org.opends.server.extensions

Class DefaultEntryCache

java.lang.Object

org.opends.server.api.MonitorProvider

org.opends.server.api.EntryCache<EntryCacheCfg>

org.opends.server.extensions.DefaultEntryCache

All Implemented Interfaces:

MeterBinder, ConfigurationChangeListener<EntryCacheCfg>, LocalBackendInitializationListener

public class DefaultEntryCache
extends EntryCache<EntryCacheCfg>
implements ConfigurationChangeListener<EntryCacheCfg>, LocalBackendInitializationListener

This class defines the default entry cache which acts as an arbiter for every entry cache implementation configured and installed within the Directory Server or acts an an empty cache if no implementation specific entry cache is configured. It does not actually store any entries, so all calls to the entry cache public API are routed to underlying entry cache according to the current configuration order and preferences.

This class records total-tries and misses metrics globaly:

• Try to retrieve an entry from multiple cache implementations: record one try.
• None of the entry cache implementations have succeeded to retrieve the entry: record one miss.

Field Summary

Fields inherited from class org.opends.server.api.MonitorProvider

registry

Constructor Summary

Constructors

Constructor and Description
DefaultEntryCache() Creates a new instance of this default entry cache.

Method Summary

Modifier and Type	Method and Description
ConfigChangeResult	applyConfigurationChange(EntryCacheCfg configuration) Applies the configuration changes to this change listener.
void	clear() Removes all entries from the cache.
void	clearBackend(String backendID) Removes all entries from the cache that are associated with the provided backend.
protected Dn	computeMonitorInstanceDn() Returns the monitor instance DN for this monitor provider.
boolean	containsEntry(Dn entryDN) Indicates whether the entry cache currently contains the entry with the specified DN.
void	finalizeEntryCache() 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.
Entry	getEntry(Dn entryDN) Retrieves the entry with the specified DN from the cache.
Entry	getEntry(String backendID, long entryID) Retrieves the requested entry if it is present in the cache.
long	getEntryCount() Retrieves the current number of entries stored within the cache.
Dn	getEntryDN(String backendID, long entryID) Retrieves the entry DN for the entry with the specified ID on the specific backend from the cache.
long	getEntryID(Dn entryDN) Retrieves the entry ID for the entry with the specified DN from the cache.
void	handleLowMemory() Attempts to react to a scenario in which it is determined that the system is running low on available memory.
boolean	isConfigurationChangeAcceptable(EntryCacheCfg configuration, List<LocalizableMessage> unacceptableReasons) Indicates whether the proposed change to the configuration is acceptable to this change listener.
protected MeterRegistryHolder	newMeterRegistryHolder(MeterRegistry parent) Creates a MeterRegistryHolder with the appropriate name prefixes and tags.
void	performBackendPostFinalizationProcessing(LocalBackend<?> backend) Performs any processing that may be required whenever a backend is finalized.
void	putEntry(Entry entry, String backendID, long entryID) Stores the provided entry in the cache.
boolean	putEntryIfAbsent(Entry entry, String backendID, long entryID) Stores the provided entry in the cache only if it does not conflict with an entry that already exists.
protected void	recordMiss() Records a failure to retrieve an entry from this cache.
protected void	recordTry() Records an attempt to retrieve an entry from this cache.
void	removeEntry(Dn entryDN) Removes the specified entry from the cache.
static void	setCacheOrder(SortedMap<Integer,EntryCache<? extends EntryCacheCfg>> cacheOrderMap) Sets the current cache order array.
String	toVerboseString() Return a verbose string representation of the current cache maps.

Methods inherited from class org.opends.server.api.EntryCache

addMonitorObjectClassNames, bindTo, filtersAllowCaching, initializeEntryCache, isConfigurationAcceptable, setIncludeExcludeFilters

Methods inherited from class org.opends.server.api.MonitorProvider

configurationDnToMonitorDn, deregisterAll, getMonitorEntry, getMonitorInstanceDn, toString

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Methods inherited from interface org.opends.server.api.LocalBackendInitializationListener

performBackendPostInitializationProcessing, performBackendPreFinalizationProcessing, performBackendPreInitializationProcessing

Constructor Detail

DefaultEntryCache

public DefaultEntryCache()

Creates a new instance of this default entry cache.

Method Detail

containsEntry

public boolean containsEntry(Dn entryDN)

Description copied from class: EntryCache

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)

Specified by:

containsEntry in class EntryCache<EntryCacheCfg>

Parameters:

entryDN - The DN for which to make the determination.

Returns:

true if the entry cache currently contains the entry with the specified DN, or false if not.

getEntry

public Entry getEntry(String backendID,
                      long entryID)

Description copied from class: EntryCache

Retrieves the requested entry if it is present in the cache.

Overrides:

getEntry in class EntryCache<EntryCacheCfg>

Parameters:

backendID - ID of the backend associated with the entry to retrieve.

entryID - The entry ID within the provided backend for the specified entry.

Returns:

The requested entry if it is present in the cache, or null if it is not present.

getEntry

public Entry getEntry(Dn entryDN)

Description copied from class: EntryCache

Retrieves the entry with the specified DN from the cache.

Specified by:

getEntry in class EntryCache<EntryCacheCfg>

Parameters:

entryDN - The DN of the entry to retrieve.

Returns:

The requested entry if it is present in the cache, or null if it is not present.

getEntryID

public long getEntryID(Dn entryDN)

Description copied from class: EntryCache

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.

Specified by:

getEntryID in class EntryCache<EntryCacheCfg>

Parameters:

entryDN - The DN of the entry for which to retrieve the entry ID.

Returns:

The entry ID for the requested entry, or -1 if it is not present in the cache.

getEntryDN

public Dn getEntryDN(String backendID,
                     long entryID)

Description copied from class: EntryCache

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)

Specified by:

getEntryDN in class EntryCache<EntryCacheCfg>

Parameters:

backendID - ID of the backend associated with the entry for which to retrieve the entry DN.

entryID - The entry ID within the provided backend for which to retrieve the entry DN.

Returns:

The entry DN for the requested entry, or null if it is not present in the cache.

putEntry

public void putEntry(Entry entry,
                     String backendID,
                     long entryID)

Description copied from class: EntryCache

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.

Specified by:

putEntry in class EntryCache<EntryCacheCfg>

Parameters:

entry - The entry to store in the cache.

backendID - ID of the backend with which the entry is associated.

entryID - The entry ID within the provided backend that uniquely identifies the specified entry.

putEntryIfAbsent

public boolean putEntryIfAbsent(Entry entry,
                                String backendID,
                                long entryID)

Description copied from class: EntryCache

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.

Specified by:

putEntryIfAbsent in class EntryCache<EntryCacheCfg>

Parameters:

entry - The entry to store in the cache.

backendID - ID of the backend with which the entry is associated.

entryID - The entry ID within the provided backend that uniquely identifies the specified entry.

Returns:

false if an existing entry or some other problem prevented the method from completing successfully, or 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.

removeEntry

public void removeEntry(Dn entryDN)

Description copied from class: EntryCache

Removes the specified entry from the cache.

Specified by:

removeEntry in class EntryCache<EntryCacheCfg>

Parameters:

entryDN - The DN of the entry to remove from the cache.

clear

public void clear()

Description copied from class: EntryCache

Removes all entries from the cache. The cache should still be available for future use.

Specified by:

clear in class EntryCache<EntryCacheCfg>

clearBackend

public void clearBackend(String backendID)

Description copied from class: EntryCache

Removes all entries from the cache that are associated with the provided backend.

Specified by:

clearBackend in class EntryCache<EntryCacheCfg>

Parameters:

backendID - ID of the backend for which to flush the associated entries.

handleLowMemory

public void handleLowMemory()

Description copied from class: EntryCache

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.

Specified by:

handleLowMemory in class EntryCache<EntryCacheCfg>

isConfigurationChangeAcceptable

public boolean isConfigurationChangeAcceptable(EntryCacheCfg configuration,
                                               List<LocalizableMessage> unacceptableReasons)

Description copied from interface: ConfigurationChangeListener

Indicates whether the proposed change to the configuration is acceptable to this change listener.

Specified by:

isConfigurationChangeAcceptable in interface ConfigurationChangeListener<EntryCacheCfg>

Parameters:

configuration - The new configuration containing the changes.

unacceptableReasons - A list that can be used to hold messages about why the provided configuration is not acceptable.

Returns:

Returns true if the proposed change is acceptable, or false if it is not.

applyConfigurationChange

public ConfigChangeResult applyConfigurationChange(EntryCacheCfg configuration)

Description copied from interface: ConfigurationChangeListener

Applies the configuration changes to this change listener.

Specified by:

applyConfigurationChange in interface ConfigurationChangeListener<EntryCacheCfg>

Parameters:

configuration - The new configuration containing the changes.

Returns:

Returns information about the result of changing the configuration.

getEntryCount

public long getEntryCount()

Description copied from class: EntryCache

Retrieves the current number of entries stored within the cache.

Specified by:

getEntryCount in class EntryCache<EntryCacheCfg>

Returns:

The current number of entries stored within the cache.

toVerboseString

public String toVerboseString()

Description copied from class: EntryCache

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.

This method is invoked by unit tests for debugging.

Specified by:

toVerboseString in class EntryCache<EntryCacheCfg>

Returns:

String verbose string representation of the current cache maps in the following format: dn:id:backend one cache entry map representation per line or null if all maps are empty.

setCacheOrder

public static final void setCacheOrder(SortedMap<Integer,EntryCache<? extends EntryCacheCfg>> cacheOrderMap)

Sets the current cache order array.

Parameters:

cacheOrderMap - The current cache order array.

performBackendPostFinalizationProcessing

public void performBackendPostFinalizationProcessing(LocalBackend<?> backend)

Description copied from interface: LocalBackendInitializationListener

Performs any processing that may be required whenever a backend is finalized. This method will be invoked after the backend has been taken out of service but before it has been finalized.

Specified by:

performBackendPostFinalizationProcessing in interface LocalBackendInitializationListener

Parameters:

backend - The backend that has been taken out of service and is about to be finalized.

computeMonitorInstanceDn

protected Dn computeMonitorInstanceDn()

Description copied from class: MonitorProvider

Returns the monitor instance DN for this monitor provider.

Overrides:

computeMonitorInstanceDn in class EntryCache<EntryCacheCfg>

Returns:

the monitor instance DN.

newMeterRegistryHolder

protected MeterRegistryHolder newMeterRegistryHolder(MeterRegistry parent)

Description copied from class: EntryCache

Creates a MeterRegistryHolder with the appropriate name prefixes and tags.

Overrides:

newMeterRegistryHolder in class EntryCache<EntryCacheCfg>

Parameters:

parent - The meter registry to be decorated.

Returns:

The meter registry holder.

finalizeEntryCache

public void finalizeEntryCache()

Description copied from class: EntryCache

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.

Specified by:

finalizeEntryCache in class EntryCache<EntryCacheCfg>

recordTry

protected void recordTry()

Description copied from class: EntryCache

Records an attempt to retrieve an entry from this cache.

Overrides:

recordTry in class EntryCache<EntryCacheCfg>

recordMiss

protected void recordMiss()

Description copied from class: EntryCache

Records a failure to retrieve an entry from this cache.

Overrides:

recordMiss in class EntryCache<EntryCacheCfg>