net.openhft.chronicle.engine.map

Class CMap2EngineReplicator

java.lang.Object

net.openhft.chronicle.engine.map.CMap2EngineReplicator

All Implemented Interfaces:

EngineReplication, Replication, View, net.openhft.chronicle.hash.replication.EngineReplicationLangBytesConsumer

public class CMap2EngineReplicator
extends Object
implements EngineReplication, net.openhft.chronicle.hash.replication.EngineReplicationLangBytesConsumer, View

Created by Rob Austin

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	CMap2EngineReplicator.VanillaReplicatedEntry

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

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

Constructor Summary

Constructors

Constructor and Description
CMap2EngineReplicator(RequestContext context)
CMap2EngineReplicator(RequestContext requestContext, Asset asset)

Method Summary

Modifier and Type	Method and Description
EngineReplication.ModificationIterator	acquireModificationIterator(byte remoteIdentifier) 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 entry) removes or puts the entry into the map
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	put(net.openhft.chronicle.bytes.BytesStore key, net.openhft.chronicle.bytes.BytesStore value, byte remoteIdentifier, long timestamp)
void	set(net.openhft.chronicle.map.EngineReplicationLangBytes engineReplicationLangBytes)
void	setLastModificationTime(byte identifier, long timestamp)
String	toString()

Methods inherited from class java.lang.Object

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

Constructor Detail

CMap2EngineReplicator

public CMap2EngineReplicator(RequestContext requestContext,
                             @NotNull
                             Asset asset)

CMap2EngineReplicator

public CMap2EngineReplicator(RequestContext context)

Method Detail

set

public void set(net.openhft.chronicle.map.EngineReplicationLangBytes engineReplicationLangBytes)

Specified by:

set in interface net.openhft.chronicle.hash.replication.EngineReplicationLangBytesConsumer

put

public void put(@NotNull
                net.openhft.chronicle.bytes.BytesStore key,
                @NotNull
                net.openhft.chronicle.bytes.BytesStore value,
                byte remoteIdentifier,
                long timestamp)

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

applyReplication

public void applyReplication(@NotNull
                             EngineReplication.ReplicationEntry entry)

Description copied from interface: Replication

removes or puts the entry into the map

Specified by:

applyReplication in interface Replication

acquireModificationIterator

@Nullable
public EngineReplication.ModificationIterator acquireModificationIterator(byte remoteIdentifier)

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:

remoteIdentifier - the identifier of the remote node

Returns:

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

See Also:

EngineReplication.identifier()

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

toString

@NotNull
public String toString()

Overrides:

toString in class Object