documentation-notes

A Day at the Races

* What are race conditions?
  * Simple example with changing a node
  * Simple example with a node being deleted
* What pattern do we use in ZK to manage this problem?

```ruby
def block_until_node_deleted(zk, abs_node_path)
  node_deletion_cb = lambda do |event|
    if event.node_deleted?
    queue.enq(:deleted) 
    else
    queue.enq(:deleted) unless exists?(abs_node_path, :watch => true)
    end
  end

subs << event_handler.register(abs_node_path, &node_deletion_cb)
```