org.mmbase.cache
Class QueryResultCache

java.lang.Object
  java.util.Dictionary
      java.util.Hashtable
          org.mmbase.util.LRUHashtable
              org.mmbase.cache.Cache
                  org.mmbase.cache.QueryResultCache

All Implemented Interfaces:

java.lang.Cloneable, java.util.Map, java.io.Serializable, SizeMeasurable

Direct Known Subclasses:

AggregatedResultCache, MultilevelCache, NodeListCache, RelatedNodesCache

public abstract class QueryResultCache

extends Cache

This cache provides a base implementation to cache the result of SearchQuery's. Such a cache links a SearchQuery object to a list of MMObjectNodes. A cache entry is automaticly invalidated if arbitrary node of one of the types present in the SearchQuery is changed (,created or deleted). This mechanism is not very subtle but it is garanteed to be correct. It means though that your cache can be considerably less effective for queries containing node types from which often node are edited.

Since:

MMBase-1.7

Version:

$Id: QueryResultCache.java,v 1.5.2.1 2004/08/26 12:03:10 michiel Exp $

Author:

Daniel Ockeloen, Michiel Meeuwissen

See Also:

SearchQuery, Serialized Form

Nested Class Summary

Nested classes inherited from class org.mmbase.util.LRUHashtable

LRUHashtable.LRUEntry, LRUHashtable.LRUEntrySet, LRUHashtable.LRUEntrySetIterator

Field Summary

Fields inherited from class org.mmbase.cache.Cache

maxEntrySize

Method Summary

static int	invalidateAll(MMObjectBuilder builder) Explicitely invalidates all Query caches for a certain builder.
java.lang.Object	put(java.lang.Object key, java.lang.Object value) Like 'put' of LRUHashtable but considers if the cache is active or not.
java.lang.Object	put(SearchQuery query, java.util.List queryResult) Puts a search result in this cache.
java.lang.Object	remove(java.lang.Object key) Removes an object from the cache.
java.lang.String	toString() Returns a description of the table.

Methods inherited from class org.mmbase.cache.Cache

get, getByteSize, getByteSize, getCache, getCaches, getDefaultMaxEntrySize, getDescription, getMaxEntrySize, getName, getTotalByteSize, isActive, main, putCache, putCache, setActive

Methods inherited from class org.mmbase.util.LRUHashtable

clear, clone, elements, entrySet, getCount, getHits, getMisses, getOrderedElements, getOrderedElements, getOrderedEntries, getOrderedEntries, getPuts, getRatio, getSize, getStats, keySet, setSize, size, toString, values

Methods inherited from class java.util.Hashtable

contains, containsKey, containsValue, equals, hashCode, isEmpty, keys, putAll, rehash

Methods inherited from class java.lang.Object

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

Method Detail

invalidateAll

public static int invalidateAll(MMObjectBuilder builder)

Explicitely invalidates all Query caches for a certain builder. This is used in MMObjectBuilder for 'local' changes, to ensure that imediate select after update always works.

Returns:

number of entries invalidated

put

public java.lang.Object put(java.lang.Object key,
                            java.lang.Object value)

Description copied from class: Cache

Like 'put' of LRUHashtable but considers if the cache is active or not.

Specified by:

put in interface java.util.Map

Overrides:

put in class Cache

Throws:

java.lang.ClassCastException - if key not a SearchQuery or value not a List.

put

public java.lang.Object put(SearchQuery query,
                            java.util.List queryResult)

Puts a search result in this cache.

remove

public java.lang.Object remove(java.lang.Object key)

Removes an object from the cache. It alsos remove the watch from the observers which are watching this entry.

Specified by:

remove in interface java.util.Map

Overrides:

remove in class LRUHashtable

Parameters:

key - A SearchQuery object.

Returns:

the original value of the element if it existed, null if it could not be found

toString

public java.lang.String toString()

Description copied from class: LRUHashtable

Returns a description of the table. The information shown includes current size, maximum size, ratio of misses and hits, and a description of the underlying hashtable

Overrides:

toString in class LRUHashtable