com.opencms.flex.cache
Class CmsFlexCache

java.lang.Object
  |
  +--com.opencms.flex.cache.CmsFlexCache

All Implemented Interfaces:

I_CmsEventListener

public class CmsFlexCache

extends Object

implements I_CmsEventListener

This class implements the FlexCache.

The data structure used is a two-level hashtable. This is optimized for the structure of the keys that are used to describe the caching behaviour of the entries. The first hash-level is calculated from the resource name, i.e. the name of the resource as it is referred to in the VFS of OpenCms. A suffix [online] or [offline] is appended to te resource name to distinguish between the online and offline projects of OpenCms. The second hash-level is calculated from the cache-key of the resource, which also is a String representing the specifc variation of the cached entry.

Entries in the first level of the cache are of type CmsFlexCacheVariation, which is a sub-class of CmsFlexCache. This class is a simple data type that contains of a Map of CmsFlexCacheEntries, with variations - Strings as keys.

Here's a short summary of used terms:

• key: A combination of a resource name and a variation. The data structure used is CmsFlexCacheKey.
• resource: A String with the resource name and an appended [online] of [offline] suffix.
• variation: A String describing a variation of a cached entry in the CmsFlexCache language.
• entry: A CmsFlexCacheEntry data structure which is describes a cached OpenCms resource. For every entry a key is saved which contains the resource name and the variation.

Currenty the whole cache is flushed if something is published. Implement partial cache flushing, i.e. remove only changed elements at publish or change event (in case of offline resources).

Version:

$Revision: 1.17 $

Author:

Alexander Kandzior (a.kandzior@alkacon.com), Thomas Weckert (t.weckert@alkacon.com)

See Also:

CmsFlexCacheKey, CmsFlexCacheEntry, CmsFlexLruCache, I_CmsFlexLruCacheObject

Field Summary

static String	C_CACHE_OFFLINESUFFIX Suffix to append to online cache entries
static String	C_CACHE_ONLINESUFFIX Suffix to append to online cache entries
static int	C_CLEAR_ALL Static ints to trigger clearcache events
static int	C_CLEAR_ENTRIES
static int	C_CLEAR_OFFLINE_ALL
static int	C_CLEAR_OFFLINE_ENTRIES
static int	C_CLEAR_ONLINE_ALL
static int	C_CLEAR_ONLINE_ENTRIES
static int	C_INITIAL_CAPACITY_CACHE Initial Cache size, this should be a power of 2 because of the Java collections implementation
static int	C_INITIAL_CAPACITY_VARIATIONS Initial size for variation lists, should be a power of 2

Fields inherited from interface com.opencms.flex.I_CmsEventListener

EVENT_CLEAR_CACHES, EVENT_FLEX_CACHE_CLEAR, EVENT_FLEX_CLUSTER_CHECK_SOURCE, EVENT_FLEX_CLUSTER_HOOK, EVENT_FLEX_PURGE_JSP_REPOSITORY, EVENT_LOGIN_USER, EVENT_PUBLISH_BO_RESOURCE, EVENT_PUBLISH_PROJECT, EVENT_PUBLISH_RESOURCE, EVENT_STATIC_EXPORT

Constructor Summary

CmsFlexCache(OpenCms openCms)
Constructor for class CmsFlexCache.

Method Summary

boolean	cacheOffline() Indicates if offline project resources are cached.
void	cmsEvent(CmsEvent event) Implements the CmsEvent interface, the FlexCache uses the events to clear itself in case a project is published.
protected void	finalize() Clears the cache for finalization.
CmsFlexCacheKey	getCachedKey(String key, CmsObject cms) Returns the CmsFlexCacheKey data structure for a given key (i.e. resource name).
Set	getCachedResources(CmsObject cms) Returns a set of all cached resource names.
Set	getCachedVariations(String key, CmsObject cms) Returns all variations in the cache for a given resource name.
CmsFlexLruCache	getEntryLruCache() Returns the LRU cache where the CacheEntries are cached.
boolean	isEnabled() Indicates if the cache is enabled (i.e. actually caching entries) or not.
int	keySize() Returns the total number of cached resource keys.
int	size() Returns the total number of entries in the cache.

Methods inherited from class java.lang.Object

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

Field Detail

C_INITIAL_CAPACITY_CACHE

public static final int C_INITIAL_CAPACITY_CACHE

Initial Cache size, this should be a power of 2 because of the Java collections implementation

See Also:

Constant Field Values

C_INITIAL_CAPACITY_VARIATIONS

public static final int C_INITIAL_CAPACITY_VARIATIONS

Initial size for variation lists, should be a power of 2

See Also:

Constant Field Values

C_CACHE_ONLINESUFFIX

public static String C_CACHE_ONLINESUFFIX

Suffix to append to online cache entries

C_CACHE_OFFLINESUFFIX

public static String C_CACHE_OFFLINESUFFIX

Suffix to append to online cache entries

C_CLEAR_ALL

public static final int C_CLEAR_ALL

Static ints to trigger clearcache events

See Also:

Constant Field Values

C_CLEAR_ENTRIES

public static final int C_CLEAR_ENTRIES

See Also:

Constant Field Values

C_CLEAR_ONLINE_ALL

public static final int C_CLEAR_ONLINE_ALL

See Also:

Constant Field Values

C_CLEAR_ONLINE_ENTRIES

public static final int C_CLEAR_ONLINE_ENTRIES

See Also:

Constant Field Values

C_CLEAR_OFFLINE_ALL

public static final int C_CLEAR_OFFLINE_ALL

See Also:

Constant Field Values

C_CLEAR_OFFLINE_ENTRIES

public static final int C_CLEAR_OFFLINE_ENTRIES

See Also:

Constant Field Values

Constructor Detail

CmsFlexCache

public CmsFlexCache(OpenCms openCms)

Constructor for class CmsFlexCache.

The parameter "enabled" is used to control if the cache is actually on or off. Even if you don't need the cache, you still have to create an instance of it with enabled=false. This is because you need some of the FlexCache data structures for JSP inclusion buffering.

Parameters:

openCms - the OpenCms instance

Method Detail

finalize

protected void finalize()
                 throws Throwable

Clears the cache for finalization.

Overrides:

finalize in class Object

Throwable

isEnabled

public boolean isEnabled()

Indicates if the cache is enabled (i.e. actually caching entries) or not.

Returns:

true if the cache is enabled, false if not

cacheOffline

public boolean cacheOffline()

Indicates if offline project resources are cached.

Returns:

true if offline projects are cached, false if not

getCachedResources

public Set getCachedResources(CmsObject cms)

Returns a set of all cached resource names. Usefull if you want to show a list of all cached resources, like on the FlexCache administration page.

Only users with administrator permissions are allowed to perform this operation.

Parameters:

cms - the CmsObject used for user authorization

Returns:

a Set of cached resource names (which are of type String)

getCachedVariations

public Set getCachedVariations(String key,
                               CmsObject cms)

Returns all variations in the cache for a given resource name. The variations are of type String.

Usefull if you want to show a list of all cached entry - variations, like on the FlexCache administration page.

Only users with administrator permissions are allowed to perform this operation.

Parameters:

key - the resource name for which to look up the variations for

cms - the CmsObject used for user authorization

Returns:

a Set of cached variations (which are of type String)

getCachedKey

public CmsFlexCacheKey getCachedKey(String key,
                                    CmsObject cms)

Returns the CmsFlexCacheKey data structure for a given key (i.e. resource name).

Usefull if you want to show the cache key for a resources, like on the FlexCache administration page.

Only users with administrator permissions are allowed to perform this operation.

Parameters:

key - the resource name for which to look up the variation for

cms - the CmsObject used for user authorization

Returns:

the CmsFlexCacheKey data structure found for the resource

size

public int size()

Returns the total number of entries in the cache.

Returns:

the number of entries in the cache

keySize

public int keySize()

Returns the total number of cached resource keys.

Returns:

the number of resource keys in the cache

cmsEvent

public void cmsEvent(CmsEvent event)

Implements the CmsEvent interface, the FlexCache uses the events to clear itself in case a project is published.

Specified by:

cmsEvent in interface I_CmsEventListener

Parameters:

event - CmsEvent that has occurred

getEntryLruCache

public CmsFlexLruCache getEntryLruCache()

Returns the LRU cache where the CacheEntries are cached.

Returns:

the LRU cache where the CacheEntries are cached