org.aredis.util.pool

Class AsyncObjectPool<E>

java.lang.Object

org.aredis.util.pool.AsyncObjectPool<E>

Type Parameters:

E -

Direct Known Subclasses:

LeakCheckingAsyncObjectPool

public class AsyncObjectPool<E>
extends Object

An fixed size Object pool with the feature of Async borrow used as connection pool by aredis for MULTI-EXEC transactions with WATCH commands. The pool assumes the object to be self managed. So it does not do things like validation or re-connections. It works by using a stack and a Q. The stack is used to store free objects and the Q for waiting users. Ideally one of the stack or Q are empty. A stack is used for the Objects so that the Most Recently used object is again re-used. This ensures that idle Objects can be timed out as it is done in AsyncRedisConnection.

Author:

suresh

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
protected static class	AsyncObjectPool.PoolMemberHolder<T> Class Holding pool members.

Field Summary

Fields

Modifier and Type	Field and Description
AtomicInteger	reconcileCount This is only intended for debugging purposes to measure how many times the relatively expensive call to ensureEmptyWaitersOrMembers is made.

Constructor Summary

Constructors

Constructor and Description
AsyncObjectPool(AsyncPoolMemberManager<E> pobjectManager, int ppoolSize, Executor ptaskExecutor) Creates an AsyncObject Pool.

Method Summary

Methods

Modifier and Type	Method and Description
E	asyncBorrow(AvailabeCallback<E> callback) Asynchronous borrow.
Future<E>	borrow(long timeoutMillis) Borrow returning a Future
int	getPoolSize() Get the current pool size.
protected Iterator<AsyncObjectPool.PoolMemberHolder<E>>	memberIterator() Iterator over the current pool members.
void	printStatus() Prints a message using System.out.println giving the number of waiting users and free member Objects.
void	returnToPool(E member) Return a member Object back to the pool
void	setPoolSize(int newSize) Change the pool size
E	syncBorrow(long timeoutMillis) Synchronously borrow from the pool.

Methods inherited from class java.lang.Object

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

Field Detail

reconcileCount

public AtomicInteger reconcileCount

This is only intended for debugging purposes to measure how many times the relatively expensive call to ensureEmptyWaitersOrMembers is made. To track Assign this to an AtomicInteger.

Constructor Detail

AsyncObjectPool

public AsyncObjectPool(AsyncPoolMemberManager<E> pobjectManager,
               int ppoolSize,
               Executor ptaskExecutor)

Creates an AsyncObject Pool.

Parameters:

pobjectManager - Object Manager to Create and Destroy Pool member objects

ppoolSize - Pool Size

ptaskExecutor - Executor to use. Mandatory in case of async usage, not needed otherwise

Method Detail

syncBorrow

public E syncBorrow(long timeoutMillis)

Synchronously borrow from the pool.

Parameters:

timeoutMillis - Max time to wait

Returns:

member Object from pool or null if timeout has expired

borrow

public Future<E> borrow(long timeoutMillis)

Borrow returning a Future

Parameters:

timeoutMillis - Max time intended to wait. The actual timeout on the get call on the future object should be at least 10 ms greater than this value. Otherwise the member Object would returning after the timeout passed to get will be considered as borrowed by the pool leading to a leak. The get method on the future may return a null if this timeout is past.

Returns:

Future result for the borrowed Object

asyncBorrow

public E asyncBorrow(AvailabeCallback<E> callback)

Asynchronous borrow. Note that if a member Object is immediately available in pool it will be returned and the callback will not be made.

Parameters:

callback - Callback which will be invoked in case with an available member in case no pool member is currently free

Returns:

member Object if immediately available or null if not

returnToPool

public void returnToPool(E member)

Return a member Object back to the pool

Parameters:

member - Object to return

setPoolSize

public void setPoolSize(int newSize)

Change the pool size

Parameters:

newSize - New Pool Size

memberIterator

protected Iterator<AsyncObjectPool.PoolMemberHolder<E>> memberIterator()

Iterator over the current pool members.

Returns:

Iterator of PoolMembers

getPoolSize

public int getPoolSize()

Get the current pool size.

Returns:

Pool Size

printStatus

public void printStatus()

Prints a message using System.out.println giving the number of waiting users and free member Objects.