org.apache.beam.sdk.transforms.splittabledofn

Interface GrowableOffsetRangeTracker.RangeEndEstimator

Enclosing class:

GrowableOffsetRangeTracker

Functional Interface:

This is a functional interface and can therefore be used as the assignment target for a lambda expression or method reference.

@FunctionalInterface
public static interface GrowableOffsetRangeTracker.RangeEndEstimator

Provides the estimated end offset of the range.

estimate() is called to give the end offset when GrowableOffsetRangeTracker.trySplit(double) or GrowableOffsetRangeTracker.getProgress() is invoked. The end offset is exclusive for the range. The estimated end is not required to monotonically increase as it will only be taken into consideration when the estimated end offset is larger than the current position. Returning Long.MAX_VALUE as the estimate implies the largest possible position for the range is Long.MAX_VALUE - 1. Return Long.MIN_VALUE if an estimate can not be provided.

Providing a good estimate is important for an accurate progress signal and will impact splitting decisions by the runner.

If estimate() is expensive to compute, consider wrapping the implementation with Suppliers.memoizeWithExpiration(org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.base.Supplier<T>, long, java.util.concurrent.TimeUnit) or equivalent as an optimization.

TODO(https://github.com/apache/beam/issues/20227): Also consider using GrowableOffsetRangeTracker.RangeEndEstimator when the range is not ended with Long.MAX_VALUE.

Method Summary

Modifier and Type	Method and Description
long	estimate()

Method Detail

estimate

long estimate()