/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License, Version 1.0 only
* (the "License"). You may not use this file except in compliance
* with the License.
*
* You can obtain a copy of the license at
* trunk/opends/resource/legal-notices/OpenDS.LICENSE
* or https://OpenDS.dev.java.net/OpenDS.LICENSE.
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at
* trunk/opends/resource/legal-notices/OpenDS.LICENSE. If applicable,
* add the following below this CDDL HEADER, with the fields enclosed
* by brackets "[]" replaced with your own identifying information:
* Portions Copyright [yyyy] [name of copyright owner]
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*
*
* Copyright 2006-2008 Sun Microsystems, Inc.
* Portions copyright 2013 ForgeRock AS.
*/
package org.opends.server.api;
import org.opends.messages.Message;
import java.util.List;
import java.util.ArrayList;
import java.util.HashSet;
import java.util.Set;
import java.util.concurrent.atomic.AtomicLong;
import org.opends.server.config.ConfigException;
import org.opends.server.types.DN;
import org.opends.server.types.Entry;
import org.opends.server.types.InitializationException;
import org.opends.server.types.SearchFilter;
import org.opends.server.types.DebugLogLevel;
import org.opends.server.admin.std.server.EntryCacheCfg;
import org.opends.server.loggers.debug.DebugTracer;
import org.opends.server.monitors.EntryCacheMonitorProvider;
import org.opends.server.types.Attribute;
import static org.opends.server.loggers.debug.DebugLogger.*;
/**
* This class defines the set of methods that must be implemented by a
* Directory Server entry cache. Note that components accessing the
* entry cache must not depend on any particular behavior. For
* example, if a call is made to {@code putEntry} to store an entry in
* the cache, there is no guarantee that immediately calling
* {@code getEntry} will be able to retrieve it. There are several
* potential reasons for this, including:
* <UL>
* <LI>The entry may have been deleted or replaced by another thread
* between the {@code putEntry} and {@code getEntry} calls.</LI>
* <LI>The entry cache may implement a purging mechanism and the
* entry added may have been purged between the
* {@code putEntry} and {@code getEntry} calls.</LI>
* <LI>The entry cache may implement some kind of filtering
* mechanism to determine which entries to store, and entries
* not matching the appropriate criteria may not be stored.</LI>
* <LI>The entry cache may not actually store any entries (this is
* the behavior of the default cache if no implementation
* specific entry cache is available).</LI>
* </UL>
*
* @param <T> The type of configuration handled by this entry
* cache.
*/
@org.opends.server.types.PublicAPI(
stability=org.opends.server.types.StabilityLevel.VOLATILE,
mayInstantiate=false,
mayExtend=true,
mayInvoke=true,
notes="Entry cache methods may only be invoked by backends")
public abstract class EntryCache
<T extends EntryCacheCfg>
{
/**
* The tracer object for the debug logger.
*/
private static final DebugTracer TRACER = getTracer();
// The set of filters that define the entries that should be
// excluded from the cache.
private Set<SearchFilter> excludeFilters =
new HashSet<SearchFilter>(0);
// The set of filters that define the entries that should be
// included in the cache.
private Set<SearchFilter> includeFilters =
new HashSet<SearchFilter>(0);
/**
* Arbitrary number of cache hits for monitoring.
*/
protected AtomicLong cacheHits = new AtomicLong(0);
/**
* Arbitrary number of cache misses for monitoring.
*/
protected AtomicLong cacheMisses = new AtomicLong(0);
// The monitor associated with this entry cache.
private EntryCacheMonitorProvider entryCacheMonitor = null;
/**
* Default constructor which is implicitly called from all entry
* cache implementations.
*/
public EntryCache()
{
// No implementation required.
}
/**
* Initializes this entry cache implementation so that it will be
* available for storing and retrieving entries.
*
* @param configuration The configuration to use to initialize
* the entry cache.
*
* @throws ConfigException If there is a problem with the provided
* configuration entry that would prevent
* this entry cache from being used.
*
* @throws InitializationException If a problem occurs during the
* initialization process that is
* not related to the
* configuration.
*/
public abstract void initializeEntryCache(T configuration)
throws ConfigException, InitializationException;
/**
* Indicates whether the provided configuration is acceptable for
* this entry cache. It should be possible to call this method on
* an uninitialized entry cache instance in order to determine
* whether the entry cache would be able to use the provided
* configuration.
* <BR><BR>
* Note that implementations which use a subclass of the provided
* configuration class will likely need to cast the configuration
* to the appropriate subclass type.
*
* @param configuration The entry cache configuration for
* which to make the determination.
* @param unacceptableReasons A list that may be used to hold the
* reasons that the provided
* configuration is not acceptable.
*
* @return {@code true} if the provided configuration is acceptable
* for this entry cache, or {@code false} if not.
*/
public boolean isConfigurationAcceptable(
EntryCacheCfg configuration,
List<Message> unacceptableReasons)
{
// This default implementation does not perform any special
// validation. It should be overridden by entry cache
// implementations that wish to perform more detailed validation.
return true;
}
/**
* Performs any necessary cleanup work (e.g., flushing all cached
* entries and releasing any other held resources) that should be
* performed when the server is to be shut down or the entry cache
* destroyed or replaced.
*/
public abstract void finalizeEntryCache();
/**
* Indicates whether the entry cache currently contains the entry
* with the specified DN. This method may be called without holding
* any locks if a point-in-time check is all that is required.
* Note that this method is called from @see #getEntry(DN entryDN,
* LockType lockType, List lockList)
*
* @param entryDN The DN for which to make the determination.
*
* @return {@code true} if the entry cache currently contains the
* entry with the specified DN, or {@code false} if not.
*/
public abstract boolean containsEntry(DN entryDN);
/**
* Retrieves the entry with the specified DN from the cache.
*
* @param entryDN The DN of the entry to retrieve.
*
* @return The requested entry if it is present in the cache, or
* {@code null} if it is not present.
*/
public abstract Entry getEntry(DN entryDN);
/**
* Retrieves the requested entry if it is present in the cache.
*
* @param backend The backend associated with the entry to
* retrieve.
* @param entryID The entry ID within the provided backend for
* the specified entry.
*
* @return The requested entry if it is present in the cache, or
* {@code null} if it is not present.
*/
public Entry getEntry(Backend backend, long entryID)
{
// Translate given backend/entryID pair to entryDN.
DN entryDN = getEntryDN(backend, entryID);
if (entryDN == null)
{
// Indicate cache miss.
cacheMisses.getAndIncrement();
return null;
}
// Delegate to by DN lock and load method.
return getEntry(entryDN);
}
/**
* Retrieves the entry ID for the entry with the specified DN from
* the cache. The caller should have already acquired a read or
* write lock for the entry if such protection is needed.
*
* @param entryDN The DN of the entry for which to retrieve the
* entry ID.
*
* @return The entry ID for the requested entry, or -1 if it is
* not present in the cache.
*/
public abstract long getEntryID(DN entryDN);
/**
* Retrieves the entry DN for the entry with the specified ID on
* the specific backend from the cache. The caller should have
* already acquired a read or write lock for the entry if such
* protection is needed.
* Note that this method is called from @see #getEntry(Backend
* backend, long entryID, LockType lockType, List lockList)
*
* @param backend The backend associated with the entry for
* which to retrieve the entry DN.
* @param entryID The entry ID within the provided backend
* for which to retrieve the entry DN.
*
* @return The entry DN for the requested entry, or
* {@code null} if it is not present in the cache.
*/
public abstract DN getEntryDN(Backend backend, long entryID);
/**
* Stores the provided entry in the cache. Note that the mechanism
* that it uses to achieve this is implementation-dependent, and it
* is acceptable for the entry to not actually be stored in any
* cache.
*
* @param entry The entry to store in the cache.
* @param backend The backend with which the entry is associated.
* @param entryID The entry ID within the provided backend that
* uniquely identifies the specified entry.
*/
public abstract void putEntry(Entry entry, Backend backend,
long entryID);
/**
* Stores the provided entry in the cache only if it does not
* conflict with an entry that already exists. Note that the
* mechanism that it uses to achieve this is
* implementation-dependent, and it is acceptable for the entry to
* not actually be stored in any cache. However, this method must
* not overwrite an existing version of the entry.
*
* @param entry The entry to store in the cache.
* @param backend The backend with which the entry is associated.
* @param entryID The entry ID within the provided backend that
* uniquely identifies the specified entry.
*
* @return {@code false} if an existing entry or some other problem
* prevented the method from completing successfully, or
* {@code true} if there was no conflict and the entry was
* either stored or the cache determined that this entry
* should never be cached for some reason.
*/
public abstract boolean putEntryIfAbsent(Entry entry,
Backend backend,
long entryID);
/**
* Removes the specified entry from the cache.
*
* @param entryDN The DN of the entry to remove from the cache.
*/
public abstract void removeEntry(DN entryDN);
/**
* Removes all entries from the cache. The cache should still be
* available for future use.
*/
public abstract void clear();
/**
* Removes all entries from the cache that are associated with the
* provided backend.
*
* @param backend The backend for which to flush the associated
* entries.
*/
public abstract void clearBackend(Backend backend);
/**
* Removes all entries from the cache that are below the provided
* DN.
*
* @param baseDN The base DN below which all entries should be
* flushed.
*/
public abstract void clearSubtree(DN baseDN);
/**
* Attempts to react to a scenario in which it is determined that
* the system is running low on available memory. In this case, the
* entry cache should attempt to free some memory if possible to try
* to avoid out of memory errors.
*/
public abstract void handleLowMemory();
/**
* Retrieves the monitor that is associated with this entry
* cache.
*
* @return The monitor that is associated with this entry
* cache, or {@code null} if none has been assigned.
*/
public final EntryCacheMonitorProvider getEntryCacheMonitor()
{
return entryCacheMonitor;
}
/**
* Sets the monitor for this entry cache.
*
* @param entryCacheMonitor The monitor for this entry cache.
*/
public final void setEntryCacheMonitor(
EntryCacheMonitorProvider entryCacheMonitor)
{
this.entryCacheMonitor = entryCacheMonitor;
}
/**
* Retrieves a set of attributes containing monitor data that should
* be returned to the client if the corresponding monitor entry is
* requested.
*
* @return A set of attributes containing monitor data that should
* be returned to the client if the corresponding monitor
* entry is requested.
*/
public abstract ArrayList<Attribute> getMonitorData();
/**
* Retrieves the current number of entries stored within the cache.
*
* @return The current number of entries stored within the cache.
*/
public abstract Long getCacheCount();
/**
* Retrieves the current number of cache hits for this cache.
*
* @return The current number of cache hits for this cache.
*/
public Long getCacheHits()
{
return new Long(cacheHits.longValue());
}
/**
* Retrieves the current number of cache misses for this cache.
*
* @return The current number of cache misses for this cache.
*/
public Long getCacheMisses()
{
return new Long(cacheMisses.longValue());
}
/**
* Retrieves the set of search filters that may be used to determine
* whether an entry should be excluded from the cache.
*
* @return The set of search filters that may be used to determine
* whether an entry should be excluded from the cache.
*/
public Set<SearchFilter> getExcludeFilters()
{
return excludeFilters;
}
/**
* Specifies the set of search filters that may be used to determine
* whether an entry should be excluded from the cache.
*
* @param excludeFilters The set of search filters that may be
* used to determine whether an entry should
* be excluded from the cache.
*/
public void setExcludeFilters(Set<SearchFilter> excludeFilters)
{
if (excludeFilters == null)
{
this.excludeFilters = new HashSet<SearchFilter>(0);
}
else
{
this.excludeFilters = excludeFilters;
}
}
/**
* Retrieves the set of search filters that may be used to determine
* whether an entry should be included in the cache.
*
* @return The set of search filters that may be used to determine
* whether an entry should be included in the cache.
*/
public Set<SearchFilter> getIncludeFilters()
{
return includeFilters;
}
/**
* Specifies the set of search filters that may be used to determine
* whether an entry should be included in the cache.
*
* @param includeFilters The set of search filters that may be
* used to determine whether an entry should
* be included in the cache.
*/
public void setIncludeFilters(Set<SearchFilter> includeFilters)
{
if (includeFilters == null)
{
this.includeFilters = new HashSet<SearchFilter>(0);
}
else
{
this.includeFilters = includeFilters;
}
}
/**
* Indicates whether the current set of exclude and include filters
* allow caching of the specified entry.
*
* @param entry The entry to evaluate against exclude and include
* filter sets.
*
* @return {@code true} if current set of filters allow caching the
* entry and {@code false} otherwise.
*/
public boolean filtersAllowCaching(Entry entry)
{
// If there is a set of exclude filters, then make sure that the
// provided entry doesn't match any of them.
if (! excludeFilters.isEmpty())
{
for (SearchFilter f : excludeFilters)
{
try
{
if (f.matchesEntry(entry))
{
return false;
}
}
catch (Exception e)
{
if (debugEnabled())
{
TRACER.debugCaught(DebugLogLevel.ERROR, e);
}
// This shouldn't happen, but if it does then we can't be
// sure whether the entry should be excluded, so we will
// by default.
return false;
}
}
}
// If there is a set of include filters, then make sure that the
// provided entry matches at least one of them.
if (! includeFilters.isEmpty())
{
boolean matchFound = false;
for (SearchFilter f : includeFilters)
{
try
{
if (f.matchesEntry(entry))
{
matchFound = true;
break;
}
}
catch (Exception e)
{
if (debugEnabled())
{
TRACER.debugCaught(DebugLogLevel.ERROR, e);
}
// This shouldn't happen, but if it does, then
// just ignore it.
}
}
if (! matchFound)
{
return false;
}
}
return true;
}
/**
* Return a verbose string representation of the current cache maps. This is
* useful primary for debugging and diagnostic purposes such as in the entry
* cache unit tests.
* <p>
* This method is invoked by unit tests for debugging.
*
* @return String verbose string representation of the current cache maps in
* the following format: dn:id:backend one cache entry map
* representation per line or <CODE>null</CODE> if all maps are empty.
*/
public abstract String toVerboseString();
}