org.apache.beam.sdk.transforms.splittabledofn

Class OffsetRangeTracker

java.lang.Object

org.apache.beam.sdk.transforms.splittabledofn.RestrictionTracker<OffsetRange,java.lang.Long>

org.apache.beam.sdk.transforms.splittabledofn.OffsetRangeTracker

public class OffsetRangeTracker
extends RestrictionTracker<OffsetRange,java.lang.Long>

A RestrictionTracker for claiming offsets in an OffsetRange in a monotonically increasing fashion.

Nested Class Summary

Nested classes/interfaces inherited from class org.apache.beam.sdk.transforms.splittabledofn.RestrictionTracker

RestrictionTracker.ClaimObserver<PositionT>

Constructor Summary

Constructors

Constructor and Description
OffsetRangeTracker(OffsetRange range)

Method Summary

Modifier and Type	Method and Description
void	checkDone() Called by the runner after DoFn.ProcessElement returns.
OffsetRange	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.
OffsetRange	currentRestriction() Returns a restriction accurately describing the full range of work the current DoFn.ProcessElement call will do, including already completed work.
void	markDone() Marks that there are no more offsets to be claimed in the range.
java.lang.String	toString()
protected boolean	tryClaimImpl(java.lang.Long i) Attempts to claim the given offset.

Methods inherited from class org.apache.beam.sdk.transforms.splittabledofn.RestrictionTracker

setClaimObserver, tryClaim

Methods inherited from class java.lang.Object

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

Constructor Detail

OffsetRangeTracker

public OffsetRangeTracker(OffsetRange range)

Method Detail

currentRestriction

public OffsetRange 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<OffsetRange,java.lang.Long>

checkpoint

public OffsetRange 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. Must not be called before the first successful RestrictionTracker.tryClaim(PositionT) call.

Specified by:

checkpoint in class RestrictionTracker<OffsetRange,java.lang.Long>

tryClaimImpl

protected boolean tryClaimImpl(java.lang.Long i)

Attempts to claim the given offset.

Must be larger than the last successfully claimed offset.

Specified by:

tryClaimImpl in class RestrictionTracker<OffsetRange,java.lang.Long>

Returns:

true if the offset was successfully claimed, false if it is outside the current OffsetRange of this tracker (in that case this operation is a no-op).

markDone

public void markDone()

Marks that there are no more offsets to be claimed in the range.

E.g., a DoFn reading a file and claiming the offset of each record in the file might call this if it hits EOF - even though the last attempted claim was before the end of the range, there are no more offsets to claim.

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<OffsetRange,java.lang.Long>

Throws:

java.lang.IllegalStateException

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object