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From PramodSSImmaneni <...@git.apache.org>
Subject [GitHub] incubator-apex-core pull request: Providing a way for operator to ...
Date Tue, 17 Nov 2015 17:50:04 GMT
Github user PramodSSImmaneni commented on a diff in the pull request:

    --- Diff: engine/src/main/java/com/datatorrent/stram/engine/Node.java ---
    @@ -600,6 +605,19 @@ public void activate()
    +    int dagChkptWndwCnt = context.getValue(Context.DAGContext.CHECKPOINT_WINDOW_COUNT);
    +    if (PROCESSING_MODE != ProcessingMode.EXACTLY_ONCE) {
    +      int chkOffset = dagChkptWndwCnt % CHECKPOINT_WINDOW_COUNT;
    +      if (chkOffset != 0) {
- chkOffset;
    +      } else {
    +      }
    +    } else {
    +    }
    --- End diff --
    @ilooner Normally windowsFromCheckpoint does not have to be saved as the operator is going
to recover at a checkpoint. However I think we may have to save a few other things like checkpointWindowCount
as well because we are saying that we are going to checkpoint at a window divisible by the
operator checkpoint window count and this count should be from the beginning of the application
and not necessarily a restart. I will look at this comprehensively.
    Regarding your second point you could at the beginWindow check the windows from checkpoint
and use that information later. Are you thinking about cases where application window spans
multiple streaming window? In the first phase implementation of iteration support we had talked
about limiting it to cases where application window was same as streaming window if you remember.
In future when we add support for full application windows we will need the callbacks you
are suggesting so we know when the streaming window starts so as to be able to not only save
but inject those tuples at the right streaming window for ingestion. However you will still
need to that how far the streaming window is from the checkpoint and you will need a method
like this.

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