/*
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* The contents of this file are subject to the terms of the Common Development and
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* Distribution License (the License). You may not use this file except in compliance with the
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* License.
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*
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* You can obtain a copy of the License at legal/CDDLv1.0.txt. See the License for the
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* specific language governing permission and limitations under the License.
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*
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* When distributing Covered Software, include this CDDL Header Notice in each file and include
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* the License file at legal/CDDLv1.0.txt. If applicable, add the following below the CDDL
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* Header, with the fields enclosed by brackets [] replaced by your own identifying
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* information: "Portions Copyright [year] [name of copyright owner]".
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*
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* Copyright 2006-2008 Sun Microsystems, Inc.
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* Portions Copyright 2013-2016 ForgeRock AS.
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*/
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package org.opends.server.api;
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import java.util.HashSet;
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import java.util.List;
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import java.util.Set;
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import java.util.concurrent.atomic.AtomicLong;
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import org.forgerock.i18n.LocalizableMessage;
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import org.forgerock.i18n.slf4j.LocalizedLogger;
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import org.forgerock.opendj.config.server.ConfigException;
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import org.opends.server.admin.std.server.EntryCacheCfg;
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import org.opends.server.monitors.EntryCacheMonitorProvider;
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import org.opends.server.types.Attribute;
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import org.forgerock.opendj.ldap.DN;
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import org.opends.server.types.Entry;
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import org.opends.server.types.InitializationException;
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import org.opends.server.types.SearchFilter;
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/**
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* This class defines the set of methods that must be implemented by a
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* Directory Server entry cache. Note that components accessing the
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* entry cache must not depend on any particular behavior. For
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* example, if a call is made to {@code putEntry} to store an entry in
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* the cache, there is no guarantee that immediately calling
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* {@code getEntry} will be able to retrieve it. There are several
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* potential reasons for this, including:
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* <UL>
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* <LI>The entry may have been deleted or replaced by another thread
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* between the {@code putEntry} and {@code getEntry} calls.</LI>
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* <LI>The entry cache may implement a purging mechanism and the
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* entry added may have been purged between the
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* {@code putEntry} and {@code getEntry} calls.</LI>
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* <LI>The entry cache may implement some kind of filtering
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* mechanism to determine which entries to store, and entries
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* not matching the appropriate criteria may not be stored.</LI>
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* <LI>The entry cache may not actually store any entries (this is
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* the behavior of the default cache if no implementation
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* specific entry cache is available).</LI>
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* </UL>
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*
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* @param <T> The type of configuration handled by this entry
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* cache.
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*/
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@org.opends.server.types.PublicAPI(
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stability=org.opends.server.types.StabilityLevel.VOLATILE,
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mayInstantiate=false,
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mayExtend=true,
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mayInvoke=true,
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notes="Entry cache methods may only be invoked by backends")
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public abstract class EntryCache<T extends EntryCacheCfg>
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{
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private static final LocalizedLogger logger = LocalizedLogger.getLoggerForThisClass();
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/**
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* The set of filters that define the entries that should be
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* excluded from the cache.
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*/
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private Set<SearchFilter> excludeFilters = new HashSet<>(0);
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/**
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* The set of filters that define the entries that should be
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* included in the cache.
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*/
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private Set<SearchFilter> includeFilters = new HashSet<>(0);
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/**
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* Arbitrary number of cache hits for monitoring.
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*/
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protected AtomicLong cacheHits = new AtomicLong(0);
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/**
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* Arbitrary number of cache misses for monitoring.
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*/
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protected AtomicLong cacheMisses = new AtomicLong(0);
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/** The monitor associated with this entry cache. */
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private EntryCacheMonitorProvider entryCacheMonitor;
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/**
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* Default constructor which is implicitly called from all entry
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* cache implementations.
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*/
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public EntryCache()
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{
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// No implementation required.
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}
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/**
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* Initializes this entry cache implementation so that it will be
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* available for storing and retrieving entries.
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*
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* @param configuration The configuration to use to initialize
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* the entry cache.
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*
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* @throws ConfigException If there is a problem with the provided
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* configuration entry that would prevent
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* this entry cache from being used.
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*
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* @throws InitializationException If a problem occurs during the
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* initialization process that is
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* not related to the
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* configuration.
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*/
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public abstract void initializeEntryCache(T configuration)
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throws ConfigException, InitializationException;
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/**
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* Indicates whether the provided configuration is acceptable for
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* this entry cache. It should be possible to call this method on
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* an uninitialized entry cache instance in order to determine
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* whether the entry cache would be able to use the provided
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* configuration.
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* <BR><BR>
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* Note that implementations which use a subclass of the provided
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* configuration class will likely need to cast the configuration
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* to the appropriate subclass type.
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*
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* @param configuration The entry cache configuration for
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* which to make the determination.
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* @param unacceptableReasons A list that may be used to hold the
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* reasons that the provided
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* configuration is not acceptable.
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*
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* @return {@code true} if the provided configuration is acceptable
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* for this entry cache, or {@code false} if not.
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*/
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public boolean isConfigurationAcceptable(
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EntryCacheCfg configuration,
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List<LocalizableMessage> unacceptableReasons)
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{
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// This default implementation does not perform any special
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// validation. It should be overridden by entry cache
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// implementations that wish to perform more detailed validation.
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return true;
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}
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/**
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* Performs any necessary cleanup work (e.g., flushing all cached
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* entries and releasing any other held resources) that should be
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* performed when the server is to be shut down or the entry cache
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* destroyed or replaced.
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*/
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public abstract void finalizeEntryCache();
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/**
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* Indicates whether the entry cache currently contains the entry
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* with the specified DN. This method may be called without holding
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* any locks if a point-in-time check is all that is required.
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* Note that this method is called from @see #getEntry(DN entryDN,
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* LockType lockType, List lockList)
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*
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* @param entryDN The DN for which to make the determination.
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*
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* @return {@code true} if the entry cache currently contains the
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* entry with the specified DN, or {@code false} if not.
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*/
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public abstract boolean containsEntry(DN entryDN);
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/**
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* Retrieves the entry with the specified DN from the cache.
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*
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* @param entryDN The DN of the entry to retrieve.
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*
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* @return The requested entry if it is present in the cache, or
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* {@code null} if it is not present.
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*/
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public abstract Entry getEntry(DN entryDN);
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/**
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* Retrieves the requested entry if it is present in the cache.
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*
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* @param backendID ID of the backend associated with the entry
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* to retrieve.
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* @param entryID The entry ID within the provided backend for
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* the specified entry.
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*
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* @return The requested entry if it is present in the cache, or
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* {@code null} if it is not present.
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*/
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public Entry getEntry(String backendID, long entryID)
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{
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// Translate given backend/entryID pair to entryDN.
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DN entryDN = getEntryDN(backendID, entryID);
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if (entryDN == null)
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{
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// Indicate cache miss.
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cacheMisses.getAndIncrement();
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return null;
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}
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// Delegate to by DN lock and load method.
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return getEntry(entryDN);
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}
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/**
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* Retrieves the entry ID for the entry with the specified DN from
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* the cache. The caller should have already acquired a read or
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* write lock for the entry if such protection is needed.
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*
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* @param entryDN The DN of the entry for which to retrieve the
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* entry ID.
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*
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* @return The entry ID for the requested entry, or -1 if it is
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* not present in the cache.
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*/
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public abstract long getEntryID(DN entryDN);
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/**
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* Retrieves the entry DN for the entry with the specified ID on
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* the specific backend from the cache. The caller should have
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* already acquired a read or write lock for the entry if such
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* protection is needed.
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* Note that this method is called from @see #getEntry(Backend
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* backend, long entryID, LockType lockType, List lockList)
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*
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* @param backendID ID of the backend associated with the
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* entry for which to retrieve the entry DN.
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* @param entryID The entry ID within the provided backend
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* for which to retrieve the entry DN.
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*
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* @return The entry DN for the requested entry, or
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* {@code null} if it is not present in the cache.
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*/
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public abstract DN getEntryDN(String backendID, long entryID);
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/**
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* Stores the provided entry in the cache. Note that the mechanism
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* that it uses to achieve this is implementation-dependent, and it
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* is acceptable for the entry to not actually be stored in any
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* cache.
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*
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* @param entry The entry to store in the cache.
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* @param backendID ID of the backend with which the entry is
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* associated.
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* @param entryID The entry ID within the provided backend that
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* uniquely identifies the specified entry.
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*/
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public abstract void putEntry(Entry entry, String backendID, long entryID);
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/**
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* Stores the provided entry in the cache only if it does not
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* conflict with an entry that already exists. Note that the
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* mechanism that it uses to achieve this is
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* implementation-dependent, and it is acceptable for the entry to
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* not actually be stored in any cache. However, this method must
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* not overwrite an existing version of the entry.
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*
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* @param entry The entry to store in the cache.
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* @param backendID ID of the backend with which the entry is
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* associated.
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* @param entryID The entry ID within the provided backend that
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* uniquely identifies the specified entry.
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*
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* @return {@code false} if an existing entry or some other problem
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* prevented the method from completing successfully, or
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* {@code true} if there was no conflict and the entry was
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* either stored or the cache determined that this entry
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* should never be cached for some reason.
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*/
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public abstract boolean putEntryIfAbsent(Entry entry,
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String backendID,
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long entryID);
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/**
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* Removes the specified entry from the cache.
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*
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* @param entryDN The DN of the entry to remove from the cache.
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*/
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public abstract void removeEntry(DN entryDN);
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/**
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* Removes all entries from the cache. The cache should still be
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* available for future use.
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*/
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public abstract void clear();
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/**
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* Removes all entries from the cache that are associated with the
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* provided backend.
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*
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* @param backendID ID of the backend for which to flush the
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* associated entries.
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*/
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public abstract void clearBackend(String backendID);
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/**
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* Removes all entries from the cache that are below the provided
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* DN.
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*
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* @param baseDN The base DN below which all entries should be
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* flushed.
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*/
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public abstract void clearSubtree(DN baseDN);
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/**
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* Attempts to react to a scenario in which it is determined that
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* the system is running low on available memory. In this case, the
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* entry cache should attempt to free some memory if possible to try
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* to avoid out of memory errors.
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*/
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public abstract void handleLowMemory();
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/**
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* Retrieves the monitor that is associated with this entry
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* cache.
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*
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* @return The monitor that is associated with this entry
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* cache, or {@code null} if none has been assigned.
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*/
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public final EntryCacheMonitorProvider getEntryCacheMonitor()
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{
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return entryCacheMonitor;
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}
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/**
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* Sets the monitor for this entry cache.
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*
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* @param entryCacheMonitor The monitor for this entry cache.
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*/
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public final void setEntryCacheMonitor(
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EntryCacheMonitorProvider entryCacheMonitor)
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{
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this.entryCacheMonitor = entryCacheMonitor;
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}
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/**
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* Retrieves a set of attributes containing monitor data that should
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* be returned to the client if the corresponding monitor entry is
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* requested.
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*
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* @return A list of attributes containing monitor data that should
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* be returned to the client if the corresponding monitor
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* entry is requested.
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*/
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public abstract List<Attribute> getMonitorData();
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/**
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* Retrieves the current number of entries stored within the cache.
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*
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* @return The current number of entries stored within the cache.
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*/
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public abstract Long getCacheCount();
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/**
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* Retrieves the current number of cache hits for this cache.
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*
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* @return The current number of cache hits for this cache.
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*/
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public long getCacheHits()
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{
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return cacheHits.longValue();
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}
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/**
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* Retrieves the current number of cache misses for this cache.
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*
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* @return The current number of cache misses for this cache.
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*/
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public long getCacheMisses()
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{
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return cacheMisses.longValue();
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}
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/**
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* Retrieves the set of search filters that may be used to determine
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* whether an entry should be excluded from the cache.
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*
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* @return The set of search filters that may be used to determine
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* whether an entry should be excluded from the cache.
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*/
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public Set<SearchFilter> getExcludeFilters()
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{
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return excludeFilters;
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}
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/**
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* Specifies the set of search filters that may be used to determine
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* whether an entry should be excluded from the cache.
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*
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* @param excludeFilters The set of search filters that may be
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* used to determine whether an entry should
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* be excluded from the cache.
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*/
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public void setExcludeFilters(Set<SearchFilter> excludeFilters)
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{
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if (excludeFilters == null)
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{
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this.excludeFilters = new HashSet<>(0);
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}
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else
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{
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this.excludeFilters = excludeFilters;
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}
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}
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/**
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* Retrieves the set of search filters that may be used to determine
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* whether an entry should be included in the cache.
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*
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* @return The set of search filters that may be used to determine
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* whether an entry should be included in the cache.
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*/
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public Set<SearchFilter> getIncludeFilters()
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{
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return includeFilters;
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}
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/**
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* Specifies the set of search filters that may be used to determine
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* whether an entry should be included in the cache.
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*
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* @param includeFilters The set of search filters that may be
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* used to determine whether an entry should
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* be included in the cache.
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*/
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public void setIncludeFilters(Set<SearchFilter> includeFilters)
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{
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if (includeFilters == null)
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{
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this.includeFilters = new HashSet<>(0);
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}
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else
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{
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this.includeFilters = includeFilters;
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}
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}
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/**
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* Indicates whether the current set of exclude and include filters
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* allow caching of the specified entry.
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*
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* @param entry The entry to evaluate against exclude and include
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* filter sets.
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*
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* @return {@code true} if current set of filters allow caching the
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* entry and {@code false} otherwise.
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*/
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public boolean filtersAllowCaching(Entry entry)
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{
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// If there is a set of exclude filters, then make sure that the
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// provided entry doesn't match any of them.
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if (! excludeFilters.isEmpty())
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{
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for (SearchFilter f : excludeFilters)
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{
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try
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{
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if (f.matchesEntry(entry))
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{
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return false;
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}
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}
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catch (Exception e)
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{
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logger.traceException(e);
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// This shouldn't happen, but if it does then we can't be
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// sure whether the entry should be excluded, so we will
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// by default.
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return false;
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}
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}
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}
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// If there is a set of include filters, then make sure that the
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// provided entry matches at least one of them.
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if (! includeFilters.isEmpty())
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{
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boolean matchFound = false;
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for (SearchFilter f : includeFilters)
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{
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try
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{
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if (f.matchesEntry(entry))
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{
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matchFound = true;
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break;
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}
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}
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catch (Exception e)
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{
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logger.traceException(e);
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// This shouldn't happen, but if it does, then
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// just ignore it.
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}
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}
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if (! matchFound)
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{
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return false;
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}
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}
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return true;
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}
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/**
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* Return a verbose string representation of the current cache maps. This is
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* useful primary for debugging and diagnostic purposes such as in the entry
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* cache unit tests.
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* <p>
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* This method is invoked by unit tests for debugging.
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*
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* @return String verbose string representation of the current cache maps in
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* the following format: dn:id:backend one cache entry map
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* representation per line or <CODE>null</CODE> if all maps are empty.
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*/
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public abstract String toVerboseString();
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}
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