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| 1 | +package com.dwolla.util.async |
| 2 | + |
| 3 | +import cats.* |
| 4 | +import cats.effect.* |
| 5 | +import cats.effect.std.* |
| 6 | +import cats.effect.testkit.TestControl |
| 7 | +import cats.syntax.all.* |
| 8 | +import cats.effect.syntax.all.* |
| 9 | +import com.dwolla.util.async.twitter.{CancelledViaCatsEffect, liftFuture} |
| 10 | +import com.twitter.util.{Duration as _, *} |
| 11 | +import munit.{AnyFixture, CatsEffectSuite, ScalaCheckEffectSuite} |
| 12 | +import org.scalacheck.Arbitrary.arbitrary |
| 13 | +import org.scalacheck.effect.PropF |
| 14 | +import org.scalacheck.{Arbitrary, Gen, Prop, Test} |
| 15 | + |
| 16 | +import java.util.concurrent.CancellationException |
| 17 | +import scala.concurrent.duration.* |
| 18 | +import scala.util.control.NoStackTrace |
| 19 | + |
| 20 | +class TwitterFutureAsyncMapKTests extends CatsEffectSuite with ScalaCheckEffectSuite { |
| 21 | + override def munitIOTimeout: Duration = 1.minute |
| 22 | + |
| 23 | + override protected def scalaCheckTestParameters: Test.Parameters = |
| 24 | + super.scalaCheckTestParameters.withMinSuccessfulTests(100000) |
| 25 | + |
| 26 | + test("lift a Twitter Future into IO") { |
| 27 | + PropF.forAllF { (i: Int) => |
| 28 | + for { |
| 29 | + promise <- IO(Promise[Int]()) |
| 30 | + (x, _) <- liftFuture[IO](IO(promise)).both(IO(promise.setValue(i))) |
| 31 | + } yield { |
| 32 | + assertEquals(x, i) |
| 33 | + } |
| 34 | + } |
| 35 | + } |
| 36 | + |
| 37 | + test("cancelling a running Twitter Future lifted into IO should interrupt the underlying Twitter Future") { |
| 38 | + for { |
| 39 | + promise <- IO(Promise[Int]()) |
| 40 | + startedLatch <- CountDownLatch[IO](1) |
| 41 | + fiber <- IO.uncancelable { poll => // we want only the Future to be cancellable |
| 42 | + poll(liftFuture[IO](startedLatch.release.as(promise))).start |
| 43 | + } |
| 44 | + _ <- startedLatch.await |
| 45 | + _ <- fiber.cancel |
| 46 | + } yield { |
| 47 | + assert(promise.isInterrupted.isDefined) |
| 48 | + } |
| 49 | + } |
| 50 | + |
| 51 | + private val supervisorAndDispatcher = ResourceTestLocalFixture("supervisorAndDispatcher", |
| 52 | + Supervisor[IO](await = true).product(Dispatcher.sequential[IO](await = true)) |
| 53 | + ) |
| 54 | + |
| 55 | + override def munitFixtures: Seq[AnyFixture[?]] = super.munitFixtures ++ Seq(supervisorAndDispatcher) |
| 56 | + |
| 57 | + test("a running Twitter Future lifted into IO can be completed (as success or failure) or cancelled") { |
| 58 | + PropF.forAllF { (i: Outcome[IO, Throwable, Int]) => |
| 59 | + val (supervisor, dispatcher) = supervisorAndDispatcher() |
| 60 | + |
| 61 | + TestControl.executeEmbed { |
| 62 | + for { |
| 63 | + expectedResult <- i.embed(CancelledViaCatsEffect.raiseError[IO, Int]).attempt |
| 64 | + capturedInterruptionThrowable <- Deferred[IO, Throwable] |
| 65 | + twitterPromise <- IO(new Promise[Int]()).flatTap(captureThrowableOnInterruption(dispatcher, capturedInterruptionThrowable)) |
| 66 | + startedLatch <- CountDownLatch[IO](1) |
| 67 | + promiseFiber <- IO.uncancelable { poll => // we want only the Future to be cancellable |
| 68 | + supervisor.supervise(poll(liftFuture[IO](startedLatch.release.as(twitterPromise)))) |
| 69 | + } |
| 70 | + _ <- startedLatch.await |
| 71 | + |
| 72 | + (outcome, _) <- promiseFiber.join.both(completeOrCancel(i, twitterPromise, promiseFiber)) |
| 73 | + |
| 74 | + outcomeEmittedValue <- outcome.embed(CancelledViaCatsEffect.raiseError[IO, Int]).attempt |
| 75 | + |
| 76 | + expectCancellation = i.isCanceled |
| 77 | + _ <- interceptMessageIO[CancellationException]("Cancelled via cats-effect") { |
| 78 | + capturedInterruptionThrowable |
| 79 | + .get |
| 80 | + .timeout(10.millis) |
| 81 | + .map(_.asLeft) |
| 82 | + .rethrow // interceptMessageIO works by throwing an exception, so we need to rethrow it to get the message |
| 83 | + } |
| 84 | + .whenA(expectCancellation) |
| 85 | + } yield { |
| 86 | + assertEquals(outcomeEmittedValue, expectedResult) |
| 87 | + assertEquals(outcome.isCanceled, i.isCanceled) |
| 88 | + assertEquals(Option(CancelledViaCatsEffect).filter(_ => expectCancellation), twitterPromise.isInterrupted) |
| 89 | + } |
| 90 | + } |
| 91 | + } |
| 92 | + } |
| 93 | + |
| 94 | + // just here to make sure we understand how Twitter Future / Promise handles interruption |
| 95 | + test("the Twitter Future cancellation protocol") { |
| 96 | + Prop.forAll { (throwable: Throwable) => |
| 97 | + val promise = Promise[Int]() |
| 98 | + |
| 99 | + promise.raise(throwable) |
| 100 | + |
| 101 | + assertEquals(promise.isInterrupted, throwable.some) |
| 102 | + } |
| 103 | + } |
| 104 | + |
| 105 | + private def genOutcome[F[_] : Applicative, A: Arbitrary]: Gen[Outcome[F, Throwable, A]] = |
| 106 | + Gen.oneOf( |
| 107 | + arbitrary[A].map(_.pure[F]).map(Outcome.succeeded[F, Throwable, A]), |
| 108 | + Gen.const(new RuntimeException("arbitrary exception") with NoStackTrace).map(Outcome.errored[F, Throwable, A]), |
| 109 | + Gen.const(Outcome.canceled[F, Throwable, A]), |
| 110 | + ) |
| 111 | + private implicit def arbOutcome[F[_] : Applicative, A: Arbitrary]: Arbitrary[Outcome[F, Throwable, A]] = Arbitrary(genOutcome) |
| 112 | + |
| 113 | + private def captureThrowableOnInterruption[F[_] : Sync, A](dispatcher: Dispatcher[F], |
| 114 | + capture: Deferred[F, Throwable]) |
| 115 | + (p: Promise[A]): F[Unit] = |
| 116 | + Sync[F].delay { |
| 117 | + p.setInterruptHandler { case ex => |
| 118 | + dispatcher.unsafeRunSync(capture.complete(ex).void) |
| 119 | + } |
| 120 | + } |
| 121 | + |
| 122 | + private def completeOrCancel[F[_] : Async, A](maybeA: Outcome[F, Throwable, A], |
| 123 | + promise: Promise[A], |
| 124 | + fiber: Fiber[F, Throwable, A]): F[Unit] = |
| 125 | + maybeA match { |
| 126 | + case Outcome.Succeeded(fa) => |
| 127 | + fa.flatMap(a => Sync[F].delay(promise.setValue(a))).void |
| 128 | + |
| 129 | + case Outcome.Errored(ex) => |
| 130 | + // If the fiber is in the background (i.e. not joined) when it completes with an exception, |
| 131 | + // the IO runtime will print its stacktrace to stderr. We always plan to `join` the fiber |
| 132 | + // our tests are complete, so this feels like a false error report. |
| 133 | + |
| 134 | + // To work around the issue, we delay the completion of the promise to make sure the fiber |
| 135 | + // is joined before the promise is completed with the exception. |
| 136 | + Sync[F].delay(promise.setException(ex)).delayBy(10.millis) |
| 137 | + |
| 138 | + case Outcome.Canceled() => |
| 139 | + fiber.cancel |
| 140 | + } |
| 141 | + |
| 142 | +} |
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