Package org.apache.flink.runtime.state

Class SnapshotDirectory

java.lang.Object

org.apache.flink.runtime.state.SnapshotDirectory

public abstract class SnapshotDirectory
extends Object

This class represents a directory that is the target for a state snapshot. This class provides some method that simplify resource management when dealing with such directories, e.g. it can produce a DirectoryStateHandle when the snapshot is completed and disposal considers whether or not a snapshot was already completed. For a completed snapshot, the ownership for cleanup is transferred to the created directory state handle. For incomplete snapshots, calling cleanup() will delete the underlying directory resource.

Field Summary

Fields

Modifier and Type	Field	Description
protected Path	directory	This path describes the underlying directory for the snapshot.
protected AtomicReference<org.apache.flink.runtime.state.SnapshotDirectory.State>	state	This reference tracks the lifecycle state of the snapshot directory.

Method Summary

Modifier and Type	Method	Description
boolean	cleanup()	Calling this method will attempt delete the underlying snapshot directory recursively, if the state is "ongoing".
abstract DirectoryStateHandle	completeSnapshotAndGetHandle()	Calling this method completes the snapshot for this snapshot directory, if possible, and creates a corresponding DirectoryStateHandle that points to the snapshot directory.
boolean	equals(Object o)
boolean	exists()
Path	getDirectory()
int	hashCode()
boolean	isSnapshotCompleted()	Returns true if the snapshot is marked as completed.
Path[]	listDirectory()	List the files in the snapshot directory.
boolean	mkdirs()
static SnapshotDirectory	permanent(Path directory)	Creates a permanent snapshot directory for the given path, which will not delete the underlying directory in cleanup() after completeSnapshotAndGetHandle() was called.
static SnapshotDirectory	temporary(File directory)	Creates a local temporary snapshot directory for the given path.
String	toString()

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

directory

@Nonnull
protected final Path directory

This path describes the underlying directory for the snapshot.

state

@Nonnull
protected AtomicReference<org.apache.flink.runtime.state.SnapshotDirectory.State> state

This reference tracks the lifecycle state of the snapshot directory.

Method Detail

getDirectory

@Nonnull
public Path getDirectory()

mkdirs

public boolean mkdirs()
               throws IOException

Throws:

IOException

exists

public boolean exists()
               throws IOException

Throws:

IOException

listDirectory

public Path[] listDirectory()
                     throws IOException

List the files in the snapshot directory.

Returns:

the files in the snapshot directory.

Throws:

IOException - if there is a problem creating the file statuses.

cleanup

public boolean cleanup()
                throws IOException

Calling this method will attempt delete the underlying snapshot directory recursively, if the state is "ongoing". In this case, the state will be set to "deleted" as a result of this call.

Returns:

true if delete is successful, false otherwise.

Throws:

IOException - if an exception happens during the delete.

isSnapshotCompleted

public boolean isSnapshotCompleted()

Returns true if the snapshot is marked as completed.

completeSnapshotAndGetHandle

@Nullable
public abstract DirectoryStateHandle completeSnapshotAndGetHandle()
                                                           throws IOException

Calling this method completes the snapshot for this snapshot directory, if possible, and creates a corresponding DirectoryStateHandle that points to the snapshot directory. Calling this method can change the lifecycle state from ONGOING to COMPLETED if the directory should no longer deleted in cleanup(). This method can return Can return true if the directory is temporary and should therefore not be referenced in a handle.

Returns:

A directory state handle that points to the snapshot directory. Can return true if the directory is temporary and should therefore not be referenced in a handle.

Throws:

IOException - if the state of this snapshot directory object is different from "ongoing".

equals

public boolean equals(Object o)

Overrides:

equals in class Object

hashCode

public int hashCode()

Overrides:

hashCode in class Object

toString

public String toString()

Overrides:

toString in class Object

temporary

public static SnapshotDirectory temporary(@Nonnull
                                          File directory)
                                   throws IOException

Creates a local temporary snapshot directory for the given path. This will always return "null" as result of completeSnapshotAndGetHandle() and always attempt to delete the underlying directory in cleanup().

Throws:

IOException

permanent

public static SnapshotDirectory permanent(@Nonnull
                                          Path directory)
                                   throws IOException

Creates a permanent snapshot directory for the given path, which will not delete the underlying directory in cleanup() after completeSnapshotAndGetHandle() was called.

Throws:

IOException