Implement loadAndRun (#7)

it/src/test/scala/integration/LoadExampleIntSpec.scala

@@ -83,6 +83,6 @@ class LoadExampleIntSpec extends KafkaSpecBase[IO] {
   private def withKafkaContext(test: TestContext[IO] => IO[Assertion]): IO[Assertion] = {
     object testContext extends TestContext[IO]
     import testContext.*
-    embeddedKafka.use(_ => test(testContext))
+    embeddedKafka.surround(test(testContext))
   }
 }

src/main/scala/uk/sky/fs2/kafka/topicloader/TopicLoader.scala

@@ -2,6 +2,7 @@ package uk.sky.fs2.kafka.topicloader
 
 import cats.data.{NonEmptyList, NonEmptyMap, OptionT}
 import cats.effect.Async
+import cats.effect.kernel.Resource
 import cats.syntax.all.*
 import cats.{Monad, Order}
 import fs2.kafka.{ConsumerRecord, ConsumerSettings, KafkaConsumer}
@@ -43,20 +44,40 @@ trait TopicLoader {
       .evalMap { consumer =>
         {
           for {
-            allLogOffsets <- OptionT.liftF(logOffsetsForTopics(topics, strategy, consumer))
-            logOffsets    <- OptionT.fromOption(NonEmptyMap.fromMap(SortedMap.from(allLogOffsets)))
+            logOffsets <- OptionT(logOffsetsForTopics(topics, strategy, consumer))
+            _          <- OptionT.liftF(
+                            consumer.assign(logOffsets.keys) *>
+                              logOffsets.toNel.traverse { case (tp, o) => consumer.seek(tp, o.lowest) }
+                          )
+          } yield load(consumer, logOffsets)
+        }.getOrElse(Stream.empty)
+      }
+      .flatten
+
+  def loadAndRun[F[_] : Async : LoggerFactory, K, V](
+      topics: NonEmptyList[String],
+      consumerSettings: ConsumerSettings[F, K, V]
+  )(onLoad: Resource.ExitCase => F[Unit]): Stream[F, ConsumerRecord[K, V]] =
+    KafkaConsumer
+      .stream(consumerSettings)
+      .evalMap { consumer =>
+        {
+          for {
+            logOffsets    <- OptionT(logOffsetsForTopics(topics, LoadAll, consumer))
             _             <- OptionT.liftF(
                                consumer.assign(logOffsets.keys) *>
                                  logOffsets.toNel.traverse { case (tp, o) => consumer.seek(tp, o.lowest) }
                              )
-          } yield consumer.records
-            .map(_.record)
-            .through(filterBelowHighestOffset(logOffsets))
+            preLoadStream <- OptionT.pure(load(consumer, logOffsets))
+          } yield preLoadStream.onFinalizeCase(onLoad) ++ consumer.records.map(_.record)
         }.getOrElse(Stream.empty)
       }
       .flatten
 
-  def loadAndRun(): Unit = ()
+  private def load[F[_] : Async : LoggerFactory, K, V](
+      consumer: KafkaConsumer[F, K, V],
+      logOffsets: NonEmptyMap[TopicPartition, LogOffsets]
+  ): Stream[F, ConsumerRecord[K, V]] = consumer.records.map(_.record).through(filterBelowHighestOffset(logOffsets))
 
   private def filterBelowHighestOffset[F[_] : Monad : LoggerFactory, K, V](
       logOffsets: NonEmptyMap[TopicPartition, LogOffsets]
@@ -73,20 +94,24 @@ trait TopicLoader {
       topics: NonEmptyList[String],
       strategy: LoadTopicStrategy,
       consumer: KafkaConsumer[F, K, V]
-  ): F[Map[TopicPartition, LogOffsets]] = for {
-    _                           <- consumer.subscribe(topics)
-    partitionInfo               <- topics.toList.flatTraverse(consumer.partitionsFor)
-    topicPartitions              = partitionInfo.map(pi => new TopicPartition(pi.topic, pi.partition)).toSet
-    beginningOffsetPerPartition <- consumer.beginningOffsets(topicPartitions)
-    endOffsets                  <- strategy match {
-                                     case LoadAll       => consumer.endOffsets(topicPartitions)
-                                     case LoadCommitted => earliestOffsets(consumer, beginningOffsetPerPartition)
-                                   }
-    logOffsets                   = beginningOffsetPerPartition.map { case (partition, offset) =>
-                                     partition -> LogOffsets(offset, endOffsets(partition))
-                                   }
-    _                           <- consumer.unsubscribe
-  } yield logOffsets.filter { case (_, o) => o.highest > o.lowest }
+  ): F[Option[NonEmptyMap[TopicPartition, LogOffsets]]] =
+    for {
+      _                           <- consumer.subscribe(topics)
+      partitionInfo               <- topics.toList.flatTraverse(consumer.partitionsFor)
+      topicPartitions              = partitionInfo.map(pi => new TopicPartition(pi.topic, pi.partition)).toSet
+      beginningOffsetPerPartition <- consumer.beginningOffsets(topicPartitions)
+      endOffsets                  <- strategy match {
+                                       case LoadAll       => consumer.endOffsets(topicPartitions)
+                                       case LoadCommitted => earliestOffsets(consumer, beginningOffsetPerPartition)
+                                     }
+      logOffsets                   = beginningOffsetPerPartition.map { case (partition, offset) =>
+                                       partition -> LogOffsets(offset, endOffsets(partition))
+                                     }
+      _                           <- consumer.unsubscribe
+    } yield {
+      val offsets = logOffsets.filter { case (_, o) => o.highest > o.lowest }
+      NonEmptyMap.fromMap(SortedMap.from(offsets))
+    }
 
   private def earliestOffsets[F[_] : Monad, K, V](
       consumer: KafkaConsumer[F, K, V],

src/test/scala/base/AsyncIntSpec.scala

@@ -1,8 +1,30 @@
 package base
 
+import cats.effect.Async
+import cats.effect.std.Dispatcher
 import cats.effect.testing.scalatest.AsyncIOSpec
+import cats.syntax.all.*
+import org.scalactic.source.Position
 import org.scalatest.OptionValues
+import org.scalatest.concurrent.Eventually
+import org.scalatest.enablers.Retrying
 import org.scalatest.matchers.should.Matchers
+import org.scalatest.time.Span
 import org.scalatest.wordspec.AsyncWordSpec
 
-trait AsyncIntSpec extends AsyncWordSpec with AsyncIOSpec with Matchers with OptionValues
+import scala.concurrent.duration.*
+
+trait AsyncIntSpec[F[_]] extends AsyncWordSpec with AsyncIOSpec with Matchers with OptionValues with Eventually {
+  override implicit val patienceConfig: PatienceConfig = PatienceConfig(30.seconds, 500.millis)
+
+  implicit def fRetrying[T](implicit F: Async[F]): Retrying[F[T]] = new Retrying[F[T]] {
+    override def retry(timeout: Span, interval: Span, pos: Position)(fun: => F[T]): F[T] =
+      Dispatcher.sequential[F].use { dispatcher =>
+        F.fromFuture(
+          F.executionContext.map(
+            Retrying.retryingNatureOfFutureT[T](_).retry(timeout, interval, pos)(dispatcher.unsafeToFuture(fun))
+          )
+        )
+      }
+  }
+}

src/test/scala/base/KafkaSpecBase.scala

@@ -2,4 +2,4 @@ package base
 
 import utils.{EmbeddedKafka, KafkaHelpers}
 
-abstract class KafkaSpecBase[F[_]] extends AsyncIntSpec with KafkaHelpers[F] with EmbeddedKafka[F]
+abstract class KafkaSpecBase[F[_]] extends AsyncIntSpec[F] with KafkaHelpers[F] with EmbeddedKafka[F]

src/test/scala/integration/TopicLoaderIntSpec.scala

@@ -2,7 +2,7 @@ package integration
 
 import base.KafkaSpecBase
 import cats.data.NonEmptyList
-import cats.effect.IO
+import cats.effect.{IO, Ref}
 import fs2.kafka.{AutoOffsetReset, ConsumerSettings}
 import io.github.embeddedkafka.EmbeddedKafkaConfig
 import org.apache.kafka.common.errors.TimeoutException as KafkaTimeoutException
@@ -184,8 +184,31 @@ class TopicLoaderIntSpec extends KafkaSpecBase[IO] {
 
   "loadAndRun" should {
 
-    "execute callback when finished loading and keep streaming" in {
-      pending
+    "execute callback when finished loading and keep streaming" in withKafkaContext { ctx =>
+      import ctx.*
+
+      val (preLoad, postLoad) = records(1 to 15).splitAt(10)
+
+      for {
+        loadState  <- Ref.of[IO, Boolean](false)
+        topicState <- Ref.empty[IO, Seq[(String, String)]]
+        _          <- createCustomTopics(NonEmptyList.one(testTopic1))
+        _          <- publishStringMessages(testTopic1, preLoad)
+        assertion  <- loadAndRunR(NonEmptyList.one(testTopic1))(
+                        _ => loadState.set(true),
+                        r => topicState.getAndUpdate(_ :+ r).void
+                      ).surround {
+                        for {
+                          _         <- eventually(topicState.get.asserting(_ should contain theSameElementsAs preLoad))
+                          _         <- loadState.get.asserting(_ shouldBe true)
+                          _         <- publishStringMessages(testTopic1, postLoad)
+                          assertion <-
+                            eventually(
+                              topicState.get.asserting(_ should contain theSameElementsAs (preLoad ++ postLoad))
+                            )
+                        } yield assertion
+                      }
+      } yield assertion
     }
 
   }
@@ -198,6 +221,6 @@ class TopicLoaderIntSpec extends KafkaSpecBase[IO] {
   private def withKafkaContext(test: TestContext[IO] => IO[Assertion]): IO[Assertion] = {
     object testContext extends TestContext[IO]
     import testContext.*
-    embeddedKafka.use(_ => test(testContext))
+    embeddedKafka.surround(test(testContext))
   }
 }

src/test/scala/utils/KafkaHelpers.scala

@@ -2,22 +2,25 @@ package utils
 
 import java.util.UUID
 
+import base.AsyncIntSpec
 import cats.data.{NonEmptyList, NonEmptySet}
+import cats.effect.implicits.*
+import cats.effect.kernel.Fiber
 import cats.effect.{Async, Resource}
 import cats.syntax.all.*
 import fs2.Stream
 import fs2.kafka.{AutoOffsetReset, ConsumerRecord, ConsumerSettings, KafkaConsumer}
 import io.github.embeddedkafka.EmbeddedKafkaConfig
 import org.apache.kafka.common.TopicPartition
-import org.scalatest.exceptions.TestFailedException
+import org.scalatest.Assertion
 import org.typelevel.log4cats.LoggerFactory
 import org.typelevel.log4cats.slf4j.Slf4jFactory
 import uk.sky.fs2.kafka.topicloader.{LoadTopicStrategy, TopicLoader}
 
 import scala.concurrent.duration.*
 
 trait KafkaHelpers[F[_]] {
-  self: EmbeddedKafka[F] =>
+  self: AsyncIntSpec[F] & EmbeddedKafka[F] =>
 
   val groupId    = "test-consumer-group"
   val testTopic1 = "load-state-topic-1"
@@ -65,6 +68,29 @@ trait KafkaHelpers[F[_]] {
     TopicLoader.load(topics, strategy, consumerSettings).compile.toList.map(_.map(recordToTuple))
   }
 
+  def loadAndRunR(topics: NonEmptyList[String])(
+      onLoad: Resource.ExitCase => F[Unit],
+      onRecord: ((String, String)) => F[Unit]
+  )(implicit
+      consumerSettings: ConsumerSettings[F, String, String],
+      F: Async[F]
+  ): Resource[F, Fiber[F, Throwable, Unit]] = Resource.make {
+    loadAndRunLoader(topics)(onLoad)
+      .map(recordToTuple)
+      .evalTap(onRecord)
+      .compile
+      .drain
+      .start
+  }(_.cancel.void)
+
+  def loadAndRunLoader(topics: NonEmptyList[String])(onLoad: Resource.ExitCase => F[Unit])(implicit
+      consumerSettings: ConsumerSettings[F, String, String],
+      F: Async[F]
+  ): Stream[F, ConsumerRecord[String, String]] = {
+    implicit val loggerFactory: LoggerFactory[F] = Slf4jFactory.create[F]
+    TopicLoader.loadAndRun(topics, consumerSettings)(onLoad)
+  }
+
   def moveOffsetToEnd(
       partitions: NonEmptySet[TopicPartition]
   )(implicit kafkaConfig: EmbeddedKafkaConfig, F: Async[F]): Stream[F, KafkaConsumer[F, String, String]] =
@@ -92,43 +118,33 @@ trait KafkaHelpers[F[_]] {
 
   def waitForCompaction(
       partitions: NonEmptySet[TopicPartition]
-  )(implicit kafkaConfig: EmbeddedKafkaConfig, F: Async[F]): F[Unit] =
+  )(implicit kafkaConfig: EmbeddedKafkaConfig, F: Async[F]): F[Assertion] =
     consumeEventually(partitions) { r =>
       for {
         records    <- r
         messageKeys = records.map { case (k, _) => k }
-        result     <-
-          if (messageKeys.sorted == messageKeys.toSet.toList.sorted) F.unit
-          else F.raiseError(new TestFailedException("Topic has not compacted within timeout", 1))
-      } yield result
+      } yield {
+        messageKeys should not be empty
+        messageKeys should contain theSameElementsAs messageKeys.toSet
+      }
     }
 
   def consumeEventually(
       partitions: NonEmptySet[TopicPartition],
       groupId: String = UUID.randomUUID().toString
   )(
-      f: F[List[(String, String)]] => F[Unit]
-  )(implicit kafkaConfig: EmbeddedKafkaConfig, F: Async[F]): F[Unit] =
-    retry(
-      fa = {
-        val records = withAssignedConsumer[F[List[ConsumerRecord[String, String]]]](
-          autoCommit = false,
-          offsetReset = AutoOffsetReset.Earliest,
-          partitions,
-          groupId.some
-        )(
-          _.records
-            .map(_.record)
-            .interruptAfter(5.second)
-            .compile
-            .toList
-        )
-
-        f(records.map(_.map(r => r.key -> r.value)))
-      },
-      delay = 1.second,
-      max = 5
-    )
+      f: F[List[(String, String)]] => F[Assertion]
+  )(implicit kafkaConfig: EmbeddedKafkaConfig, F: Async[F]): F[Assertion] =
+    eventually {
+      val records = withAssignedConsumer[F[List[ConsumerRecord[String, String]]]](
+        autoCommit = false,
+        offsetReset = AutoOffsetReset.Earliest,
+        partitions,
+        groupId.some
+      )(_.records.map(_.record).interruptAfter(5.second).compile.toList)
+
+      f(records.map(_.map(r => r.key -> r.value)))
+    }
 
   def withAssignedConsumer[T](
       autoCommit: Boolean,
@@ -164,11 +180,4 @@ trait KafkaHelpers[F[_]] {
     val settings = groupId.fold(baseSettings)(baseSettings.withGroupId)
     KafkaConsumer[F].resource(settings)
   }
-
-  def retry[A](fa: F[A], delay: FiniteDuration, max: Int)(implicit F: Async[F]): F[A] =
-    if (max <= 1) fa
-    else
-      fa handleErrorWith { _ =>
-        F.sleep(delay) *> retry(fa, delay, max - 1)
-      }
 }