volatile variables and memory barrier in java

Question

I\'ve got a data structure which consists of linked nodes. You can think of it as of a simple LinkedList. Each node of the list consists of some value and a next field pointing

Answer 1

Your root node actually does not need to be a node. You only need a reference to the first "real" node.

public class LinkedList {
  private volatile Node firstNode;
  ...
  addNode(Node node) {
    node.next = firstNode;
    firstNode = node;
  }
}

So you don't need to make the next field volatile in all your nodes; the nodes are not synchronized at all. You could use that class for the non-synchronized linked lists if you don't mind the cost of the volatile access to the first node. Or you could instead simply rewrite the class with a non-volatile firstNode for the non-synchronized version.