ConcurrentLinkedPool (Vibur Object Pool 8.0 API)

java.lang.Object
- org.vibur.objectpool.ConcurrentLinkedPool<T>

Type Parameters:

T - the type of objects held in this object pool

All Implemented Interfaces:

PoolService<T>
```
public class ConcurrentLinkedPool<T>
extends Object
implements PoolService<T>
```
An object pool based on a ConcurrentLinkedQueue guarded by a Semaphore. This object pool does not provide any validation whether the currently restored object has been taken before that from the object pool or whether this object is currently in taken state. Correct usage of the pool is established by programming convention in the application.
This object pool provides support for fairness with regards to the waiting takers threads. The creation of new objects and their lifecycle are controlled by a supplied during the object pool creation time PoolObjectFactory. If a Listener instance has been supplied when instantiating the pool, its methods will be when the pool executes take or restore operations.
This object pool has support for shrinking (reduction) of the number of allocated on the pool objects. Note that the shrinking may reduce the createdTotal() to less than the pool initialSize().

Author:

Simeon Malchev

Constructor Summary

Constructors
Constructor and Description
`ConcurrentLinkedPool(PoolObjectFactory<T> poolObjectFactory, int initialSize, int maxSize, boolean fair)` Creates a new `ConcurrentLinkedPool` with the given `PoolObjectFactory`, initial and max sizes, fairness setting.
`ConcurrentLinkedPool(PoolObjectFactory<T> poolObjectFactory, int initialSize, int maxSize, boolean fair, Listener<T> listener)` Creates a new `ConcurrentLinkedPool` with the given `PoolObjectFactory`, initial and max sizes, fairness setting.

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`int`	`createdTotal()` Returns the total number of created objects which currently exist for this object pool.
`int`	`drainCreated()` Tries to remove (and destroy) as many created objects from this object pool as possible.
`int`	`initialSize()` Returns the `initialSize` of this object pool at construction time.
`boolean`	`isFair()` Returns the fairness setting of this object pool.
`boolean`	`isTerminated()` Returns the current terminated state of this object pool.
`Listener<T>`	`listener()` Returns the `Listener` interface instance associated with this object pool, if any.
`int`	`maxSize()` Returns the `maxSize` of this object pool.
`protected T`	`newObject()`
`int`	`reduceCreated(int reduction, boolean ignoreInitialSize)` Tries to remove (and destroy) up to `reduction` objects from the object pool.
`int`	`remainingCapacity()` Returns the remaining capacity of this object pool, i.e.
`int`	`remainingCreated()` Returns the number of remaining created objects which currently exist in this object pool.
`void`	`restore(T object)` Restores (returns) an object to the object pool.
`void`	`restore(T object, boolean valid)` Restores (returns) an object to the object pool.
`T`	`take()` Takes an object from the object pool if there is such available.
`int`	`taken()` Returns the number of objects taken from this object pool.
`T`	`takeUninterruptibly()` Takes an object from the object pool if there is such available.
`void`	`terminate()` Terminates this object pool.
`String`	`toString()`
`T`	`tryTake()` Tries to take an object from the object pool if there is one which is immediately available.
`T`	`tryTake(long timeout, TimeUnit unit)` Takes an object from the object pool if there is such available.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

- Constructor Detail
  - ConcurrentLinkedPool
```
public ConcurrentLinkedPool(PoolObjectFactory<T> poolObjectFactory,
                            int initialSize,
                            int maxSize,
                            boolean fair)
```
    Creates a new ConcurrentLinkedPool with the given PoolObjectFactory, initial and max sizes, fairness setting.
    
    Parameters:
    
    poolObjectFactory - the factory which will be used to create new objects in this object pool as well as to control their lifecycle
    
    initialSize - the object pool initial size, i.e. the initial number of allocated in the object pool objects; this parameter never changes
    
    maxSize - the object pool max size, i.e. the max number of allocated in the object pool objects; this parameter never changes
    
    fair - the object pool fairness setting with regards to waiting threads
    
    Throws:
    
    IllegalArgumentException - if one of the following holds:
    initialSize < 0 || maxSize < 1 || maxSize < initialSize
    
    NullPointerException - if poolObjectFactory is null
  - ConcurrentLinkedPool
```
public ConcurrentLinkedPool(PoolObjectFactory<T> poolObjectFactory,
                            int initialSize,
                            int maxSize,
                            boolean fair,
                            Listener<T> listener)
```
    Creates a new ConcurrentLinkedPool with the given PoolObjectFactory, initial and max sizes, fairness setting.
    
    Parameters:
    
    poolObjectFactory - the factory which will be used to create new objects in this object pool as well as to control their lifecycle
    
    initialSize - the object pool initial size, i.e. the initial number of allocated in the object pool objects; this parameter never changes
    
    maxSize - the object pool max size, i.e. the max number of allocated in the object pool objects; this parameter never changes
    
    fair - the object pool fairness setting with regards to waiting threads
    
    listener - if not null, this listener instance methods will be called when the pool executes take or restore operations
    
    Throws:
    
    IllegalArgumentException - if one of the following holds:
    initialSize < 0 || maxSize < 1 || maxSize < initialSize
    
    NullPointerException - if poolObjectFactory is null
- Method Detail
  - take
```
public T take()
```
    Takes an object from the object pool if there is such available. This is a blocking call which waits indefinitely until an object becomes available. If the calling thread is interrupted while waiting this call will return null and the thread's interrupted status will be set to true.
    
    Specified by:
    
    take in interface PoolService<T>
    
    Returns:
    
    an object taken from the object pool or null if was interrupted while waiting
  - takeUninterruptibly
```
public T takeUninterruptibly()
```
    Takes an object from the object pool if there is such available. This is a blocking call which waits indefinitely until an object becomes available.
    
    Specified by:
    
    takeUninterruptibly in interface PoolService<T>
    
    Returns:
    
    an object taken from the object pool
  - tryTake
```
public T tryTake(long timeout,
                 TimeUnit unit)
```
    Takes an object from the object pool if there is such available. This is a blocking call which waits up to the specified timeout for an object to become available. If the calling thread is interrupted while waiting this call will return null and the thread's interrupted status will be set to true.
    
    Specified by:
    
    tryTake in interface PoolService<T>
    
    Parameters:
    
    timeout - the maximum time to wait for an object to become available in the object pool
    
    unit - the time unit of the timeout argument
    
    Returns:
    
    an object taken from the object pool or null if the specified timeout expires or if it was interrupted while waiting
  - tryTake
```
public T tryTake()
```
    Tries to take an object from the object pool if there is one which is immediately available. Returns null if no object is available at the moment of the call.
    
    Specified by:
    
    tryTake in interface PoolService<T>
    
    Returns:
    
    an object from the object pool or null if there is no object available in the object pool
  - newObject
```
protected T newObject()
```
  - restore
```
public void restore(T object)
```
    Restores (returns) an object to the object pool. The object pool will not validate whether the currently restored object has been taken before that from this object pool or whether it is currently in taken state. Equivalent to calling restore(Object, true).
    
    Specified by:
    
    restore in interface PoolService<T>
    
    Parameters:
    
    object - an object to be restored (returned) to this object pool
  - restore
```
public void restore(T object,
                    boolean valid)
```
    Restores (returns) an object to the object pool. The object pool will not validate whether the currently restored object has been taken before that from this object pool or whether it is currently in taken state.
    
    Specified by:
    
    restore in interface PoolService<T>
    
    Parameters:
    
    object - an object to be restored (returned) to this object pool
    
    valid - if true the restored object is presumed to be in valid (healthy) state, otherwise it is treated as invalid
  - listener
```
public Listener<T> listener()
```
    Returns the Listener interface instance associated with this object pool, if any.
    
    Specified by:
    
    listener in interface PoolService<T>
    
    Returns:
    
    see above. null means no Listener is associated with this object pool.
  - taken
```
public int taken()
```
    Returns the number of objects taken from this object pool. This number is less than or equal to the object pool PoolService.createdTotal(). Typically used for testing and debugging purposes.
    
    Specified by:
    
    taken in interface PoolService<T>
    
    Returns:
    
    the number of objects taken from this object pool
  - remainingCreated
```
public int remainingCreated()
```
    Returns the number of remaining created objects which currently exist in this object pool. This number is less than or equal to the object pool PoolService.remainingCapacity(). Typically used for testing and debugging purposes.
    
    Specified by:
    
    remainingCreated in interface PoolService<T>
    
    Returns:
    
    the number of remaining created objects in this object pool
  - drainCreated
```
public int drainCreated()
```
    Tries to remove (and destroy) as many created objects from this object pool as possible. May bring the object pool PoolService.createdTotal() to a number less then its PoolService.initialSize().
    
    Specified by:
    
    drainCreated in interface PoolService<T>
    
    Returns:
    
    the actual amount of objects removed (and destroyed)
  - toString
```
public String toString()
```
    Overrides:
    
    toString in class Object
  - createdTotal
```
public int createdTotal()
```
    Returns the total number of created objects which currently exist for this object pool. This number is equal to PoolService.taken() + PoolService.remainingCreated(). Typically used for testing and debugging purposes.
    
    Specified by:
    
    createdTotal in interface PoolService<T>
    
    Returns:
    
    the total number of created objects for this object pool
  - remainingCapacity
```
public int remainingCapacity()
```
    Returns the remaining capacity of this object pool, i.e. the number of objects which could be taken from this object pool without blocking. It is not guaranteed that all these objects exist at the time of the call (i.e. are already created) in the object pool - some of them might be created on demand upon take requests. Also see PoolService.remainingCreated(). Typically used for testing and debugging purposes.
    
    Specified by:
    
    remainingCapacity in interface PoolService<T>
    
    Returns:
    
    the object pool remaining capacity
  - initialSize
```
public int initialSize()
```
    Returns the initialSize of this object pool at construction time. This parameter never changes.
    
    Specified by:
    
    initialSize in interface PoolService<T>
    
    Returns:
    
    the object pool initialSize
  - maxSize
```
public int maxSize()
```
    Returns the maxSize of this object pool. This parameter never changes.
    
    Specified by:
    
    maxSize in interface PoolService<T>
    
    Returns:
    
    the object pool maxSize
  - reduceCreated
```
public int reduceCreated(int reduction,
                         boolean ignoreInitialSize)
```
    Tries to remove (and destroy) up to reduction objects from the object pool. May bring the object pool PoolService.createdTotal() to a number less then its PoolService.initialSize().
    
    Specified by:
    
    reduceCreated in interface PoolService<T>
    
    Parameters:
    
    reduction - the desired amount of objects to be removed
    
    ignoreInitialSize - specifies whether the PoolService.createdTotal() may be reduced to less than PoolService.initialSize()
    
    Returns:
    
    the actual amount of objects removed
  - terminate
```
public void terminate()
```
    Terminates this object pool. Once terminated the object pool cannot be more revived. All take and restore operations called on a terminated object pool should throw an exception or be ignored. Invocation has no additional effect if already terminated.
    
    Specified by:
    
    terminate in interface PoolService<T>
  - isTerminated
```
public boolean isTerminated()
```
    Returns the current terminated state of this object pool.
    
    Specified by:
    
    isTerminated in interface PoolService<T>
    
    Returns:
    
    true if the object pool is terminated
  - isFair
```
public boolean isFair()
```
    Returns the fairness setting of this object pool.
    
    Specified by:
    
    isFair in interface PoolService<T>
    
    Returns:
    
    true if the object pool is fair to waiting taker threads

Class ConcurrentLinkedPool<T>

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Detail

ConcurrentLinkedPool

ConcurrentLinkedPool

Method Detail

take

takeUninterruptibly

tryTake

tryTake

newObject

restore

restore

listener

taken

remainingCreated

drainCreated

toString

createdTotal

remainingCapacity

initialSize

maxSize

reduceCreated

terminate

isTerminated

isFair