org.apache.beam.sdk.transforms.splittabledofn

Class ByteKeyRangeTracker

java.lang.Object

org.apache.beam.sdk.transforms.splittabledofn.RestrictionTracker<ByteKeyRange,ByteKey>

org.apache.beam.sdk.transforms.splittabledofn.ByteKeyRangeTracker

All Implemented Interfaces:

Backlogs.HasBacklog

public class ByteKeyRangeTracker
extends RestrictionTracker<ByteKeyRange,ByteKey>
implements Backlogs.HasBacklog

A RestrictionTracker for claiming ByteKeys in a ByteKeyRange in a monotonically increasing fashion. The range is a semi-open bounded interval [startKey, endKey) where the limits are both represented by ByteKey.EMPTY.

Note, one can complete a range by claiming the ByteKey.EMPTY once one runs out of keys to process.

Method Summary

Modifier and Type	Method and Description
void	checkDone() Called by the runner after DoFn.ProcessElement returns.
ByteKeyRange	checkpoint() Signals that the current DoFn.ProcessElement call should terminate as soon as possible: after this method returns, the tracker MUST refuse all future claim calls, and RestrictionTracker.checkDone() MUST succeed.
ByteKeyRange	currentRestriction() Returns a restriction accurately describing the full range of work the current DoFn.ProcessElement call will do, including already completed work.
Backlog	getBacklog()
static ByteKeyRangeTracker	of(ByteKeyRange range)
java.lang.String	toString()
boolean	tryClaim(ByteKey key) Attempts to claim the given key.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Method Detail

of

public static ByteKeyRangeTracker of(ByteKeyRange range)

currentRestriction

public ByteKeyRange currentRestriction()

Description copied from class: RestrictionTracker

Returns a restriction accurately describing the full range of work the current DoFn.ProcessElement call will do, including already completed work.

Specified by:

currentRestriction in class RestrictionTracker<ByteKeyRange,ByteKey>

checkpoint

public ByteKeyRange checkpoint()

Description copied from class: RestrictionTracker

Signals that the current DoFn.ProcessElement call should terminate as soon as possible: after this method returns, the tracker MUST refuse all future claim calls, and RestrictionTracker.checkDone() MUST succeed.

Modifies RestrictionTracker.currentRestriction(). Returns a restriction representing the rest of the work: the old value of RestrictionTracker.currentRestriction() is equivalent to the new value and the return value of this method combined.

Must be called at most once on a given object.

Specified by:

checkpoint in class RestrictionTracker<ByteKeyRange,ByteKey>

tryClaim

public boolean tryClaim(ByteKey key)

Attempts to claim the given key.

Must be larger than the last attempted key. Since this restriction tracker represents a range over a semi-open bounded interval [start, end), the last key that was attempted may have failed but still have consumed the interval [lastAttemptedKey, end) since this range tracker processes keys in a monotonically increasing order. Note that passing in ByteKey.EMPTY claims all keys to the end of range and can only be claimed once.

Specified by:

tryClaim in class RestrictionTracker<ByteKeyRange,ByteKey>

Returns:

true if the key was successfully claimed, false if it is outside the current ByteKeyRange of this tracker.

checkDone

public void checkDone()
               throws java.lang.IllegalStateException

Description copied from class: RestrictionTracker

Called by the runner after DoFn.ProcessElement returns.

Must throw an exception with an informative error message, if there is still any unclaimed work remaining in the restriction.

Specified by:

checkDone in class RestrictionTracker<ByteKeyRange,ByteKey>

Throws:

java.lang.IllegalStateException

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

getBacklog

public Backlog getBacklog()

Specified by:

getBacklog in interface Backlogs.HasBacklog