org.mongodb.scala.internal.IterableObservable.scala Maven / Gradle / Ivy

Go to download

Show more of this group Show more artifacts with this name
Show all versions of mongo-scala-driver_2.11 Show documentation

A Scala wrapper of the MongoDB Reactive Streams Java driver

There is a newer version: 5.3.0

Show newest version

/*
 * Copyright 2015 MongoDB, Inc.
 *
 * 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 org.mongodb.scala.internal

import org.mongodb.scala.{ Observable, Observer, Subscription }

private[scala] case class IterableObservable[A](from: Iterable[A]) extends Observable[A] {

  override def subscribe(observer: Observer[_ >: A]): Unit = {
    observer.onSubscribe(
      new Subscription {
        @volatile
        private var left: Iterable[A] = from
        @volatile
        private var subscribed: Boolean = true

        override def isUnsubscribed: Boolean = !subscribed

        override def request(n: Long): Unit = {
          if (n < 1) {
            throw new IllegalArgumentException(s"Number requested cannot be negative: $n")
          }
          var counter = n
          while (subscribed && counter > 0 && left.nonEmpty) {
            val head = left.head
            left = left.tail
            observer.onNext(head)
            counter -= 1
          }

          if (subscribed && left.isEmpty) {
            observer.onComplete()
          }
        }

        override def unsubscribe(): Unit = subscribed = false
      }
    )
  }
}