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
Journal	createJournal(JournalEntryStateMachine master) Creates a journal for the given state machine.
void	format() Formats the journal system.
void	gainPrimacy() Transitions the journal to primary mode.
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 secondary mode.
void	start() Starts the journal system.
void	stop() Stops the journal system.

Methods inherited from class java.lang.Object

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

Constructor Detail

NoopJournalSystem

public NoopJournalSystem()

Constructs a new NoopJournalSystem.

Method Detail

createJournal

public Journal createJournal(JournalEntryStateMachine 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 secondary mode, it will call JournalEntryStateMachine#processJournalEntry(JournalEntry) and JournalEntryStateMachine.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 state machine 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 secondary mode.

Specified by:

losePrimacy in interface JournalSystem

isFormatted

public boolean isFormatted()
                    throws IOException

Specified by:

isFormatted in interface JournalSystem

Returns:

whether the journal system has been formatted

Throws:

IOException

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()
            throws IOException

Description copied from interface: JournalSystem

Formats the journal system.

Specified by:

format in interface JournalSystem

Throws:

IOException

start

public void start()
           throws InterruptedException,
                  IOException

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 secondary mode.

Specified by:

start in interface JournalSystem

Throws:

InterruptedException

IOException

stop

public void stop()
          throws InterruptedException,
                 IOException

Description copied from interface: JournalSystem

Stops the journal system.

Specified by:

stop in interface JournalSystem

Throws:

InterruptedException

IOException