alluxio.master.journal.raft

Class BufferedJournalApplier

java.lang.Object

alluxio.master.journal.raft.BufferedJournalApplier

@ThreadSafe
public class BufferedJournalApplier
extends Object

Used to control applying to masters. It is supported by this class to suspend and resume applies, without blocking the callers. During suspend, entries will be buffered in-memory in order to not block caller when it wants new entries to be processed. These buffered entries will be applied to masters when this applier is resumed. TODO(ggezer): Extend with on-disk buffering.

Constructor Summary

Constructors

Constructor and Description
BufferedJournalApplier(Map<String,RaftJournal> journals, java.util.function.Supplier<Set<JournalSink>> journalSinks) Creates a buffered applier over given journals.

Method Summary

Modifier and Type	Method and Description
CatchupFuture	catchup(long sequence) Initiates catching up of the applier to a target sequence.
void	close() Resets the suspend-applier.
boolean	isSuspended()
void	processJournalEntry(Journal.JournalEntry journalEntry) Processes given journal entry for applying.
void	resume() Resumes the applier.
void	suspend() Suspend the applier.

Methods inherited from class java.lang.Object

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

Constructor Detail

BufferedJournalApplier

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

Creates a buffered applier over given journals.

Parameters:

journals - journals

journalSinks - journal sinks

Method Detail

processJournalEntry

public void processJournalEntry(Journal.JournalEntry journalEntry)

Processes given journal entry for applying. Entry could be applied or buffered based on buffer's state.

Parameters:

journalEntry - the journal entry

isSuspended

public boolean isSuspended()

Returns:

true if this applier was suspended

suspend

public void suspend()
             throws IOException

Suspend the applier. After this call, journal entries will be buffered until resume() or catchup(long) is called.

Throws:

IOException - if suspension fails

resume

public void resume()
            throws IOException

Resumes the applier. This method will apply all buffered entries before returning.

Throws:

IOException - if resuming fails

catchup

public CatchupFuture catchup(long sequence)

Initiates catching up of the applier to a target sequence. This method leaves the applier in suspended state.

Parameters:

sequence - target sequence

Returns:

the future to track when applier reaches the target sequence

close

public void close()

Resets the suspend-applier. Should only be used when the state machine is reset.