Re: [RFC PATCH v3 3/3] trace2: write overload message to sentinel files

[Josh Steadmon <steadmon@google.com>]

On 2019.09.16 08:07, Derrick Stolee wrote:
> On 9/13/2019 8:26 PM, Josh Steadmon wrote:
> > Add a new "overload" event type for trace2 event destinations. Write
> > this event into the sentinel file created by the trace2.maxFiles
> > feature. Bump up the event format version since we've added a new event
> > type.
> > 
> > Writing this message into the sentinel file is useful for tracking how
> > often the overload protection feature is triggered in practice.
> 
> Putting meaningful data into the sentinel file is valuable. It's
> important to know a bit about when and why this happened. A user
> would be able to inspect the modified time, and the directory info
> you include is unnecessary. The data you include is only for the
> log aggregator to keep valuable data around overloads.
>  
> > +`"overload"`::
> > +	This event is created in a sentinel file if we are overloading a target
> > +	trace directory (see the trace2.maxFiles config option).
> > ++
> > +------------
> > +{
> > +	"event":"overload",
> > +	...
> > +	"dir":"/trace/target/dir/", # The configured trace2 target directory
> > +	"evt":"2",		    # EVENT format version
> > +}
> That said, do we really need to resort to a new event format and
> event type? Could we instead use the "data" event with a key
> "overload" and put the target dir in the value?

Yeah, that sounds reasonable. Thanks for the suggestion.