alluxio.master.journal.noop

Class NoopJournalSystem

java.lang.Object

alluxio.master.journal.noop.NoopJournalSystem

All Implemented Interfaces:

JournalSystem

public final class NoopJournalSystem
extends Object
implements JournalSystem

Journal system which doesn't do anything.

Nested Class Summary

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

JournalSystem.Builder, JournalSystem.Mode

Constructor Summary

Constructors

Constructor and Description
NoopJournalSystem() Constructs a new NoopJournalSystem.

Method Summary

Modifier and Type	Method and Description
void	addJournalSink(Master master, JournalSink journalSink)
CatchupFuture	catchup(Map<String,Long> journalSequenceNumbers) Initiates a catching up of journals to given sequences.
void	checkpoint() Creates a checkpoint in the primary master journal system.
Journal	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.
Set<JournalSink>	getJournalSinks(Master master)
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	removeJournalSink(Master master, JournalSink journalSink)
void	resume() Resumes applying for all journals.
void	start() Starts the journal system.
void	stop() Stops the journal system.
void	suspend(Runnable interruptCallback) Suspends applying for all journals.

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, waitForCatchup

Constructor Detail

NoopJournalSystem

public NoopJournalSystem()

Constructs a new NoopJournalSystem.

Method Detail

createJournal

public Journal 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.

Specified by:

createJournal in interface JournalSystem

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.

Specified by:

gainPrimacy in interface JournalSystem

losePrimacy

public void losePrimacy()

Description copied from interface: JournalSystem

Transitions the journal to standby mode.

Specified by:

losePrimacy in interface JournalSystem

suspend

public void suspend(Runnable interruptCallback)

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.

Specified by:

suspend in interface JournalSystem

Parameters:

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

resume

public void resume()

Description copied from interface: JournalSystem

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

Specified by:

resume in interface JournalSystem

catchup

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

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.

Specified by:

catchup in interface JournalSystem

Parameters:

journalSequenceNumbers - sequence to advance per each journal

Returns:

the future to track when catching up is completed

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.

Specified by:

getCurrentSequenceNumbers in interface JournalSystem

Returns:

the current map of sequences for each master

isFormatted

public boolean isFormatted()

Specified by:

isFormatted in interface JournalSystem

Returns:

whether the journal system has been formatted

addJournalSink

public void addJournalSink(Master master,
                           JournalSink journalSink)

Specified by:

addJournalSink in interface JournalSystem

Parameters:

master - the master for which to add the journal sink

journalSink - the journal sink to add

removeJournalSink

public void removeJournalSink(Master master,
                              JournalSink journalSink)

Specified by:

removeJournalSink in interface JournalSystem

Parameters:

master - the master from which to remove the journal sink

journalSink - the journal sink to remove

getJournalSinks

public Set<JournalSink> getJournalSinks(@Nullable
                                        Master master)

Specified by:

getJournalSinks in interface JournalSystem

Parameters:

master - the master to get the journal sinks for, or null to get all sinks

Returns:

a set of JournalSink for the given master, or all sinks if master is null

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.

Specified by:

isEmpty in interface JournalSystem

Returns:

whether the journal system is freshly formatted

format

public void format()

Description copied from interface: JournalSystem

Formats the journal system.

Specified by:

format in interface JournalSystem

start

public void start()

Description copied from interface: JournalSystem

Starts the journal system. All journals must be created before starting the journal system. This method will block until the journal system is successfully started. The journal always starts in standby mode.

Specified by:

start in interface JournalSystem

stop

public void stop()

Description copied from interface: JournalSystem

Stops the journal system.

Specified by:

stop in interface JournalSystem

checkpoint

public void checkpoint()

Description copied from interface: JournalSystem

Creates a checkpoint in the primary master journal system.

Specified by:

checkpoint in interface JournalSystem