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Add ability to only count certain exceptions as failures #252

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Apr 12, 2023
Merged

Add ability to only count certain exceptions as failures #252

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50 changes: 36 additions & 14 deletions core/src/main/scala/io/chrisdavenport/circuit/CircuitBreaker.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -247,14 +247,17 @@ object CircuitBreaker {
* default implementations.
* @param maxResetTimeout is the maximum timeout the circuit breaker
* is allowed to use when applying the `backoff` result.
* @param exceptionFilter a predicate that returns true for exceptions which should trigger the circuitbreaker,
* and false for those which should not (ie be treated the same as success)
*/
def of[F[_]](
maxFailures: Int,
resetTimeout: FiniteDuration,
backoff: FiniteDuration => FiniteDuration = Backoff.exponential,
maxResetTimeout: Duration = 1.minute
maxResetTimeout: Duration = 1.minute,
exceptionFilter: Throwable => Boolean = Function.const(true)
)(implicit F: Temporal[F]): F[CircuitBreaker[F]] = {
of(maxFailures, resetTimeout, backoff, maxResetTimeout, F.unit, F. unit, F.unit, F.unit)
of(maxFailures, resetTimeout, backoff, maxResetTimeout, exceptionFilter, F.unit, F. unit, F.unit, F.unit)
}

/**
Expand All @@ -275,14 +278,17 @@ object CircuitBreaker {
* default implementations.
* @param maxResetTimeout is the maximum timeout the circuit breaker
* is allowed to use when applying the `backoff`
* @param exceptionFilter a predicate that returns true for exceptions which should trigger the circuitbreaker,
* and false for those which should not (ie be treated the same as success)
*/
def in[F[_], G[_]](
maxFailures: Int,
resetTimeout: FiniteDuration,
backoff: FiniteDuration => FiniteDuration = Backoff.exponential,
maxResetTimeout: Duration = 1.minute
maxResetTimeout: Duration = 1.minute,
exceptionFilter: Throwable => Boolean = Function.const(true)
)(implicit F: Sync[F], G: Async[G]): F[CircuitBreaker[G]] = {
in[F, G](maxFailures, resetTimeout, backoff, maxResetTimeout, G.unit, G.unit, G.unit, G.unit)
in[F, G](maxFailures, resetTimeout, backoff, maxResetTimeout, exceptionFilter, G.unit, G.unit, G.unit, G.unit)
}

/**
Expand All @@ -303,6 +309,8 @@ object CircuitBreaker {
* default implementations.
* @param maxResetTimeout is the maximum timeout the circuit breaker
* is allowed to use when applying the `backoff`
* @param exceptionFilter a predicate that returns true for exceptions which should trigger the circuitbreaker,
* and false for those which should not (ie be treated the same as success)
*
* @param onRejected is for signaling rejected tasks
* @param onClosed is for signaling a transition to `Closed`
Expand All @@ -314,6 +322,7 @@ object CircuitBreaker {
resetTimeout: FiniteDuration,
backoff: FiniteDuration => FiniteDuration,
maxResetTimeout: Duration,
exceptionFilter: Throwable => Boolean,
onRejected: F[Unit],
onClosed: F[Unit],
onHalfOpen: F[Unit],
Expand All @@ -327,6 +336,7 @@ object CircuitBreaker {
resetTimeout,
backoff,
maxResetTimeout,
exceptionFilter,
onRejected,
onClosed,
onHalfOpen,
Expand Down Expand Up @@ -355,6 +365,8 @@ object CircuitBreaker {
* default implementations.
* @param maxResetTimeout is the maximum timeout the circuit breaker
* is allowed to use when applying the `backoff`
* @param exceptionFilter a predicate that returns true for exceptions which should trigger the circuitbreaker,
* and false for those which should not (ie be treated the same as success)
*
* @param onRejected is for signaling rejected tasks
* @param onClosed is for signaling a transition to `Closed`
Expand All @@ -366,6 +378,7 @@ object CircuitBreaker {
resetTimeout: FiniteDuration,
backoff: FiniteDuration => FiniteDuration,
maxResetTimeout: Duration,
exceptionFilter: Throwable => Boolean,
onRejected: G[Unit],
onClosed: G[Unit],
onHalfOpen: G[Unit],
Expand All @@ -378,6 +391,7 @@ object CircuitBreaker {
resetTimeout,
backoff,
maxResetTimeout,
exceptionFilter,
onRejected,
onClosed,
onHalfOpen,
Expand All @@ -397,6 +411,7 @@ object CircuitBreaker {
resetTimeout: FiniteDuration,
backoff: FiniteDuration => FiniteDuration,
maxResetTimeout: Duration,
exceptionFilter: Throwable => Boolean,
onRejected: G[Unit],
onClosed: G[Unit],
onHalfOpen: G[Unit],
Expand All @@ -407,6 +422,7 @@ object CircuitBreaker {
resetTimeout,
backoff,
maxResetTimeout,
exceptionFilter,
onRejected,
onClosed,
onHalfOpen,
Expand Down Expand Up @@ -510,6 +526,7 @@ object CircuitBreaker {
resetTimeout: FiniteDuration,
backoff: FiniteDuration => FiniteDuration,
maxResetTimeout: Duration,
exceptionFilter: Throwable => Boolean,
onRejected: F[Unit],
onClosed: F[Unit],
onHalfOpen: F[Unit],
Expand All @@ -523,9 +540,7 @@ object CircuitBreaker {
require(maxResetTimeout > Duration.Zero, "maxResetTimeout > 0")


def state: F[CircuitBreaker.State] =
ref.get

def state: F[CircuitBreaker.State] = ref.get

def doOnRejected(callback: F[Unit]): CircuitBreaker[F] = {
val onRejected = this.onRejected.flatMap(_ => callback)
Expand All @@ -535,6 +550,7 @@ object CircuitBreaker {
resetTimeout = resetTimeout,
backoff = backoff,
maxResetTimeout = maxResetTimeout,
exceptionFilter = exceptionFilter,
onRejected = onRejected,
onClosed = onClosed,
onHalfOpen = onHalfOpen,
Expand All @@ -549,6 +565,7 @@ object CircuitBreaker {
resetTimeout = resetTimeout,
backoff = backoff,
maxResetTimeout = maxResetTimeout,
exceptionFilter = exceptionFilter,
onRejected = onRejected,
onClosed = onClosed,
onHalfOpen = onHalfOpen,
Expand All @@ -563,6 +580,7 @@ object CircuitBreaker {
resetTimeout = resetTimeout,
backoff = backoff,
maxResetTimeout = maxResetTimeout,
exceptionFilter = exceptionFilter,
onRejected = onRejected,
onClosed = onClosed,
onHalfOpen = onHalfOpen,
Expand All @@ -578,6 +596,7 @@ object CircuitBreaker {
resetTimeout = resetTimeout,
backoff = backoff,
maxResetTimeout = maxResetTimeout,
exceptionFilter = exceptionFilter,
onRejected = onRejected,
onClosed = onClosed,
onHalfOpen = onHalfOpen,
Expand All @@ -593,14 +612,15 @@ object CircuitBreaker {
case HalfOpen => (ClosedZero, onClosed.attempt.void)
case Open(_,_) => (ClosedZero, onClosed.attempt.void)
}.flatten
case Outcome.Errored(_) =>
case Outcome.Errored(e) =>
Temporal[F].monotonic.map(_.toMillis).flatMap { now =>

ref.modify {
case Closed(failures) =>
val count = failures + 1
if (count >= maxFailures) (Open(now, resetTimeout), onOpen.attempt.void)
else (Closed(count), Applicative[F].unit)
case closed @ Closed(failures) =>
if (exceptionFilter(e)) {
val count = failures + 1
if (count >= maxFailures) (Open(now, resetTimeout), onOpen.attempt.void)
else (Closed(count), Applicative[F].unit)
} else (closed, Applicative[F].unit)
case open: Open => (open, Applicative[F].unit)
case HalfOpen => (HalfOpen, Applicative[F].unit)
}.flatten
Expand Down Expand Up @@ -631,7 +651,9 @@ object CircuitBreaker {
def resetOnSuccess(poll: Poll[F]): F[A] = {
poll(fa).guaranteeCase {
case Outcome.Succeeded(_) => ref.set(ClosedZero) >> onClosed.attempt.void
case Outcome.Errored(_) => ref.set(nextBackoff(open, now)) >> onOpen.attempt.void
case Outcome.Errored(e) =>
if (exceptionFilter(e)) ref.set(nextBackoff(open, now)) >> onOpen.attempt.void
else ref.set(ClosedZero) >> onClosed.attempt.void
case Outcome.Canceled() => ref.modify{
case HalfOpen => (open, onOpen.attempt.void)
case closed: Closed => (closed, F.unit)
Expand Down
24 changes: 20 additions & 4 deletions core/src/test/scala/io/chrisdavenport/circuit/CircuitBreakerTests.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -28,17 +28,13 @@ import cats.syntax.all._
import scala.concurrent.duration._
import cats.effect._
// import cats.effect.syntax._
import cats.effect.unsafe._

// import catalysts.Platform
import munit.CatsEffectSuite

class CircuitBreakerTests extends CatsEffectSuite {
private val Tries = 10000 //if (Platform.isJvm) 10000 else 5000


implicit val runtime: IORuntime = cats.effect.unsafe.IORuntime.global

private def mkBreaker() = CircuitBreaker.in[SyncIO, IO](
maxFailures = 5,
resetTimeout = 1.minute
Expand Down Expand Up @@ -335,4 +331,24 @@ class CircuitBreakerTests extends CatsEffectSuite {

test
}

test("should only count allowed exceptions") {
case class MyException(foo: String) extends Throwable

for {
circuitBreaker <- CircuitBreaker.of[IO](maxFailures = 1, resetTimeout = 10.seconds, exceptionFilter = !_.isInstanceOf[MyException])
action = circuitBreaker.protect(IO.raiseError(MyException("Boom!"))).attempt
_ <- action >> action >> action >> action
_ <- circuitBreaker.state.map {
case _: CircuitBreaker.Closed => assert(true)
case _ => assert(false)
}
badAction = circuitBreaker.protect(IO.raiseError(new RuntimeException("Boom!"))).attempt
_ <- badAction >> badAction >> badAction >> badAction
_ <- circuitBreaker.state.map {
case _: CircuitBreaker.Open => assert(true)
case _ => assert(false)
}
} yield ()
}
}