Re: [Hawkular-dev] [metrics] Looking for advice on ListenableFuture usage

On Jan 16, 2015, at 10:48 AM, Thomas Segismont <tsegismo(a)redhat.com&gt; wrote: Sorry I overlooked the metrics-core code. Indeed, almost every call where a ListenableFuture returned by the C* driver is involved uses the overloaded version (with the metricsTasks ListenableExecutor instance). Should I open a JIRA for the few places where it's missing? My understanding from you reply is that: * all transformations on ListenableFuture returned by the C* driver should happen in a thread of the metricsTasks pool ==> use the overloaded version * subsequent transformations may happen on the metricsTasks thread or on the thread executing the rest handler code ==> use the base version Is that correct? Thanks Le 16/01/2015 14:23, John Sanda a écrit : > In the metrics code, at least where a response from the C* driver is involved, the versions that take an executor is used almost everywhere. We do not want to block I/O threads doing work so in general it is best to use the overloaded versions of the methods. B> >> On Jan 16, 2015, at 4:47 AM, Thomas Segismont <tsegismo(a)redhat.com&gt; wrote: >> >> Hi everyone, >> >> I'm looking for advice on how to use Futures#transform[1] and friends >> (#addCallback, #withFallback) >> >> These methods all have an overloaded version which takes a JDK Executor >> instance as additional argument. >> >> When the base method is called, Guava will use the so-called >> "sameThreadExecutor". Consequently, the code will be executed: >> * by the caller thread, if the underlying Future has completed already >> * otherwise, by the thread completing the underlying Future >> >> When the overloaded method is called, Guava will submit tasks to the >> provided executor. >> >> In the metrics code right now, the base method is used almost >> everywhere. Considering that in most cases it will take more time to get >> the response from C* than to complete the REST Handler code, it's the >> Datastax driver threads which will execute the chain of callbacks, down >> to the call to javax.ws.rs.container.AsyncResponse#resume >> >> Could that be a problem? I guess it's safe when callbacks only >> transforms the data loaded. I'm not sure about the call to >> AsyncResponse#resume. >> >> Thoughts? >> >> Thanks, >> Thomas >> >> >> [1] >> http://docs.guava-libraries.googlecode.com/git-history/v16.0.1/javadoc/co... >> >> _______________________________________________ >> Hawkular-dev mailing list >> Hawkular-dev(a)lists.jboss.org >> https://lists.jboss.org/mailman/listinfo/hawkular-dev >