tree 6c60cad99a9dab8a108e4c9bd13276748a91d47d
parent 18c25fdcfabb7ba1c56ea374d0d7f6777d99d7fd
author Sergiy Matusevych <motus@apache.org> 1476219125 -0700
committer Markus Weimer <weimer@apache.org> 1476743451 -0700

[REEF-1642] Make sure there is only one instance of Evaluators per REEFEnvironment/Driver

   * Improve `SingletonAsserter` to support both global and scoped singletons
   * Add unit tests for new functionality of `SingletonAsserter`
   * Use scoped `SingletonAsserter` in the `Evaluators` class

This is work towards [REEF-1561](https://issues.apache.org/jira/browse/REEF-1561)
*"REEF as a library"* effort.

JIRA:
  [REEF-1642](https://issues.apache.org/jira/browse/REEF-1642)

Pull Request:
  This closes #1157