Hi Yutao, look at the return type – Option, so it's a single element. It returns the leader of a given role (role == multiple nodes, 1 of them is the leader). I.e. it would host the the Singleton if it were constrained to this role.
-- Konrad `ktoso` Malawski Akka <http://akka.io> @ Lightbend <http://lightbend.com> On 15 August 2016 at 04:23:26, Yutao Shuai (szqs...@gmail.com) wrote: <https://lh3.googleusercontent.com/-tZtLqoK9VUY/V7EnCA2ZVKI/AAAAAAAAAL0/Gm66R8FjZqIZOmBWrT8b29IL8PdUJboCwCLcB/s1600/TT%25E6%2588%25AA%25E5%259B%25BE%25E6%259C%25AA%25E5%2591%25BD1%25E5%2590%258D.jpg> What this function means? Select a nodes with specfic roles as the cluster leader or every roles has its leader? -- >>>>>>>>>> Read the docs: http://akka.io/docs/ >>>>>>>>>> Check the FAQ: http://doc.akka.io/docs/akka/current/additional/faq.html >>>>>>>>>> Search the archives: https://groups.google.com/group/akka-user --- You received this message because you are subscribed to the Google Groups "Akka User List" group. To unsubscribe from this group and stop receiving emails from it, send an email to akka-user+unsubscr...@googlegroups.com. To post to this group, send email to akka-user@googlegroups.com. Visit this group at https://groups.google.com/group/akka-user. For more options, visit https://groups.google.com/d/optout. -- >>>>>>>>>> Read the docs: http://akka.io/docs/ >>>>>>>>>> Check the FAQ: >>>>>>>>>> http://doc.akka.io/docs/akka/current/additional/faq.html >>>>>>>>>> Search the archives: https://groups.google.com/group/akka-user --- You received this message because you are subscribed to the Google Groups "Akka User List" group. To unsubscribe from this group and stop receiving emails from it, send an email to akka-user+unsubscr...@googlegroups.com. To post to this group, send email to akka-user@googlegroups.com. Visit this group at https://groups.google.com/group/akka-user. For more options, visit https://groups.google.com/d/optout.
