Frequently Asked Questions¶
Some questions are hard because they are ultimately decided by your application’s design. Lithoxyl is mostly an API to instrumentation. There are many right ways.
What is the difference between failure status and exception status?¶
There are a couple angles to answer this. First, it is pretty rare to
set an exception status manually, as exception information is usually
populated automatically when there are uncaught exceptions. That
failure(), which is seen more often.
So when to call
failure()? As with many design
questions, an example is often best. With an HTTP server, returning a
4xx or even a 503 can be viewed as failures outside of the control of
the application, which is performing fine. A 500, on the other hand,
is generally unexpected and deserves an exception status.
Why does Lithoxyl sometimes fail silently?¶
Built-in to the design of Lithoxyl itself, there are several deviations from what one might consider standard practice. With most libraries, one expects that code will “fail fast”. However, failing fast does not work well for instrumentation code.
Lithoxyl assumes that you are instrumenting a system which has behavior other than logging and statistics collection. Your system’s primary functions take priority. Instrumentation must degrade gracefully.
This means if your message is malformed Lithoxyl will do its best to output the most that it can and no exception will be raised. If your logging service is down, maybe the Sink queues the message, but eventually that queues bounds will be overrun and messages may silently drop.
This graceful degradation takes place at all the runtime integration points, i.e., action usage within your application code. For Sink and Logger configuration, actions which are typically performed at startup and import time, exceptions are still raised as usual. In fact, it is considered good Lithoxyl practice to forward-check these configurations. This means checking that callable arguments are
If you discover a runtime scenario that should degrade with more grace or a configuration-time scenario which could prevent runtime failures through more forward checking, please do file an issue.