[SPARK-7326] [STREAMING] Performing window() on a WindowedDStream doesn't work all the time

tdas

https://issues.apache.org/jira/browse/SPARK-7326

The problem most likely resides in DStream.slice() implementation, as shown below.

  def slice(fromTime: Time, toTime: Time): Seq[RDD[T]] = {
    if (!isInitialized) {
      throw new SparkException(this + " has not been initialized")
    }
    if (!(fromTime - zeroTime).isMultipleOf(slideDuration)) {
      logWarning("fromTime (" + fromTime + ") is not a multiple of slideDuration ("
        + slideDuration + ")")
    }
    if (!(toTime - zeroTime).isMultipleOf(slideDuration)) {
      logWarning("toTime (" + fromTime + ") is not a multiple of slideDuration ("
        + slideDuration + ")")
    }
    val alignedToTime = toTime.floor(slideDuration, zeroTime)
    val alignedFromTime = fromTime.floor(slideDuration, zeroTime)

    logInfo("Slicing from " + fromTime + " to " + toTime +
      " (aligned to " + alignedFromTime + " and " + alignedToTime + ")")

    alignedFromTime.to(alignedToTime, slideDuration).flatMap(time => {
      if (time >= zeroTime) getOrCompute(time) else None
    })
  }

Here after performing floor() on both fromTime and toTime, the result (alignedFromTime - zeroTime) and (alignedToTime - zeroTime) may no longer be multiple of the slidingDuration, thus making isTimeValid() check failed for all the remaining computation.

The fix is to add a new floor() function in Time.scala to respect the zeroTime while performing the floor :

  def floor(that: Duration, zeroTime: Time): Time = {
    val t = that.milliseconds
    new Time(((this.millis - zeroTime.milliseconds) / t) * t + zeroTime.milliseconds)
  }

And then change the DStream.slice to call this new floor function by passing in its zeroTime.

    val alignedToTime = toTime.floor(slideDuration, zeroTime)
    val alignedFromTime = fromTime.floor(slideDuration, zeroTime)

This way the alignedToTime and alignedFromTime are *really* aligned in respect to zeroTime whose value is not really a 0.

Author: Wesley Miao <wesley.miao@gmail.com>
Author: Wesley <wesley.miao@autodesk.com>

Closes #5871 from wesleymiao/spark-7326 and squashes the following commits:

82a4d8c [Wesley Miao] [SPARK-7326] [STREAMING] Performing window() on a WindowedDStream dosen't work all the time
48b4dc0 [Wesley] [SPARK-7326] [STREAMING] Performing window() on a WindowedDStream doesn't work all the time
6ade399 [Wesley] [SPARK-7326] [STREAMING] Performing window() on a WindowedDStream doesn't work all the time
2611745 [Wesley Miao] [SPARK-7326] [STREAMING] Performing window() on a WindowedDStream doesn't work all the time

0 files changed, 0 insertions, 0 deletions