wvlet.airframe.rx.Cancelable.scala Maven / Gradle / Ivy

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AirSpec: A Functional Testing Framework for Scala

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/*
 * 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 wvlet.airframe.rx

import wvlet.log.LogSupport

import scala.util.{Failure, Try}
import scala.util.control.NonFatal

/**
  */
trait Cancelable {
  def cancel: Unit = {}
}

object Cancelable extends LogSupport {
  val empty: Cancelable = new Cancelable {}

  def apply(canceller: () => Unit): Cancelable =
    new Cancelable {
      override def cancel: Unit = canceller()
    }

  def merge(c1: => Cancelable, c2: => Cancelable): Cancelable = {
    Cancelable { () =>
      try {
        c1.cancel
      } finally {
        c2.cancel
      }
    }
  }

  def merge(it: Iterable[Cancelable]): Cancelable = {
    val lst = it.toIndexedSeq
    lst.size match {
      case 1 => lst.head
      case _ =>
        val nonEmpty = lst.filter(_ != Cancelable.empty)
        if (nonEmpty.isEmpty) {
          Cancelable.empty
        } else {
          Cancelable { () =>
            val failures =
              nonEmpty
                .map(c => Try(c.cancel))
                .collect { case Failure(ex) =>
                  warn(ex)
                  ex
                }
            failures.size match {
              case 0 => // ok
              case 1 =>
                throw failures.head
              case n if n > 1 =>
                warn(s"Multiple exception occurred while cancelling")
                for (f <- failures.tail) {
                  warn(f)
                }
                throw failures.head
            }
          }
        }
    }
  }
}