Re: MI non-stop mode spec

[Vladimir Prus <ghost at cs dot msu dot su>]

Pawel Piech wrote:

>> Currently commands like -break-insert gives synchronous MI output for the
>> frontend to parse while the CLI command "break" issued under MI,
>> "-interpreter-exec console break", say, just gives CLI output.  I think this is
>> the wrong approach and that -break-insert shouldn't generate the output
>> directly but instead MI should generate event notifications informing the
>> frontend of changes:
>>
>> =breakpoints-changed,...
>>
>> This could be done with observers like Vladimir has done for threads and
>> would produce the same notifications regardless of whether the breakpoint
>> was created with a CLI or MI command.
>>
>> Likewise with the new commands for non-stop mode

> Thank you for the explanation.  I agree.  Currently MI lacks out of band
> notifications for thread state changes (it has a running event only),
> thread lifecycle events, memory changed events, 

Oh, I think that last one might be tricky to implement :-)

> registers changed 
> events, modules changed events, and as you mention above breakpoints
> changed events.  Like I said, I'm not familiar with GDB internals, but
> since CLI has notifications for most of these I can't imagine it would
> be that hard to add them to MI.
> 
> One note about the =breakpoints-changed proposed above.  I think it
> would be a mistake to just replace the ^done reply to
> -break-insert/-break-remove with an event alone, 

It's not being proposed. Per my spec, each MI command results in one of
^done, ^error, ^connected or ^running to be output.

> because a client would 
> have no way of knowing whether an event was in response to that client's
> request or another client's request.  I.e. a client would not be able to
> positively determine the ID of the breakpoint he just created.  I see
> two equally good ways to address this:
> 1) Add the =breakpoints-changed event in addition to the ^done with
> breakpoint info, but the =breakpoints-changed would have to be sent
> AFTER the ^done reply.

We probably can suppress =breakpoints-changed for the -break-insert command.

- Volodya