ml.shifu.guagua.util

Class MemoryDiskList<T extends Serializable>

java.lang.Object

ml.shifu.guagua.util.MemoryDiskList<T>

All Implemented Interfaces:

Iterable<T>, AppendList<T>

public class MemoryDiskList<T extends Serializable>
extends Object
implements AppendList<T>

A list to store data firstly into memory then into disk if over threshold.

Only two stages support in such kind of list. The first one is WRITE, the next is read. So far random WRITE and READ are not supported in this list.

WARNING: close() should be called at last to release file descriptor.

User should provide fileName in constructor and only one file is used to store data.

Author:

Zhang David (pengzhang@paypal.com)

Nested Class Summary

Nested classes/interfaces inherited from interface ml.shifu.guagua.util.AppendList

AppendList.State

Constructor Summary

Constructors

Constructor and Description
MemoryDiskList() Default constructor.
MemoryDiskList(List<T> delegationList) Constructor with only memory delegationList.
MemoryDiskList(long maxSize) Constructor with only memory bytes size limit.
MemoryDiskList(long maxSize, List<T> delegationList) Constructor with max bytes size of memory and delegationList.
MemoryDiskList(long maxSize, List<T> delegationList, String fileName) Constructor with max bytes size of memory and delegationList and disk file name in current working dir.
MemoryDiskList(long maxSize, String fileName) Constructor with max bytes size of memory and disk file name in current working dir.

Method Summary

Methods

Modifier and Type	Method and Description
boolean	append(T t) Append object to this list
void	clear() Clear all elements.
void	close() Close disk stream.
Iterator<T>	iterator()
void	reOpen() Reopen stream for iteration.
int	size() Return size of this list.
void	switchState() After appending, switch state from WRITE to READ to allow iterating.

Methods inherited from class java.lang.Object

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

Constructor Detail

MemoryDiskList

public MemoryDiskList(long maxSize,
              List<T> delegationList)

Constructor with max bytes size of memory and delegationList. Disk file name is random filename in current working dir.

MemoryDiskList

public MemoryDiskList(List<T> delegationList)

Constructor with only memory delegationList. By default no limit of bytes size in memory.

MemoryDiskList

public MemoryDiskList(long maxSize,
              List<T> delegationList,
              String fileName)

Constructor with max bytes size of memory and delegationList and disk file name in current working dir.

MemoryDiskList

public MemoryDiskList(long maxSize,
              String fileName)

Constructor with max bytes size of memory and disk file name in current working dir. By default LinkedList is used for memory list.

MemoryDiskList

public MemoryDiskList(long maxSize)

Constructor with only memory bytes size limit.

MemoryDiskList

public MemoryDiskList()

Default constructor. By default no memory limit, LinkedList and random file name.

Method Detail

append

public boolean append(T t)

Description copied from interface: AppendList

Append object to this list

Specified by:

append in interface AppendList<T extends Serializable>

Parameters:

t - the object to append

Returns:

whether appending object successful

close

public void close()

Close disk stream. Should be called at the end of usage of MemoryDiskList.

reOpen

public void reOpen()

Reopen stream for iteration.

iterator

public Iterator<T> iterator()

Specified by:

iterator in interface Iterable<T extends Serializable>

switchState

public void switchState()

Description copied from interface: AppendList

After appending, switch state from WRITE to READ to allow iterating.

Specified by:

switchState in interface AppendList<T extends Serializable>

size

public int size()

Description copied from interface: AppendList

Return size of this list.

Specified by:

size in interface AppendList<T extends Serializable>

clear

public void clear()

Description copied from interface: AppendList

Clear all elements.

Specified by:

clear in interface AppendList<T extends Serializable>