com.aspc.remote.memory.internal

Class CacheTableTemplate<V>

java.lang.Object

com.aspc.remote.memory.internal.CacheTableTemplate<V>

Type Parameters:

V - the class of that is stored.

All Implemented Interfaces:

MemoryHandler

Direct Known Subclasses:

CacheLongTable, CacheTable

public abstract class CacheTableTemplate<V>
extends java.lang.Object
implements MemoryHandler

Cache Table template. Originated from two HashMap, one for weak references and one for hard references.
THREAD MODE: MULTI-THREADED memory management

Since:

31 December 1998

Author:

Nigel Leck

Nested Class Summary

Nested classes/interfaces inherited from interface com.aspc.remote.memory.MemoryHandler

MemoryHandler.Cost

Field Summary

Fields

Modifier and Type	Field and Description
protected MemoryHandler.Cost	cost the cost
protected int	count the count
protected java.lang.Object[]	data the data
protected java.lang.String	description the description
protected int	estEmptyCount The estimated empty count
protected static int	INITIAL_CAPACITY the capacity
protected int	memoryMangerThreshold the threshold
static java.lang.String	PROPERTY_ENABLE_POINTER_CHECK The property to enable pointer check.
protected java.util.concurrent.locks.ReentrantReadWriteLock	rwLock
protected int	unallocated the number unallocated

Constructor Summary

Constructors

Constructor and Description
CacheTableTemplate(java.lang.String description, MemoryHandler.Cost theCost) create a new cache table.

Method Summary

Modifier and Type	Method and Description
protected void	checkRegister() check registered
void	clear() Removes all mappings from this map.
void	compact() Compact
boolean	containsValue(V value) Returns true if this map maps one or more keys to the specified value.
protected abstract InterfaceEntry[]	createArray(int size) Create the underlying entry array
long	freeMemory(double requiredPercent) When called if the items are stored as softRefernces and in tidy up mode then just clear the ones that have being removed.
int	getAverageSize() The estimated average size.
MemoryHandler.Cost	getCost() The cost of this cache table.
java.lang.String	getDescription() gets the description of this cache table.
long	getEstimatedSize() The estimated amount of memory held by this cache table.
int	getHardLinkCount() The number of entries that have hard links.
long	getLastAccessed() The last time this cache table was accessed.
boolean	isEmpty() Returns true if this map contains no key-value mappings.
long	panicFreeMemory() Clear all memory ASAP.
long	queuedFreeMemory(double requiredPercent) The queued called to freeMemory which is needed to prevent a deadlock.
protected int	rehash(int indexTemp, int hash) Rehashes the contents of this map into a new HashMap instance with a larger capacity.
protected void	removeElement(InterfaceEntry current, int pos, InterfaceEntry prev, boolean updateUnallocated)
void	setAverageSize(int size) Sets the estimated average size of the objects held.
void	setMayReleaseReferences(boolean flag) The default behavior of a cache table is to not release objects that are still referred to elsewhere in the system when release memory is called.
void	setThreshold(int count) sets the threshold to register with the Memory Manager
int	size() Returns the number of key-value mappings in this map.
void	stats(StatsCollector collector)
long	tidyUp() Tidy up the memory handler
protected void	tidyUpRequired() tidy up
java.lang.String	toString() The description of this cache table
protected void	touch(InterfaceEntry e)

Methods inherited from class java.lang.Object

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

Field Detail

rwLock

protected final java.util.concurrent.locks.ReentrantReadWriteLock rwLock

cost

protected MemoryHandler.Cost cost

the cost

estEmptyCount

protected int estEmptyCount

The estimated empty count

unallocated

protected int unallocated

the number unallocated

memoryMangerThreshold

protected int memoryMangerThreshold

the threshold

description

protected java.lang.String description

the description

data

protected java.lang.Object[] data

the data

count

protected int count

the count

INITIAL_CAPACITY

protected static final int INITIAL_CAPACITY

the capacity

See Also:

Constant Field Values

PROPERTY_ENABLE_POINTER_CHECK

public static final java.lang.String PROPERTY_ENABLE_POINTER_CHECK

The property to enable pointer check.

See Also:

Constant Field Values

Constructor Detail

CacheTableTemplate

public CacheTableTemplate(@Nonnull
                          java.lang.String description,
                          @Nonnull
                          MemoryHandler.Cost theCost)

create a new cache table.

Parameters:

description - the description of the cache table.

theCost - the relative cost of this cache table.

Method Detail

setMayReleaseReferences

public void setMayReleaseReferences(boolean flag)

The default behavior of a cache table is to not release objects that are still referred to elsewhere in the system when release memory is called. This is to prevent duplicates from being loaded and generally taking up more memory.

The default behavior can be changed by setting this flag to true.

Good examples are DBData we must never load two lots of DBData for one row as only one set of DBObjects would receive the incoming events. In other places we don't care.

Parameters:

flag - may release ?

setThreshold

public final void setThreshold(int count)

sets the threshold to register with the Memory Manager

Parameters:

count - the number of elements before we register with the memory manager.

stats

public void stats(@Nullable
                  StatsCollector collector)

Parameters:

collector - the collector

getDescription

@CheckReturnValue
 @Nonnull
public java.lang.String getDescription()

gets the description of this cache table.

Returns:

the description.

getCost

@CheckReturnValue
 @Nonnull
public final MemoryHandler.Cost getCost()

The cost of this cache table.

Specified by:

getCost in interface MemoryHandler

Returns:

the relative cost

size

@CheckReturnValue
 @Nonnegative
public final int size()

Returns the number of key-value mappings in this map.

Returns:

the number of key-value mappings in this map.

getHardLinkCount

@CheckReturnValue
 @Nonnegative
public final int getHardLinkCount()

The number of entries that have hard links.

Returns:

the count

isEmpty

@CheckReturnValue
public final boolean isEmpty()

Returns true if this map contains no key-value mappings.

Returns:

true if this map contains no key-value mappings.

containsValue

@CheckReturnValue
public final boolean containsValue(@Nonnull
                                                     V value)

Returns true if this map maps one or more keys to the specified value.

Parameters:

value - value whose presence in this map is to be tested.

Returns:

true if this map maps one or more keys to the specified value.

clear

public final void clear()

Removes all mappings from this map.

getLastAccessed

@CheckReturnValue
public final long getLastAccessed()

The last time this cache table was accessed.

Specified by:

getLastAccessed in interface MemoryHandler

Returns:

The last time the cache table was access.

setAverageSize

public final void setAverageSize(@Nonnegative
                                 int size)

Sets the estimated average size of the objects held.

Parameters:

size - the estimated average size.

getAverageSize

@CheckReturnValue
 @Nonnegative
public final int getAverageSize()

The estimated average size.

Returns:

the size in bytes

toString

@CheckReturnValue
 @Nonnull
public java.lang.String toString()

The description of this cache table

Overrides:

toString in class java.lang.Object

Returns:

the description

getEstimatedSize

@CheckReturnValue
 @Nonnegative
public final long getEstimatedSize()

The estimated amount of memory held by this cache table.

Specified by:

getEstimatedSize in interface MemoryHandler

Returns:

the estimated size in bytes

freeMemory

@Nonnegative
public final long freeMemory(@Nonnegative
                                          double requiredPercent)

When called if the items are stored as softRefernces and in tidy up mode then just clear the ones that have being removed. Otherwise clear all memory held

Specified by:

freeMemory in interface MemoryHandler

Parameters:

requiredPercent - The required percent to free.

Returns:

The amount cleared in bytes.

panicFreeMemory

@Nonnegative
public long panicFreeMemory()

Clear all memory ASAP.

Specified by:

panicFreeMemory in interface MemoryHandler

Returns:

The estimated total number of bytes released.

queuedFreeMemory

@Nonnegative
public final long queuedFreeMemory(double requiredPercent)

The queued called to freeMemory which is needed to prevent a deadlock.

Specified by:

queuedFreeMemory in interface MemoryHandler

Parameters:

requiredPercent - The memory to free

Returns:

The estimate amount of memory released.

compact

public void compact()

Compact

tidyUp

@Nonnegative
public final long tidyUp()

Description copied from interface: MemoryHandler

Tidy up the memory handler

Specified by:

tidyUp in interface MemoryHandler

Returns:

the amount cleared.

tidyUpRequired

protected void tidyUpRequired()

tidy up

removeElement

protected final void removeElement(InterfaceEntry current,
                                   int pos,
                                   InterfaceEntry prev,
                                   boolean updateUnallocated)

Parameters:

current - the interface

pos - the position

prev - the previous entry

updateUnallocated - update the unallocated

checkRegister

protected final void checkRegister()

check registered

touch

protected final void touch(InterfaceEntry e)

Parameters:

e - The entry to touch.

createArray

protected abstract InterfaceEntry[] createArray(int size)

Create the underlying entry array

Parameters:

size - the number of entries to create

Returns:

the array

rehash

protected final int rehash(int indexTemp,
                           int hash)

Rehashes the contents of this map into a new HashMap instance with a larger capacity. This method is called automatically when the number of keys in this map exceeds its capacity and load factor.

Parameters:

indexTemp - the index

hash - the hash code

Returns:

the new index