org.semanticweb.elk.util.concurrent.collections

Class ConcurrentLinkedActivationStack<E>

java.lang.Object

org.semanticweb.elk.util.concurrent.collections.ConcurrentLinkedActivationStack<E>

Type Parameters:

E - the type of elements in the stack

All Implemented Interfaces:

ActivationStack<E>

public class ConcurrentLinkedActivationStack<E>
extends Object
implements ActivationStack<E>

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

Constructors

Constructor and Description
ConcurrentLinkedActivationStack()

Method Summary

Modifier and Type	Method and Description
E	peek() Returns but does not remove the head element of the stack.
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

ConcurrentLinkedActivationStack

public ConcurrentLinkedActivationStack()

Method Detail

push

public boolean push(E element)

Description copied from interface: ActivationStack

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 clear in the beginning and is cleared every time ActivationStack.pop() returns null. Note that the stack might be empty in the sense that ActivationStack.pop() would return null, but not cleared.

Specified by:

push in interface ActivationStack<E>

Parameters:

element - the element to be inserted at the head of the stack

Returns:

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

peek

public E peek()

Description copied from interface: ActivationStack

Returns but does not remove the head element of the stack. This method does not modify the stack and calling this method does not have any effect on the results of the other methods.

Specified by:

peek in interface ActivationStack<E>

Returns:

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

pop

public E pop()

Description copied from interface: ActivationStack

Takes and removes the head element of the stack.

Specified by:

pop in interface ActivationStack<E>

Returns:

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