org.pentaho.di.core.xml
Class XMLHandlerCache

java.lang.Object
  org.pentaho.di.core.xml.XMLHandlerCache

public class XMLHandlerCache
extends Object

Singleton to help speed up lookups in an XML DOM tree.
The theory is that you often loop over occurrences of a certain tag in a Node.
If there are 20 occurrences, you go from index 0..19.
Every time we do the following
- found node 0
- found node 0, 1
- found node 0, 1, 2
- ...
So the time to search node index 19 is 20 times larger on average then index 0.

We can solve this by caching the position of index 18 and by starting back at that position.

This class is a singleton to keep everyting 100% compatible with the rest of the codebase.

Since:

22-Apr-2006

Author:

Matt

Field Summary

static int

MAX_NUMBER_OF_ENTRIES

Method Summary

void	clear() Clears the cache
int	getCacheHits()
static XMLHandlerCache	getInstance()
int	getLastChildNr(XMLHandlerCacheEntry entry) Retrieve the last child were we left off...
void	setCacheHits(int cacheHits) Allows you to (re-)set the number of cache hits
void	storeCache(XMLHandlerCacheEntry entry, int lastChildNr) Store a cache entry

Methods inherited from class java.lang.Object

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

Field Detail

MAX_NUMBER_OF_ENTRIES

public static final int MAX_NUMBER_OF_ENTRIES

See Also:

Constant Field Values

Method Detail

getInstance

public static final XMLHandlerCache getInstance()

storeCache

public void storeCache(XMLHandlerCacheEntry entry,
                       int lastChildNr)

Store a cache entry

Parameters:

entry - The cache entry to store

getLastChildNr

public int getLastChildNr(XMLHandlerCacheEntry entry)

Retrieve the last child were we left off...

Parameters:

entry - The cache entry to look for.

Returns:

the last child position or -1 if nothing was found.

getCacheHits

public int getCacheHits()

Returns:

the number of cache hits for your statistical pleasure.

setCacheHits

public void setCacheHits(int cacheHits)

Allows you to (re-)set the number of cache hits

Parameters:

cacheHits - the number of cache hits.

clear

public void clear()

Clears the cache