com.hazelcast.crdt.pncounter

Class PNCounterImpl

java.lang.Object

com.hazelcast.crdt.pncounter.PNCounterImpl

All Implemented Interfaces:

CRDT<PNCounterImpl>, DataSerializable, IdentifiedDataSerializable

public class PNCounterImpl
extends Object
implements CRDT<PNCounterImpl>, IdentifiedDataSerializable

PN (Positive-Negative) CRDT counter where each replica is identified by a String.

Constructor Summary

Constructors

Constructor and Description
PNCounterImpl()

Method Summary

Modifier and Type	Method and Description
CRDTTimestampedLong	addAndGet(long delta, VectorClock observedTimestamps) Adds the given value to the current value.
CRDTTimestampedLong	get(VectorClock observedTimestamps) Returns the current value of the counter.
CRDTTimestampedLong	getAndAdd(long delta, VectorClock observedTimestamps) Adds the given value to the current value.
CRDTTimestampedLong	getAndSubtract(long delta, VectorClock observedTimestamps) Subtracts the given value from the current value.
VectorClock	getCurrentVectorClock() Returns the current vector clock which reflects the current CRDT state.
int	getFactoryId() Returns DataSerializableFactory factory ID for this class.
int	getId() Returns type identifier for this class.
void	markMigrated() Unconditionally marks this CRDT as migrated.
boolean	markMigrated(VectorClock vectorClock) Marks this CRDT as migrated.
void	merge(PNCounterImpl other) Merges the state of a different replica into this CRDT.
void	readData(ObjectDataInput in) Reads fields from the input stream
CRDTTimestampedLong	subtractAndGet(long delta, VectorClock observedTimestamps) Subtracts the given value from the current value.
void	writeData(ObjectDataOutput out) Writes object fields to output stream

Methods inherited from class java.lang.Object

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

Constructor Detail

PNCounterImpl

public PNCounterImpl()

Method Detail

get

public CRDTTimestampedLong get(VectorClock observedTimestamps)

Returns the current value of the counter.

The method can throw a ConsistencyLostException when the state of this CRDT is not causally related to the observed timestamps. This means that it cannot provide the session guarantees of RYW (read your writes) and monotonic read.

Parameters:

observedTimestamps - the vector clock last observed by the client of this counter

Returns:

the current counter value with the current counter vector clock

Throws:

ConsistencyLostException - if this replica cannot provide the session guarantees

getAndAdd

public CRDTTimestampedLong getAndAdd(long delta,
                                     VectorClock observedTimestamps)

Adds the given value to the current value.

The method can throw a ConsistencyLostException when the state of this CRDT is not causally related to the observed timestamps. This means that it cannot provide the session guarantees of RYW (read your writes) and monotonic read.

Parameters:

delta - the value to add

observedTimestamps - the vector clock last observed by the client of this counter

Returns:

the current counter value with the current counter vector clock

Throws:

ConsistencyLostException - if this replica cannot provide the session guarantees

addAndGet

public CRDTTimestampedLong addAndGet(long delta,
                                     VectorClock observedTimestamps)

Adds the given value to the current value.

The method can throw a ConsistencyLostException when the state of this CRDT is not causally related to the observed timestamps. This means that it cannot provide the session guarantees of RYW (read your writes) and monotonic read.

Parameters:

delta - the value to add

observedTimestamps - the vector clock last observed by the client of this counter

Returns:

the current counter value with the current counter vector clock

Throws:

ConsistencyLostException - if this replica cannot provide the session guarantees

getAndSubtract

public CRDTTimestampedLong getAndSubtract(long delta,
                                          VectorClock observedTimestamps)

Subtracts the given value from the current value.

The method can throw a ConsistencyLostException when the state of this CRDT is not causally related to the observed timestamps. This means that it cannot provide the session guarantees of RYW (read your writes) and monotonic read.

Parameters:

delta - the value to add

observedTimestamps - the vector clock last observed by the client of this counter

Returns:

the current counter value with the current counter vector clock

Throws:

ConsistencyLostException - if this replica cannot provide the session guarantees

subtractAndGet

public CRDTTimestampedLong subtractAndGet(long delta,
                                          VectorClock observedTimestamps)

Subtracts the given value from the current value.

The method can throw a ConsistencyLostException when the state of this CRDT is not causally related to the observed timestamps. This means that it cannot provide the session guarantees of RYW (read your writes) and monotonic read.

Parameters:

delta - the value to subtract

observedTimestamps - the vector clock last observed by the client of this counter

Returns:

the current counter value with the current counter vector clock

Throws:

ConsistencyLostException - if this replica cannot provide the session guarantees

merge

public void merge(PNCounterImpl other)

Description copied from interface: CRDT

Merges the state of a different replica into this CRDT. The merge method should not leave the CRDT in a failed state.

Specified by:

merge in interface CRDT<PNCounterImpl>

Parameters:

other - the CRDT to merge into this CRDT

getCurrentVectorClock

public VectorClock getCurrentVectorClock()

Description copied from interface: CRDT

Returns the current vector clock which reflects the current CRDT state.

Specified by:

getCurrentVectorClock in interface CRDT<PNCounterImpl>

getFactoryId

public int getFactoryId()

Description copied from interface: IdentifiedDataSerializable

Returns DataSerializableFactory factory ID for this class.

Specified by:

getFactoryId in interface IdentifiedDataSerializable

Returns:

factory ID

getId

public int getId()

Description copied from interface: IdentifiedDataSerializable

Returns type identifier for this class. It should be unique per DataSerializableFactory.

Specified by:

getId in interface IdentifiedDataSerializable

Returns:

type ID

writeData

public void writeData(ObjectDataOutput out)
               throws IOException

Description copied from interface: DataSerializable

Writes object fields to output stream

Specified by:

writeData in interface DataSerializable

Parameters:

out - output

Throws:

IOException - if an I/O error occurs. In particular, an IOException may be thrown if the output stream has been closed.

readData

public void readData(ObjectDataInput in)
              throws IOException

Description copied from interface: DataSerializable

Reads fields from the input stream

Specified by:

readData in interface DataSerializable

Parameters:

in - input

Throws:

IOException - if an I/O error occurs. In particular, an IOException may be thrown if the input stream has been closed.

markMigrated

public boolean markMigrated(VectorClock vectorClock)

Marks this CRDT as migrated. A migrated CRDT can no longer be mutated. For this CRDT to be marked as migrated, the provided vectorClock must be equal to the current vector clock.

Parameters:

vectorClock - a vector clock to compare the current clock to

Returns:

true if this CRDT has been marked as migrated, false otherwise

markMigrated

public void markMigrated()

Unconditionally marks this CRDT as migrated. A migrated CRDT can no longer be mutated.