org.semanticweb.elk.util.concurrent.collections
Class ActivationStack<E>

java.lang.Object
  org.semanticweb.elk.util.concurrent.collections.ActivationStack<E>

Type Parameters:

E - the type of elements in the stack

public class ActivationStack<E>
extends Object

A thread-safe implementation of stack based on the non-blocking Treiber's Algorithm (Treiber, 1986). The implementation allows to check when the pushed element is the first element in the stack. This stack does not allow storing null values.

Author:

"Yevgeny Kazakov"

Constructor Summary

ActivationStack()

Method Summary

E	peek()
E	pop() Takes and removes the head element of the stack.
boolean	push(E element) Inserts the given element at the head of the stack.

Methods inherited from class java.lang.Object

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

Constructor Detail

ActivationStack

public ActivationStack()

Method Detail

push

public boolean push(E element)

Inserts the given element at the head of the stack. Returns true if this is the first element inserted after the stack has been cleared. A stack is cleared after it has been constructed or after pop() returns null. Note that the stack might be empty in the sense that the next call to pop() should return null, but not cleared. In this case the stack is cleared only after pop() returns null.

Parameters:

element -

Returns:

true if this is the first element inserted after the stack has been cleared.

Throws:

IllegalArgumentException - if null element is inserted

peek

public E peek()

pop

public E pop()

Takes and removes the head element of the stack.

Returns:

the head element in the stack or null if there are no elements in the stack