Java tutorial
/* * Adito * * Copyright (C) 2003-2006 3SP LTD. All Rights Reserved * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License * as published by the Free Software Foundation; either version 2 of * the License, or (at your option) any later version. * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public * License along with this program; if not, write to the Free Software * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */ package com.adito.policyframework; import java.io.File; import java.io.Serializable; import java.util.ArrayList; import java.util.Collection; import java.util.Iterator; import org.apache.commons.cache.BaseStorageListener; import org.apache.commons.cache.Cache; import org.apache.commons.cache.EvictionPolicy; import org.apache.commons.cache.FileStash; import org.apache.commons.cache.GroupMapImpl; import org.apache.commons.cache.LRUEvictionPolicy; import org.apache.commons.cache.MemoryStash; import org.apache.commons.cache.SimpleCache; import org.apache.commons.cache.Stash; import org.apache.commons.cache.StorageListener; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import com.adito.boot.ContextHolder; import com.adito.boot.SystemProperties; import com.adito.core.BundleActionMessage; import com.adito.core.GlobalWarning; import com.adito.core.GlobalWarningManager; import com.adito.core.GlobalWarning.DismissType; /** * @param <T> */ public class PrincipalCache<T extends Principal> { private static final Log logger = LogFactory.getLog(PrincipalCache.class); private final int cacheSize; private final boolean inMemoryCache; private final boolean caseSensitive; private final String cacheType; private final Cache principalCache; /** * @param cacheSize * @param inMemoryCache * @param caseSensitive * @param cacheType * @param messageBundle * @param cacheFullText */ public PrincipalCache(int cacheSize, boolean inMemoryCache, boolean caseSensitive, String cacheType, String messageBundle, String cacheFullText) { this.cacheSize = cacheSize; this.inMemoryCache = inMemoryCache; this.caseSensitive = caseSensitive; this.cacheType = cacheType; this.principalCache = createCache(messageBundle, cacheFullText); } /** * @param principalName * @return <tt>true</tt> if the principal is found */ public final synchronized boolean containsPrincipal(String principalName) { principalName = fixUpPrincipalName(principalName); return retrievePrincipal(principalName) != null; } /** * @param principalName * @return principal */ @SuppressWarnings("unchecked") public final synchronized T retrievePrincipal(String principalName) { principalName = fixUpPrincipalName(principalName); return (T) principalCache.retrieve(principalName); } /** * @return principal names */ public final synchronized Collection<String> retrievePrincipalNames() { Serializable[] keysForGroup = principalCache.getKeysForGroup(cacheType); Collection<String> principalNames = new ArrayList<String>(keysForGroup.length); for (Serializable principalName : keysForGroup) { principalNames.add(principalName.toString()); } return principalNames; } /** * @return principals */ @SuppressWarnings("unchecked") public final synchronized Iterator<T> retrievePrincipals() { Serializable[] keysForGroup = principalCache.getKeysForGroup(cacheType); return new PrincipalCacheIterator(keysForGroup, this); } /** * @param principal * @return principal key */ public final synchronized String storePrincipal(T principal) { String fixUpPrincipalName = fixUpPrincipalName(principal.getPrincipalName()); if (logger.isDebugEnabled()) { logger.debug("Caching " + fixUpPrincipalName); } principalCache.store(fixUpPrincipalName, (Serializable) principal, Long.MAX_VALUE, null, cacheType); return fixUpPrincipalName; } /** * @param missingPrincipals */ public final synchronized void updateRemovedPrincipals(Collection<String> missingPrincipals) { for (String principalName : missingPrincipals) { removePrincipal(principalName); } } /** * @param principal */ public final synchronized void removePrincipal(T principal) { removePrincipal(principal.getPrincipalName()); } /** * @param principleName */ public final void removePrincipal(String principleName) { String fixUpPrincipalName = fixUpPrincipalName(principleName); principalCache.store(fixUpPrincipalName, null, 0L, null, cacheType); } protected String fixUpPrincipalName(String principalName) { return toLowerCaseIfRequired(principalName); } /** * @param principalName * @return to lower case if required */ private String toLowerCaseIfRequired(String principalName) { return caseSensitive ? principalName : principalName.toLowerCase(); } /** */ public synchronized void close() { closeCache(principalCache); } protected final Cache createCache(String messageBundle, String cacheFullText) { File cacheDirectory = new File(ContextHolder.getContext().getTempDirectory(), "cache"); File cacheTypeDirectory = new File(cacheDirectory, cacheType); Stash stash = inMemoryCache ? new MemoryStash(cacheSize) : new FileStash(Long.MAX_VALUE, cacheSize, new File[] { cacheTypeDirectory }, true); // eviction can't be used in testing as the policy creates a thread // which is only stopped on JVM exit, hence breaking the tests boolean isTestMode = "true".equals(SystemProperties.get("adito.testing", "false")); EvictionPolicy evictionPolicy = isTestMode ? null : new LRUEvictionPolicy(); SimpleCache cache = new SimpleCache(stash, evictionPolicy, null, new GroupMapImpl()); cache.registerStorageListener(getStorageListener(messageBundle, cacheFullText)); return cache; } private StorageListener getStorageListener(final String messageBundle, final String cacheFullText) { return new BaseStorageListener() { private static final long serialVersionUID = 4283488241230531541L; private int storageCounter = 0; private boolean addedWarning; public synchronized void stored(Serializable arg0, Serializable arg1, Long arg2, Long arg3, Serializable arg4) { storageCounter++; } public synchronized void cleared(Serializable arg0) { if (storageCounter == cacheSize && !addedWarning) { BundleActionMessage message = new BundleActionMessage(messageBundle, cacheFullText, String.valueOf(cacheSize)); GlobalWarningManager.getInstance().addMultipleGlobalWarning(new GlobalWarning( GlobalWarning.MANAGEMENT_USERS, message, DismissType.DISMISS_FOR_USER)); addedWarning = true; } storageCounter--; } public synchronized void cleared() { storageCounter = 0; addedWarning = false; GlobalWarningManager.getInstance().removeGlobalWarningFromAllSessions(cacheFullText); } }; } protected static void closeCache(Cache cache) { try { cache.clear(); cache.unregisterStorageListeners(); } catch (Exception e) { logger.error("Failed to close cache", e); } } }