Package uk.gov.gchq.gaffer.time

Class BoundedTimestampSet

java.lang.Object

uk.gov.gchq.gaffer.time.BoundedTimestampSet

All Implemented Interfaces:

TimestampSet

public class BoundedTimestampSet
extends Object
implements TimestampSet

A BoundedTimestampSet is an implementation of TimestampSet that can contain a maximum number N of timestamps. If more than N timestamps are added then a uniform random sample of size approximately N of the timestamps is retained.

This is useful in avoiding the in-memory or serialised size of the set of timestamps becoming too large. If less than N timestamps are added then the timestamps are stored in a RBMBackedTimestampSet. If more than N timestamps are added then a uniform random sample of size N of the timestamps is retained.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	BoundedTimestampSet.Builder
static class	BoundedTimestampSet.State

Constructor Summary

Constructors

Constructor	Description
BoundedTimestampSet(CommonTimeUtil.TimeBucket timeBucket, int maxSize)

Method Summary

Modifier and Type	Method	Description
void	add(Instant instant)	Adds the provided timestamp to the set.
void	add(Collection<Instant> instants)	Adds all the provided timestamps to the set.
boolean	equals(Object obj)	Important - this equals method requires the underlying timestamps to be exactly the same.
Instant	getEarliest()	The earliest timestamp in the set.
Instant	getLatest()	The latest timestamp in the set.
int	getMaxSize()
long	getNumberOfTimestamps()	Returns the number of distinct timestamps in the set.
RBMBackedTimestampSet	getRbmBackedTimestampSet()	This exposes the underlying RBMBackedTimestampSet so that serialisers can access it.
org.apache.datasketches.sampling.ReservoirLongsUnion	getReservoirLongsUnion()	This exposes the underlying ReservoirLongsUnion so that serialisers can access it.
BoundedTimestampSet.State	getState()	Returns BoundedTimestampSet.State.NOT_FULL if less than or equal to getMaxSize() timestamps have been added.
CommonTimeUtil.TimeBucket	getTimeBucket()
SortedSet<Instant>	getTimestamps()	Returns all the timestamps in the set, sorted in their natural order.
int	hashCode()	Important - this hash code method will produce different values if the underlying timestamps are different.
void	setRbmBackedTimestampSet(RBMBackedTimestampSet rbmBackedTimestampSet)	Allows the RBMBackedTimestampSet to be set.
void	setReservoirLongsUnion(org.apache.datasketches.sampling.ReservoirLongsUnion reservoirLongsUnion)	Allows the ReservoirLongsUnion to be set.
void	switchToSampleState()
String	toString()

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

BoundedTimestampSet

public BoundedTimestampSet(CommonTimeUtil.TimeBucket timeBucket,
                           int maxSize)

Method Detail

add

public void add(Instant instant)

Description copied from interface: TimestampSet

Adds the provided timestamp to the set.

Specified by:

add in interface TimestampSet

Parameters:

instant - The timestamp to be added.

add

public void add(Collection<Instant> instants)

Description copied from interface: TimestampSet

Adds all the provided timestamps to the set.

Specified by:

add in interface TimestampSet

Parameters:

instants - The Collection of timestamps to be added.

getTimestamps

public SortedSet<Instant> getTimestamps()

Description copied from interface: TimestampSet

Returns all the timestamps in the set, sorted in their natural order.

Specified by:

getTimestamps in interface TimestampSet

Returns:

All the timestamps in the set, sorted in their natural order.

getNumberOfTimestamps

public long getNumberOfTimestamps()

Description copied from interface: TimestampSet

Returns the number of distinct timestamps in the set.

Specified by:

getNumberOfTimestamps in interface TimestampSet

Returns:

The number of distinct timestamps in the set.

getEarliest

public Instant getEarliest()

Description copied from interface: TimestampSet

The earliest timestamp in the set.

Specified by:

getEarliest in interface TimestampSet

Returns:

The earliest timestamp in the set.

getLatest

public Instant getLatest()

Description copied from interface: TimestampSet

The latest timestamp in the set.

Specified by:

getLatest in interface TimestampSet

Returns:

The latest timestamp in the set.

getTimeBucket

public CommonTimeUtil.TimeBucket getTimeBucket()

getMaxSize

public int getMaxSize()

getState

public BoundedTimestampSet.State getState()

Returns BoundedTimestampSet.State.NOT_FULL if less than or equal to getMaxSize() timestamps have been added. Otherwise BoundedTimestampSet.State.SAMPLE is returned.

Returns:

The BoundedTimestampSet.State that this object is currently in.

getRbmBackedTimestampSet

public RBMBackedTimestampSet getRbmBackedTimestampSet()

This exposes the underlying RBMBackedTimestampSet so that serialisers can access it. If the object is currently in the state of NOT_FULL then an exception is thrown.

Returns:

the RBMBackedTimestampSet used by this class to store the timestamps if it is in state NOT_FULL

setRbmBackedTimestampSet

public void setRbmBackedTimestampSet(RBMBackedTimestampSet rbmBackedTimestampSet)

Allows the RBMBackedTimestampSet to be set.

Parameters:

rbmBackedTimestampSet - the RBMBackedTimestampSet to set the RBMBackedTimestampSet of this class to.

getReservoirLongsUnion

public org.apache.datasketches.sampling.ReservoirLongsUnion getReservoirLongsUnion()

This exposes the underlying ReservoirLongsUnion so that serialisers can access it. If the object is currently in the state of NOT_FULL then an exception is thrown.

Returns:

the ReservoirLongsUnion used by this class to store the timestamps if it is in state SAMPLE

setReservoirLongsUnion

public void setReservoirLongsUnion(org.apache.datasketches.sampling.ReservoirLongsUnion reservoirLongsUnion)

Allows the ReservoirLongsUnion to be set.

Parameters:

reservoirLongsUnion - the ReservoirLongsUnion to be set.

switchToSampleState

public void switchToSampleState()

equals

public boolean equals(Object obj)

Important - this equals method requires the underlying timestamps to be exactly the same. If it's in the state where it's sampling then it's randomly generated samples must be the same. So two BoundedTimestampSets which have had exactly the same data added might not be equal if the random samples are different.

Overrides:

equals in class Object

Parameters:

obj - the object to compare

Returns:

true if the obj is equal to this.

hashCode

public int hashCode()

Important - this hash code method will produce different values if the underlying timestamps are different. This may cause issues when using the randomly sampled data. So two BoundedTimestampSets which have had exactly the same data added might have different hash codes if the random samples are different.

Overrides:

hashCode in class Object

Returns:

the hash code

toString

public String toString()

Overrides:

toString in class Object