’s best to have only one handler defined
- The handler should be stateful, meaning it should be able to capture something like a
LoggerInterface - The additional handler shouldn’t hide the code location, meaning that in logs, we should see the file and line of the previous hop in the stack trace, not the handler’s
- Registering handlers should be simple and straightforward
Here’s an example of an implementation that meets these criteria:
class ErrorHandler implements GenericHandler
{
private $logger;
public function __construct(LoggerInterface $logger)
{
$this->logger = $logger;
}
public function __invoke($code, $message, $file, $line)
{
switch ($code) {
case E_USER_ERROR:
if (extension_loaded('newrelic')) {
newrelic_notice_error($message);
}
$this->logger->critical($message);
break;
default:
$this->logger->warning($message);
break;
}
return true;
}
}
And here’s an example of an exception handler:
class ExceptionHandler implements GenericHandler
{
private $logger;
public function __construct(LoggerInterface $logger)
{
$this->logger = $logger;
}
public function __invoke(Throwable $exception)
{
if (extension_loaded('newrelic')) {
newrelic_notice_error($exception->getMessage(), $exception);
}
$this->logger->warning($exception->getMessage(), ['exception' => $exception]);
http_response_code(500);
}
}
And for the regisration:
set_error_handler(new ErrorHandler($logger), E_ALL);
set_exception_handler(new ExceptionHandler($logger));
In addition, to make this work, you will need to use a fork of Log4Php, version 4.*, that:
- includes namespaces,
- implements the
psr/loginterface, - accounts for the new
Throwablehierarchy change in PHP 7, - adds
GenericHandlerandGenericLoggermarker interfaces that are used to skip additional logging layers in stack traces.