Package herddb.core

Class ClockProPolicy

java.lang.Object

herddb.core.ClockProPolicy

All Implemented Interfaces:

PageReplacementPolicy

public class ClockProPolicy
extends Object
implements PageReplacementPolicy

Basic implementation of ClockPro algorithm.

Based on the original work:

 CLOCK-Pro: An Effective Improvement of the CLOCK Replacement

 Song Jiang                                    Feng Chen and Xiaodong Zhang

 Performance and Architecture Laboratory (PAL) Computer Science Department
 Los Alamos National Laboratory, CCS Division  College of William and Mary
 Los Alamos, NM 87545, USA                     Williamsburg, VA 23187, USA
 sjiang@lanl.gov                               fchen@cs.wm.edu, zhang@cs.wm.edu
 

See http://web.cse.ohio-state.edu/hpcs/WWW/HTML/publications/papers/TR-05-3.pdf

Author:

diego.salvi

Constructor Summary

Constructors

Constructor	Description
ClockProPolicy(int capacity)

Method Summary

Modifier and Type	Method	Description
herddb.core.ClockProPolicy.CPMetadata	add(Page<?> page)	Add a new Page to memory.
int	capacity()	Returns the maximum number of Pages memorizable.
void	clear()	Clear any memorized data.
void	pageHit(Page<?> page)	Track a page cache hit.
boolean	remove(Page<?> page)	Remove a Page from memory.
<P extends Page<?>> void	remove(Collection<P> pages)	Remove many Page Pages from memory.
int	size()	Returns the current number of Pages memorized.

Methods inherited from class java.lang.Object

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

Constructor Detail

ClockProPolicy

public ClockProPolicy(int capacity)

Method Detail

add

public herddb.core.ClockProPolicy.CPMetadata add(Page<?> page)

Description copied from interface: PageReplacementPolicy

Add a new Page to memory.

Adding a new page could force an older page to be unloaded

Specified by:

add in interface PageReplacementPolicy

Parameters:

page - page to be added

Returns:

selected page to be unloaded or null

remove

public boolean remove(Page<?> page)

Description copied from interface: PageReplacementPolicy

Remove a Page from memory.

Specified by:

remove in interface PageReplacementPolicy

Parameters:

page - page to be removed.

Returns:

true if the memory really contained the given page

remove

public <P extends Page<?>> void remove(Collection<P> pages)

Description copied from interface: PageReplacementPolicy

Remove many Page Pages from memory.

This method is logically equivalent to multiple PageReplacementPolicy.remove(Page) invocations but is expected to be more efficient.

Specified by:

remove in interface PageReplacementPolicy

Parameters:

pages - pages to be removed.

size

public int size()

Description copied from interface: PageReplacementPolicy

Returns the current number of Pages memorized.

Specified by:

size in interface PageReplacementPolicy

Returns:

current number of Pages

capacity

public int capacity()

Description copied from interface: PageReplacementPolicy

Returns the maximum number of Pages memorizable.

Specified by:

capacity in interface PageReplacementPolicy

Returns:

maximum number of Pages

clear

public void clear()

Description copied from interface: PageReplacementPolicy

Clear any memorized data.

Specified by:

clear in interface PageReplacementPolicy

pageHit

public void pageHit(Page<?> page)

Description copied from interface: PageReplacementPolicy

Track a page cache hit.

Specified by:

pageHit in interface PageReplacementPolicy

Parameters:

page - for which track an hit