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Implement Graceful Shutdown #55

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merged 5 commits into from
Nov 19, 2019
Merged

Implement Graceful Shutdown #55

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1645477
implement graceful shutdown
adamgfraser Oct 29, 2019
0db5046
address review comments
adamgfraser Oct 31, 2019
9d655f2
call handlePoll
adamgfraser Nov 1, 2019
c0fa49f
merge upstream changes
adamgfraser Nov 18, 2019
1113c96
eagerly resolve pending requests
adamgfraser Nov 18, 2019
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7 changes: 7 additions & 0 deletions src/main/scala/zio/kafka/client/Consumer.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -32,6 +32,13 @@ class Consumer private (
): BlockingTask[Map[TopicPartition, Long]] =
consumer.withConsumer(_.endOffsets(partitions.asJava, timeout.asJava).asScala.mapValues(_.longValue()).toMap)

/**
* Stops consumption of data, drains buffered records, and ends the attached
* streams while still serving commit requests.
*/
def stopConsumption: UIO[Unit] =
runloop.deps.gracefulShutdown

def listTopics(timeout: Duration = Duration.Infinity): BlockingTask[Map[String, List[PartitionInfo]]] =
consumer.withConsumer(_.listTopics(timeout.asJava).asScala.mapValues(_.asScala.toList).toMap)

Expand Down
119 changes: 83 additions & 36 deletions src/main/scala/zio/kafka/client/Runloop.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -46,7 +46,8 @@ object Runloop {
partitions: Queue[Take[Throwable, (TopicPartition, ZStreamChunk[Any, Throwable, ByteArrayCommittableRecord])]],
rebalancingRef: Ref[Boolean],
rebalanceListener: ConsumerRebalanceListener,
diagnostics: Diagnostics
diagnostics: Diagnostics,
shutdownRef: Ref[Boolean]
) {
def commit(cmd: Command.Commit) = commitQueue.offer(cmd).unit
def commits = ZStream.fromQueue(commitQueue)
Expand All @@ -60,6 +61,14 @@ object Runloop {
partitions.offer(Take.Value(tp -> data)).unit

def emitIfEnabledDiagnostic(event: DiagnosticEvent) = diagnostics.emitIfEnabled(event)

val isShutdown = shutdownRef.get

def gracefulShutdown: UIO[Unit] =
for {
shutdown <- shutdownRef.modify((_, true))
_ <- partitions.offer(Take.End).when(!shutdown)
} yield ()
}
object Deps {
def make(
Expand All @@ -76,6 +85,12 @@ object Runloop {
.unbounded[
Take[Throwable, (TopicPartition, ZStreamChunk[Any, Throwable, ByteArrayCommittableRecord])]
]
.map { queue =>
queue.mapM {
case Take.End => queue.shutdown.as(Take.End)
case x => ZIO.succeed(x)
}
}
.toManaged(_.shutdown)
listener <- ZIO
.runtime[Blocking]
Expand All @@ -100,6 +115,7 @@ object Runloop {
}
}
.toManaged_
shutdownRef <- Ref.make(false).toManaged_
} yield Deps(
consumer,
pollFrequency,
Expand All @@ -109,7 +125,8 @@ object Runloop {
partitions,
rebalancingRef,
listener,
diagnostics
diagnostics,
shutdownRef
)
}

Expand Down Expand Up @@ -320,38 +337,44 @@ object Runloop {
// is empty because pattern subscriptions start out as empty.
case _: IllegalStateException => null
}
deps.isShutdown.flatMap { shutdown =>
if (shutdown)
ZIO.effectTotal(deps.consumer.consumer.pause(requestedPartitions.asJava)) *>
ZIO.succeed(
(Set(), (state.pendingRequests, Map[TopicPartition, Chunk[ByteArrayConsumerRecord]]()))
)
else if (records eq null)
ZIO.succeed(
(Set(), (state.pendingRequests, Map[TopicPartition, Chunk[ByteArrayConsumerRecord]]()))
)
else {

if (records eq null)
ZIO.succeed(
(Set(), (state.pendingRequests, Map[TopicPartition, Chunk[ByteArrayConsumerRecord]]()))
)
else {

val tpsInResponse = records.partitions.asScala
val currentAssigned = c.assignment().asScala
val newlyAssigned = currentAssigned -- prevAssigned
val revoked = prevAssigned -- currentAssigned
val unrequestedRecords =
bufferUnrequestedPartitions(records, tpsInResponse -- requestedPartitions)

endRevoked(
state.pendingRequests,
state.addBufferedRecords(unrequestedRecords).bufferedRecords,
revoked(_)
).flatMap {
case (pendingRequests, bufferedRecords) =>
for {
output <- fulfillRequests(pendingRequests, bufferedRecords, records)
(notFulfilled, fulfilled) = output
_ <- deps.emitIfEnabledDiagnostic(
DiagnosticEvent.Poll(
requestedPartitions,
fulfilled.keySet,
notFulfilled.map(_.tp).toSet
val tpsInResponse = records.partitions.asScala
val currentAssigned = c.assignment().asScala
val newlyAssigned = currentAssigned -- prevAssigned
val revoked = prevAssigned -- currentAssigned
val unrequestedRecords =
bufferUnrequestedPartitions(records, tpsInResponse -- requestedPartitions)

endRevoked(
state.pendingRequests,
state.addBufferedRecords(unrequestedRecords).bufferedRecords,
revoked(_)
).flatMap {
case (pendingRequests, bufferedRecords) =>
for {
output <- fulfillRequests(pendingRequests, bufferedRecords, records)
(notFulfilled, fulfilled) = output
_ <- deps.emitIfEnabledDiagnostic(
DiagnosticEvent.Poll(
requestedPartitions,
fulfilled.keySet,
notFulfilled.map(_.tp).toSet
)
)
)
} yield output
}.map((newlyAssigned.toSet, _))
} yield output
}.map((newlyAssigned.toSet, _))
}
}
}
}
Expand Down Expand Up @@ -384,17 +407,41 @@ object Runloop {
else doCommit(List(cmd)).as(state)
} yield newState

def handleShutdown(state: State, cmd: Command): BlockingTask[State] = cmd match {
case Command.Poll() =>
state.pendingRequests match {
case h :: t =>
handleShutdown(state, h).flatMap { s =>
handleShutdown(s.copy(pendingRequests = t), cmd)
}
case Nil => handlePoll(state)
}
case Command.Request(tp, cont) =>
state.bufferedRecords.get(tp) match {
case Some(recs) =>
cont
.succeed(recs.map(CommittableRecord(_, commit(_))))
.as(state.removeBufferedRecordsFor(tp))
case None => cont.fail(None).as(state)
}
case cmd @ Command.Commit(_, _) => handleCommit(state, cmd)
}

ZStream
.mergeAll(3, 32)(
deps.polls,
deps.requests,
deps.commits
)
.foldM(State.initial) { (state, cmd) =>
cmd match {
case Command.Poll() => handlePoll(state)
case req @ Command.Request(_, _) => handleRequest(state, req)
case cmd @ Command.Commit(_, _) => handleCommit(state, cmd)
deps.isShutdown.flatMap { shutdown =>
if (shutdown) handleShutdown(state, cmd)
else
cmd match {
case Command.Poll() => handlePoll(state)
case req @ Command.Request(_, _) => handleRequest(state, req)
case cmd @ Command.Commit(_, _) => handleCommit(state, cmd)
}
}
}
.onError { cause =>
Expand Down
15 changes: 15 additions & 0 deletions src/test/scala/zio/kafka/client/ConsumerTest.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -146,6 +146,21 @@ object ConsumerTest
_ => assertCompletes,
_ => assert("result", equalTo("Expected consumeWith to fail"))
)
},
testM("not receive messages after shutting down") {
val kvs = (1 to 5).toList.map(i => (s"key$i", s"msg$i"))
for {
_ <- produceMany("topic150", kvs)
records <- withConsumer("group150", "client150") { consumer =>
consumer.stopConsumption *>
consumer
.subscribeAnd(Subscription.Topics(Set("topic150")))
.plainStream(Serde.string, Serde.string)
.flattenChunks
.take(5)
.runCollect
}
} yield assert(records, isEmpty)
}
).provideManagedShared(KafkaTestUtils.kafkaEnvironment)
)