com.protomatter.pool
Class SimpleObjectPool

java.lang.Object
  |
  +--com.protomatter.pool.SimpleObjectPool

All Implemented Interfaces:

ObjectPool

Direct Known Subclasses:

GrowingObjectPool

public abstract class SimpleObjectPool

extends java.lang.Object

implements ObjectPool

A minimal implementation of an ObjectPool. This class provides a non-growing pool that sleeps the threads that are trying to check something out of the pool, and wakes them up in-order when something is checked back in.

See Also:

ObjectPool

Field Summary

protected java.lang.Object

sync

Constructor Summary

SimpleObjectPool()
Initialize the object pool.

SimpleObjectPool(boolean monitorCheckedOutObjects)
Initialize the object pool.

Method Summary

void	checkin(ObjectPoolObject opo) Check an object back into the pool.
protected abstract void	checkinPoolObject(ObjectPoolObject o) This method needs to be implemented by sub-classes.
ObjectPoolObject	checkout() Implements a first in, first out reservation scheme.
protected abstract ObjectPoolObject	createObjectPoolObject() To be implemented by sub-classes.
protected java.util.List	getCheckedOutObjects() Get the list of objects that are currently checked out of the pool.
protected abstract ObjectPoolObject	getNextPoolObject() This method needs to be implemented by sub-classes.
int	getNumWaiters() Get the number of threads waiting for an object to become available.
int	getObjectsInUse() Get the number of objects that are currently checked out.
protected java.lang.Object	getSyncObject() Get a reference to the object being used as a synchronization lock.

Methods inherited from class java.lang.Object

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

Methods inherited from interface com.protomatter.pool.ObjectPool

init, reInitializeObjectPool

Field Detail

sync

protected java.lang.Object sync

Constructor Detail

SimpleObjectPool

public SimpleObjectPool()

Initialize the object pool. Checked out objects will be monitored.

SimpleObjectPool

public SimpleObjectPool(boolean monitorCheckedOutObjects)

Initialize the object pool. Checked out objects will be monitored if monitorCheckedOutObjects is true.

Method Detail

getSyncObject

protected java.lang.Object getSyncObject()

Get a reference to the object being used as a synchronization lock. Subclasses that need to lock the operation of the pool while they perform maintenance should synchronize on this object and then manipulate the pool.

getNumWaiters

public int getNumWaiters()

Get the number of threads waiting for an object to become available.

getObjectsInUse

public int getObjectsInUse()

Get the number of objects that are currently checked out.

Specified by:

getObjectsInUse in interface ObjectPool

checkout

public ObjectPoolObject checkout()
                          throws java.lang.Exception

Implements a first in, first out reservation scheme. If no threads are waiting for the object, then the caller never blocks. If there are waiters, then the caller "get's in line," and waits for their turn with the object.

Specified by:

checkout in interface ObjectPool

Throws:

java.lang.Exception - If there is a problem checking an object out of the pool.

checkin

public void checkin(ObjectPoolObject opo)
             throws java.lang.Exception

Check an object back into the pool. If there are threads in the wait queue, the thread that has been waiting longest will get the shared object next. The waiter may not receive the shared object immediately, however.

Specified by:

checkin in interface ObjectPool

Throws:

java.lang.Exception - If there was a problem checking in the object.

getCheckedOutObjects

protected java.util.List getCheckedOutObjects()

Get the list of objects that are currently checked out of the pool.

getNextPoolObject

protected abstract ObjectPoolObject getNextPoolObject()
                                               throws java.lang.Exception

This method needs to be implemented by sub-classes. It should return the next element in the pool, or null if the pool is empty. Growable implementations should use this method to add more elements to the pool.

Throws:

java.lang.Exception - If there is a problem getting the next object for the pool -- this is implementation specific.

checkinPoolObject

protected abstract void checkinPoolObject(ObjectPoolObject o)
                                   throws java.lang.Exception

This method needs to be implemented by sub-classes. It should add the given ObjectPoolObject to the pool.

Throws:

java.lang.Exception - If there is a problem checking in the object -- this is implementation specific.

createObjectPoolObject

protected abstract ObjectPoolObject createObjectPoolObject()
                                                    throws java.lang.Exception

To be implemented by sub-classes. This is a factory method for creating objects that go in this pool.

Throws:

java.lang.Exception - If there is a problem creating the next object for the pool -- this is implementation specific.