[GitHub] [cassandra-accord] belliottsmith commented on pull request #15: Routables refactor

[GitBox <gi...@apache.org>]

belliottsmith commented on PR #15:
URL: https://github.com/apache/cassandra-accord/pull/15#issuecomment-1319955179

   One issue with this refactor is that it exposes us potentially quite extensively to the "type pollution" bug in the JVM whereby instanceof and checked casts may be costly.
   
   Now, at the very least in C* this will be somewhat mitigated by having `RoutingKey` and `Key` split their hierarchy - though I believe we currently implement that with a shared interface as well, we can perhaps migrate to a shared abstract class.
   But that still leaves 2-3 interfaces we may regularly perform checked-casts on, most notably as part of generic type parameters, e.g. in Sortables, Routables, Route, etc.
   
   MOST of these locations SHOULD be eliminated by HotSpot, and I will take a look at some of the call-sites via print assembly. But we are unlikely to readily eliminate them all.
   
   ```
   1:	accord.impl.IntHashKey
   Count:	426454
   Types:
   	accord.primitives.SortableKey
   	accord.api.RoutingKey
   	accord.api.Key
   	accord.primitives.Routable
   	accord.primitives.Seekable
   Traces:
   	accord.impl.IntHashKey.compareTo(IntHashKey.java:35)
   		class: accord.primitives.SortableKey
   		count: 156796
   	accord.primitives.KeyRoute.<init>(KeyRoute.java:17)
   		class: accord.api.RoutingKey
   		count: 118564
   	accord.impl.list.ListUpdate.slice(ListUpdate.java:57)
   		class: accord.api.Key
   		count: 38289
   	accord.local.Node.trySelectProgressKey(Node.java:440)
   		class: accord.primitives.Routable
   		count: 34471
   	accord.primitives.Deps.slice(Deps.java:466)
   		class: accord.api.Key
   		count: 29730
   	accord.impl.list.ListUpdate.slice(ListUpdate.java:56)
   		class: accord.primitives.SortableKey
   		count: 13098
   	accord.primitives.Range$EndInclusive.compareTo(Range.java:36)
   		class: accord.primitives.SortableKey
   		count: 11565
   	accord.primitives.Deps.toRoutables(Deps.java:1001)
   		class: accord.api.Key
   		count: 6177
   	accord.impl.list.ListQuery.compute(ListQuery.java:50)
   		class: accord.api.Key
   		count: 4598
   	accord.burn.BurnTest.randomKey(BurnTest.java:108)
   		class: accord.api.Key
   		count: 3000
   	accord.burn.BurnTest.lambda$burn$3(BurnTest.java:218)
   		class: accord.api.Key
   		count: 2238
   	accord.local.CommandStore.hashIntersects(CommandStore.java:100)
   		class: accord.primitives.SortableKey
   		count: 1987
   	accord.burn.BurnTest.generate(BurnTest.java:92)
   		class: accord.api.Key
   		count: 1929
   	accord.impl.list.ListUpdate.apply(ListUpdate.java:46)
   		class: accord.api.Key
   		count: 1877
   	accord.local.Node.trySelectHomeKey(Node.java:401)
   		class: accord.primitives.Seekable
   		count: 1645
   	accord.impl.InMemoryCommandStore$State.lambda$commandsForKey$1(InMemoryCommandStore.java:102)
   		class: accord.api.Key
   		count: 458
   	accord.coordinate.Invalidate.invalidate(Invalidate.java:167)
   		class: accord.primitives.Routable
   		count: 18
   	accord.impl.SimpleProgressLog$BlockingState.invalidate(SimpleProgressLog.java:477)
   		class: accord.primitives.Routable
   		count: 14
   ```


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