add an "iteration complete" hook for aggregation/reporting across iterations

This commit allows the user to specify a class which will be called upon
completion of each pregelix iteration.  This allows us to perform a user-
specified action between iterations.

As an example, a PerIterationGlobalAggregatesHook is provided which
saves the complete set of global aggregator states from every iteration,
allowing the user to observe aggregates from all iterations.

The default hook does nothing.

The hook instance is attached directly to the PregelixJob so that it can
be retrieved by the Driver's caller.
8 files changed
tree: af368cdb76cc0d8b585b9a28ac013333d1640362
  1. .gitignore
  2. algebricks/
  3. hivesterix/
  4. hyracks/
  5. pom.xml
  6. pregelix/