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https://issues.apache.org/jira/browse/HELIX-144?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13719050#comment-13719050
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kishore gopalakrishna commented on HELIX-144:
---------------------------------------------
Here is the clojure version from Kyle on validating the statemodel.
https://gist.github.com/aphyr/ab2d1cd9da8879b408b2
We should also take in the statemodel class and verify that it confirms to this
FSM
(defn fsm-definition
"An FSM definition is a named collection of states, describing their
priorities, transitions, constraints, etc. It looks like:
{:name :my-fsm
:states {:master {:priority 1
:transitions :slave
:upper-bound 1}
:slave {:priority 2
:transitions [:master :offline]
:upper-bound :R}
:offline {:transitions :slave
:initial? true}}})
This function validates the structure of an FSM definition, blessing it for
use later."
[d]
; Has a name
(assert (or (string? (:name d))
(keyword? (:name d))))
(let [states (:states d)]
; Has states
(assert (map? states))
; Normalize transitions
(let [states (->> states
(map (fn [[k v]]
[k (assoc v :transitions
(let [t (:transitions v)]
(cond
(nil? t) []
(sequential? t) t
:else [t])))]))
(into {}))
; Compute all state names
state-names (->> (keys states)
(concat (mapcat :transitions (vals states)))
(remove nil?)
set)]
; Exactly one initial state.
(let [initials (->> d :states vals (filter :initial?) count)]
(assert (= 1 initials)
(str "needs exactly one initial state; has " initials)))
; Validate state names
(dorun (map validate-state-name state-names))
; Has a DROPPED state
(assert (:DROPPED states) "must have a :DROPPED state")
; All states can reach DROPPED
(doseq [state state-names]
(assert (contains? (reachable-states {:states states} state)
:DROPPED)
(str "state " state " has no path to :DROPPED")))
; No transitions to states that aren't defined.
(assert (= state-names (set (keys states))))
; Done
(assoc d :states states))))
> Need to validate StateModelDefinition when adding new StateModelDefinition to
> Cluster
> -------------------------------------------------------------------------------------
>
> Key: HELIX-144
> URL: https://issues.apache.org/jira/browse/HELIX-144
> Project: Apache Helix
> Issue Type: Bug
> Reporter: dafu
>
> we see that when DROPPED state is not in the StateModelDefinition, partition
> will fail to be dropped. this causes problem when we are using auto_rebalance
> mode, because we are dropping mappings and assign new mappings to nodes.
> things need to verify:
> 1) state transitions are all valid, no self loop/loop, no unreachable state
> 2) state meta is valid
> 3) drop state included
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