Module org.jgroups.raft

Package org.jgroups.protocols.raft

Class RaftImpl

java.lang.Object

org.jgroups.protocols.raft.RaftImpl

Direct Known Subclasses:

Follower, Leader

public abstract class RaftImpl
extends Object

Base class for the different roles a RAFT node can have (follower, candidate, leader)

Since:

0.1

Author:

Bela Ban

Field Summary

Fields

Modifier and Type	Field	Description
protected RAFT	raft

Constructor Summary

Constructors

Constructor	Description
RaftImpl(RAFT raft)

Method Summary

Modifier and Type	Method	Description
void	destroy()	Called before getting destroyed (on a role change)
protected long	getFirstIndexOfConflictingTerm(long start_index, long conflicting_term)	Finds the first index at which conflicting_term starts, going back from start_index towards the head of the log, not not going lower than commit-index
AppendResult	handleAppendEntriesRequest(LogEntries entries, org.jgroups.Address leader, long prev_index, long prev_term, long entry_term, long leader_commit)	Called (on a follower) when an AppendEntries request is received
void	handleAppendEntriesResponse(org.jgroups.Address sender, long term, AppendResult result)
void	handleInstallSnapshotRequest(org.jgroups.Message msg, org.jgroups.Address leader, long last_included_index, long last_included_term)	Called when a snapshot sent by the leader is received by a follower.
void	init()	Called right after instantiation
RAFT	raft()
RaftImpl	raft(RAFT r)

Methods inherited from class java.lang.Object

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

Field Details

raft

protected RAFT raft

Constructor Details

RaftImpl

public RaftImpl(RAFT raft)

Method Details

raft

public RAFT raft()

raft

public RaftImpl raft(RAFT r)

init

public void init()

Called right after instantiation

destroy

public void destroy()

Called before getting destroyed (on a role change)

handleAppendEntriesRequest

public AppendResult handleAppendEntriesRequest(LogEntries entries,
 org.jgroups.Address leader,
 long prev_index,
 long prev_term,
 long entry_term,
 long leader_commit)

Called (on a follower) when an AppendEntries request is received

Parameters:

entries - The data (commands to be appended to the log)

leader - The leader's address (= the sender)

prev_index - The index of the previous log entry

prev_term - The term of the previous log entry

entry_term - The term of the entry

leader_commit - The leader's commit_index

Returns:

AppendResult A result (true or false), or null if the request was ignored (e.g. due to lower term)

handleAppendEntriesResponse

public void handleAppendEntriesResponse(org.jgroups.Address sender,
 long term,
 AppendResult result)

handleInstallSnapshotRequest

public void handleInstallSnapshotRequest(org.jgroups.Message msg,
 org.jgroups.Address leader,
 long last_included_index,
 long last_included_term)

Called when a snapshot sent by the leader is received by a follower. The follower needs to overwrite its snapshot file with the received bytes and reinitialize its log to last_inluded_index and create a dummy LogEntry with last_included_term at last_included_index. This is needed by the next handleAppendEntriesRequest(LogEntries, Address, int, int, int, int) call to compare to the previous index and term.

Parameters:

msg - The snapshot message sent by the leader

leader - The leader (= sender of the message)

last_included_index - The last index that's reflected in the state (=snapshot) sent by the leader. Indices first_appended, commit_index and last_appended have to be set to last_included_index

last_included_term - The last included term. The dummy entry needs to have this term, for comparison in the next handleAppendRequest() call.

getFirstIndexOfConflictingTerm

protected long getFirstIndexOfConflictingTerm(long start_index,
 long conflicting_term)

Finds the first index at which conflicting_term starts, going back from start_index towards the head of the log, not not going lower than commit-index