Binding bug

[lxl706423651]

Suppose I currently have two bindings: Binding('vnod_1', filter=Filter(asn=151, nodeName='host_1')) and Binding('vnod_11', filter=Filter(asn=151, nodeName='host_11')). Since the default value of Binding is Action.RANDOM, the system will create a candidate node list for each virtual node (vnod) during the binding process. At this point, the candidate node list for vnod_1 is [host_1, host_11], while the candidate node list for vnod_11 is [host_11]. If vnod_1 is randomly bound to host_11, it will result in vnod_11 having no available nodes to bind to.

[kevin-w-du]

The problem is that the nodeName field is supposed to be a regular expression. By using host_1, we actually created an ambiguity, meaning any node name with the host_1 substring should match. To avoid this problem, we can use ^host_1$, instead of using host_1. This way, only host_1 will match, not host_11.

We do want to support the regular expression in Filter, so right now, we could not find a better solution, other than asking users to put ^ (start symbol) and $ (end symbol) in the expression if they want exact match.