io.permazen.kv.raft

Class Follower

java.lang.Object

io.permazen.kv.raft.Follower

public class Follower
extends Object

Contains information maintained by leaders about followers.

Field Summary

Fields

Modifier and Type	Field and Description
static Comparator<Follower>	SORT_BY_IDENTITY Sorts instances by their identities.

Method Summary

Modifier and Type	Method and Description
String	getAddress() Get the address of this follower.
String	getIdentity() Get the identity of this follower.
long	getLeaderCommit() Get the leader commit index most recently sent to this follower.
Timestamp	getLeaderTimestamp() Get the most recent (leader's) request timestamp returned by this follower in a response, if any.
long	getMatchIndex() Get the index of the highest log entry in the follower's log known to match the leader's log.
long	getNextIndex() Get the index of the next log entry to send to this follower.
Timestamp	getSnapshotTimestamp() Get the (leader's) timestamp of the most recent snapshot install sent to this follower, if any.
boolean	isReceivingSnapshot() Determine whether this follower is currently being sent a whole database snapshot download.
boolean	isSynced() Determine whether we believe this follower is "synchronized".
String	toString()

Methods inherited from class java.lang.Object

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

Field Detail

SORT_BY_IDENTITY

public static final Comparator<Follower> SORT_BY_IDENTITY

Sorts instances by their identities.

Method Detail

getIdentity

public String getIdentity()

Get the identity of this follower.

Returns:

follower identity

getAddress

public String getAddress()

Get the address of this follower.

Returns:

follower address

getNextIndex

public long getNextIndex()

Get the index of the next log entry to send to this follower.

Returns:

follower next index

getMatchIndex

public long getMatchIndex()

Get the index of the highest log entry in the follower's log known to match the leader's log.

Returns:

follower match index; will be zero if unknown

getLeaderTimestamp

public Timestamp getLeaderTimestamp()

Get the most recent (leader's) request timestamp returned by this follower in a response, if any.

Returns:

follower leader timestamp, or null if no response has been received yet from this follower

getSnapshotTimestamp

public Timestamp getSnapshotTimestamp()

Get the (leader's) timestamp of the most recent snapshot install sent to this follower, if any.

Returns:

follower leader timestamp, or null if no response has been received yet from this follower

getLeaderCommit

public long getLeaderCommit()

Get the leader commit index most recently sent to this follower.

Returns:

follower leader commit index

isSynced

public boolean isSynced()

Determine whether we believe this follower is "synchronized".

By "synchronized" we mean the most recently received AppendResponse indicated a successful match of the previous log entry. We only send "probes" to unsynchronized followers.

Returns:

true if synchronized

isReceivingSnapshot

public boolean isReceivingSnapshot()

Determine whether this follower is currently being sent a whole database snapshot download.

Returns:

true if snapshot install is in progress

toString

public String toString()

Overrides:

toString in class Object