[Bug]: Exceptions thrown in prehook callbacks are suppressed by trace_method()

[Devdits]

Bug report

The trace_method() function suppresses exceptions that are thrown inside a prehook callback.
This leads to inconsistent behavior between environments with and without dd-trace (e.g., local development vs. production).

Problem was discovered in DrupalIntegration.php, an exception thrown from $themeRegistry->getRuntime() inside a traced Drupal\Core\Theme\ThemeManager::render method is silently swallowed when dd-trace is active.

This makes debugging and consistent behavior between environments difficult.

Code to reproduce the problem:

<?php

use DDTrace\SpanData;
use function DDTrace\trace_method;

class testClass {
  private string $message = 'default';

  public function print(): void {
    echo $this->message;
  }

  public function throwException(): void {
    $this->message = 'Exception was thrown';
    throw new RuntimeException('Hello there!');
  }
}

trace_method(
  'testClass',
  'print',
  [
    'prehook' => function (SpanData $span, $args) {
      $test_class = $this;
      assert($test_class instanceof testClass);
      $test_class->throwException();
    },
  ]
);

$test_class = new testClass();
$test_class->print();

PHP version

8.3.21

Tracer or profiler version

1.13.0

Installed extensions

No response

Output of phpinfo()

No response

Upgrading from

No response

[bwoebi]

Hey @Devdits,

That's correct, and intended behaviour, to avoid having side-effects on the application code from issues in integrations (e.g. mistakes in the integrations, interactions with not actually tested versions, unexpected state and such).
These errors in integrations will be shown in the PHP error log, when DD_TRACE_DEBUG=1 or the log level is minimum warn (DD_TRACE_LOG_LEVEL=warn).

In fact, the goal here is that, production and development seemingly behave the same, except that your code is traced.

In this specific case though, am I correct in understanding, that the issue is that $themeRegistry->getRuntime() actually triggers an init(), which ultimately throws ... completely hiding the initialization failure, because that same codepath does not get reexecuted later?
If so, that's a problem in the integration, because it's not supposed to have such a side-effect.

[Devdits]

Thank you, @bwoebi, for the fast response!

The same codepath does not get re-executed late because of the runtime cache that is used in \Drupal\Core\Theme\Registry::getRuntime.

I did found the integration code in this repository in src/DDTrace/Integrations/Drupal. So I'm not sure if I need to re-create issue here or create it somewhere else. Can you, please, help me to understand, how I'd better proceed with the problem?

[bwoebi]

No, you totally reported it in the right place, I just was trying to understand the underlying problem at hand. We'll have a look at it soon!