Exception related utilities.
Bases: object
Save current exception, run some code and then re-raise.
In some cases the exception context can be cleared, resulting in None being attempted to be re-raised after an exception handler is run. This can happen when eventlet switches greenthreads or when running an exception handler, code raises and catches an exception. In both cases the exception context will be cleared.
To work around this, we save the exception state, run handler code, and then re-raise the original exception. If another exception occurs, the saved exception is logged and the new exception is re-raised.
In some cases the caller may not want to re-raise the exception, and for those circumstances this context provides a reraise flag that can be used to suppress the exception. For example:
except Exception:
with save_and_reraise_exception() as ctxt:
decide_if_need_reraise()
if not should_be_reraised:
ctxt.reraise = False
If another exception occurs and reraise flag is False, the saved exception will not be logged.
If the caller wants to raise new exception during exception handling he/she sets reraise to False initially with an ability to set it back to True if needed:
except Exception:
with save_and_reraise_exception(reraise=False) as ctxt:
[if statements to determine whether to raise a new exception]
# Not raising a new exception, so reraise
ctxt.reraise = True