com.bigdata.relation.accesspath

Class ThreadLocalBufferFactory<T extends IBuffer<E>,E>

java.lang.Object

com.bigdata.relation.accesspath.ThreadLocalBufferFactory<T,E>

Type Parameters:

T - The generic type of the thread-local object.

public abstract class ThreadLocalBufferFactory<T extends IBuffer<E>,E>
extends Object

A factory pattern for per-thread objects whose life cycle is tied to some container. The pool can be torn down when the container is torn down, which prevents its thread-local references from escaping.

Note: This implementation uses a true thread local buffers managed by a ConcurrentHashMap. This approach has approximately 3x higher concurrency than striped locks. The advantage of striped locks is that you can directly manage the #of buffers when when the threads using those buffers is unbounded. However, doing so could lead to deadlock since two threads can be hashed onto the same buffer object.

Version:

$Id: ThreadLocalBufferFactory.java 3500 2010-09-03 00:27:45Z thompsonbry $

Author:

thompsonbry@users.sourceforge.net

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	ThreadLocalBufferFactory()
protected	ThreadLocalBufferFactory(int initialCapacity, float loadFactor, int concurrencyLevel)

Method Summary

Methods

Modifier and Type	Method and Description
void	add(E e) Add the element to the thread-local buffer.
void	flush() Flush each of the unsynchronized buffers onto their backing synchronized buffer.
T	get() Return a thread-local buffer
protected abstract void	halted() Test to see if the process has been halted.
protected abstract T	initialValue() Create and return a new object.
void	reset() Reset each of the synchronized buffers, discarding their buffered writes.
int	size() Return the #of thread-local objects.

Methods inherited from class java.lang.Object

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

Constructor Detail

ThreadLocalBufferFactory

protected ThreadLocalBufferFactory()

ThreadLocalBufferFactory

protected ThreadLocalBufferFactory(int initialCapacity,
                        float loadFactor,
                        int concurrencyLevel)

Method Detail

size

public final int size()

Return the #of thread-local objects.

add

public void add(E e)

Add the element to the thread-local buffer.

Parameters:

e - An element.

Throws:

IllegalStateException - if the factory is asynchronously closed.

get

public final T get()

Return a thread-local buffer

Returns:

The thread-local buffer.

Throws:

RuntimeException - if the join is halted.

flush

public void flush()

Flush each of the unsynchronized buffers onto their backing synchronized buffer.

Throws:

RuntimeException - if the join is halted.

reset

public void reset()

Reset each of the synchronized buffers, discarding their buffered writes.

Note: This method is used during error processing, therefore it DOES NOT check JoinTask.halt.

initialValue

protected abstract T initialValue()

Create and return a new object.

halted

protected abstract void halted()

Test to see if the process has been halted.

See Also:

Haltable.halted()