alluxio.master.journalv0.ufs

Class UfsCheckpointManager

java.lang.Object

alluxio.master.journalv0.ufs.UfsCheckpointManager

public final class UfsCheckpointManager
extends Object

Manages the checkpoint for a journal. The update(URI) method will update the journal's checkpoint to the specified location, and recover() will recover from any failures that may occur during update(URI). The checkpoint updating process goes

 1. Write a new checkpoint named checkpoint.data.tmp
 2. Rename checkpoint.data to checkpoint.data.backup.tmp
 3. Rename checkpoint.data.backup.tmp to checkpoint.data.backup
 4. Rename checkpoint.data.tmp to checkpoint.data
 5. Delete completed logs
 6. Delete checkpoint.data.backup
 

Constructor Summary

Constructors

Constructor and Description
UfsCheckpointManager(UnderFileSystem ufs, URI checkpoint, UfsJournalWriter writer) Creates a new instance of UfsCheckpointManager.

Method Summary

Modifier and Type	Method and Description
void	recover() Recovers the checkpoint in case the master crashed while updating it.
void	update(URI location) Updates the checkpoint to the specified URI.

Methods inherited from class java.lang.Object

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

Constructor Detail

UfsCheckpointManager

public UfsCheckpointManager(UnderFileSystem ufs,
                            URI checkpoint,
                            UfsJournalWriter writer)

Creates a new instance of UfsCheckpointManager.

Parameters:

ufs - the under file system holding the journal

checkpoint - the location of the checkpoint

writer - a journal writer which can be used to delete completed logs

Method Detail

recover

public void recover()

Recovers the checkpoint in case the master crashed while updating it.

update

public void update(URI location)

Updates the checkpoint to the specified URI.

Parameters:

location - the location of the new checkpoint