tachyon.resource

Class ResourcePool<T>

java.lang.Object

tachyon.resource.ResourcePool<T>

Type Parameters:

T - The type of resource this pool manages.

public abstract class ResourcePool<T>
extends Object

Class representing a pool of resources to be temporarily used and returned. Inheriting classes must implement the close method as well as initialize the resources in the constructor. The implemented methods are thread-safe and inheriting classes should also written in a thread-safe manner. See tachyon.client.file.FileSystemMasterClientPool as an example.

Field Summary

Fields

Modifier and Type	Field and Description
protected Object	mCapacityLock
protected int	mCurrentCapacity
protected int	mMaxCapacity
protected BlockingQueue<T>	mResources

Constructor Summary

Constructors

Modifier	Constructor and Description
	ResourcePool(int maxCapacity) Creates a ResourcePool instance with the specified capacity.
protected	ResourcePool(int maxCapacity, BlockingQueue<T> resources) Internal constructor that can provide an object to be used for the internal queue.

Method Summary

Methods

Modifier and Type	Method and Description
T	acquire() Acquires an object of type T from the pool.
abstract void	close() Closes the resource pool.
protected abstract T	createNewResource() Creates a new resource which will be added to the resource pool after the user is done using it.
void	release(T resource) Releases an object of type T, this must be called after the thread is done using a resource obtained by acquire.

Methods inherited from class java.lang.Object

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

Field Detail

mCapacityLock

protected final Object mCapacityLock

mMaxCapacity

protected final int mMaxCapacity

mResources

protected final BlockingQueue<T> mResources

mCurrentCapacity

protected int mCurrentCapacity

Constructor Detail

ResourcePool

public ResourcePool(int maxCapacity)

Creates a ResourcePool instance with the specified capacity.

Parameters:

maxCapacity - The maximum of resources in this pool.

ResourcePool

protected ResourcePool(int maxCapacity,
            BlockingQueue<T> resources)

Internal constructor that can provide an object to be used for the internal queue.

Parameters:

maxCapacity - The maximum of resources in this pool.

resources - Blocking queue to use.

Method Detail

acquire

public T acquire()

Acquires an object of type T from the pool. This operation is blocking if no resource is available. Each call of acquire() should be paired with another call of release(T) after the use of this resource completes to return this resource to the pool.

Returns:

a resource taken from the pool

close

public abstract void close()

Closes the resource pool. After this call, the object should be discarded. Inheriting classes should clean up all their resources here.

release

public void release(T resource)

Releases an object of type T, this must be called after the thread is done using a resource obtained by acquire.

Parameters:

resource - the resource to be released, it should not be reused after calling this method

createNewResource

protected abstract T createNewResource()

Creates a new resource which will be added to the resource pool after the user is done using it. This method should only be called when the capacity of the pool has not been reached. If creating the resource will take a significant amount of time, the inheriting class should avoid calling this method and instead initialize all the resources in the constructor.

Returns:

a resource which will be added to the pool of resources