io.permazen.kv.raft.msg

Class AppendRequest

java.lang.Object

io.permazen.kv.raft.msg.Message

io.permazen.kv.raft.msg.AppendRequest

public class AppendRequest
extends Message

Sent from leaders to followers to probe the follower's log state and/or append an entry to their log.

Instances also provide the leader's lease timeout value (if any), which is used to commit read-only transactions, as well as a leader timestamp which should be reflected back in the corresponding AppendResponse.

Constructor Summary

Constructors

Constructor and Description
AppendRequest(int clusterId, String senderId, String recipientId, long term, Timestamp leaderTimestamp, Timestamp leaderLeaseTimeout, long leaderCommit, long prevLogTerm, long prevLogIndex) Constructor for a "probe" that does not contain a log entry.
AppendRequest(int clusterId, String senderId, String recipientId, long term, Timestamp leaderTimestamp, Timestamp leaderLeaseTimeout, long leaderCommit, long prevLogTerm, long prevLogIndex, long logEntryTerm, ByteBuffer mutationData) Constructor for a request that contains an actual log entry.

Method Summary

Modifier and Type	Method and Description
protected int	calculateSize(int version) Calculate an upper bound on the number of bytes required by writeTo().
long	getLeaderCommit() Get leader's commit index.
Timestamp	getLeaderLeaseTimeout()
Timestamp	getLeaderTimestamp()
long	getLogEntryTerm()
ByteBuffer	getMutationData() Get the serialized data for the log entry, if any.
long	getPrevLogIndex()
long	getPrevLogTerm()
boolean	isLeaderMessage() Determine whether this message is only sent by leaders.
boolean	isProbe()
String	toString()
void	visit(MessageSwitch handler) Apply the visitor pattern based on this instance's type.
void	writeTo(ByteBuffer dest, int version) Serialize this instance into the given buffer.

Methods inherited from class io.permazen.kv.raft.msg.Message

calculateSize, calculateSize, calculateSize, decode, decodeProtocolVersion, encode, getBoolean, getByteBuffer, getClusterId, getCurrentProtocolVersion, getRecipientId, getSenderId, getString, getTerm, getTimestamp, putBoolean, putByteBuffer, putString, putTimestamp

Methods inherited from class java.lang.Object

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

Constructor Detail

AppendRequest

public AppendRequest(int clusterId,
                     String senderId,
                     String recipientId,
                     long term,
                     Timestamp leaderTimestamp,
                     Timestamp leaderLeaseTimeout,
                     long leaderCommit,
                     long prevLogTerm,
                     long prevLogIndex)

Constructor for a "probe" that does not contain a log entry.

Note that leaderCommit is limited to prevLogIndex by this constructor, because we can't guarantee that the omitted log entry at prevLogIndex + 1 matches whatever the follower has in its log.

Parameters:

clusterId - cluster ID

senderId - identity of sender

recipientId - identity of recipient

term - sender's current term

leaderTimestamp - leader's timestamp for this request

leaderLeaseTimeout - earliest leader timestamp at which leader could be deposed (or null)

leaderCommit - current commit index for sender

prevLogTerm - term of the log entry just prior to this one

prevLogIndex - index of the log entry just prior to this one

AppendRequest

public AppendRequest(int clusterId,
                     String senderId,
                     String recipientId,
                     long term,
                     Timestamp leaderTimestamp,
                     Timestamp leaderLeaseTimeout,
                     long leaderCommit,
                     long prevLogTerm,
                     long prevLogIndex,
                     long logEntryTerm,
                     ByteBuffer mutationData)

Constructor for a request that contains an actual log entry.

Parameters:

clusterId - cluster ID

senderId - identity of sender

recipientId - identity of recipient

term - sender's current term

leaderTimestamp - leader's timestamp for this request

leaderLeaseTimeout - earliest leader timestamp at which leader could be deposed (or null)

leaderCommit - current commit index for sender

prevLogTerm - term of the log entry just prior to this one

prevLogIndex - index of the log entry just prior to this one

logEntryTerm - term of this log entry

mutationData - log entry serialized mutations, or null if follower should have the data already

Method Detail

getLeaderTimestamp

public Timestamp getLeaderTimestamp()

getLeaderLeaseTimeout

public Timestamp getLeaderLeaseTimeout()

getLeaderCommit

public long getLeaderCommit()

Get leader's commit index.

For probe requests, this value is limited to the value returned by getPrevLogIndex().

Returns:

leader's commit index

getPrevLogTerm

public long getPrevLogTerm()

getPrevLogIndex

public long getPrevLogIndex()

isProbe

public boolean isProbe()

getLogEntryTerm

public long getLogEntryTerm()

getMutationData

public ByteBuffer getMutationData()

Get the serialized data for the log entry, if any. Returns null if this is a probe or follower is expected to already have the data from a transaction.

This method may only be invoked once.

Returns:

log entry serialized mutations, or null if this message does not contain data

Throws:

IllegalStateException - if this method has already been invoked

isLeaderMessage

public boolean isLeaderMessage()

Description copied from class: Message

Determine whether this message is only sent by leaders.

Overrides:

isLeaderMessage in class Message

Returns:

true if receipt of this message implies sender is a leader

visit

public void visit(MessageSwitch handler)

Description copied from class: Message

Apply the visitor pattern based on this instance's type.

Specified by:

visit in class Message

Parameters:

handler - target for visit

writeTo

public void writeTo(ByteBuffer dest,
                    int version)

Description copied from class: Message

Serialize this instance into the given buffer.

Overrides:

writeTo in class Message

Parameters:

dest - destination for encoded data

version - protocol encoding version number

calculateSize

protected int calculateSize(int version)

Description copied from class: Message

Calculate an upper bound on the number of bytes required by writeTo().

Overrides:

calculateSize in class Message

Parameters:

version - protocol encoding version

Returns:

an upper bound on the number of encoded bytes

toString

public String toString()

Specified by:

toString in class Message