Pubsub source v2 pre-fetches more messages when blocked

modules/gcp/src/main/resources/application.conf

@@ -15,9 +15,8 @@
     "durationPerAckExtension": "10 minutes"
     "minRemainingDeadline": 0.1
     "progressTimeout": "10 seconds"
-    "modackOnProgressTimeout": true
-    "cancelOnProgressTimeout": false
-    "consistentClientId": true
+    "prefetchMin": 1
+    "prefetchMax": 10
   }
   "output": {
     "bad": ${snowplow.defaults.sinks.pubsub}

modules/gcp/src/main/scala/common-streams-extensions/v2/LeaseManager.scala

@@ -0,0 +1,85 @@
+/*
+ * Copyright (c) 2023-present Snowplow Analytics Ltd. All rights reserved.
+ *
+ * This program is licensed to you under the Snowplow Community License Version 1.0,
+ * and you may not use this file except in compliance with the Snowplow Community License Version 1.0.
+ * You may obtain a copy of the Snowplow Community License Version 1.0 at https://docs.snowplow.io/community-license-1.0
+ */
+package com.snowplowanalytics.snowplow.sources.pubsub.v2
+
+import cats.effect.{Async, Ref, Resource, Sync}
+import cats.effect.kernel.Unique
+import cats.implicits._
+import cats.effect.implicits._
+import org.typelevel.log4cats.Logger
+import org.typelevel.log4cats.slf4j.Slf4jLogger
+
+import com.google.cloud.pubsub.v1.stub.SubscriberStub
+
+private trait LeaseManager[F[_], A] {
+  def manageLeases(in: A): F[Unique.Token]
+  def stopManagingLeases(tokens: Vector[Unique.Token]): F[Unit]
+}
+
+private object LeaseManager {
+
+  private implicit def logger[F[_]: Sync]: Logger[F] = Slf4jLogger.getLogger[F]
+
+  def resource[F[_]: Async](
+    config: PubsubSourceConfigV2,
+    stub: SubscriberStub,
+    ref: Ref[F, Map[Unique.Token, PubsubBatchState]],
+    channelAffinity: Int
+  ): Resource[F, LeaseManager[F, SubscriberAction.ProcessRecords]] =
+    extendDeadlinesInBackground[F](config, stub, ref, channelAffinity)
+      .as(impl(config, ref, channelAffinity))
+
+  private def impl[F[_]: Sync](
+    config: PubsubSourceConfigV2,
+    ref: Ref[F, Map[Unique.Token, PubsubBatchState]],
+    channelAffinity: Int
+  ): LeaseManager[F, SubscriberAction.ProcessRecords] = new LeaseManager[F, SubscriberAction.ProcessRecords] {
+
+    def manageLeases(in: SubscriberAction.ProcessRecords): F[Unique.Token] =
+      Unique[F].unique.flatMap { token =>
+        val deadline = in.timeReceived.plusMillis(config.durationPerAckExtension.toMillis)
+        val ackIds   = in.records.map(_.getAckId)
+        val state    = PubsubBatchState(deadline, ackIds, channelAffinity)
+        ref.update(_ + (token -> state)).as(token)
+      }
+
+    def stopManagingLeases(tokens: Vector[Unique.Token]): F[Unit] =
+      ref.update(_.removedAll(tokens))
+  }
+
+  private def extendDeadlinesInBackground[F[_]: Async](
+    config: PubsubSourceConfigV2,
+    stub: SubscriberStub,
+    refStates: Ref[F, Map[Unique.Token, PubsubBatchState]],
+    channelAffinity: Int
+  ): Resource[F, Unit] = {
+    def go: F[Unit] = for {
+      now <- Sync[F].realTimeInstant
+      minAllowedDeadline = now.plusMillis((config.minRemainingDeadline * config.durationPerAckExtension.toMillis).toLong)
+      newDeadline        = now.plusMillis(config.durationPerAckExtension.toMillis)
+      toExtend <- refStates.modify { m =>
+                    val toExtend = m.filter { case (_, batchState) =>
+                      batchState.channelAffinity === channelAffinity && batchState.currentDeadline.isBefore(minAllowedDeadline)
+                    }
+                    val fixed = toExtend.view
+                      .mapValues(_.copy(currentDeadline = newDeadline))
+                      .toMap
+                    (m ++ fixed, toExtend.values.toVector)
+                  }
+      _ <- if (toExtend.isEmpty)
+             Sync[F].sleep(0.5 * config.minRemainingDeadline * config.durationPerAckExtension)
+           else {
+             val ackIds = toExtend.sortBy(_.currentDeadline).flatMap(_.ackIds.toVector)
+             Utils.modAck[F](config.subscription, stub, ackIds, config.durationPerAckExtension, channelAffinity)
+           }
+      _ <- go
+    } yield ()
+    go.background.void
+  }
+
+}

modules/gcp/src/main/scala/common-streams-extensions/v2/PubsubBatchState.scala

@@ -7,6 +7,8 @@
  */
 package com.snowplowanalytics.snowplow.sources.pubsub.v2
 
+import cats.data.NonEmptyVector
+
 import java.time.Instant
 
 /**
@@ -23,6 +25,6 @@ import java.time.Instant
  */
 private case class PubsubBatchState(
   currentDeadline: Instant,
-  ackIds: Vector[String],
+  ackIds: NonEmptyVector[String],
   channelAffinity: Int
 )

modules/gcp/src/main/scala/common-streams-extensions/v2/PubsubCheckpointer.scala

@@ -60,7 +60,7 @@ class PubsubCheckpointer[F[_]: Async](
       ackDatas <- refAckIds.modify(m => (m.removedAll(c), c.flatMap(m.get)))
       grouped = ackDatas.groupBy(_.channelAffinity)
       _ <- grouped.toVector.parTraverse_ { case (channelAffinity, ackDatas) =>
-             ackDatas.flatMap(_.ackIds).grouped(1000).toVector.traverse_ { ackIds =>
+             ackDatas.flatMap(_.ackIds.toVector).grouped(1000).toVector.traverse_ { ackIds =>
                val request = AcknowledgeRequest.newBuilder.setSubscription(subscription.show).addAllAckIds(ackIds.asJava).build
                val context = GrpcCallContext.createDefault.withChannelAffinity(channelAffinity)
                val attempt = for {
@@ -88,7 +88,7 @@ class PubsubCheckpointer[F[_]: Async](
       ackDatas <- refAckIds.modify(m => (m.removedAll(c), c.flatMap(m.get)))
       grouped = ackDatas.groupBy(_.channelAffinity)
       _ <- grouped.toVector.parTraverse_ { case (channelAffinity, ackDatas) =>
-             val ackIds = ackDatas.flatMap(_.ackIds)
+             val ackIds = ackDatas.flatMap(_.ackIds.toVector)
              // A nack is just a modack with zero duration
              Utils.modAck[F](subscription, stub, ackIds, Duration.Zero, channelAffinity)
            }

modules/gcp/src/main/scala/common-streams-extensions/v2/PubsubSourceConfigV2.scala

@@ -25,9 +25,8 @@ case class PubsubSourceConfigV2(
   gcpUserAgent: GcpUserAgent,
   maxPullsPerTransportChannel: Int,
   progressTimeout: FiniteDuration,
-  modackOnProgressTimeout: Boolean,
-  cancelOnProgressTimeout: Boolean,
-  consistentClientId: Boolean
+  prefetchMin: Int,
+  prefetchMax: Int
 )
 
 object PubsubSourceConfigV2 {