Writing to an appengine blob asynchronously and finalizing it when all tasks complete

Question

I have a difficult problem.

I am iterating through a set of URLs parameterized by date and fetching them. For example, here is an example of one:

somewebserv

Answer 1

All right, so here's what I did. I had to modify Mitch's solution just a bit, but he definitely got me in the right direction with the advice to return the future value instead of an immediate one.

I had to create an intermidate DummyJob that takes the output of the recursion

   public static class DummyJob extends Job1> {
      @Override
      public Value run(List dummies) {
         return null;
      }
   }

Then, I submit the output of the DummyJob to the Blob Finalizer in a waitFor

List> dummies = new ArrayList>();
for (Interval in : ins) {
   dummies.add(futureCall(new DataFetcher(), immediate(file), immediate(in.getStart()),
         immediate(in.getEnd())));
}

FutureValue fv = futureCall(new DummyJob(), futureList(dummies));

return futureCall(new DataWriter(), immediate(file), waitFor(fv));

Thank you Mitch and Nick!!