[KAFKA-5258] move all partition and replica state transition rules into their states

• Type: Sub-task
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Fix Version/s: 0.11.0.0
• Assignee: Onur Karaman
• Reporter: Onur Karaman
• Created: 16/May/17 20:43
• Updated: 18/May/17 10:38
• Resolved: 18/May/17 10:37

Description

Today the PartitionStateMachine and ReplicaStateMachine defines and asserts the valid state transitions inline for each state, looking something like:

private def handleStateChange(...) {
  targetState match {
    case stateA => {
      assertValidPreviousStates(topicAndPartition, List(stateX, stateY, stateZ), stateA)
      // actual work
    }
    case stateB => {
      assertValidPreviousStates(topicAndPartition, List(stateD, stateE), stateB)
      // actual work
    }
  }
}

It would be cleaner to move all partition and replica state transition rules into their states and simply do the assertion at the top of the handleStateChange method like so:

private def handleStateChange(...) {
  assertValidTransition(targetState)
  targetState match {
    case stateA => {
      // actual work
    }
    case stateB => {
      // actual work
    }
  }
}

sealed trait State {
  def state: Byte
  def validPreviousStates: Set[State]
}

case object StateA extends State {
  val state: Byte = 1
  val validPreviousStates: Set[State] = Set(StateX)
}

case object StateB extends State {
  val state: Byte = 2
  val validPreviousStates: Set[State] = Set(StateX, StateY, StateZ)
}

Issue Links

• links to: GitHub Pull Request #3071