Package org.eclipse.jetty.util

Class Pool<T>

java.lang.Object

org.eclipse.jetty.util.Pool<T>

Type Parameters:

T - the type of the pooled objects

All Implemented Interfaces:

AutoCloseable, Dumpable

@ManagedObject
public class Pool<T>
extends Object
implements AutoCloseable, Dumpable

A pool of objects, with optional support for multiplexing, max usage count and several optimized strategies plus an optional ThreadLocal cache of the last release entry.

When the method close() is called, all Closeables object pooled by the pool are also closed.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
class	Pool.Entry	A Pool entry that holds metadata and a pooled object.
static enum	Pool.StrategyType	The type of the strategy to use for the pool.

Nested classes/interfaces inherited from interface org.eclipse.jetty.util.component.Dumpable

Dumpable.DumpableContainer

Field Summary

Fields inherited from interface org.eclipse.jetty.util.component.Dumpable

KEY

Constructor Summary

Constructors

Constructor	Description
Pool(Pool.StrategyType strategyType, int maxEntries)	Construct a Pool with a specified lookup strategy and no ThreadLocal cache.
Pool(Pool.StrategyType strategyType, int maxEntries, boolean cache)	Construct a Pool with the specified thread-local cache size and an optional ThreadLocal cache.

Method Summary

Modifier and Type	Method	Description
Pool<T>.Entry	acquire()	Acquires an entry from the pool.
Pool<T>.Entry	acquire(Function<Pool<T>.Entry,T> creator)	Acquires an entry from the pool, reserving and creating a new entry if necessary.
void	close()
void	dump(Appendable out, String indent)	Dump this object (and children) into an Appendable using the provided indent after any new lines.
int	getClosedCount()
int	getIdleCount()
int	getInUseCount()
int	getMaxEntries()
int	getMaxMultiplex()	Deprecated. Multiplex functionalities will be removed
protected int	getMaxMultiplex(T pooled)	Deprecated. Multiplex functionalities will be removed
int	getMaxUsageCount()	Deprecated. MaxUsage functionalities will be removed
protected int	getMaxUsageCount(T pooled)	Deprecated. MaxUsage functionalities will be removed
int	getReservedCount()
boolean	isClosed()
boolean	release(Pool<T>.Entry entry)	Releases an acquired entry to the pool.
boolean	remove(Pool<T>.Entry entry)	Removes an entry from the pool.
Pool<T>.Entry	reserve()	Creates a new disabled slot into the pool.
Pool<T>.Entry	reserve(int allotment)	Deprecated. Use reserve() instead
final void	setMaxMultiplex(int maxMultiplex)	Deprecated. Multiplex functionalities will be removed
final void	setMaxUsageCount(int maxUsageCount)	Deprecated. MaxUsage functionalities will be removed
int	size()
String	toString()
Collection<Pool<T>.Entry>	values()

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.eclipse.jetty.util.component.Dumpable

dump, dumpSelf

Constructor Details

Pool

public Pool(Pool.StrategyType strategyType,
 int maxEntries)

Construct a Pool with a specified lookup strategy and no ThreadLocal cache.

Parameters:

strategyType - The strategy to used for looking up entries.

maxEntries - the maximum amount of entries that the pool will accept.

Pool

public Pool(Pool.StrategyType strategyType,
 int maxEntries,
 boolean cache)

Construct a Pool with the specified thread-local cache size and an optional ThreadLocal cache.

Parameters:

strategyType - The strategy to used for looking up entries.

maxEntries - the maximum amount of entries that the pool will accept.

cache - True if a ThreadLocal cache should be used to try the most recently released entry.

Method Details

getReservedCount

@ManagedAttribute("The number of reserved entries")
public int getReservedCount()

Returns:

the number of reserved entries

getIdleCount

@ManagedAttribute("The number of idle entries")
public int getIdleCount()

Returns:

the number of idle entries

getInUseCount

@ManagedAttribute("The number of in-use entries")
public int getInUseCount()

Returns:

the number of in-use entries

getClosedCount

@ManagedAttribute("The number of closed entries")
public int getClosedCount()

Returns:

the number of closed entries

getMaxEntries

@ManagedAttribute("The maximum number of entries")
public int getMaxEntries()

Returns:

the maximum number of entries

getMaxMultiplex

@ManagedAttribute("The default maximum multiplex count of entries")
@Deprecated
public int getMaxMultiplex()

Deprecated.

Multiplex functionalities will be removed

Returns:

the default maximum multiplex count of entries

getMaxMultiplex

@Deprecated
protected int getMaxMultiplex(T pooled)

Deprecated.

Multiplex functionalities will be removed

Retrieves the max multiplex count for the given pooled object.

Parameters:

pooled - the pooled object

Returns:

the max multiplex count for the given pooled object

setMaxMultiplex

@Deprecated
public final void setMaxMultiplex(int maxMultiplex)

Deprecated.

Multiplex functionalities will be removed

Sets the default maximum multiplex count for the Pool's entries.

Parameters:

maxMultiplex - the default maximum multiplex count of entries

getMaxUsageCount

@ManagedAttribute("The default maximum usage count of entries")
@Deprecated
public int getMaxUsageCount()

Deprecated.

MaxUsage functionalities will be removed

Returns the maximum number of times the entries of the pool can be acquired.

Returns:

the default maximum usage count of entries

getMaxUsageCount

@Deprecated
protected int getMaxUsageCount(T pooled)

Deprecated.

MaxUsage functionalities will be removed

Retrieves the max usage count for the given pooled object.

Parameters:

pooled - the pooled object

Returns:

the max usage count for the given pooled object

setMaxUsageCount

@Deprecated
public final void setMaxUsageCount(int maxUsageCount)

Deprecated.

MaxUsage functionalities will be removed

Sets the maximum usage count for the Pool's entries.

All existing idle entries that have a usage count larger than this new value are removed from the Pool and closed.

Parameters:

maxUsageCount - the default maximum usage count of entries

reserve

@Deprecated
public Pool<T>.Entry reserve(int allotment)

Deprecated.

Use reserve() instead

Creates a new disabled slot into the pool.

The returned entry must ultimately have the Pool.Entry.enable(Object, boolean) method called or be removed via Pool.Entry.remove() or remove(Pool.Entry).

Parameters:

allotment - the desired allotment, where each entry handles an allotment of maxMultiplex, or a negative number to always trigger the reservation of a new entry.

Returns:

a disabled entry that is contained in the pool, or null if the pool is closed or if the pool already contains getMaxEntries() entries, or the allotment has already been reserved

reserve

public Pool<T>.Entry reserve()

Creates a new disabled slot into the pool.

The returned entry must ultimately have the Pool.Entry.enable(Object, boolean) method called or be removed via Pool.Entry.remove() or remove(Pool.Entry).

Returns:

a disabled entry that is contained in the pool, or null if the pool is closed or if the pool already contains getMaxEntries() entries

acquire

public Pool<T>.Entry acquire()

Acquires an entry from the pool.

Only enabled entries will be returned from this method and their Pool.Entry.enable(Object, boolean) method must not be called.

Returns:

an entry from the pool or null if none is available.

acquire

public Pool<T>.Entry acquire(Function<Pool<T>.Entry,T> creator)

Acquires an entry from the pool, reserving and creating a new entry if necessary.

Parameters:

creator - a function to create the pooled value for a reserved entry.

Returns:

an entry from the pool or null if none is available.

release

public boolean release(Pool<T>.Entry entry)

Releases an acquired entry to the pool.

Entries that are acquired from the pool but never released will result in a memory leak.

Parameters:

entry - the value to return to the pool

Returns:

true if the entry was released and could be acquired again, false if the entry should be removed by calling remove(Pool.Entry) and the object contained by the entry should be disposed.

remove

public boolean remove(Pool<T>.Entry entry)

Removes an entry from the pool.

Parameters:

entry - the value to remove

Returns:

true if the entry was removed, false otherwise

isClosed

public boolean isClosed()

close

public void close()

Specified by:

close in interface AutoCloseable

size

public int size()

values

public Collection<Pool<T>.Entry> values()

dump

public void dump(Appendable out,
 String indent)
          throws IOException

Description copied from interface: Dumpable

Dump this object (and children) into an Appendable using the provided indent after any new lines. The indent should not be applied to the first object dumped.

Specified by:

dump in interface Dumpable

Parameters:

out - The appendable to dump to

indent - The indent to apply after any new lines.

Throws:

IOException - if unable to write to Appendable

toString

public String toString()

Overrides:

toString in class Object