oracle.ifs.common

Class LooselyBoundedCache

java.lang.Object

oracle.ifs.common.Cache

oracle.ifs.common.BoundedCache

oracle.ifs.common.LooselyBoundedCache

Direct Known Subclasses:

TieLooselyBoundedCache

public class LooselyBoundedCache
extends BoundedCache

An LooselyBoundedCache is a cache that is bounded to hold a limited number of items. The upper bound is maintained by an efficient but non-exact algorithm that removes LRU entries.

Version:

1.0

Author:

Dave Long

(Published)

Field Summary

Fields

Modifier and Type	Field and Description
protected long	m_AccessSequence The access sequence.
protected int	m_CacheCountEstimate The estimate of the current cache count
protected int	m_Capacity Target max hashtable capacity; alos used as initial Capacity in hashtable constructor
protected int	m_EmergencyCapacityTrigger capacity at which an "emergency" purge is performed
protected boolean	m_EmergencyPurgeRequested Emergency cache purge requested
protected long	m_HitCount The number of cache hits.
protected ConcurrentHashMap	m_Items The cache items.
protected long	m_LockCount The number of locked cache puts.
protected long	m_MissCount The number of cache misses.
protected int	m_NormalCapacityTrigger capacity at which a "normal" purge is posted
protected boolean	m_NormalPurgeRequested Normal cache purge requested
protected long	m_PurgeCount The number of cache removes.
protected int	m_PurgeCycleCount Total number of purge cycles performed
protected long	m_PurgeCycleTime Total elapsed time (in ms) of the purge cycles performed.
protected boolean	m_PurgeInProgress Cache purge in progress
protected int	m_PurgeTarget Number of items desired in the cache after a purge operation
protected long	m_PutCount The number of cache puts.
protected long	m_RemoveCount The number of cache removes.
protected long	m_SequenceAtPreviousPurge Cache purge in progress
protected int	m_UrgentCapacityTrigger capacity at which an "urgent" purge is posted
protected boolean	m_UrgentPurgeRequested Urgent cache purge requested

Fields inherited from class oracle.ifs.common.Cache

m_Configuration

Constructor Summary

Constructors

Constructor and Description
LooselyBoundedCache(BoundedCacheConfiguration configuration) Constructs an loosely bounded cache.

Method Summary

Modifier and Type	Method and Description
protected void	addEntry(Object id, LooselyBoundedCacheable value, long seq)
protected void	addLockedEntry(Object id, LooselyBoundedCacheable value)
protected void	checkIfPurgeNeeded()
void	dispose() Disposes this cache.
Object	find(Object id) Gets an item from this cache.
CachePerformance	getCachePerformance() Gets the performance information for this cache.
Enumeration	getElements() Gets an Enumeration of the LooselyBoundedCacheable objects in this cache.
void	lock(Object id, LooselyBoundedCacheable lbc) Locks an item in this cache.
void	lock(Object id, Object value) Locks an item in this cache.
void	performNormalPurgeIfNeeded() Purge Cache if a request for "normal" purge is indicated
void	performUrgentPurgeIfNeeded() Purge Cache if a request for "urgent" purge is indicated
protected void	purge()
protected void	purgeEntry(Object id) Purges an item from this cache.
void	put(Object id, LooselyBoundedCacheable lbc) Puts an item in this cache.
void	put(Object id, Object value) Puts an item in this cache.
void	remove(Object id) Removes an item from this cache.
void	reset() Resets this cache.
void	resetCachePerformance() Resets the performance information for this cache.
void	setCacheConfiguration(CacheConfiguration configuration) Alters the configuration of this cache.
protected void	validateCacheConfiguration(CacheConfiguration configuration) Validates cache configuration information.

Methods inherited from class oracle.ifs.common.Cache

getCacheConfiguration

Methods inherited from class java.lang.Object

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

Field Detail

m_Items

protected ConcurrentHashMap m_Items

The cache items.

(Unpublished)

m_Capacity

protected int m_Capacity

Target max hashtable capacity; alos used as initial Capacity in hashtable constructor

(Unpublished)

m_NormalCapacityTrigger

protected int m_NormalCapacityTrigger

capacity at which a "normal" purge is posted

(Unpublished)

m_UrgentCapacityTrigger

protected int m_UrgentCapacityTrigger

capacity at which an "urgent" purge is posted

(Unpublished)

m_EmergencyCapacityTrigger

protected int m_EmergencyCapacityTrigger

capacity at which an "emergency" purge is performed

(Unpublished)

m_PurgeTarget

protected int m_PurgeTarget

Number of items desired in the cache after a purge operation

(Unpublished)

m_AccessSequence

protected long m_AccessSequence

The access sequence.

(Unpublished)

m_CacheCountEstimate

protected int m_CacheCountEstimate

The estimate of the current cache count

(Unpublished)

m_SequenceAtPreviousPurge

protected long m_SequenceAtPreviousPurge

Cache purge in progress

(Unpublished)

m_PurgeCycleCount

protected int m_PurgeCycleCount

Total number of purge cycles performed

(Unpublished)

m_PurgeCycleTime

protected long m_PurgeCycleTime

Total elapsed time (in ms) of the purge cycles performed. Used to calculate an average purge cycle time.

(Unpublished)

m_PurgeInProgress

protected boolean m_PurgeInProgress

Cache purge in progress

(Unpublished)

m_NormalPurgeRequested

protected boolean m_NormalPurgeRequested

Normal cache purge requested

(Unpublished)

m_UrgentPurgeRequested

protected boolean m_UrgentPurgeRequested

Urgent cache purge requested

(Unpublished)

m_EmergencyPurgeRequested

protected boolean m_EmergencyPurgeRequested

Emergency cache purge requested

(Unpublished)

m_HitCount

protected long m_HitCount

The number of cache hits.

(Unpublished)

m_MissCount

protected long m_MissCount

The number of cache misses.

(Unpublished)

m_PutCount

protected long m_PutCount

The number of cache puts.

(Unpublished)

m_LockCount

protected long m_LockCount

The number of locked cache puts.

(Unpublished)

m_RemoveCount

protected long m_RemoveCount

The number of cache removes.

(Unpublished)

m_PurgeCount

protected long m_PurgeCount

The number of cache removes.

(Unpublished)

Constructor Detail

LooselyBoundedCache

public LooselyBoundedCache(BoundedCacheConfiguration configuration)
                    throws IfsException

Constructs an loosely bounded cache.

Parameters:

configuration - the configuration paramaters for the new cache

Throws:

IfsException

(Unpublished)

Method Detail

setCacheConfiguration

public void setCacheConfiguration(CacheConfiguration configuration)
                           throws IfsException

Alters the configuration of this cache.

The following cache configuration parameters can be changed using this method:

• Capacity
• Normal capacity trigger
• Urgent capacity trigger
• Emergency capacity trigger
• Purge target

All other cache configuration parameters specified in the CacheConfiguration are ignored.

Specified by:

setCacheConfiguration in class Cache

Parameters:

configuration - the configuration parameters; must be a BoundedCacheConfiguration

Throws:

IfsException - (IFS-10810) if the operation fails

(Unpublished)

put

public void put(Object id,
                Object value)
         throws IfsException

Puts an item in this cache.

Specified by:

put in class Cache

Parameters:

id - the item id

value - the item

Throws:

IfsException - if the operation fails

(Unpublished)

put

public void put(Object id,
                LooselyBoundedCacheable lbc)
         throws IfsException

Puts an item in this cache.

Parameters:

id - the item id

lbc - the item

Throws:

IfsException - if the operation fails

(Unpublished)

lock

public void lock(Object id,
                 Object value)
          throws IfsException

Locks an item in this cache.

Specified by:

lock in class BoundedCache

Parameters:

id - the item id

value - the item

Throws:

IfsException - if the operation fails

(Unpublished)

lock

public void lock(Object id,
                 LooselyBoundedCacheable lbc)
          throws IfsException

Locks an item in this cache.

Parameters:

id - the item id

lbc - the item

Throws:

IfsException - if the operation fails

(Unpublished)

remove

public void remove(Object id)
            throws IfsException

Removes an item from this cache.

Specified by:

remove in class Cache

Parameters:

id - the item id

Throws:

IfsException - if the operation fails

(Unpublished)

purgeEntry

protected void purgeEntry(Object id)

Purges an item from this cache.

Parameters:

id - the item id

Throws:

IfsException - if the operation fails

(Unpublished)

find

public Object find(Object id)
            throws IfsException

Gets an item from this cache.

Specified by:

find in class Cache

Parameters:

id - the item id

Returns:

the item, or null if the item is not in this cache

Throws:

IfsException - if the operation fails

(Unpublished)

performNormalPurgeIfNeeded

public void performNormalPurgeIfNeeded()

Purge Cache if a request for "normal" purge is indicated

Specified by:

performNormalPurgeIfNeeded in class BoundedCache

(Unpublished)

performUrgentPurgeIfNeeded

public void performUrgentPurgeIfNeeded()

Purge Cache if a request for "urgent" purge is indicated

Specified by:

performUrgentPurgeIfNeeded in class BoundedCache

(Unpublished)

purge

protected void purge()

addEntry

protected void addEntry(Object id,
                        LooselyBoundedCacheable value,
                        long seq)

getElements

public Enumeration getElements()
                        throws IfsException

Gets an Enumeration of the LooselyBoundedCacheable objects in this cache.

Overrides:

getElements in class Cache

Returns:

the enumeration of LooselyBoundedCacheable

Throws:

IfsException - if operation fails

(Unpublished)

addLockedEntry

protected void addLockedEntry(Object id,
                              LooselyBoundedCacheable value)

checkIfPurgeNeeded

protected void checkIfPurgeNeeded()

getCachePerformance

public CachePerformance getCachePerformance()

Gets the performance information for this cache.

Specified by:

getCachePerformance in class Cache

Returns:

a cache performance object

(Unpublished)

resetCachePerformance

public void resetCachePerformance()

Resets the performance information for this cache.

Specified by:

resetCachePerformance in class Cache

(Unpublished)

reset

public void reset()

Resets this cache.

This causes the cache to be emptied and its performance information to be reset.

Overrides:

reset in class Cache

(Unpublished)

dispose

public void dispose()

Disposes this cache.

After the cache is disposed, it is invalid to use this cache.

Overrides:

dispose in class Cache

(Unpublished)

validateCacheConfiguration

protected void validateCacheConfiguration(CacheConfiguration configuration)
                                   throws IfsException

Validates cache configuration information.

Checks purge target, normal capacity trigger, urgent capacity trigger, and emergency capacity trigger.

Parameters:

configuration - the configuration paramaters for the new cache

Throws:

IfsException - if the configuration is not valid

(Unpublished)