On 12/7/2011 1:30 PM, Frederic Parain wrote:
The execute method doesn't throw any exception other than
IAE. What happens if the specified command execution fails
in the target VM? If no exception is thrown, how does the
caller detect if the command succeeds or not and handle it
gracefully? It seems that this mechanism should provide
a way to detect if a command succeeds or fails programmatically
rather than burying the error message in the returned string.
This changeset contains the framework, and the framework
only throws NPE or IAE. However, a diagnostic command
impementation is free to throw any other exception. If such
an exception is thrown, it is simply printed on the output
stream if the command has been invoked through the attachAPI,
or it is propagated like any other exception through JMX
if the command has been invoked from the HotSpotDiagnosticMXBean.
What happens when HotSpotDiagnosticMXBean is called locally within the
same process but through JMX MBeanServer?
I still think you might need DiagnosticCommandException (something like
that).
L133: do you need to check if command == null and throw NPE?
or NPE will be thrown somewhere?
The native code is protected against null commands, it will
throw the NPE.
Ok. It's still good to add the null check to make this more explicit -
you can use the java.util.Objects.requireNonNull method.
L158, 172: this should never happen unless the hotspot/jdk is
mismatched. But would it better to throw an exception with
an informative message to help diagnostic in case the mismatch
does happen?
If a mismatch is detected, the implementation now throws an
UnsupportedOperationException("Diagnostic commands are not supported
by this VM").
That's better.
Thanks
Mandy
