David Mollitor created CURATOR-515:
--------------------------------------
Summary: Backgrounding CheckError
Key: CURATOR-515
URL: https://issues.apache.org/jira/browse/CURATOR-515
Project: Apache Curator
Issue Type: Improvement
Reporter: David Mollitor
Assignee: Jordan Zimmerman
This code is confusing to me:
{code:java|title=Backgrounding.java}
void checkError(Throwable e, Watching watching) throws Exception
{
if ( e != null )
{
if ( errorListener != null )
{
errorListener.unhandledError("n/a", e);
}
else if ( e instanceof Exception )
{
throw (Exception)e;
}
else
{
Throwables.propagate(e);
}
}
}
{code}
[https://github.com/apache/curator/blob/master/curator-framework/src/main/java/org/apache/curator/framework/imps/Backgrounding.java#L123-L140]
I *think* the code here is meaning to take a run-time Exception and wrap it in
a checked Exception. However, that is not actually happening here.
If the {{Throwable}} argument is an {{Exception}}, it is thrown as-is. Fair
enough. However, if the {{Throwable}} is a {{RuntimeException}} it is also
thrown here because {{RuntimeException}} is a sub-class of {{Exception}}. It is
not turned into a checked exception. So, if the {{Throwable}} is not an
{{Exception}}, the only other sub-class of {{Throwable}} is an {{Error}}. The
call {{Throwables.propagate(e)}} will will see that it is an {{Error}} and
simply throw it.
[https://docs.oracle.com/javase/8/docs/api/java/lang/RuntimeException.html]
[https://github.com/google/guava/blob/master/guava/src/com/google/common/base/Throwables.java#L132-L134]
So, really, whatever the {{Throwable}} argument is, it is simply re-thrown.
This code could be simplified to:
{code:java|title=Backgrounding.java}
void checkError(Throwable e, Watching watching) throws Exception
{
if ( e != null )
{
if ( errorListener != null )
{
errorListener.unhandledError("n/a", e);
}
else if ( e instanceof Exception )
{
throw (Exception)e;
}
else
{
throw (Error)e;
}
}
}
{code}
Is this the intended behavior our should {{RuntimeException}} and {{Error}} be
wrapped into a checked {{Error}}?
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