org.apache.reef.io.checkpoint.fs

Class FSCheckpointService

java.lang.Object

org.apache.reef.io.checkpoint.fs.FSCheckpointService

All Implemented Interfaces:

CheckpointService

public class FSCheckpointService
extends Object
implements CheckpointService

A FileSystem based CheckpointService. Note that this implementation creates a temporary file first and moves it to final destination at commit time.

Nested Class Summary

Nested classes/interfaces inherited from interface org.apache.reef.io.checkpoint.CheckpointService

CheckpointService.CheckpointReadChannel, CheckpointService.CheckpointWriteChannel

Constructor Summary

Constructors

Constructor and Description
FSCheckpointService(org.apache.hadoop.fs.FileSystem fs, org.apache.hadoop.fs.Path base, CheckpointNamingService namingPolicy, short replication)

Method Summary

Methods

Modifier and Type	Method and Description
void	abort(CheckpointService.CheckpointWriteChannel ch) Aborts the current checkpoint.
CheckpointID	commit(CheckpointService.CheckpointWriteChannel ch) Closes an existing checkpoint for writes and returns the CheckpointID that can be later used to get the read-only access to this checkpoint.
CheckpointService.CheckpointWriteChannel	create() Creates a checkpoint and provides a channel to write to it.
boolean	delete(CheckpointID id) Discards an existing checkpoint identified by its CheckpointID.
CheckpointService.CheckpointReadChannel	open(CheckpointID id) Returns a reading channel to a checkpoint identified by the CheckpointID.

Methods inherited from class java.lang.Object

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

Constructor Detail

FSCheckpointService

public FSCheckpointService(org.apache.hadoop.fs.FileSystem fs,
                   org.apache.hadoop.fs.Path base,
                   CheckpointNamingService namingPolicy,
                   short replication)

Method Detail

create

public CheckpointService.CheckpointWriteChannel create()
                                                throws IOException

Description copied from interface: CheckpointService

Creates a checkpoint and provides a channel to write to it. The name/location of the checkpoint are unknown to the user as of this time, in fact, the CheckpointID is not released to the user until commit is called. This makes enforcing atomicity of writes easy.

Specified by:

create in interface CheckpointService

Returns:

a CheckpointWriteChannel that can be used to write to the checkpoint

Throws:

IOException

open

public CheckpointService.CheckpointReadChannel open(CheckpointID id)
                                             throws IOException,
                                                    InterruptedException

Description copied from interface: CheckpointService

Returns a reading channel to a checkpoint identified by the CheckpointID.

Specified by:

open in interface CheckpointService

Parameters:

id - CheckpointID for the checkpoint to be opened

Returns:

a CheckpointReadChannel

Throws:

IOException

InterruptedException

commit

public CheckpointID commit(CheckpointService.CheckpointWriteChannel ch)
                    throws IOException,
                           InterruptedException

Description copied from interface: CheckpointService

Closes an existing checkpoint for writes and returns the CheckpointID that can be later used to get the read-only access to this checkpoint. Implementation is supposed to return the CheckpointID to the caller only on the successful completion of checkpoint to guarantee atomicity of the checkpoint.

Specified by:

commit in interface CheckpointService

Parameters:

ch - the CheckpointWriteChannel to commit

Returns:

a CheckpointID

Throws:

IOException

InterruptedException

abort

public void abort(CheckpointService.CheckpointWriteChannel ch)
           throws IOException

Description copied from interface: CheckpointService

Aborts the current checkpoint. Garbage collection choices are left to the implementation. The CheckpointID is neither generated nor released to the client so the checkpoint is not accessible.

Specified by:

abort in interface CheckpointService

Parameters:

ch - the CheckpointWriteChannel to abort

Throws:

IOException

delete

public boolean delete(CheckpointID id)
               throws IOException,
                      InterruptedException

Description copied from interface: CheckpointService

Discards an existing checkpoint identified by its CheckpointID.

Specified by:

delete in interface CheckpointService

Parameters:

id - CheckpointID for the checkpoint to be deleted

Returns:

a boolean confirming success of the deletion

Throws:

IOException

InterruptedException