following changes
- introduced notion of event bus with publish, subscribe, unsubscribe
semantics
- a plug-in can implement the EventBus abstraction to provide event
bug to CloudStack
- A rabbitMQ based plug-in that can interact with AMQP servers to
provide message broker based event-bug
- stream lines, action events, usage events, alerts publishing in to
convineance classed which are also used to publish corresponding
event on to event bus
- introduced notion of state change event. On a state change, in the
state machine corrsponding to the resource, a state change event is
published on the event bug
- associated a state machined with Snapshot and Network objects
- Virtual Machine, Volume, Snaphost, Network object state changes wil
result in a state change event
The basic idea behind this is, deploy a fix sized threadpool for updating RvR
status, then using producer/consumer model. There is a global configuration
router.check.poolsize(10 by default) to control the pool size.
Using pool size 100 for 1000 RvR is tested with simulator and works well.
Also we can adjust the global configuration option router.check.interval to e.g.
60s from default 30s to mitigate the issue.
