On 12/28/2011 05:25 PM, Coda Hale wrote:
> FWIW, I've just added a metrics-jersey module to Metrics
> 2.0.0-BETA19-SNAPSHOT which has a ResourceMethodDispatchProvider
> implementation which adds support for all
> @Timed/_at_Metered/_at_ExceptionMetered-annotated resource methods:
>
> https://github.com/codahale/metrics/blob/master/metrics-jersey/src/main/java/com/yammer/metrics/jersey/InstrumentedResourceMethodDispatchProvider.java
>
> Feedback appreciated.
>
Coda,
First of all, thanks for Metrics. :)
That's an interesting approach. I hadn't noticed the
ResourceMethodDispatchProvider extension point before. (Are all these
various provider and factories documented somewhere I haven't found, or
do I just need to chase down every usage of an interface that ends with
'Provider' or 'Factory'?)
I do have a few reservations, though. It looks like subclassing
EntityParamDispatchProvider would effectively route all requests through
EPDP since InstrumentedResourceMethodDispatchProvider would be checked
before the system-provided implementations. (Unless EPDP would return
null for a given request, in which case no metrics would be applied,
though it doesn't like like this would happen in practice.) I could be
off base here; I haven't had time to try this out yet so I'm not sure if
it behaves this way in practice. Ideally I'd like to let the default
dispatch provider selection mechanism follow the normal path and then
apply metrics around whatever it selects. It looks like this mechanism
also wouldn't play nice if I wanted my own separate dispatch provider to
be used, though I might be misunderstanding how dispatch provider
selection works.
It'd also be nice to abstract out the application of metrics to a given
AbstractResourceMethod. Ideally I'd like to be able to register my own
code to decides not only what to name the per-AbstractResourceMethod
metric but whether or not the metric is used at all. In other words,
while I think those annotations are useful, I'd like to be able to apply
timing (or any other metric) to *all* resource methods without having to
put @Timed on each of them.
Marshall