/*
* Copyright (c) 2002-2003 by OpenSymphony
* All rights reserved.
*/
package com.opensymphony.oscache.base;
import java.io.Serializable;
import java.text.ParseException;
import java.util.Date;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;
import javax.swing.event.EventListenerList;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import com.opensymphony.oscache.base.algorithm.AbstractConcurrentReadCache;
import com.opensymphony.oscache.base.algorithm.LRUCache;
import com.opensymphony.oscache.base.algorithm.UnlimitedCache;
import com.opensymphony.oscache.base.events.CacheEntryEvent;
import com.opensymphony.oscache.base.events.CacheEntryEventListener;
import com.opensymphony.oscache.base.events.CacheEntryEventType;
import com.opensymphony.oscache.base.events.CacheEventListener;
import com.opensymphony.oscache.base.events.CacheGroupEvent;
import com.opensymphony.oscache.base.events.CacheMapAccessEvent;
import com.opensymphony.oscache.base.events.CacheMapAccessEventListener;
import com.opensymphony.oscache.base.events.CacheMapAccessEventType;
import com.opensymphony.oscache.base.events.CachePatternEvent;
import com.opensymphony.oscache.base.events.CachewideEvent;
import com.opensymphony.oscache.base.events.CachewideEventType;
import com.opensymphony.oscache.base.persistence.PersistenceListener;
import com.opensymphony.oscache.util.FastCronParser;
/**
* Provides an interface to the cache itself. Creating an instance of this class
* will create a cache that behaves according to its construction parameters.
* The public API provides methods to manage objects in the cache and configure
* any cache event listeners.
*
* @version $Revision: 1.1 $
* @author <a href="mailto:mike@atlassian.com">Mike Cannon-Brookes</a>
* @author <a href="mailto:tgochenour@peregrine.com">Todd Gochenour</a>
* @author <a href="mailto:fbeauregard@pyxis-tech.com">Francois Beauregard</a>
* @author <a href="mailto:chris@swebtec.com">Chris Miller</a>
*/
public class Cache implements Serializable {
/**
* An event that origininated from within another event.
*/
public static final String NESTED_EVENT = "NESTED";
private static transient final Log log = LogFactory.getLog(Cache.class);
/**
* A list of all registered event listeners for this cache.
*/
protected EventListenerList listenerList = new EventListenerList();
/**
* The actual cache map. This is where the cached objects are held.
*/
public AbstractConcurrentReadCache cacheMap = null;
/**
* Date of last complete cache flush.
*/
private Date flushDateTime = null;
/**
* A map that holds keys of cache entries that are currently being built, and EntryUpdateState instance as values. This is used to coordinate threads
* that modify/access a same key in concurrence.
*
* The cache checks against this map when a stale entry is requested, or a cache miss is observed.
*
* If the requested key is in here, we know the entry is currently being
* built by another thread and hence we can either block and wait or serve
* the stale entry (depending on whether cache blocking is enabled or not).
* <p>
* To avoid data races, values in this map should remain present during the whole time distinct threads deal with the
* same key. We implement this using explicit reference counting in the EntryUpdateState instance, to be able to clean up
* the map once all threads have declared they are done accessing/updating a given key.
*
* It is not possible to locate this into the CacheEntry because this would require to have a CacheEntry instance for all cache misses, and
* may therefore generate a memory leak. More over, the CacheEntry instance may not be hold in memory in the case no
* memory cache is configured.
*/
private Map updateStates = new HashMap();
/**
* Indicates whether the cache blocks requests until new content has
* been generated or just serves stale content instead.
*/
private boolean blocking = false;
/**
* Create a new Cache
*
* @param useMemoryCaching Specify if the memory caching is going to be used
* @param unlimitedDiskCache Specify if the disk caching is unlimited
* @param overflowPersistence Specify if the persistent cache is used in overflow only mode
*/
public Cache(boolean useMemoryCaching, boolean unlimitedDiskCache, boolean overflowPersistence) {
this(useMemoryCaching, unlimitedDiskCache, overflowPersistence, false, null, 0);
}
/**
* Create a new Cache.
*
* If a valid algorithm class is specified, it will be used for this cache.
* Otherwise if a capacity is specified, it will use LRUCache.
* If no algorithm or capacity is specified UnlimitedCache is used.
*
* @see com.opensymphony.oscache.base.algorithm.LRUCache
* @see com.opensymphony.oscache.base.algorithm.UnlimitedCache
* @param useMemoryCaching Specify if the memory caching is going to be used
* @param unlimitedDiskCache Specify if the disk caching is unlimited
* @param overflowPersistence Specify if the persistent cache is used in overflow only mode
* @param blocking This parameter takes effect when a cache entry has
* just expired and several simultaneous requests try to retrieve it. While
* one request is rebuilding the content, the other requests will either
* block and wait for the new content (<code>blocking == true</code>) or
* instead receive a copy of the stale content so they don't have to wait
* (<code>blocking == false</code>). the default is <code>false</code>,
* which provides better performance but at the expense of slightly stale
* data being served.
* @param algorithmClass The class implementing the desired algorithm
* @param capacity The capacity
*/
public Cache(boolean useMemoryCaching, boolean unlimitedDiskCache, boolean overflowPersistence, boolean blocking, String algorithmClass, int capacity) {
// Instantiate the algo class if valid
if (((algorithmClass != null) && (algorithmClass.length() > 0)) && (capacity > 0)) {
try {
cacheMap = (AbstractConcurrentReadCache) Class.forName(algorithmClass).newInstance();
cacheMap.setMaxEntries(capacity);
} catch (Exception e) {
log.error("Invalid class name for cache algorithm class. " + e.toString());
}
}
if (cacheMap == null) {
// If we have a capacity, use LRU cache otherwise use unlimited Cache
if (capacity > 0) {
cacheMap = new LRUCache(capacity);
} else {
cacheMap = new UnlimitedCache();
}
}
cacheMap.setUnlimitedDiskCache(unlimitedDiskCache);
cacheMap.setOverflowPersistence(overflowPersistence);
cacheMap.setMemoryCaching(useMemoryCaching);
this.blocking = blocking;
}
/**
* @return the maximum number of items to cache can hold.
*/
public int getCapacity() {
return cacheMap.getMaxEntries();
}
/**
* Allows the capacity of the cache to be altered dynamically. Note that
* some cache implementations may choose to ignore this setting (eg the
* {@link UnlimitedCache} ignores this call).
*
* @param capacity the maximum number of items to hold in the cache.
*/
public void setCapacity(int capacity) {
cacheMap.setMaxEntries(capacity);
}
/**
* Checks if the cache was flushed more recently than the CacheEntry provided.
* Used to determine whether to refresh the particular CacheEntry.
*
* @param cacheEntry The cache entry which we're seeing whether to refresh
* @return Whether or not the cache has been flushed more recently than this cache entry was updated.
*/
public boolean isFlushed(CacheEntry cacheEntry) {
if (flushDateTime != null) {
final long lastUpdate = cacheEntry.getLastUpdate();
final long flushTime = flushDateTime.getTime();
// CACHE-241: check flushDateTime with current time also
return (flushTime <= System.currentTimeMillis()) && (flushTime >= lastUpdate);
} else {
return false;
}
}
/**
* Retrieve an object from the cache specifying its key.
*
* @param key Key of the object in the cache.
*
* @return The object from cache
*
* @throws NeedsRefreshException Thrown when the object either
* doesn't exist, or exists but is stale. When this exception occurs,
* the CacheEntry corresponding to the supplied key will be locked
* and other threads requesting this entry will potentially be blocked
* until the caller repopulates the cache. If the caller choses not
* to repopulate the cache, they <em>must</em> instead call
* {@link #cancelUpdate(String)}.
*/
public Object getFromCache(String key) throws NeedsRefreshException {
return getFromCache(key, CacheEntry.INDEFINITE_EXPIRY, null);
}
/**
* Retrieve an object from the cache specifying its key.
*
* @param key Key of the object in the cache.
* @param refreshPeriod How long before the object needs refresh. To
* allow the object to stay in the cache indefinitely, supply a value
* of {@link CacheEntry#INDEFINITE_EXPIRY}.
*
* @return The object from cache
*
* @throws NeedsRefreshException Thrown when the object either
* doesn't exist, or exists but is stale. When this exception occurs,
* the CacheEntry corresponding to the supplied key will be locked
* and other threads requesting this entry will potentially be blocked
* until the caller repopulates the cache. If the caller choses not
* to repopulate the cache, they <em>must</em> instead call
* {@link #cancelUpdate(String)}.
*/
public Object getFromCache(String key, int refreshPeriod) throws NeedsRefreshException {
return getFromCache(key, refreshPeriod, null);
}
/**
* Retrieve an object from the cache specifying its key.
*
* @param key Key of the object in the cache.
* @param refreshPeriod How long before the object needs refresh. To
* allow the object to stay in the cache indefinitely, supply a value
* of {@link CacheEntry#INDEFINITE_EXPIRY}.
* @param cronExpiry A cron expression that specifies fixed date(s)
* and/or time(s) that this cache entry should
* expire on.
*
* @return The object from cache
*
* @throws NeedsRefreshException Thrown when the object either
* doesn't exist, or exists but is stale. When this exception occurs,
* the CacheEntry corresponding to the supplied key will be locked
* and other threads requesting this entry will potentially be blocked
* until the caller repopulates the cache. If the caller choses not
* to repopulate the cache, they <em>must</em> instead call
* {@link #cancelUpdate(String)}.
*/
public Object getFromCache(String key, int refreshPeriod, String cronExpiry) throws NeedsRefreshException {
CacheEntry cacheEntry = this.getCacheEntry(key, null, null);
Object content = cacheEntry.getContent();
CacheMapAccessEventType accessEventType = CacheMapAccessEventType.HIT;
boolean reload = false;
// Check if this entry has expired or has not yet been added to the cache. If
// so, we need to decide whether to block, serve stale content or throw a
// NeedsRefreshException
if (this.isStale(cacheEntry, refreshPeriod, cronExpiry)) {
//Get access to the EntryUpdateState instance and increment the usage count during the potential sleep
EntryUpdateState updateState = getUpdateState(key);
//log.debug("Stale:" + updateState.state + EntryUpdateState.NOT_YET_UPDATING);
try {
synchronized (updateState) {
if (updateState.isAwaitingUpdate() || updateState.isCancelled()) {
// No one else is currently updating this entry - grab ownership
updateState.startUpdate();
if (cacheEntry.isNew()) {
accessEventType = CacheMapAccessEventType.MISS;
} else {
accessEventType = CacheMapAccessEventType.STALE_HIT;
}
} else if (updateState.isUpdating()) {
// Another thread is already updating the cache. We block if this
// is a new entry, or blocking mode is enabled. Either putInCache()
// or cancelUpdate() can cause this thread to resume.
log.debug("Yes - it's updating...");
if (cacheEntry.isNew() || blocking) {
do {
try {
log.debug("updateState was in:" + cacheEntry.isNew() + ":" + blocking);
updateState.wait();
} catch (InterruptedException e) {
}
} while (updateState.isUpdating());
if (updateState.isCancelled()) {
// The updating thread cancelled the update, let this one have a go.
// This increments the usage count for this EntryUpdateState instance
updateState.startUpdate();
if (cacheEntry.isNew()) {
accessEventType = CacheMapAccessEventType.MISS;
} else {
accessEventType = CacheMapAccessEventType.STALE_HIT;
}
} else if (updateState.isComplete()) {
reload = true;
} else {
log.error("Invalid update state for cache entry " + key);
}
}
} else {
reload = true;
}
}
} finally {
//Make sure we release the usage count for this EntryUpdateState since we don't use it anymore. If the current thread started the update, then the counter was
//increased by one in startUpdate()
releaseUpdateState(updateState, key);
}
}
// If reload is true then another thread must have successfully rebuilt the cache entry
if (reload) {
cacheEntry = (CacheEntry) cacheMap.get(key);
if (cacheEntry != null) {
content = cacheEntry.getContent();
} else {
log.error("Could not reload cache entry after waiting for it to be rebuilt");
}
}
dispatchCacheMapAccessEvent(accessEventType, cacheEntry, null);
// If we didn't end up getting a hit then we need to throw a NRE
if (accessEventType != CacheMapAccessEventType.HIT) {
throw new NeedsRefreshException(content);
}
return content;
}
/**
* Set the listener to use for data persistence. Only one
* <code>PersistenceListener</code> can be configured per cache.
*
* @param listener The implementation of a persistance listener
*/
public void setPersistenceListener(PersistenceListener listener) {
cacheMap.setPersistenceListener(listener);
}
/**
* Retrieves the currently configured <code>PersistenceListener</code>.
*
* @return the cache's <code>PersistenceListener</code>, or <code>null</code>
* if no listener is configured.
*/
public PersistenceListener getPersistenceListener() {
return cacheMap.getPersistenceListener();
}
/**
* Register a listener for Cache events. The listener must implement
* one of the child interfaces of the {@link CacheEventListener} interface.
*
* @param listener The object that listens to events.
* @since 2.4
*/
public void addCacheEventListener(CacheEventListener listener) {
// listenerList.add(CacheEventListener.class, listener);
listenerList.add((Class)listener.getClass(), listener);
}
/**
* Register a listener for Cache events. The listener must implement
* one of the child interfaces of the {@link CacheEventListener} interface.
*
* @param listener The object that listens to events.
* @param clazz the type of the listener to be added
* @deprecated use {@link #addCacheEventListener(CacheEventListener)}
*/
public void addCacheEventListener(CacheEventListener listener, Class clazz) {
if (CacheEventListener.class.isAssignableFrom(clazz)) {
listenerList.add(clazz, listener);
} else {
log.error("The class '" + clazz.getName() + "' is not a CacheEventListener. Ignoring this listener.");
}
}
/**
* Returns the list of all CacheEventListeners.
* @return the CacheEventListener's list of the Cache
*/
public EventListenerList getCacheEventListenerList() {
return listenerList;
}
/**
* Cancels any pending update for this cache entry. This should <em>only</em>
* be called by the thread that is responsible for performing the update ie
* the thread that received the original {@link NeedsRefreshException}.<p/>
* If a cache entry is not updated (via {@link #putInCache} and this method is
* not called to let OSCache know the update will not be forthcoming, subsequent
* requests for this cache entry will either block indefinitely (if this is a new
* cache entry or cache.blocking=true), or forever get served stale content. Note
* however that there is no harm in cancelling an update on a key that either
* does not exist or is not currently being updated.
*
* @param key The key for the cache entry in question.
* @throws IllegalStateException if the cache entry isn't in the state UPDATE_IN_PROGRESS
*/
public void cancelUpdate(String key) {
EntryUpdateState state;
if (key != null) {
synchronized (updateStates) {
state = (EntryUpdateState) updateStates.get(key);
if (state != null) {
synchronized (state) {
int usageCounter = state.cancelUpdate();
state.notify();
checkEntryStateUpdateUsage(key, state, usageCounter);
}
} else {
if (log.isErrorEnabled()) {
log.error("internal error: expected to get a state from key [" + key + "]");
}
}
}
}
}
/**
* Utility method to check if the specified usage count is zero, and if so remove the corresponding EntryUpdateState from the updateStates. This is designed to factor common code.
*
* Warning: This method should always be called while holding both the updateStates field and the state parameter
* @throws Exception
*/
private void checkEntryStateUpdateUsage(String key, EntryUpdateState state, int usageCounter) {
//Clean up the updateStates map to avoid a memory leak once no thread is using this EntryUpdateState instance anymore.
if (usageCounter ==0) {
EntryUpdateState removedState = (EntryUpdateState) updateStates.remove(key);
if (state != removedState) {
if (log.isErrorEnabled()) {
try {
throw new Exception("OSCache: internal error: removed state [" + removedState + "] from key [" + key + "] whereas we expected [" + state + "]");
} catch (Exception e) {
log.error(e);
}
}
}
}
}
/**
* Flush all entries in the cache on the given date/time.
*
* @param date The date at which all cache entries will be flushed.
*/
public void flushAll(Date date) {
flushAll(date, null);
}
/**
* Flush all entries in the cache on the given date/time.
*
* @param date The date at which all cache entries will be flushed.
* @param origin The origin of this flush request (optional)
*/
public void flushAll(Date date, String origin) {
flushDateTime = date;
if (listenerList.getListenerCount() > 0) {
dispatchCachewideEvent(CachewideEventType.CACHE_FLUSHED, date, origin);
}
}
/**
* Flush the cache entry (if any) that corresponds to the cache key supplied.
* This call will flush the entry from the cache and remove the references to
* it from any cache groups that it is a member of. On completion of the flush,
* a <tt>CacheEntryEventType.ENTRY_FLUSHED</tt> event is fired.
*
* @param key The key of the entry to flush
*/
public void flushEntry(String key) {
flushEntry(key, null);
}
/**
* Flush the cache entry (if any) that corresponds to the cache key supplied.
* This call will mark the cache entry as flushed so that the next access
* to it will cause a {@link NeedsRefreshException}. On completion of the
* flush, a <tt>CacheEntryEventType.ENTRY_FLUSHED</tt> event is fired.
*
* @param key The key of the entry to flush
* @param origin The origin of this flush request (optional)
*/
public void flushEntry(String key, String origin) {
flushEntry(getCacheEntry(key, null, origin), origin);
}
/**
* Flushes all objects that belong to the supplied group. On completion
* this method fires a <tt>CacheEntryEventType.GROUP_FLUSHED</tt> event.
*
* @param group The group to flush
*/
public void flushGroup(String group) {
flushGroup(group, null);
}
/**
* Flushes all unexpired objects that belong to the supplied group. On
* completion this method fires a <tt>CacheEntryEventType.GROUP_FLUSHED</tt>
* event.
*
* @param group The group to flush
* @param origin The origin of this flush event (optional)
*/
public void flushGroup(String group, String origin) {
// Flush all objects in the group
Set groupEntries = cacheMap.getGroup(group);
if (groupEntries != null) {
Iterator itr = groupEntries.iterator();
String key;
CacheEntry entry;
while (itr.hasNext()) {
key = (String) itr.next();
entry = (CacheEntry) cacheMap.get(key);
if ((entry != null) && !entry.needsRefresh(CacheEntry.INDEFINITE_EXPIRY)) {
flushEntry(entry, NESTED_EVENT);
}
}
}
if (listenerList.getListenerCount() > 0) {
dispatchCacheGroupEvent(CacheEntryEventType.GROUP_FLUSHED, group, origin);
}
}
/**
* Flush all entries with keys that match a given pattern
*
* @param pattern The key must contain this given value
* @deprecated For performance and flexibility reasons it is preferable to
* store cache entries in groups and use the {@link #flushGroup(String)} method
* instead of relying on pattern flushing.
*/
public void flushPattern(String pattern) {
flushPattern(pattern, null);
}
/**
* Flush all entries with keys that match a given pattern
*
* @param pattern The key must contain this given value
* @param origin The origin of this flush request
* @deprecated For performance and flexibility reasons it is preferable to
* store cache entries in groups and use the {@link #flushGroup(String, String)}
* method instead of relying on pattern flushing.
*/
public void flushPattern(String pattern, String origin) {
// Check the pattern
if ((pattern != null) && (pattern.length() > 0)) {
String key = null;
CacheEntry entry = null;
Iterator itr = cacheMap.keySet().iterator();
while (itr.hasNext()) {
key = (String) itr.next();
if (key.indexOf(pattern) >= 0) {
entry = (CacheEntry) cacheMap.get(key);
if (entry != null) {
flushEntry(entry, origin);
}
}
}
if (listenerList.getListenerCount() > 0) {
dispatchCachePatternEvent(CacheEntryEventType.PATTERN_FLUSHED, pattern, origin);
}
} else {
// Empty pattern, nothing to do
}
}
/**
* Put an object in the cache specifying the key to use.
*
* @param key Key of the object in the cache.
* @param content The object to cache.
*/
public void putInCache(String key, Object content) {
putInCache(key, content, null, null, null);
}
/**
* Put an object in the cache specifying the key and refresh policy to use.
*
* @param key Key of the object in the cache.
* @param content The object to cache.
* @param policy Object that implements refresh policy logic
*/
public void putInCache(String key, Object content, EntryRefreshPolicy policy) {
putInCache(key, content, null, policy, null);
}
/**
* Put in object into the cache, specifying both the key to use and the
* cache groups the object belongs to.
*
* @param key Key of the object in the cache
* @param content The object to cache
* @param groups The cache groups to add the object to
*/
public void putInCache(String key, Object content, String[] groups) {
putInCache(key, content, groups, null, null);
}
/**
* Put an object into the cache specifying both the key to use and the
* cache groups the object belongs to.
*
* @param key Key of the object in the cache
* @param groups The cache groups to add the object to
* @param content The object to cache
* @param policy Object that implements the refresh policy logic
*/
public void putInCache(String key, Object content, String[] groups, EntryRefreshPolicy policy, String origin) {
CacheEntry cacheEntry = this.getCacheEntry(key, policy, origin);
boolean isNewEntry = cacheEntry.isNew();
// [CACHE-118] If we have an existing entry, create a new CacheEntry so we can still access the old one later
if (!isNewEntry) {
cacheEntry = new CacheEntry(key, policy);
}
cacheEntry.setContent(content);
cacheEntry.setGroups(groups);
cacheMap.put(key, cacheEntry);
// Signal to any threads waiting on this update that it's now ready for them
// in the cache!
completeUpdate(key);
if (listenerList.getListenerCount() > 0) {
CacheEntryEvent event = new CacheEntryEvent(this, cacheEntry, origin);
if (isNewEntry) {
dispatchCacheEntryEvent(CacheEntryEventType.ENTRY_ADDED, event);
} else {
dispatchCacheEntryEvent(CacheEntryEventType.ENTRY_UPDATED, event);
}
}
}
/**
* Unregister a listener for Cache events.
*
* @param listener The object that currently listens to events.
* @param clazz The registrated class of listening object.
* @deprecated use instead {@link #removeCacheEventListener(CacheEventListener)}
*/
public void removeCacheEventListener(CacheEventListener listener, Class clazz) {
listenerList.remove(clazz, listener);
}
/**
* Unregister a listener for Cache events.
*
* @param listener The object that currently listens to events.
* @since 2.4
*/
public void removeCacheEventListener(CacheEventListener listener) {
// listenerList.remove(CacheEventListener.class, listener);
listenerList.remove((Class)listener.getClass(), listener);
}
/**
* Get an entry from this cache or create one if it doesn't exist.
*
* @param key The key of the cache entry
* @param policy Object that implements refresh policy logic
* @param origin The origin of request (optional)
* @return CacheEntry for the specified key.
*/
protected CacheEntry getCacheEntry(String key, EntryRefreshPolicy policy, String origin) {
CacheEntry cacheEntry = null;
// Verify that the key is valid
if ((key == null) || (key.length() == 0)) {
throw new IllegalArgumentException("getCacheEntry called with an empty or null key");
}
cacheEntry = (CacheEntry) cacheMap.get(key);
// if the cache entry does not exist, create a new one
if (cacheEntry == null) {
if (log.isDebugEnabled()) {
log.debug("No cache entry exists for key='" + key + "', creating");
}
cacheEntry = new CacheEntry(key, policy);
}
return cacheEntry;
}
/**
* Indicates whether or not the cache entry is stale.
*
* @param cacheEntry The cache entry to test the freshness of.
* @param refreshPeriod The maximum allowable age of the entry, in seconds.
* @param cronExpiry A cron expression specifying absolute date(s) and/or time(s)
* that the cache entry should expire at. If the cache entry was refreshed prior to
* the most recent match for the cron expression, the entry will be considered stale.
*
* @return <code>true</code> if the entry is stale, <code>false</code> otherwise.
*/
protected boolean isStale(CacheEntry cacheEntry, int refreshPeriod, String cronExpiry) {
boolean result = cacheEntry.needsRefresh(refreshPeriod) || isFlushed(cacheEntry);
if ((!result) && (cronExpiry != null) && (cronExpiry.length() > 0)) {
try {
FastCronParser parser = new FastCronParser(cronExpiry);
result = result || parser.hasMoreRecentMatch(cacheEntry.getLastUpdate());
} catch (ParseException e) {
log.warn(e);
}
}
return result;
}
/**
* Get the updating cache entry from the update map. If one is not found,
* create a new one (with state {@link EntryUpdateState#NOT_YET_UPDATING})
* and add it to the map.
*
* @param key The cache key for this entry
*
* @return the CacheEntry that was found (or added to) the updatingEntries
* map.
*/
protected EntryUpdateState getUpdateState(String key) {
EntryUpdateState updateState;
synchronized (updateStates) {
// Try to find the matching state object in the updating entry map.
updateState = (EntryUpdateState) updateStates.get(key);
if (updateState == null) {
// It's not there so add it.
updateState = new EntryUpdateState();
updateStates.put(key, updateState);
} else {
//Otherwise indicate that we start using it to prevent its removal until all threads are done with it.
updateState.incrementUsageCounter();
}
}
return updateState;
}
/**
* releases the usage that was made of the specified EntryUpdateState. When this reaches zero, the entry is removed from the map.
* @param state the state to release the usage of
* @param key the associated key.
*/
protected void releaseUpdateState(EntryUpdateState state, String key) {
synchronized (updateStates) {
int usageCounter = state.decrementUsageCounter();
checkEntryStateUpdateUsage(key, state, usageCounter);
}
}
/**
* Completely clears the cache.
*/
protected void clear() {
cacheMap.clear();
}
/**
* Removes the update state for the specified key and notifies any other
* threads that are waiting on this object. This is called automatically
* by the {@link #putInCache} method, so it is possible that no EntryUpdateState was hold
* when this method is called.
*
* @param key The cache key that is no longer being updated.
*/
protected void completeUpdate(String key) {
EntryUpdateState state;
synchronized (updateStates) {
state = (EntryUpdateState) updateStates.get(key);
if (state != null) {
synchronized (state) {
int usageCounter = state.completeUpdate();
state.notifyAll();
checkEntryStateUpdateUsage(key, state, usageCounter);
}
} else {
//If putInCache() was called directly (i.e. not as a result of a NeedRefreshException) then no EntryUpdateState would be found.
}
}
}
/**
* Completely removes a cache entry from the cache and its associated cache
* groups.
*
* @param key The key of the entry to remove.
*/
public void removeEntry(String key) {
removeEntry(key, null);
}
/**
* Completely removes a cache entry from the cache and its associated cache
* groups.
*
* @param key The key of the entry to remove.
* @param origin The origin of this remove request.
*/
protected void removeEntry(String key, String origin) {
CacheEntry cacheEntry = (CacheEntry) cacheMap.get(key);
cacheMap.remove(key);
if (listenerList.getListenerCount() > 0) {
CacheEntryEvent event = new CacheEntryEvent(this, cacheEntry, origin);
dispatchCacheEntryEvent(CacheEntryEventType.ENTRY_REMOVED, event);
}
}
/**
* Dispatch a cache entry event to all registered listeners.
*
* @param eventType The type of event (used to branch on the proper method)
* @param event The event that was fired
*/
private void dispatchCacheEntryEvent(CacheEntryEventType eventType, CacheEntryEvent event) {
// Guaranteed to return a non-null array
Object[] listeners = listenerList.getListenerList();
// Process the listeners last to first, notifying
// those that are interested in this event
for (int i = listeners.length - 2; i >= 0; i -= 2) {
if (listeners[i+1] instanceof CacheEntryEventListener) {
CacheEntryEventListener listener = (CacheEntryEventListener) listeners[i+1];
if (eventType.equals(CacheEntryEventType.ENTRY_ADDED)) {
listener.cacheEntryAdded(event);
} else if (eventType.equals(CacheEntryEventType.ENTRY_UPDATED)) {
listener.cacheEntryUpdated(event);
} else if (eventType.equals(CacheEntryEventType.ENTRY_FLUSHED)) {
listener.cacheEntryFlushed(event);
} else if (eventType.equals(CacheEntryEventType.ENTRY_REMOVED)) {
listener.cacheEntryRemoved(event);
}
}
}
}
/**
* Dispatch a cache group event to all registered listeners.
*
* @param eventType The type of event (this is used to branch to the correct method handler)
* @param group The cache group that the event applies to
* @param origin The origin of this event (optional)
*/
private void dispatchCacheGroupEvent(CacheEntryEventType eventType, String group, String origin) {
CacheGroupEvent event = new CacheGroupEvent(this, group, origin);
// Guaranteed to return a non-null array
Object[] listeners = listenerList.getListenerList();
// Process the listeners last to first, notifying
// those that are interested in this event
for (int i = listeners.length - 2; i >= 0; i -= 2) {
if (listeners[i+1] instanceof CacheEntryEventListener) {
CacheEntryEventListener listener = (CacheEntryEventListener) listeners[i + 1];
if (eventType.equals(CacheEntryEventType.GROUP_FLUSHED)) {
listener.cacheGroupFlushed(event);
}
}
}
}
/**
* Dispatch a cache map access event to all registered listeners.
*
* @param eventType The type of event
* @param entry The entry that was affected.
* @param origin The origin of this event (optional)
*/
private void dispatchCacheMapAccessEvent(CacheMapAccessEventType eventType, CacheEntry entry, String origin) {
CacheMapAccessEvent event = new CacheMapAccessEvent(eventType, entry, origin);
// Guaranteed to return a non-null array
Object[] listeners = listenerList.getListenerList();
// Process the listeners last to first, notifying
// those that are interested in this event
for (int i = listeners.length - 2; i >= 0; i -= 2) {
if (listeners[i+1] instanceof CacheMapAccessEventListener) {
CacheMapAccessEventListener listener = (CacheMapAccessEventListener) listeners[i + 1];
listener.accessed(event);
}
}
}
/**
* Dispatch a cache pattern event to all registered listeners.
*
* @param eventType The type of event (this is used to branch to the correct method handler)
* @param pattern The cache pattern that the event applies to
* @param origin The origin of this event (optional)
*/
private void dispatchCachePatternEvent(CacheEntryEventType eventType, String pattern, String origin) {
CachePatternEvent event = new CachePatternEvent(this, pattern, origin);
// Guaranteed to return a non-null array
Object[] listeners = listenerList.getListenerList();
// Process the listeners last to first, notifying
// those that are interested in this event
for (int i = listeners.length - 2; i >= 0; i -= 2) {
if (listeners[i+1] instanceof CacheEntryEventListener) {
if (eventType.equals(CacheEntryEventType.PATTERN_FLUSHED)) {
CacheEntryEventListener listener = (CacheEntryEventListener) listeners[i+1];
listener.cachePatternFlushed(event);
}
}
}
}
/**
* Dispatches a cache-wide event to all registered listeners.
*
* @param eventType The type of event (this is used to branch to the correct method handler)
* @param origin The origin of this event (optional)
*/
private void dispatchCachewideEvent(CachewideEventType eventType, Date date, String origin) {
CachewideEvent event = new CachewideEvent(this, date, origin);
// Guaranteed to return a non-null array
Object[] listeners = listenerList.getListenerList();
// Process the listeners last to first, notifying
// those that are interested in this event
for (int i = listeners.length - 2; i >= 0; i -= 2) {
if (listeners[i] instanceof CacheEntryEventListener) {
if (eventType.equals(CachewideEventType.CACHE_FLUSHED)) {
CacheEntryEventListener listener = (CacheEntryEventListener) listeners[i+1];
listener.cacheFlushed(event);
}
}
}
}
/**
* Flush a cache entry. On completion of the flush, a
* <tt>CacheEntryEventType.ENTRY_FLUSHED</tt> event is fired.
*
* @param entry The entry to flush
* @param origin The origin of this flush event (optional)
*/
private void flushEntry(CacheEntry entry, String origin) {
String key = entry.getKey();
// Flush the object itself
entry.flush();
if (!entry.isNew()) {
// Update the entry's state in the map
cacheMap.put(key, entry);
}
// Trigger an ENTRY_FLUSHED event. [CACHE-107] Do this for all flushes.
if (listenerList.getListenerCount() > 0) {
CacheEntryEvent event = new CacheEntryEvent(this, entry, origin);
dispatchCacheEntryEvent(CacheEntryEventType.ENTRY_FLUSHED, event);
}
}
/**
* @return the total number of cache entries held in this cache.
*/
public int getSize() {
synchronized(cacheMap) {
return cacheMap.size();
}
}
/**
* Test support only: return the number of EntryUpdateState instances within the updateStates map.
*/
protected int getNbUpdateState() {
synchronized(updateStates) {
return updateStates.size();
}
}
/**
* Test support only: return the number of entries currently in the cache map
* @deprecated use getSize()
*/
public int getNbEntries() {
synchronized(cacheMap) {
return cacheMap.size();
}
}
/**
* Get's all objects that belong to the supplied group.
*
* @param group The group to flush
*/
public Set getGroup(String group) {
Set<String> copy = new HashSet<String>();
// Flush all objects in the group
Set groupEntries = cacheMap.getGroup(group);
if (groupEntries != null) {
Iterator itr = groupEntries.iterator();
String key;
CacheEntry entry;
while (itr.hasNext()) {
key = (String) itr.next();
copy.add(key);
}
}
return copy;
}
}