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improve paxos interface by caching proposed values
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Modules/RDTs/src/test/scala/test/rdts/protocols/SimplePaxosTest.scala
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| package test.rdts.protocols.simplified | ||
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| import rdts.base.{Bottom, LocalUid, Uid} | ||
| import rdts.datatypes.GrowOnlyMap | ||
| import rdts.datatypes.experiments.protocols.simplified.Paxos | ||
| import rdts.datatypes.experiments.protocols.simplified.Paxos.{*, given} | ||
| import rdts.time.Dots | ||
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| import scala.math.Ordering.Implicits.infixOrderingOps | ||
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| class SimplePaxosTest extends munit.FunSuite { | ||
| given Bottom[Int] with | ||
| override def empty: Int = Int.MinValue | ||
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| given dots: Dots = Dots.empty | ||
| val id1 = LocalUid.gen() | ||
| val id2 = LocalUid.gen() | ||
| val id3 = LocalUid.gen() | ||
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| given members: Set[Uid] = Set(id1, id2, id3).map(_.uid) | ||
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| var emptyPaxosObject: Paxos[Int] = Paxos.init(members) | ||
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| // test("Merge fails with different members") { | ||
| // val p1: Paxos[Int] = Paxos.unchanged.copy(members = Set(id1).map(_.uid)) | ||
| // val p2: Paxos[Int] = Paxos.unchanged.copy(members = Set(id2).map(_.uid)) | ||
| // interceptMessage[IllegalArgumentException]( | ||
| // "requirement failed: cannot merge two Paxos instances with differing members" | ||
| // ) { | ||
| // p1 `merge` p2 | ||
| // } | ||
| // } | ||
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| test("Paxos for 3 participants without errors") { | ||
| var a: Paxos[Int] = emptyPaxosObject | ||
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| val proposal = a.chooseProposalNumber(using id1) | ||
| a = a `merge` a.prepare()(using id1) | ||
| a = a `merge` a.upkeep()(using id1) `merge` a.upkeep()(using id2) `merge` a.upkeep()(using id3) | ||
| assertEquals(a.read, None) | ||
| a = a `merge` a.propose(proposal, 1)(using id1) | ||
| a = a `merge` a.upkeep()(using id1) `merge` a.upkeep()(using id2) `merge` a.upkeep()(using id3) | ||
| assertEquals(a.read, Some(1)) | ||
| } | ||
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| test("newer proposal numbers are bigger") { | ||
| var testPaxosObject = emptyPaxosObject | ||
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| testPaxosObject = testPaxosObject.merge(testPaxosObject.prepare()(using id1)) | ||
| val firstProposalNumber = testPaxosObject.prepares.head.proposal | ||
| val secondProposalNumber = testPaxosObject.chooseProposalNumber(using id1) | ||
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| assert(firstProposalNumber < secondProposalNumber) | ||
| } | ||
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| test("No changes for older proposals") { | ||
| var testPaxosObject1 = emptyPaxosObject | ||
| // replica 1 sends prepare | ||
| testPaxosObject1 = testPaxosObject1.merge(testPaxosObject1.prepare()(using id1)) | ||
| // replica 2 sends prepare | ||
| testPaxosObject1 = testPaxosObject1.merge(testPaxosObject1.prepare()(using id2)) | ||
| testPaxosObject1 = | ||
| testPaxosObject1.merge(testPaxosObject1.upkeep()(using id1)).merge(testPaxosObject1.upkeep()(using id2)) | ||
| var testPaxosObject2 = emptyPaxosObject | ||
| // replica 3 sends prepare, with smaller proposal number | ||
| testPaxosObject2 = testPaxosObject2.merge(testPaxosObject2.prepare()(using id3)) | ||
| // replica 1 receives 3's prepare | ||
| testPaxosObject1 = testPaxosObject1.merge(testPaxosObject2) | ||
| // assert that the object before and after replica 1 calls upkeep is the same | ||
| assertEquals(testPaxosObject1, testPaxosObject1.merge(testPaxosObject1.upkeep()(using id1))) | ||
| } | ||
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| test("promise sends previously accepted value") { | ||
| var testPaxosObject = emptyPaxosObject | ||
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| // replica 1 sends prepare | ||
| testPaxosObject = testPaxosObject.merge(testPaxosObject.prepare()(using id1)) | ||
| // replica 2 and 3 receive prepare | ||
| testPaxosObject = | ||
| testPaxosObject.merge(testPaxosObject.upkeep()(using id2)).merge(testPaxosObject.upkeep()(using id3)) | ||
| // replica 1 receives 2 and 3's promise | ||
| testPaxosObject = testPaxosObject.merge(testPaxosObject.upkeep()(using id1)) | ||
| // replica 1 sends propose(1) | ||
| testPaxosObject = testPaxosObject.merge(testPaxosObject.propose(1)(using id1)) | ||
| // replica 2 and 3 receive propose | ||
| testPaxosObject = | ||
| testPaxosObject.merge(testPaxosObject.upkeep()(using id2)).merge(testPaxosObject.upkeep()(using id3)) | ||
| // replica 1 receives accepted | ||
| testPaxosObject = testPaxosObject.merge(testPaxosObject.upkeep()(using id1)) | ||
| // replica 2 sends prepare to propose a new value | ||
| testPaxosObject = testPaxosObject.merge(testPaxosObject.prepare()(using id2)) | ||
| // replica 1 receives 2's new prepare, get the value in 1's promise | ||
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| val promiseValue = testPaxosObject.upkeep()(using id1).promises.maxBy(_.proposal).highestAccepted.get._2 | ||
| // assert the promise contains the previously accepted value | ||
| assertEquals(promiseValue, 1) | ||
| } | ||
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| test("acceptor sends promise with highest proposal number") { | ||
| var testPaxosObject = emptyPaxosObject | ||
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| testPaxosObject = testPaxosObject.merge(testPaxosObject.prepare()(using id1)) | ||
| .merge(testPaxosObject.prepare()(using id2)) | ||
| .merge(testPaxosObject.prepare()(using id3)) | ||
| val highestProposalNumber = testPaxosObject.prepares.map(_.proposal).max | ||
| testPaxosObject = testPaxosObject.upkeep()(using id1) | ||
| val promiseProposalNumber = testPaxosObject.promises.head.proposal | ||
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| assertEquals(promiseProposalNumber, highestProposalNumber) | ||
| } | ||
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| test("accept contains value of promise with highest proposal number") { | ||
| var testPaxosObject = emptyPaxosObject | ||
| // replica 1 sends prepare | ||
| testPaxosObject = testPaxosObject.merge(testPaxosObject.prepare()(using id1)) | ||
| // 1, 2 and 3 receive prepare | ||
| testPaxosObject = testPaxosObject.merge(testPaxosObject.upkeep()(using id1)).merge(testPaxosObject.upkeep()(using | ||
| id2)).merge(testPaxosObject.upkeep()(using id3)) | ||
| // 1 sends accept | ||
| testPaxosObject = testPaxosObject.merge(testPaxosObject.propose(1)(using id1)) | ||
| // 1,2 and 3 receive accept | ||
| testPaxosObject = testPaxosObject.merge(testPaxosObject.upkeep()(using id1)).merge(testPaxosObject.upkeep()(using | ||
| id2)).merge(testPaxosObject.upkeep()(using id3)) | ||
| // replica 2 sends prepare | ||
| testPaxosObject = testPaxosObject.merge(testPaxosObject.prepare()(using id2)) | ||
| // 1 and 2 receives 2's prepare | ||
| testPaxosObject = | ||
| testPaxosObject.merge(testPaxosObject.upkeep()(using id1)).merge(testPaxosObject.upkeep()(using id2)) | ||
| // 2 sends accept, which should contain the value of 1's promise and not the value "2" | ||
| val acceptValue = testPaxosObject.propose(2)(using id2).accepts.head.value | ||
| // assert that the value in 2's accept message is the value of 1's promise | ||
| assertEquals(acceptValue, 1) | ||
| } | ||
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| test("write works as expected") { | ||
| var testPaxosObject = emptyPaxosObject | ||
| val writeValue = 1 | ||
| // replica 1 tries to write | ||
| testPaxosObject = testPaxosObject.merge(testPaxosObject.write(writeValue)(using id1)) | ||
| testPaxosObject = testPaxosObject.merge(testPaxosObject.upkeep()(using id1)).merge(testPaxosObject.upkeep()(using | ||
| id2)).merge(testPaxosObject.upkeep()(using id3)) | ||
| assertEquals(testPaxosObject.read, None) | ||
| // replica 1 tries to write again | ||
| testPaxosObject = testPaxosObject.merge(testPaxosObject.write(writeValue)(using id1)) | ||
| testPaxosObject = testPaxosObject.merge(testPaxosObject.upkeep()(using id1)).merge(testPaxosObject.upkeep()(using | ||
| id2)).merge(testPaxosObject.upkeep()(using id3)) | ||
| assertEquals(testPaxosObject.read, Some(writeValue)) | ||
| } | ||
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| test("concurrent writes") { | ||
| var testPaxosObject = emptyPaxosObject | ||
| // replica 1 and 2 try to write | ||
| testPaxosObject = | ||
| testPaxosObject.merge(testPaxosObject.write(1)(using id1)).merge(testPaxosObject.write(2)(using id2)) | ||
| // deliver prepares | ||
| testPaxosObject = testPaxosObject.merge(testPaxosObject.upkeep()(using id1)).merge(testPaxosObject.upkeep()(using | ||
| id2)).merge(testPaxosObject.upkeep()(using id3)) | ||
| assertEquals(testPaxosObject.read, None) | ||
| // deliver proposal | ||
| testPaxosObject = testPaxosObject.merge(testPaxosObject.upkeep()(using id1)).merge(testPaxosObject.upkeep()(using | ||
| id2)).merge(testPaxosObject.upkeep()(using id3)) | ||
| // deliver accepted | ||
| testPaxosObject = testPaxosObject.merge(testPaxosObject.upkeep()(using id1)).merge(testPaxosObject.upkeep()(using | ||
| id2)).merge(testPaxosObject.upkeep()(using id3)) | ||
| assert(clue(testPaxosObject.read) == Some(2) || clue(testPaxosObject.read) == Some(1)) | ||
| } | ||
| } |