RFR: 8039173 Propagate errors from Diagnostic Commands as exceptions in the attach framework

[Alan Bateman]

On 03/04/2014 15:23, Staffan Larsen wrote:
> All,
>
> In the attach framework, the result is sent back to the attaching process as a stream. The first value in the stream is an integer that is interpreted as the completion status. For successful operations, this value is 0. In that case the attaching process continues to read output from the stream and displays that as the result of the operation.
>
> When the completion status signals an error, the rest of the stream output is ignored. This means that there is currently no way for an attach operation to signal an error and provide an error message.
>
> :
>
> At a later stage, I am planning to change the hotspot code so that exceptions in Diagnostic Commands actually set the completion status to an error. Today, the completation status is set to success, just because we want the error message to propagate.
>
> bug: https://bugs.openjdk.java.net/browse/JDK-8039173
> webrev: http://cr.openjdk.java.net/~sla/8039173/webrev.00/
>
For someone looking at the Virtualmachine API then I don't think the 
javadoc is clear enough to understand when one might get the specific 
AttachOperationFailedException vs. the more general IOException. I think 
it means that there was communication with the target VM but that the 
operation failed for some reason but I don't think this will be obvious 
to the reader.

For the new exception then it would be good to add @since and also a 
copyright header.

Sorry I don't have time to look at the implementation at this time.

-Alan.