water.persist

Class Persist

java.lang.Object

water.persist.Persist

Direct Known Subclasses:

PersistHdfs, PersistNFS, PersistS3

public abstract class Persist
extends java.lang.Object

Abstract class describing various persistence targets.

• store(Value v) - Store a Value, using storage space.
• load(Value v) - Load a previously stored Value.
• delete(Value v) - Free storage from a previously store Value.

This class is used to implement both user-mode swapping, and the initial load of files - typically raw text for parsing.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	Persist.Schemes Persistence schemes; used as file prefixes eg "hdfs://some_hdfs_path/some_file"

Field Summary

Fields

Modifier and Type	Field and Description
static Persist[]	I All available back-ends, C.f.

Constructor Summary

Constructors

Constructor and Description
Persist()

Method Summary

Methods

Modifier and Type	Method and Description
static Key	anyURIToKey(java.net.URI uri)
abstract void	delete(Value v) Reclaim space from a previously stored Value
static Persist	getIce() Get the current Persist flavor for user-mode swapping.
long	getTotalSpace() Total storage space, or -1 for unknown
long	getUsableSpace() Usable storage space, or -1 for unknown
abstract byte[]	load(Value v) Load a previously stored Value
abstract void	store(Value v) Store a Value into persistent storage, consuming some storage space.
abstract Key	uriToKey(java.net.URI uri) Transform given uri into file vector holding file name.

Methods inherited from class java.lang.Object

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

Field Detail

I

public static final Persist[] I

All available back-ends, C.f. Value for indexes

Constructor Detail

Persist

public Persist()

Method Detail

getIce

public static Persist getIce()

Get the current Persist flavor for user-mode swapping.

store

public abstract void store(Value v)

Store a Value into persistent storage, consuming some storage space.

load

public abstract byte[] load(Value v)
                     throws java.io.IOException

Load a previously stored Value

Throws:

java.io.IOException

delete

public abstract void delete(Value v)

Reclaim space from a previously stored Value

getUsableSpace

public long getUsableSpace()

Usable storage space, or -1 for unknown

getTotalSpace

public long getTotalSpace()

Total storage space, or -1 for unknown

uriToKey

public abstract Key uriToKey(java.net.URI uri)
                      throws java.io.IOException

Transform given uri into file vector holding file name.

Throws:

java.io.IOException

anyURIToKey

public static final Key anyURIToKey(java.net.URI uri)
                             throws java.io.IOException

Throws:

java.io.IOException