Module org.eclipse.jetty.util

Package org.eclipse.jetty.util

Class ConcurrentPool<P>

java.lang.Object

org.eclipse.jetty.util.ConcurrentPool<P>

Type Parameters:

P - the type of the pooled objects

All Implemented Interfaces:

Dumpable, Pool<P>

@ManagedObject
public class ConcurrentPool<P>
extends Object
implements Pool<P>, Dumpable

A concurrent implementation of Pool.

This implementation offers a number of strategies used to select the entry returned from acquire(), and its capacity is bounded to a max size.

When a pooled item is acquired from this pool, it is only held by a WeakReference, so that if it is collected before being released, then that leak is detected and the entry is removed (see getLeaked().

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	ConcurrentPool.ConcurrentEntry<E>	A Pool entry that holds metadata and a pooled object.
static enum	ConcurrentPool.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, Dumpable.DumpAppendable

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

Pool.Entry<E>, Pool.Factory<F>, Pool.Wrapper<W>

Field Summary

Fields

Modifier and Type	Field	Description
static final int	OPTIMAL_MAX_SIZE	ConcurrentPool internally needs to linearly scan a list to perform an acquisition.

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

LEGEND

Constructor Summary

Constructors

Constructor	Description
ConcurrentPool(ConcurrentPool.StrategyType strategyType, int maxSize)	Creates an instance with the specified strategy.
ConcurrentPool(ConcurrentPool.StrategyType strategyType, int maxSize, ToIntFunction<P> maxMultiplex)	Creates an instance with the specified strategy.

Method Summary

Modifier and Type	Method	Description
Pool.Entry<P>	acquire()	Acquires an entry from the pool.
void	dump(Appendable out, String indent)	Dump this object (and children) into an Appendable using the provided indent after any new lines.
int	getIdleCount()
int	getInUseCount()
long	getLeaked()
int	getMaxSize()
int	getReservedCount()
int	getTerminatedCount()
boolean	isTerminated()
protected void	leaked()
Pool.Entry<P>	reserve()	Creates a new disabled slot into the pool.
int	size()
Stream<Pool.Entry<P>>	stream()
Collection<Pool.Entry<P>>	terminate()	Terminates this Pool.
String	toString()

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

Methods inherited from interface org.eclipse.jetty.util.Pool

acquire

Field Details

OPTIMAL_MAX_SIZE

public static final int OPTIMAL_MAX_SIZE

ConcurrentPool internally needs to linearly scan a list to perform an acquisition. This list needs to be reasonably short otherwise there is a risk that scanning the list becomes a bottleneck. Instances created with a size at most this value should be immune to this problem.

See Also:

• Constant Field Values

Constructor Details

ConcurrentPool

public ConcurrentPool(ConcurrentPool.StrategyType strategyType,
 int maxSize)

Creates an instance with the specified strategy.

Parameters:

strategyType - the strategy to used to lookup entries

maxSize - the maximum number of pooled entries

ConcurrentPool

public ConcurrentPool(ConcurrentPool.StrategyType strategyType,
 int maxSize,
 ToIntFunction<P> maxMultiplex)

Creates an instance with the specified strategy. and a function that returns the max multiplex count for a given pooled object.

Parameters:

strategyType - the strategy to used to lookup entries

maxSize - the maximum number of pooled entries

maxMultiplex - a function that given the pooled object returns the max multiplex count

Method Details

getLeaked

@ManagedAttribute("number of entries leaked (not released nor referenced)")
public long getLeaked()

leaked

protected void leaked()

reserve

public Pool.Entry<P> reserve()

Description copied from interface: Pool

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().

Specified by:

reserve in interface Pool<P>

Returns:

a disabled entry that is contained in the pool, or null if the pool is terminated or if the pool cannot reserve an entry

acquire

public Pool.Entry<P> acquire()

Description copied from interface: Pool

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.

Specified by:

acquire in interface Pool<P>

Returns:

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

isTerminated

public boolean isTerminated()

Specified by:

isTerminated in interface Pool<P>

Returns:

whether this Pool has been terminated

See Also:

• Pool.terminate()

terminate

public Collection<Pool.Entry<P>> terminate()

Description copied from interface: Pool

Terminates this Pool.

All the entries are marked as terminated and cannot be acquired nor released, but only removed.

The returned list of all entries may be iterated to perform additional operations on the pooled objects.

The pool cannot be used anymore after it is terminated.

Specified by:

terminate in interface Pool<P>

Returns:

a list of all entries

size

public int size()

Specified by:

size in interface Pool<P>

Returns:

the current number of entries in this Pool

getMaxSize

public int getMaxSize()

Specified by:

getMaxSize in interface Pool<P>

Returns:

the maximum number of entries in this Pool

stream

public Stream<Pool.Entry<P>> stream()

Specified by:

stream in interface Pool<P>

Returns:

a Stream over the entries

getReservedCount

public int getReservedCount()

Specified by:

getReservedCount in interface Pool<P>

Returns:

the number of reserved entries

getIdleCount

public int getIdleCount()

Specified by:

getIdleCount in interface Pool<P>

Returns:

the number of idle entries

getInUseCount

public int getInUseCount()

Specified by:

getInUseCount in interface Pool<P>

Returns:

the number of in-use entries

getTerminatedCount

public int getTerminatedCount()

Specified by:

getTerminatedCount in interface Pool<P>

Returns:

the number of terminated entries

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