alluxio.master.journal.raft

Class JournalStateMachine

java.lang.Object

io.atomix.copycat.server.StateMachine

alluxio.master.journal.raft.JournalStateMachine

All Implemented Interfaces:

io.atomix.copycat.server.Snapshottable, AutoCloseable

@ThreadSafe
public class JournalStateMachine
extends io.atomix.copycat.server.StateMachine
implements io.atomix.copycat.server.Snapshottable

A state machine for managing all of Alluxio's journaled state. Entries applied to this state machine will be forwarded to the appropriate internal master. The state machine starts by resetting all state, then applying the entries offered by copycat. When the master becomes primary, it should wait until the state machine is up to date and no other primary master is serving, then call upgrade(). Once the state machine is upgraded, it will ignore all entries appended by copycat because those entries are applied to primary master state before being written to copycat.

Field Summary

Fields inherited from class io.atomix.copycat.server.StateMachine

clock, context, executor, sessions

Constructor Summary

Constructors

Constructor and Description
JournalStateMachine(Map<String,RaftJournal> journals, java.util.function.Supplier<Set<JournalSink>> journalSinks)

Method Summary

Modifier and Type	Method and Description
void	applyJournalEntryCommand(io.atomix.copycat.server.Commit<JournalEntryCommand> commit) Applies a journal entry commit to the state machine.
void	close() Closes the journal state machine, causing all further modification requests to be ignored.
long	getLastAppliedSequenceNumber()
long	getLastPrimaryStartSequenceNumber()
long	getLastSnapshotStartTime()
void	install(io.atomix.copycat.server.storage.snapshot.SnapshotReader snapshotReader)
boolean	isSnapshotting()
void	snapshot(io.atomix.copycat.server.storage.snapshot.SnapshotWriter writer)
long	upgrade() Upgrades the journal state machine to primary mode.

Methods inherited from class io.atomix.copycat.server.StateMachine

configure, init

Methods inherited from class java.lang.Object

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

Constructor Detail

JournalStateMachine

public JournalStateMachine(Map<String,RaftJournal> journals,
                           java.util.function.Supplier<Set<JournalSink>> journalSinks)

Parameters:

journals - master journals; these journals are still owned by the caller, not by the journal state machine

journalSinks - a supplier for journal sinks

Method Detail

applyJournalEntryCommand

public void applyJournalEntryCommand(io.atomix.copycat.server.Commit<JournalEntryCommand> commit)

Applies a journal entry commit to the state machine. This method is automatically discovered by the Copycat framework.

Parameters:

commit - the commit

snapshot

public void snapshot(io.atomix.copycat.server.storage.snapshot.SnapshotWriter writer)

Specified by:

snapshot in interface io.atomix.copycat.server.Snapshottable

install

public void install(io.atomix.copycat.server.storage.snapshot.SnapshotReader snapshotReader)

Specified by:

install in interface io.atomix.copycat.server.Snapshottable

upgrade

public long upgrade()

Upgrades the journal state machine to primary mode.

Returns:

the last sequence number read while in secondary mode

getLastAppliedSequenceNumber

public long getLastAppliedSequenceNumber()

Returns:

the sequence number of the last entry applied to the state machine

getLastPrimaryStartSequenceNumber

public long getLastPrimaryStartSequenceNumber()

Returns:

the last primary term start sequence number applied to this state machine

getLastSnapshotStartTime

public long getLastSnapshotStartTime()

Returns:

the start time of the most recent snapshot

isSnapshotting

public boolean isSnapshotting()

Returns:

whether the state machine is in the process of taking a snapshot

close

public void close()

Closes the journal state machine, causing all further modification requests to be ignored.

Specified by:

close in interface AutoCloseable

Overrides:

close in class io.atomix.copycat.server.StateMachine