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SUMMARY: JavaDoc of com.opensymphony.oscache.base.algorithm.AbstractConcurrentReadCache JAVADOC | Sourc code of com.opensymphony.oscache.base.algorithm.AbstractConcurrentReadCache SOURCE | Download com.opensymphony.oscache.base.algorithm.AbstractConcurrentReadCache DOWNLOAD | NESTED | FIELD | CONSTR | METHOD DETAIL: FIELD | CONSTR | METHOD

com.opensymphony.oscache.base.algorithm
Class AbstractConcurrentReadCache  view AbstractConcurrentReadCache download AbstractConcurrentReadCache.java

java.lang.Object
  extended byjava.util.AbstractMap
      extended bycom.opensymphony.oscache.base.algorithm.AbstractConcurrentReadCache
All Implemented Interfaces:
java.lang.Cloneable, java.util.Map, java.io.Serializable
Direct Known Subclasses:
FIFOCache, LRUCache, UnlimitedCache
public abstract class AbstractConcurrentReadCache
extends java.util.AbstractMap
implements java.util.Map, java.lang.Cloneable, java.io.Serializable

A version of Hashtable that supports mostly-concurrent reading, but exclusive writing. Because reads are not limited to periods without writes, a concurrent reader policy is weaker than a classic reader/writer policy, but is generally faster and allows more concurrency. This class is a good choice especially for tables that are mainly created by one thread during the start-up phase of a program, and from then on, are mainly read (with perhaps occasional additions or removals) in many threads. If you also need concurrency among writes, consider instead using ConcurrentHashMap.

Successful retrievals using get(key) and containsKey(key) usually run without locking. Unsuccessful ones (i.e., when the key is not present) do involve brief synchronization (locking). Also, the size and isEmpty methods are always synchronized.

Because retrieval operations can ordinarily overlap with writing operations (i.e., put, remove, and their derivatives), retrievals can only be guaranteed to return the results of the most recently completed operations holding upon their onset. Retrieval operations may or may not return results reflecting in-progress writing operations. However, the retrieval operations do always return consistent results -- either those holding before any single modification or after it, but never a nonsense result. For aggregate operations such as putAll and clear, concurrent reads may reflect insertion or removal of only some entries. In those rare contexts in which you use a hash table to synchronize operations across threads (for example, to prevent reads until after clears), you should either encase operations in synchronized blocks, or instead use java.util.Hashtable.

This class also supports optional guaranteed exclusive reads, simply by surrounding a call within a synchronized block, as in
AbstractConcurrentReadCache t; ... Object v;
synchronized(t) { v = t.get(k); }
But this is not usually necessary in practice. For example, it is generally inefficient to write: 

   AbstractConcurrentReadCache t; ...            // Inefficient version
   Object key; ...
   Object value; ...
   synchronized(t) {
     if (!t.containsKey(key))
       t.put(key, value);
       // other code if not previously present
     }
     else {
       // other code if it was previously present
     }
   }
Instead, just take advantage of the fact that put returns null if the key was not previously present: 
   AbstractConcurrentReadCache t; ...                // Use this instead
   Object key; ...
   Object value; ...
   Object oldValue = t.put(key, value);
   if (oldValue == null) {
     // other code if not previously present
   }
   else {
     // other code if it was previously present
   }

Iterators and Enumerations (i.e., those returned by keySet().iterator(), entrySet().iterator(), values().iterator(), keys(), and elements()) return elements reflecting the state of the hash table at some point at or since the creation of the iterator/enumeration. They will return at most one instance of each element (via next()/nextElement()), but might or might not reflect puts and removes that have been processed since they were created. They do not throw ConcurrentModificationException. However, these iterators are designed to be used by only one thread at a time. Sharing an iterator across multiple threads may lead to unpredictable results if the table is being concurrently modified. Again, you can ensure interference-free iteration by enclosing the iteration in a synchronized block.

This class may be used as a direct replacement for any use of java.util.Hashtable that does not depend on readers being blocked during updates. Like Hashtable but unlike java.util.HashMap, this class does NOT allow null to be used as a key or value. This class is also typically faster than ConcurrentHashMap when there is usually only one thread updating the table, but possibly many retrieving values from it.

Implementation note: A slightly faster implementation of this class will be possible once planned Java Memory Model revisions are in place.

[ Introduction to this package. ]

Nested Class Summary
protected static class AbstractConcurrentReadCache.Entry
          AbstractConcurrentReadCache collision list entry.
protected  class AbstractConcurrentReadCache.HashIterator
           
protected  class AbstractConcurrentReadCache.KeyIterator
           
protected  class AbstractConcurrentReadCache.ValueIterator
           
 
Nested classes inherited from class java.util.AbstractMap
 
Field Summary
protected  java.lang.Boolean barrierLock
          Lock used only for its memory effects.
protected  int count
          The total number of mappings in the hash table.
static int DEFAULT_INITIAL_CAPACITY
          The default initial number of table slots for this table (32).
static float DEFAULT_LOAD_FACTOR
          The default load factor for this table.
protected  int DEFAULT_MAX_ENTRIES
          Default cache capacity (number of entries).
protected  java.util.Set entrySet
           
protected  java.util.HashMap groups
          A HashMap containing the group information.
protected  java.util.Set keySet
           
protected  java.lang.Object lastWrite
          field written to only to guarantee lock ordering.
protected  float loadFactor
          The load factor for the hash table.
protected static org.apache.commons.logging.Log log
           
protected  int maxEntries
          Cache capacity (number of entries).
private static int MAXIMUM_CAPACITY
          The maximum capacity.
protected  boolean memoryCaching
          Use memory cache or not.
private static int MINIMUM_CAPACITY
          The minimum capacity.
protected static java.lang.String NULL
           
private  boolean overflowPersistence
          Use overflow persistence caching.
protected  com.opensymphony.oscache.base.persistence.PersistenceListener persistenceListener
          Persistence listener.
protected  AbstractConcurrentReadCache.Entry[] table
          The hash table data.
protected  int threshold
          The table is rehashed when its size exceeds this threshold.
protected  int UNLIMITED
          Max number of element in cache when considered unlimited.
protected  boolean unlimitedDiskCache
          Use unlimited disk caching.
protected  java.util.Collection values
           
 
Fields inherited from class java.util.AbstractMap
 
Constructor Summary
AbstractConcurrentReadCache()
          Constructs a new, empty map with a default initial capacity and load factor.
AbstractConcurrentReadCache(int initialCapacity)
          Constructs a new, empty map with the specified initial capacity and default load factor.
AbstractConcurrentReadCache(int initialCapacity, float loadFactor)
          Constructs a new, empty map with the specified initial capacity and the specified load factor.
AbstractConcurrentReadCache(java.util.Map t)
          Constructs a new map with the same mappings as the given map.
 
Method Summary
private  void addGroupMappings(java.lang.String key, java.util.Set newGroups, boolean persist)
          Add this cache key to the groups specified groups.
 int capacity()
          Return the number of slots in this table.
 void clear()
          Removes all mappings from this map.
 java.lang.Object clone()
          Returns a shallow copy of this.
 boolean contains(java.lang.Object value)
          Tests if some key maps into the specified value in this table.
 boolean containsKey(java.lang.Object key)
          Tests if the specified object is a key in this table.
 boolean containsValue(java.lang.Object value)
          Returns true if this map maps one or more keys to the specified value.
 java.util.Enumeration elements()
          Returns an enumeration of the values in this table.
 java.util.Set entrySet()
          Returns a collection view of the mappings contained in this map.
protected  boolean findAndRemoveEntry(java.util.Map.Entry entry)
          Helper method for entrySet remove.
 java.lang.Object get(java.lang.Object key)
          Returns the value to which the specified key is mapped in this table.
 java.util.Set getGroup(java.lang.String groupName)
          Returns a set of the cache keys that reside in a particular group.
protected  java.util.Set getGroupForReading(java.lang.String groupName)
          Get ref to group.
protected  java.util.Map getGroupsForReading()
          Get ref to groups.
 int getMaxEntries()
          Retrieve the cache capacity (number of entries).
 com.opensymphony.oscache.base.persistence.PersistenceListener getPersistenceListener()
          Get the persistence listener.
protected  AbstractConcurrentReadCache.Entry[] getTableForReading()
          Get ref to table; the reference and the cells it accesses will be at least as fresh as from last use of barrierLock
private static int hash(java.lang.Object x)
          Return hash code for Object x.
 boolean isEmpty()
          Returns true if this map contains no key-value mappings.
 boolean isMemoryCaching()
          Check if memory caching is used.
 boolean isOverflowPersistence()
          Check if we use overflowPersistence
 boolean isUnlimitedDiskCache()
          Check if we use unlimited disk cache.
protected abstract  void itemPut(java.lang.Object key)
          Notify the underlying implementation that an item was put in the cache.
protected abstract  void itemRemoved(java.lang.Object key)
          Notify the underlying implementation that an item was removed from the cache.
protected abstract  void itemRetrieved(java.lang.Object key)
          Notify any underlying algorithm that an item has been retrieved from the cache.
 java.util.Enumeration keys()
          Returns an enumeration of the keys in this table.
 java.util.Set keySet()
          Returns a set view of the keys contained in this map.
 float loadFactor()
          Return the load factor
private  int p2capacity(int initialCapacity)
          Returns the appropriate capacity (power of two) for the specified initial capacity argument.
protected  void persistClear()
          Removes the entire cache from persistent storage.
protected  void persistRemove(java.lang.Object key)
          Remove an object from the persistence.
protected  void persistRemoveGroup(java.lang.String groupName)
          Removes a cache group using the persistence listener.
protected  java.lang.Object persistRetrieve(java.lang.Object key)
          Retrieve an object from the persistence listener.
protected  java.util.Set persistRetrieveGroup(java.lang.String groupName)
          Retrieves a cache group using the persistence listener.
protected  void persistStore(java.lang.Object key, java.lang.Object obj)
          Store an object in the cache using the persistence listener.
protected  void persistStoreGroup(java.lang.String groupName, java.util.Set group)
          Creates or Updates a cache group using the persistence listener.
 java.lang.Object put(java.lang.Object key, java.lang.Object value)
          OpenSymphony BEGIN
private  java.lang.Object put(java.lang.Object key, java.lang.Object value, boolean persist)
           
 void putAll(java.util.Map t)
          Copies all of the mappings from the specified map to this one.
private  void readObject(java.io.ObjectInputStream s)
          Reconstitute the AbstractConcurrentReadCache.
protected  void recordModification(java.lang.Object x)
          Force a memory synchronization that will cause all readers to see table.
protected  void rehash()
          Rehashes the contents of this map into a new table with a larger capacity.
 java.lang.Object remove(java.lang.Object key)
          OpenSymphony BEGIN
private  java.lang.Object remove(java.lang.Object key, boolean invokeAlgorithm)
           
private  void removeGroupMappings(java.lang.String key, java.util.Set oldGroups, boolean persist)
          Remove this CacheEntry from the groups it no longer belongs to.
protected abstract  java.lang.Object removeItem()
          The cache has reached its cacpacity and an item needs to be removed.
 void setMaxEntries(int newLimit)
          Set the cache capacity
 void setMemoryCaching(boolean memoryCaching)
          Sets the memory caching flag.
 void setOverflowPersistence(boolean overflowPersistence)
          Sets the overflowPersistence flag
 void setPersistenceListener(com.opensymphony.oscache.base.persistence.PersistenceListener listener)
          Set the persistence listener to use.
 void setUnlimitedDiskCache(boolean unlimitedDiskCache)
          Sets the unlimited disk caching flag.
 int size()
          Returns the total number of cache entries held in this map.
protected  java.lang.Object sput(java.lang.Object key, java.lang.Object value, int hash, boolean persist)
          OpenSymphony BEGIN
protected  java.lang.Object sremove(java.lang.Object key, int hash, boolean invokeAlgorithm)
          OpenSymphony BEGIN
private  void updateGroups(com.opensymphony.oscache.base.CacheEntry oldValue, com.opensymphony.oscache.base.CacheEntry newValue, boolean persist)
          Updates the groups to reflect the differences between the old and new cache entries.
private  void updateGroups(java.lang.Object oldValue, java.lang.Object newValue, boolean persist)
          Updates the groups to reflect the differences between the old and new cache entries.
 java.util.Collection values()
          Returns a collection view of the values contained in this map.
private  void writeObject(java.io.ObjectOutputStream s)
          Save the state of the AbstractConcurrentReadCache instance to a stream.
 
Methods inherited from class java.util.AbstractMap
equals, hashCode, toString
 
Methods inherited from class java.lang.Object
finalize, getClass, notify, notifyAll, wait, wait, wait
 
Methods inherited from interface java.util.Map
equals, hashCode
 

Field Detail

DEFAULT_INITIAL_CAPACITY

public static int DEFAULT_INITIAL_CAPACITY
The default initial number of table slots for this table (32). Used when not otherwise specified in constructor.

MINIMUM_CAPACITY

private static final int MINIMUM_CAPACITY
The minimum capacity. Used if a lower value is implicitly specified by either of the constructors with arguments. MUST be a power of two.

See Also:
Constant Field Values

MAXIMUM_CAPACITY

private static final int MAXIMUM_CAPACITY
The maximum capacity. Used if a higher value is implicitly specified by either of the constructors with arguments. MUST be a power of two <= 1<<30.

See Also:
Constant Field Values

DEFAULT_LOAD_FACTOR

public static final float DEFAULT_LOAD_FACTOR
The default load factor for this table. Used when not otherwise specified in constructor, the default is 0.75f.

See Also:
Constant Field Values

NULL

protected static final java.lang.String NULL
See Also:
Constant Field Values

log

protected static org.apache.commons.logging.Log log

barrierLock

protected final java.lang.Boolean barrierLock
Lock used only for its memory effects. We use a Boolean because it is serializable, and we create a new one because we need a unique object for each cache instance.

lastWrite

protected transient java.lang.Object lastWrite
field written to only to guarantee lock ordering.

table

protected transient AbstractConcurrentReadCache.Entry[] table
The hash table data.

count

protected transient int count
The total number of mappings in the hash table.

persistenceListener

protected com.opensymphony.oscache.base.persistence.PersistenceListener persistenceListener
Persistence listener.

memoryCaching

protected boolean memoryCaching
Use memory cache or not.

unlimitedDiskCache

protected boolean unlimitedDiskCache
Use unlimited disk caching.

loadFactor

protected float loadFactor
The load factor for the hash table.

DEFAULT_MAX_ENTRIES

protected final int DEFAULT_MAX_ENTRIES
Default cache capacity (number of entries).

See Also:
Constant Field Values

UNLIMITED

protected final int UNLIMITED
Max number of element in cache when considered unlimited.

See Also:
Constant Field Values

values

protected transient java.util.Collection values

groups

protected java.util.HashMap groups
A HashMap containing the group information. Each entry uses the group name as the key, and holds a Set of containing keys of all the cache entries that belong to that particular group.

entrySet

protected transient java.util.Set entrySet

keySet

protected transient java.util.Set keySet

maxEntries

protected int maxEntries
Cache capacity (number of entries).

threshold

protected int threshold
The table is rehashed when its size exceeds this threshold. (The value of this field is always (int)(capacity * loadFactor).)

overflowPersistence

private boolean overflowPersistence
Use overflow persistence caching.

Constructor Detail

AbstractConcurrentReadCache

public AbstractConcurrentReadCache(int initialCapacity,
                                   float loadFactor)
Constructs a new, empty map with the specified initial capacity and the specified load factor.

AbstractConcurrentReadCache

public AbstractConcurrentReadCache(int initialCapacity)
Constructs a new, empty map with the specified initial capacity and default load factor.

AbstractConcurrentReadCache

public AbstractConcurrentReadCache()
Constructs a new, empty map with a default initial capacity and load factor.

AbstractConcurrentReadCache

public AbstractConcurrentReadCache(java.util.Map t)
Constructs a new map with the same mappings as the given map. The map is created with a capacity of twice the number of mappings in the given map or 11 (whichever is greater), and a default load factor.

Method Detail

isEmpty

public boolean isEmpty()
Returns true if this map contains no key-value mappings.

Specified by:
isEmpty in interface java.util.Map

getGroup

public java.util.Set getGroup(java.lang.String groupName)
Returns a set of the cache keys that reside in a particular group.

setMaxEntries

public void setMaxEntries(int newLimit)
Set the cache capacity

getMaxEntries

public int getMaxEntries()
Retrieve the cache capacity (number of entries).

setMemoryCaching

public void setMemoryCaching(boolean memoryCaching)
Sets the memory caching flag.

isMemoryCaching

public boolean isMemoryCaching()
Check if memory caching is used.

setPersistenceListener

public void setPersistenceListener(com.opensymphony.oscache.base.persistence.PersistenceListener listener)
Set the persistence listener to use.

getPersistenceListener

public com.opensymphony.oscache.base.persistence.PersistenceListener getPersistenceListener()
Get the persistence listener.

setUnlimitedDiskCache

public void setUnlimitedDiskCache(boolean unlimitedDiskCache)
Sets the unlimited disk caching flag.

isUnlimitedDiskCache

public boolean isUnlimitedDiskCache()
Check if we use unlimited disk cache.

isOverflowPersistence

public boolean isOverflowPersistence()
Check if we use overflowPersistence

setOverflowPersistence

public void setOverflowPersistence(boolean overflowPersistence)
Sets the overflowPersistence flag

capacity

public int capacity()
Return the number of slots in this table.

clear

public void clear()
Removes all mappings from this map.

Specified by:
clear in interface java.util.Map

clone

public java.lang.Object clone()
Returns a shallow copy of this. AbstractConcurrentReadCache instance: the keys and values themselves are not cloned.

contains

public boolean contains(java.lang.Object value)
Tests if some key maps into the specified value in this table. This operation is more expensive than the containsKey method.

Note that this method is identical in functionality to containsValue, (which is part of the Map interface in the collections framework).

containsKey

public boolean containsKey(java.lang.Object key)
Tests if the specified object is a key in this table.

Specified by:
containsKey in interface java.util.Map

containsValue

public boolean containsValue(java.lang.Object value)
Returns true if this map maps one or more keys to the specified value. Note: This method requires a full internal traversal of the hash table, and so is much slower than method containsKey.

Specified by:
containsValue in interface java.util.Map

elements

public java.util.Enumeration elements()
Returns an enumeration of the values in this table. Use the Enumeration methods on the returned object to fetch the elements sequentially.

entrySet

public java.util.Set entrySet()
Returns a collection view of the mappings contained in this map. Each element in the returned collection is a Map.Entry. The collection is backed by the map, so changes to the map are reflected in the collection, and vice-versa. The collection supports element removal, which removes the corresponding mapping from the map, via the Iterator.remove, Collection.remove, removeAll, retainAll, and clear operations. It does not support the add or addAll operations.

Specified by:
entrySet in interface java.util.Map

get

public java.lang.Object get(java.lang.Object key)
Returns the value to which the specified key is mapped in this table.

Specified by:
get in interface java.util.Map

keySet

public java.util.Set keySet()
Returns a set view of the keys contained in this map. The set is backed by the map, so changes to the map are reflected in the set, and vice-versa. The set supports element removal, which removes the corresponding mapping from this map, via the Iterator.remove, Set.remove, removeAll, retainAll, and clear operations. It does not support the add or addAll operations.

Specified by:
keySet in interface java.util.Map

keys

public java.util.Enumeration keys()
Returns an enumeration of the keys in this table.

loadFactor

public float loadFactor()
Return the load factor

put

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

Specified by:
put in interface java.util.Map

putAll

public void putAll(java.util.Map t)
Copies all of the mappings from the specified map to this one. These mappings replace any mappings that this map had for any of the keys currently in the specified Map.

Specified by:
putAll in interface java.util.Map

remove

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

Specified by:
remove in interface java.util.Map

size

public int size()
Returns the total number of cache entries held in this map.

Specified by:
size in interface java.util.Map

values

public java.util.Collection values()
Returns a collection view of the values contained in this map. The collection is backed by the map, so changes to the map are reflected in the collection, and vice-versa. The collection supports element removal, which removes the corresponding mapping from this map, via the Iterator.remove, Collection.remove, removeAll, retainAll, and clear operations. It does not support the add or addAll operations.

Specified by:
values in interface java.util.Map

getGroupForReading

protected final java.util.Set getGroupForReading(java.lang.String groupName)
Get ref to group. CACHE-127 Synchronized copying of the group entry set since the new HashSet(Collection c) constructor uses the iterator. This may slow things down but it is better than a ConcurrentModificationException. We might have to revisit the code if performance is too adversely impacted.

getGroupsForReading

protected final java.util.Map getGroupsForReading()
Get ref to groups. The reference and the cells it accesses will be at least as fresh as from last use of barrierLock

getTableForReading

protected final AbstractConcurrentReadCache.Entry[] getTableForReading()
Get ref to table; the reference and the cells it accesses will be at least as fresh as from last use of barrierLock

recordModification

protected final void recordModification(java.lang.Object x)
Force a memory synchronization that will cause all readers to see table. Call only when already holding main synch lock.

findAndRemoveEntry

protected boolean findAndRemoveEntry(java.util.Map.Entry entry)
Helper method for entrySet remove.

persistRemove

protected void persistRemove(java.lang.Object key)
Remove an object from the persistence.

persistRemoveGroup

protected void persistRemoveGroup(java.lang.String groupName)
Removes a cache group using the persistence listener.

persistRetrieve

protected java.lang.Object persistRetrieve(java.lang.Object key)
Retrieve an object from the persistence listener.

persistRetrieveGroup

protected java.util.Set persistRetrieveGroup(java.lang.String groupName)
Retrieves a cache group using the persistence listener.

persistStore

protected void persistStore(java.lang.Object key,
                            java.lang.Object obj)
Store an object in the cache using the persistence listener.

persistStoreGroup

protected void persistStoreGroup(java.lang.String groupName,
                                 java.util.Set group)
Creates or Updates a cache group using the persistence listener.

persistClear

protected void persistClear()
Removes the entire cache from persistent storage.

itemPut

protected abstract void itemPut(java.lang.Object key)
Notify the underlying implementation that an item was put in the cache.

itemRetrieved

protected abstract void itemRetrieved(java.lang.Object key)
Notify any underlying algorithm that an item has been retrieved from the cache.

itemRemoved

protected abstract void itemRemoved(java.lang.Object key)
Notify the underlying implementation that an item was removed from the cache.

removeItem

protected abstract java.lang.Object removeItem()
The cache has reached its cacpacity and an item needs to be removed. (typically according to an algorithm such as LRU or FIFO).

readObject

private void readObject(java.io.ObjectInputStream s)
                 throws java.io.IOException,
                        java.lang.ClassNotFoundException
Reconstitute the AbstractConcurrentReadCache. instance from a stream (i.e., deserialize it).

rehash

protected void rehash()
Rehashes the contents of this map into a new table with a larger capacity. This method is called automatically when the number of keys in this map exceeds its capacity and load factor.

sput

protected java.lang.Object sput(java.lang.Object key,
                                java.lang.Object value,
                                int hash,
                                boolean persist)
OpenSymphony BEGIN

sremove

protected java.lang.Object sremove(java.lang.Object key,
                                   int hash,
                                   boolean invokeAlgorithm)
OpenSymphony BEGIN

writeObject

private void writeObject(java.io.ObjectOutputStream s)
                  throws java.io.IOException
Save the state of the AbstractConcurrentReadCache instance to a stream. (i.e., serialize it).

hash

private static int hash(java.lang.Object x)
Return hash code for Object x. Since we are using power-of-two tables, it is worth the effort to improve hashcode via the same multiplicative scheme as used in IdentityHashMap.

addGroupMappings

private void addGroupMappings(java.lang.String key,
                              java.util.Set newGroups,
                              boolean persist)
Add this cache key to the groups specified groups. We have to treat the memory and disk group mappings seperately so they remain valid for their corresponding memory/disk caches. (eg if mem is limited to 100 entries and disk is unlimited, the group mappings will be different).

p2capacity

private int p2capacity(int initialCapacity)
Returns the appropriate capacity (power of two) for the specified initial capacity argument.

put

private java.lang.Object put(java.lang.Object key,
                             java.lang.Object value,
                             boolean persist)

remove

private java.lang.Object remove(java.lang.Object key,
                                boolean invokeAlgorithm)

removeGroupMappings

private void removeGroupMappings(java.lang.String key,
                                 java.util.Set oldGroups,
                                 boolean persist)
Remove this CacheEntry from the groups it no longer belongs to. We have to treat the memory and disk group mappings seperately so they remain valid for their corresponding memory/disk caches. (eg if mem is limited to 100 entries and disk is unlimited, the group mappings will be different).

updateGroups

private void updateGroups(java.lang.Object oldValue,
                          java.lang.Object newValue,
                          boolean persist)
Updates the groups to reflect the differences between the old and new cache entries. Either of the old or new values can be null or contain a null group list, in which case the entry's groups will all be added or removed respectively.

updateGroups

private void updateGroups(com.opensymphony.oscache.base.CacheEntry oldValue,
                          com.opensymphony.oscache.base.CacheEntry newValue,
                          boolean persist)
Updates the groups to reflect the differences between the old and new cache entries. Either of the old or new values can be null or contain a null group list, in which case the entry's groups will all be added or removed respectively.

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SUMMARY: JavaDoc of com.opensymphony.oscache.base.algorithm.AbstractConcurrentReadCache JAVADOC | Sourc code of com.opensymphony.oscache.base.algorithm.AbstractConcurrentReadCache SOURCE | Download com.opensymphony.oscache.base.algorithm.AbstractConcurrentReadCache DOWNLOAD | NESTED | FIELD | CONSTR | METHOD DETAIL: FIELD | CONSTR | METHOD