net.openhft.chronicle.engine.map

Class VanillaEngineReplication<Store extends KeyValueStore<?,?,?>>

java.lang.Object

net.openhft.chronicle.engine.map.VanillaEngineReplication<Store>

All Implemented Interfaces:

Closeable, AutoCloseable, EngineReplication, Replication, View

public class VanillaEngineReplication<Store extends KeyValueStore<?,?,?>>
extends Object
implements EngineReplication, Closeable

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static interface	VanillaEngineReplication.ChangeApplier<Store>
static interface	VanillaEngineReplication.GetValue<Store>
static interface	VanillaEngineReplication.RemoteNodeReplicationState
static interface	VanillaEngineReplication.ReplicationData
static interface	VanillaEngineReplication.SegmentForKey<Store>

Nested classes/interfaces inherited from interface net.openhft.chronicle.engine.api.EngineReplication

EngineReplication.EntryCallback, EngineReplication.ModificationIterator, EngineReplication.ModificationNotifier, EngineReplication.ReplicationEntry

Field Summary

Fields

Modifier and Type	Field and Description
static int	DIRTY_WORD_COUNT
static int	MAX_MODIFICATION_ITERATORS
static int	RESERVED_MOD_ITER

Constructor Summary

Constructors

Constructor and Description

VanillaEngineReplication(java.util.function.IntFunction<KeyValueStore<net.openhft.chronicle.bytes.BytesStore,VanillaEngineReplication.ReplicationData,VanillaEngineReplication.ReplicationData>> obtainKeyReplicationDataBySegment, KeyValueStore<net.openhft.chronicle.core.values.IntValue,VanillaEngineReplication.RemoteNodeReplicationState,VanillaEngineReplication.RemoteNodeReplicationState> modIterState, byte identifier, Store store, VanillaEngineReplication.ChangeApplier<Store> changeApplier, VanillaEngineReplication.GetValue<Store> getValue, VanillaEngineReplication.SegmentForKey<Store> segmentForKey)

Method Summary

Modifier and Type	Method and Description
EngineReplication.ModificationIterator	acquireModificationIterator(byte id) Gets (if it does not exist, creates) an instance of ModificationIterator associated with a remote node, this weak associated is bound using the identifier.
void	applyReplication(EngineReplication.ReplicationEntry replicatedEntry) removes or puts the entry into the map
void	close()
byte	identifier() Provides the unique Identifier associated with this instance.
long	lastModificationTime(byte remoteIdentifier) Returns the timestamp of the last change from the specified remote node, already replicated to this host.
void	onPut(net.openhft.chronicle.bytes.BytesStore key, long putTimestamp)
void	onRemove(net.openhft.chronicle.bytes.BytesStore key, long remoteTimestamp)
void	setLastModificationTime(byte identifier, long timestamp)

Methods inherited from class java.lang.Object

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

Methods inherited from interface net.openhft.chronicle.engine.api.EngineReplication

forEach

Methods inherited from interface net.openhft.chronicle.engine.api.tree.View

keyedView

Field Detail

RESERVED_MOD_ITER

public static final int RESERVED_MOD_ITER

See Also:

Constant Field Values

MAX_MODIFICATION_ITERATORS

public static final int MAX_MODIFICATION_ITERATORS

See Also:

Constant Field Values

DIRTY_WORD_COUNT

public static final int DIRTY_WORD_COUNT

See Also:

Constant Field Values

Constructor Detail

VanillaEngineReplication

public VanillaEngineReplication(java.util.function.IntFunction<KeyValueStore<net.openhft.chronicle.bytes.BytesStore,VanillaEngineReplication.ReplicationData,VanillaEngineReplication.ReplicationData>> obtainKeyReplicationDataBySegment,
                                KeyValueStore<net.openhft.chronicle.core.values.IntValue,VanillaEngineReplication.RemoteNodeReplicationState,VanillaEngineReplication.RemoteNodeReplicationState> modIterState,
                                byte identifier,
                                Store store,
                                VanillaEngineReplication.ChangeApplier<Store> changeApplier,
                                VanillaEngineReplication.GetValue<Store> getValue,
                                VanillaEngineReplication.SegmentForKey<Store> segmentForKey)

Method Detail

identifier

public byte identifier()

Description copied from interface: EngineReplication

Provides the unique Identifier associated with this instance.

An identifier is used to determine which replicating node made the change.

If two nodes update their map at the same time with different values, we have to deterministically resolve which update wins, because of eventual consistency both nodes should end up locally holding the same data. Although it is rare two remote nodes could receive an update to their maps at exactly the same time for the same key, we have to handle this edge case, its therefore important not to rely on timestamps alone to reconcile the updates. Typically the update with the newest timestamp should win, but in this example both timestamps are the same, and the decision made to one node should be identical to the decision made to the other. We resolve this simple dilemma by using a node identifier, each node will have a unique identifier, the update from the node with the smallest identifier wins.

Specified by:

identifier in interface EngineReplication

Returns:

the unique Identifier associated with this map instance

lastModificationTime

public long lastModificationTime(byte remoteIdentifier)

Description copied from interface: EngineReplication

Returns the timestamp of the last change from the specified remote node, already replicated to this host.

Used in conjunction with replication, to back fill data from a remote node. This node may have missed updates while it was not been running or connected via TCP.

Specified by:

lastModificationTime in interface EngineReplication

Specified by:

lastModificationTime in interface Replication

Parameters:

remoteIdentifier - the identifier of the remote node to check last replicated update time from

Returns:

a timestamp of the last modification to an entry, or 0 if there are no entries.

See Also:

EngineReplication.identifier()

setLastModificationTime

public void setLastModificationTime(byte identifier,
                                    long timestamp)

Specified by:

setLastModificationTime in interface EngineReplication

applyReplication

public void applyReplication(@NotNull
                             EngineReplication.ReplicationEntry replicatedEntry)

Description copied from interface: Replication

removes or puts the entry into the map

Specified by:

applyReplication in interface Replication

acquireModificationIterator

public EngineReplication.ModificationIterator acquireModificationIterator(byte id)

Description copied from interface: EngineReplication

Gets (if it does not exist, creates) an instance of ModificationIterator associated with a remote node, this weak associated is bound using the identifier.

Specified by:

acquireModificationIterator in interface EngineReplication

Specified by:

acquireModificationIterator in interface Replication

Parameters:

id - the identifier of the remote node

Returns:

the ModificationIterator dedicated for replication to the remote node with the given identifier

See Also:

EngineReplication.identifier()

onPut

public void onPut(net.openhft.chronicle.bytes.BytesStore key,
                  long putTimestamp)

onRemove

public void onRemove(net.openhft.chronicle.bytes.BytesStore key,
                     long remoteTimestamp)

close

public void close()
           throws IOException

Specified by:

close in interface Closeable

Specified by:

close in interface AutoCloseable

Throws:

IOException