kinesis4cats.compat.retry.RetryPolicy.scala Maven / Gradle / Ivy

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/*
 * Copyright 2023-2023 etspaceman
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package kinesis4cats.compat.retry

import scala.concurrent.duration.Duration
import scala.concurrent.duration.FiniteDuration

import cats.Show
import cats.arrow.FunctionK
import cats.implicits._
import cats.kernel.BoundedSemilattice
import cats.{Applicative, Apply, Functor, Monad}

import kinesis4cats.compat.retry.PolicyDecision._

case class RetryPolicy[M[_]](
    decideNextRetry: RetryStatus => M[PolicyDecision]
) {
  def show: String = toString

  def followedBy(rp: RetryPolicy[M])(implicit M: Apply[M]): RetryPolicy[M] =
    RetryPolicy.withShow(
      status =>
        M.map2(decideNextRetry(status), rp.decideNextRetry(status)) {
          case (GiveUp, pd) => pd
          case (pd, _)      => pd
        },
      show"$show.followedBy($rp)"
    )

  /** Combine this schedule with another schedule, giving up when either of the
    * schedules want to give up and choosing the maximum of the two delays when
    * both of the schedules want to delay the next retry. The dual of the `meet`
    * operation.
    */
  def join(rp: RetryPolicy[M])(implicit M: Apply[M]): RetryPolicy[M] =
    RetryPolicy.withShow[M](
      status =>
        M.map2(decideNextRetry(status), rp.decideNextRetry(status)) {
          case (DelayAndRetry(a), DelayAndRetry(b)) => DelayAndRetry(a max b)
          case _                                    => GiveUp
        },
      show"$show.join($rp)"
    )

  /** Combine this schedule with another schedule, giving up when both of the
    * schedules want to give up and choosing the minimum of the two delays when
    * both of the schedules want to delay the next retry. The dual of the `join`
    * operation.
    */
  def meet(rp: RetryPolicy[M])(implicit M: Apply[M]): RetryPolicy[M] =
    RetryPolicy.withShow[M](
      status =>
        M.map2(decideNextRetry(status), rp.decideNextRetry(status)) {
          case (DelayAndRetry(a), DelayAndRetry(b)) => DelayAndRetry(a min b)
          case (s @ DelayAndRetry(_), GiveUp)       => s
          case (GiveUp, s @ DelayAndRetry(_))       => s
          case _                                    => GiveUp
        },
      show"$show.meet($rp)"
    )

  def mapDelay(
      f: FiniteDuration => FiniteDuration
  )(implicit M: Functor[M]): RetryPolicy[M] =
    RetryPolicy.withShow(
      status =>
        M.map(decideNextRetry(status)) {
          case GiveUp           => GiveUp
          case DelayAndRetry(d) => DelayAndRetry(f(d))
        },
      show"$show.mapDelay()"
    )

  def flatMapDelay(
      f: FiniteDuration => M[FiniteDuration]
  )(implicit M: Monad[M]): RetryPolicy[M] =
    RetryPolicy.withShow(
      status =>
        M.flatMap(decideNextRetry(status)) {
          case GiveUp           => M.pure(GiveUp)
          case DelayAndRetry(d) => M.map(f(d))(DelayAndRetry(_))
        },
      show"$show.flatMapDelay()"
    )

  def mapK[N[_]](nt: FunctionK[M, N]): RetryPolicy[N] =
    RetryPolicy.withShow(
      status => nt(decideNextRetry(status)),
      show"$show.mapK()"
    )
}

object RetryPolicy {
  def lift[M[_]](
      f: RetryStatus => PolicyDecision
  )(implicit
      M: Applicative[M]
  ): RetryPolicy[M] =
    RetryPolicy[M](decideNextRetry = retryStatus => M.pure(f(retryStatus)))

  def withShow[M[_]](
      decideNextRetry: RetryStatus => M[PolicyDecision],
      pretty: => String
  ): RetryPolicy[M] =
    new RetryPolicy[M](decideNextRetry) {
      override def show: String = pretty
      override def toString: String = pretty
    }

  def liftWithShow[M[_]: Applicative](
      decideNextRetry: RetryStatus => PolicyDecision,
      pretty: => String
  ): RetryPolicy[M] =
    withShow(rs => Applicative[M].pure(decideNextRetry(rs)), pretty)

  implicit def boundedSemilatticeForRetryPolicy[M[_]](implicit
      M: Applicative[M]
  ): BoundedSemilattice[RetryPolicy[M]] =
    new BoundedSemilattice[RetryPolicy[M]] {
      override def empty: RetryPolicy[M] =
        RetryPolicies.constantDelay[M](Duration.Zero)

      override def combine(
          x: RetryPolicy[M],
          y: RetryPolicy[M]
      ): RetryPolicy[M] = x.join(y)
    }

  implicit def showForRetryPolicy[M[_]]: Show[RetryPolicy[M]] =
    Show.show(_.show)
}