alluxio.master.journal.ufs

Class UfsJournalSystem

java.lang.Object

alluxio.master.journal.AbstractJournalSystem

alluxio.master.journal.ufs.UfsJournalSystem

All Implemented Interfaces:

JournalSystem

@NotThreadSafe
public class UfsJournalSystem
extends AbstractJournalSystem

Factory for under file storage journals.

Nested Class Summary

Nested classes/interfaces inherited from interface alluxio.master.journal.JournalSystem

JournalSystem.Builder, JournalSystem.Mode

Constructor Summary

Constructors

Constructor and Description
UfsJournalSystem(URI base, long quietTimeMs) Creates a UFS journal system with the specified base location.

Method Summary

Modifier and Type	Method and Description
CatchupFuture	catchup(Map<String,Long> journalSequenceNumbers) Initiates a catching up of journals to given sequences.
void	checkpoint(StateLockManager stateLockManager) Creates a checkpoint in the primary master journal system.
UfsJournal	createJournal(Master master) Creates a journal for the given state machine.
void	format() Formats the journal system.
void	gainPrimacy() Transitions the journal to primary mode.
Map<String,Long>	getCurrentSequenceNumbers() Used to get the current state from a leader journal system.
boolean	isEmpty() Returns whether the journal is formatted and has not had any entries written to it yet.
boolean	isFormatted()
void	losePrimacy() Transitions the journal to standby mode.
void	resume() Resumes applying for all journals.
void	startInternal() Starts the journal system.
void	stopInternal() Stops the journal system.
void	suspend(Runnable interruptCallback) Suspends applying for all journals.
void	waitForCatchup() Waits for the journal catchup to finish when the process starts.

Methods inherited from class alluxio.master.journal.AbstractJournalSystem

addJournalSink, getJournalSinks, registerMetrics, removeJournalSink, start, stop

Methods inherited from class java.lang.Object

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

Methods inherited from interface alluxio.master.journal.JournalSystem

getJournalServices

Constructor Detail

UfsJournalSystem

public UfsJournalSystem(URI base,
                        long quietTimeMs)

Creates a UFS journal system with the specified base location. When journals are created, their names are appended to the base location. The created journals all function independently.

Parameters:

base - the base location for journals created by this factory

quietTimeMs - before upgrading from STANDBY to PRIMARY mode, the journal will wait until this duration has passed without any journal entries being written.

Method Detail

createJournal

public UfsJournal createJournal(Master master)

Description copied from interface: JournalSystem

Creates a journal for the given state machine. The returned journal can create journal contexts for writing journal entries. However, no entries may be written until the journal system has been started, and entries may only be written when the journal system is in PRIMARY mode. When the journal is started in standby mode, it will call Journaled#processJournalEntry(JournalEntry) and Journaled.resetState() to keep the state machine's state in sync with the entries written to the journal.

Parameters:

master - the master to create the journal for

Returns:

a new instance of Journal

gainPrimacy

public void gainPrimacy()

Description copied from interface: JournalSystem

Transitions the journal to primary mode.

losePrimacy

public void losePrimacy()

Description copied from interface: JournalSystem

Transitions the journal to standby mode.

suspend

public void suspend(Runnable interruptCallback)
             throws IOException

Description copied from interface: JournalSystem

Suspends applying for all journals. When using suspend, the caller needs to provide a callback method as parameter. This callback is invoked when the journal needs to reload and thus cannot suspend the state changes any more. The callback should cancel any tasks that access the master states. After the callback returns, the journal assumes that the states is no longer being accessed and will reload immediately.

Parameters:

interruptCallback - the callback function to be invoked when the suspension is interrupted

Throws:

IOException

resume

public void resume()
            throws IOException

Description copied from interface: JournalSystem

Resumes applying for all journals. Note: Journal system should have been suspended prior to calling this.

Throws:

IOException

catchup

public CatchupFuture catchup(Map<String,Long> journalSequenceNumbers)
                      throws IOException

Description copied from interface: JournalSystem

Initiates a catching up of journals to given sequences. Note: Journal system should have been suspended prior to calling this.

Parameters:

journalSequenceNumbers - sequence to advance per each journal

Returns:

the future to track when catching up is completed

Throws:

IOException

waitForCatchup

public void waitForCatchup()

Description copied from interface: JournalSystem

Waits for the journal catchup to finish when the process starts. This is intended to be only be called when starting the Alluxio master process in standby mode and before the standby master becoming the primary master. This is best-effort, because even if it did not finish replaying the journal, the rest of the system will still complete the journal catchup in a different phase. This can be implemented by a journal type to optimize the journal replay, and avoid getting interrupted with primary state changes during journal replay.

getCurrentSequenceNumbers

public Map<String,Long> getCurrentSequenceNumbers()

Description copied from interface: JournalSystem

Used to get the current state from a leader journal system. Note: State changes to journals must have been effectively blocked by a state-lock before calling this method.

Returns:

the current map of sequences for each master

startInternal

public void startInternal()

Description copied from class: AbstractJournalSystem

Starts the journal system.

Specified by:

startInternal in class AbstractJournalSystem

stopInternal

public void stopInternal()

Description copied from class: AbstractJournalSystem

Stops the journal system.

Specified by:

stopInternal in class AbstractJournalSystem

isFormatted

public boolean isFormatted()

Returns:

whether the journal system has been formatted

isEmpty

public boolean isEmpty()

Description copied from interface: JournalSystem

Returns whether the journal is formatted and has not had any entries written to it yet. This can only be determined when the journal system is in primary mode because entries are written to the primary first.

Returns:

whether the journal system is freshly formatted

format

public void format()
            throws IOException

Description copied from interface: JournalSystem

Formats the journal system.

Throws:

IOException

checkpoint

public void checkpoint(StateLockManager stateLockManager)
                throws IOException

Description copied from interface: JournalSystem

Creates a checkpoint in the primary master journal system.

Parameters:

stateLockManager - used to prevent reads and writes while the journal system is checkpointing

Throws:

IOException