File	Doc	Category	Size	Date	Package
DistributedTimedCachePolicy.java	API Doc	JBoss 4.2.1	12026	Fri Jul 13 20:52:38 BST 2007	org.jboss.ha.framework.server.util

DistributedTimedCachePolicy

• java.lang.Object
  • java.util.TimerTask

Fields Summary
protected static Timer	resolutionTimer
protected static Logger	log
protected org.jboss.ha.framework.interfaces.DistributedState	entryMap The map of cached TimedEntry objects.
protected String	category
protected String	partitionName
protected int	defaultLifetime The lifetime in seconds to use for objects inserted that do not implement the TimedEntry interface.
protected long	now The caches notion of the current time
protected int	resolution The resolution in seconds of the cach current time

Constructors Summary
public DistributedTimedCachePolicy(String category, String partitionName, int defaultLifetime) Creates a new TimedCachePolicy with the given default entry lifetime that does not synchronized access to its policy store and uses a 60 second resolution. this(category, partitionName, defaultLifetime, 0);
public DistributedTimedCachePolicy(String category, String partitionName, int defaultLifetime, int resolution) Creates a new TimedCachePolicy with the given default entry lifetime that does/does not synchronized access to its policy store depending on the value of threadSafe. param category the name of the catetegory used in the DistributedState access calls. param partitionName the name of the HAPartition who's replicated state service will be used as the cache store. param defaultLifetime the lifetime in seconds to use for objects inserted that do not implement the TimedEntry interface. param resolution the resolution in seconds of the cache timer. A cache does not query the system time on every get() invocation. Rather the cache updates its notion of the current time every 'resolution' seconds. see DistributedState this.category = category; this.partitionName = partitionName; this.defaultLifetime = defaultLifetime; if( resolution <= 0 ) resolution = 60; this.resolution = resolution;

Methods Summary
public void	create() Initializes the cache for use. Prior to this the cache has no store. // Lookup the parition InitialContext ctx = new InitialContext(); String jndiName = "/HAPartition/" + partitionName; HAPartition partition = (HAPartition) ctx.lookup(jndiName); this.entryMap = partition.getDistributedStateService(); log.debug("Obtained DistributedState from partition="+partitionName); now = System.currentTimeMillis();
public long	currentTimeMillis() Get the cache time. return the cache time last obtained from System.currentTimeMillis() return now;
public void	destroy() Clears the cache of all entries.
public void	flush() Remove all entries from the cache. Collection keys = entryMap.getAllKeys(category); // Notify the entries of their removal Iterator iter = keys.iterator(); while( iter.hasNext() ) { Serializable key = (Serializable) iter.next(); TimedEntry entry = (TimedEntry) entryMap.get(category, key); entry.destroy(); }
public java.lang.Object	get(java.lang.Object key) Get the cache value for key if it has not expired. If the TimedEntry is expired its destroy method is called and then removed from the cache. return the TimedEntry value or the original value if it was not an instance of TimedEntry if key is in the cache, null otherwise. Serializable skey = (Serializable) key; TimedEntry entry = (TimedEntry) entryMap.get(category, skey); if( entry == null ) return null; if( entry.isCurrent(now) == false ) { // Try to refresh the entry if( entry.refresh() == false ) { // Failed, remove the entry and return null entry.destroy(); try { entryMap.remove(category, skey); } catch(Exception e) { log.debug("Failed to remove expired entry", e); } return null; } } Object value = entry.getValue(); return value;
public int	getDefaultLifetime() Get the default lifetime of cache entries. return default lifetime in seconds of cache entries. return defaultLifetime;
public void	insert(java.lang.Object key, java.lang.Object value) Insert a value into the cache. In order to have the cache entry reshresh itself value would have to implement TimedEntry and implement the required refresh() method logic. param key the key for the cache entry param value Either an instance of TimedEntry that will be inserted without change, or an abitrary value that will be wrapped in a non-refreshing TimedEntry. Serializable skey = (Serializable) key; TimedEntry entry = (TimedEntry) entryMap.get(category, skey); if( entry != null ) throw new IllegalStateException("Attempt to insert duplicate entry"); if( (value instanceof TimedEntry) == false ) { // Wrap the value in a DefaultTimedEntry Serializable svalue = (Serializable) value; entry = new DefaultTimedEntry(defaultLifetime, svalue); } else { entry = (TimedEntry) value; } entry.init(now); try { entryMap.set(category, skey, entry); } catch(Exception e) { log.error("Failed to set entry", e); }
public java.lang.Object	peek(java.lang.Object key) Get the cache value for key. This method does not check to see if the entry has expired. return the TimedEntry value or the original value if it was not an instancee of TimedEntry if key is in the cache, null otherwise. Serializable skey = (Serializable) key; TimedEntry entry = (TimedEntry) entryMap.get(category, skey); Object value = null; if( entry != null ) value = entry.getValue(); return value;
public org.jboss.ha.framework.server.util.DistributedTimedCachePolicy$TimedEntry	peekEntry(java.lang.Object key) Get the raw TimedEntry for key without performing any expiration check. return the TimedEntry value associated with key if one exists, null otherwise. Serializable skey = (Serializable) key; TimedEntry entry = (TimedEntry) entryMap.get(category, skey); return entry;
public void	remove(java.lang.Object key) Remove the entry associated with key and call destroy on the entry if found. Serializable skey = (Serializable) key; try { TimedEntry entry = (TimedEntry) entryMap.remove(category, skey); if( entry != null ) entry.destroy(); } catch(Exception e) { log.error("Failed to remove entry", e); }
public void	run() The TimerTask run method. It updates the cache time to the current system time. now = System.currentTimeMillis();
public void	setDefaultLifetime(int defaultLifetime) Set the default lifetime of cache entries for new values added to the cache. param defaultLifetime lifetime in seconds of cache values that do not implement TimedEntry. this.defaultLifetime = defaultLifetime;
public int	size() return entryMap.getAllKeys(category).size();
public void	start() Schedules this with the class resolutionTimer Timer object for execution every resolution seconds. resolutionTimer.scheduleAtFixedRate(this, 0, 1000*resolution);
public void	stop() Stop cancels the resolution timer and flush()es the cache. super.cancel();