Update deps, add Scala 3 support, drop Scala 2.12

Compared to conhub 1.2.1 the changes are source and binary compatible with
these exceptions:
- potential source compat breakage: NamedDispatcher doesn't have an implicit argument in the constructor anymore
  but it appears to be unused even in the internal Evolution codebase

Changes highlights:
- updated plugins and dependencies
- added Scala 3.3.3 cross-compilation
- removed Scala 2.12 support
- introduced sbt-version-policy plugin and MiMa bincompat checks
- fixed compilation warnings, minor test refactoring
- replaced CurrentThreadExecutionContext usage with direct calls to ExecutionContext.parasitic since
  we do not support 2.12 anymore
- Scala 3 compiler complained about NamedDispatcher implicit arguments in the constructor.
  Since the class is unused even in the internal Evolution codebase, implicit modifier was removed and
  the type was marked as deprecated.

.github/workflows/ci.yml

@@ -10,21 +10,21 @@ jobs:
     strategy:
       matrix:
         scala:
-          - 2.13.8
-          - 2.12.17
+          - 2.13.14
+          - 3.3.3
 
     steps:
       - uses: actions/checkout@v3
 
       - uses: coursier/cache-action@v6
 
       - name: scala
-        uses: olafurpg/setup-scala@v13
+        uses: olafurpg/setup-scala@v14
         with:
           java-version: 17
 
       - name: build ${{ matrix.scala }}
-        run: sbt ++${{ matrix.scala }} clean coverage test
+        run: sbt ++${{ matrix.scala }} clean check coverage test
 
       - name: test coverage
         if: success()

build.sbt

@@ -1,4 +1,4 @@
-import Dependencies._
+import Dependencies.*
 
 name := "conhub"
 
@@ -14,13 +14,22 @@ organizationHomepage := Some(url("https://evolution.com"))
 
 scalaVersion := crossScalaVersions.value.head
 
-crossScalaVersions := Seq("2.13.8", "2.12.17")
+crossScalaVersions := Seq("2.13.14", "3.3.3")
+
+Compile / scalacOptions ++= {
+  if (scalaBinaryVersion.value == "2.13") {
+    Seq(
+      "-Xsource:3"
+    )
+  } else Seq.empty
+}
 
 Test / fork := true
 
 publishTo := Some(Resolver.evolutionReleases)
 
 libraryDependencies ++= Seq(
+  `scodec-bits`,
   Akka.actor,
   Akka.remote,
   Akka.cluster,
@@ -38,6 +47,18 @@ libraryDependencies ++= Seq(
   `scala-tools` % Test,
   scalatest % Test)
 
+libraryDependencies ++= {
+  if (scalaBinaryVersion.value == "2.13") {
+    Seq(
+      `scodec-core1`,
+    )
+  } else {
+    Seq(
+      `scodec-core2`,
+    )
+  }
+}
+
 licenses := Seq(("MIT", url("https://opensource.org/licenses/MIT")))
 
 releaseCrossBuild := true
@@ -46,6 +67,27 @@ Compile / doc / scalacOptions ++= Seq("-groups", "-implicits", "-no-link-warning
 
 versionScheme := Some("semver-spec")
 
-//addCommandAlias("check", "all versionPolicyCheck Compile/doc")
-addCommandAlias("check", "show version")
-addCommandAlias("build", "+all compile test")
+addCommandAlias("check", "+all versionPolicyCheck Compile/doc")
+addCommandAlias("build", "+all test package")
+
+// Your next release will be binary compatible with the previous one,
+// but it may not be source compatible (ie, it will be a minor release).
+ThisBuild / versionPolicyIntention := Compatibility.BinaryCompatible
+
+/*
+versionPolicyReportDependencyIssues ignored dependencies when compared to conhub 1.2.1.
+All of those should not affect the library users, binary compatibility should be preserved.
+
+Remember to clear up after 1.3.0 release!
+ */
+ThisBuild / versionPolicyIgnored ++= Seq(
+  /*
+  Examples:
+
+  //com.chuusai:shapeless_2.13: missing dependency
+  "com.chuusai" %% "shapeless",
+  //org.scala-lang.modules:scala-java8-compat_2.13:
+  //  incompatible version change from 0.9.0 to 1.0.0 (compatibility: early semantic versioning)
+  "org.scala-lang.modules" %% "scala-java8-compat",
+   */
+)

project/Dependencies.scala

@@ -1,19 +1,22 @@
-import sbt._
+import sbt.*
 
 object Dependencies {
 
-  val `config-tools`       = "com.evolutiongaming"        %% "config-tools"       % "1.0.4"
-  val `future-helper`      = "com.evolutiongaming"        %% "future-helper"      % "1.0.6"
-  val sequentially         = "com.evolutiongaming"        %% "sequentially"       % "1.1.4"
-  val `akka-serialization` = "com.evolutiongaming"        %% "akka-serialization" % "1.0.4"
-  val nel                  = "com.evolutiongaming"        %% "nel"                % "1.3.4"
-  val `safe-actor`         = "com.evolutiongaming"        %% "safe-actor"         % "3.0.0"
-  val `scala-tools`        = "com.evolutiongaming"        %% "scala-tools"        % "3.0.5"
-  val scalatest            = "org.scalatest"              %% "scalatest"          % "3.2.14"
+  val `config-tools`       = "com.evolutiongaming"        %% "config-tools"       % "1.0.5"
+  val `future-helper`      = "com.evolutiongaming"        %% "future-helper"      % "1.0.7"
+  val sequentially         = "com.evolutiongaming"        %% "sequentially"       % "1.2.0"
+  val `akka-serialization` = "com.evolutiongaming"        %% "akka-serialization" % "1.1.0"
+  val nel                  = "com.evolutiongaming"        %% "nel"                % "1.3.5"
+  val `safe-actor`         = "com.evolutiongaming"        %% "safe-actor"         % "3.1.0"
+  val `scala-tools`        = "com.evolutiongaming"        %% "scala-tools"        % "3.0.6"
+  val scalatest            = "org.scalatest"              %% "scalatest"          % "3.2.19"
   val `scala-logging`      = "com.typesafe.scala-logging" %% "scala-logging"      % "3.9.5"
+  val `scodec-bits`        = "org.scodec"                 %% "scodec-bits"        % "1.2.1"
+  val `scodec-core1`       = "org.scodec"                 %% "scodec-core"        % "1.11.10"
+  val `scodec-core2`       = "org.scodec"                 %% "scodec-core"        % "2.3.1"
 
   object Akka {
-    private val version = "2.6.19"
+    private val version = "2.6.21"
     val actor    = "com.typesafe.akka" %% "akka-actor"    % version
     val remote   = "com.typesafe.akka" %% "akka-remote"   % version
     val cluster  = "com.typesafe.akka" %% "akka-cluster"  % version
@@ -23,12 +26,7 @@ object Dependencies {
   }
 
   object AkkaTools {
-    private val version = "3.0.12"
+    private val version = "3.0.13"
     val test = "com.evolutiongaming" %% "akka-tools-test" % version
   }
-
-  object Scodec {
-    val core = "org.scodec" %% "scodec-core" % "1.11.3"
-    val bits = "org.scodec" %% "scodec-bits" % "1.1.9"
-  }
 }

project/build.properties

@@ -1 +1 @@
-sbt.version=1.7.2
+sbt.version=1.10.1

project/plugins.sbt

@@ -1,9 +1,11 @@
-addSbtPlugin("org.scoverage" % "sbt-scoverage" % "2.0.6")
+addSbtPlugin("org.scoverage" % "sbt-scoverage" % "2.2.0")
 
-addSbtPlugin("org.scoverage" % "sbt-coveralls" % "1.3.2")
+addSbtPlugin("org.scoverage" % "sbt-coveralls" % "1.3.13")
 
-addSbtPlugin("com.github.sbt" % "sbt-release" % "1.1.0")
+addSbtPlugin("com.github.sbt" % "sbt-release" % "1.4.0")
 
 addSbtPlugin("com.evolution" % "sbt-scalac-opts-plugin" % "0.0.9")
 
-addSbtPlugin("com.evolution" % "sbt-artifactory-plugin" % "0.0.2")
+addSbtPlugin("com.evolution" % "sbt-artifactory-plugin" % "0.0.2")
+
+addSbtPlugin("ch.epfl.scala" % "sbt-version-policy" % "3.2.1")

src/main/scala/com/evolutiongaming/concurrent/NamedDispatcher.scala

@@ -4,8 +4,10 @@ import akka.actor.ActorSystem
 
 import scala.concurrent.ExecutionContext
 
-final case class NamedDispatcher(name: String, implicit val ec: ExecutionContext)
+@deprecated(message = "roll out your own NamedDispatcher, this one will be removed", since = "1.3.0")
+final case class NamedDispatcher(name: String, ec: ExecutionContext)
 
+@deprecated(message = "roll out your own NamedDispatcher, this one will be removed", since = "1.3.0")
 object NamedDispatcher {
 
   def apply(actorSystem: ActorSystem): NamedDispatcher = {

src/main/scala/com/evolutiongaming/conhub/ConHub.scala

@@ -27,7 +27,7 @@ object ConHub {
     def !(msg: M): SR
 
     /**
-      * @param msg messages will be delivered to all matched connections whether it is Local or Remote connection
+      * @param msgs messages will be delivered to all matched connections whether it is Local or Remote connection
       * @return list of local connections that matched the message
       */
     def !(msgs: Nel[M]): SR
@@ -44,7 +44,8 @@ object ConHub {
 
     def cons: Iterable[C] = conStates.values.values
 
-    def consLocal: Iterable[C.Local] = cons.collect { case x: C.Local => x }
+    //@unchecked needed to work around a Scala 3.3.3 compiler quirk with pattern matching
+    def consLocal: Iterable[C.Local] = cons.collect { case x: C.Local@unchecked => x }
 
     def consRemote: Iterable[C.Remote] = cons.collect { case x: C.Remote => x }
   }

src/main/scala/com/evolutiongaming/conhub/ConHubImpl.scala

@@ -4,7 +4,7 @@ import java.util.concurrent.atomic.AtomicBoolean
 
 import com.evolutiongaming.concurrent.sequentially.Sequentially
 import com.evolutiongaming.nel.Nel
-import com.evolutiongaming.concurrent.FutureHelper._
+import com.evolutiongaming.concurrent.FutureHelper.*
 import com.typesafe.scalalogging.LazyLogging
 
 import scala.concurrent.duration.FiniteDuration
@@ -43,7 +43,7 @@ object ConHubImpl extends LazyLogging {
     executor: ExecutionContext
   ): ConHub[Id, A, M, L] = {
 
-    implicit val executor1 = executor
+    implicit val executor1: ExecutionContext = executor
 
     new ConHub[Id, A, M, L] {
 

src/main/scala/com/evolutiongaming/conhub/ConHubSerializer.scala

@@ -3,15 +3,16 @@ package com.evolutiongaming.conhub
 import java.io.NotSerializableException
 
 import akka.serialization.SerializerWithStringManifest
-import com.evolutiongaming.conhub.{RemoteEvent => R}
+import com.evolutiongaming.conhub.RemoteEvent as R
 import com.evolutiongaming.nel.Nel
 import scodec.bits.{BitVector, ByteVector}
 import scodec.{Attempt, Codec, DecodeResult, codecs}
 
-import scala.concurrent.duration._
+import scala.annotation.nowarn
+import scala.concurrent.duration.*
 
 class ConHubSerializer extends SerializerWithStringManifest {
-  import ConHubSerializer._
+  import ConHubSerializer.*
 
   private val EventManifest = "A"
   private val MsgsManifest = "C"
@@ -43,6 +44,10 @@ class ConHubSerializer extends SerializerWithStringManifest {
   }
 }
 
+//suppresses comp warning for 2.13 with -Xsource:3
+@nowarn(
+  "msg=Implicit method .+ was found in a package prefix of the required type, which is not part of the implicit scope in Scala 3"
+)
 object ConHubSerializer {
 
   val codecBytes: Codec[ByteVector] = codecs.variableSizeBytes(codecs.int32, codecs.bytes)
@@ -68,9 +73,9 @@ object ConHubSerializer {
 
   private val codecSync = codecsNel(codecValue).as[RemoteEvent.Event.Sync]
 
-  private def notSerializable(msg: String) = throw new NotSerializableException(msg)
+  private def notSerializable(msg: String): Nothing = throw new NotSerializableException(msg)
 
-  private def illegalArgument(msg: String) = throw new IllegalArgumentException(msg)
+  private def illegalArgument(msg: String): Nothing = throw new IllegalArgumentException(msg)
 
 
   private def eventFromBinary(bits: BitVector) = {

src/main/scala/com/evolutiongaming/conhub/ConStates.scala

@@ -4,7 +4,7 @@ import java.time.Instant
 
 import akka.actor.{Address, Scheduler}
 import com.evolutiongaming.concurrent.sequentially.{MapDirective, SequentialMap}
-import com.evolutiongaming.conhub.SequentialMapHelper._
+import com.evolutiongaming.conhub.SequentialMapHelper.*
 import com.typesafe.scalalogging.LazyLogging
 import scodec.bits.ByteVector
 
@@ -70,7 +70,7 @@ object ConStates {
 
       private val send: SendEvent[Id, A] = connect(this)
 
-      def values = states.values
+      def values: collection.Map[Id, C] = states.values
 
       def update(id: Id, con: C.Local): Result = {
         updatePf(id, Some(con.version), "update") { case before =>
@@ -111,7 +111,8 @@ object ConStates {
           }
 
           (ctx, c) match {
-            case (Ctx.Local, _: C.Local)                                    => disconnect(local = true)
+            //@unchecked needed to work around a Scala 3.3.3 compiler quirk with pattern matching
+            case (Ctx.Local, _: C.Local@unchecked)                          => disconnect(local = true)
             case (ctx: Ctx.Remote, c: C.Remote) if c.address == ctx.address => disconnect(local = false)
             case _                                                          => R.Ignore
           }
@@ -130,7 +131,8 @@ object ConStates {
           def remove(local: Boolean) = this.remove(id, version, local)
 
           (ctx, c) match {
-            case (Ctx.Local, _: C.Local)                                    => remove(local = true)
+            //@unchecked needed to work around a Scala 3.3.3 compiler quirk with pattern matching
+            case (Ctx.Local, _: C.Local@unchecked)                          => remove(local = true)
             case (ctx: Ctx.Remote, c: C.Remote) if c.address == ctx.address => remove(local = false)
             case (_, _: C.Disconnected)                                     => remove(local = ctx == Ctx.Local)
             case _                                                          => R.Ignore
@@ -139,7 +141,8 @@ object ConStates {
       }
 
       def sync(id: Id) = {
-        updatePf(id, None, "sync") { case Some(c: C.Local) =>
+        //@unchecked needed to work around a Scala 3.3.3 compiler quirk with pattern matching
+        updatePf(id, None, "sync") { case Some(c: C.Local@unchecked) =>
           send.sync(id, c.value, c.version)
           R.Ignore
         }

src/main/scala/com/evolutiongaming/conhub/MemberEventSubscribe.scala

@@ -2,7 +2,7 @@ package com.evolutiongaming.conhub
 
 import akka.actor.{Actor, ActorRefFactory, Props}
 import akka.cluster.Cluster
-import akka.cluster.ClusterEvent._
+import akka.cluster.ClusterEvent.*
 import com.evolutiongaming.safeakka.actor.ActorLog
 
 object MemberEventSubscribe {
@@ -16,8 +16,9 @@ object MemberEventSubscribe {
     onEvent: MemberEvent => Unit): Unsubscribe = {
 
     def actor() = new Actor {
-      lazy val log = ActorLog(context.system, MemberEventSubscribe.getClass)
-      def receive = {
+      private lazy val log = ActorLog(context.system, classOf[MemberEventSubscribe.type])
+
+      def receive: Receive = {
         case x: CurrentClusterState => onState(x)
         case x: MemberEvent         => onEvent(x)
         case x                      => log.warn(s"unexpected $x")

src/main/scala/com/evolutiongaming/conhub/SendEvent.scala

@@ -2,7 +2,7 @@ package com.evolutiongaming.conhub
 
 import akka.actor.{ActorRefFactory, ActorSystem, Address}
 import com.evolutiongaming.conhub.transport.{ReceiveMsg, SendMsg}
-import com.evolutiongaming.conhub.{RemoteEvent => R}
+import com.evolutiongaming.conhub.RemoteEvent as R
 import com.evolutiongaming.nel.Nel
 
 import scala.concurrent.duration.FiniteDuration

src/main/scala/com/evolutiongaming/conhub/SendMsgs.scala

@@ -21,8 +21,9 @@ object SendMsgs {
 
       def apply(msg: M, con: C.Connected): Unit = {
         con match {
-          case con: C.Local  => con.send(MsgAndRemote(msg))
-          case con: C.Remote => remote(Nel(msg), List(con.address))
+          //@unchecked needed to work around a Scala 3.3.3 compiler quirk with pattern matching
+          case con: C.Local@unchecked => con.send(MsgAndRemote(msg))
+          case con: C.Remote          => remote(Nel(msg), List(con.address))
         }
       }
 
@@ -33,8 +34,9 @@ object SendMsgs {
       def local(msg: M, cons: Iterable[C], remote: Boolean): Unit = {
         val msgAndRemote = MsgAndRemote(msg, remote)
         for {con <- cons} con match {
-          case x: C.Local => x.send(msgAndRemote)
-          case _          =>
+          //@unchecked needed to work around a Scala 3.3.3 compiler quirk with pattern matching
+          case x: C.Local@unchecked => x.send(msgAndRemote)
+          case _                    =>
         }
       }
     }

src/main/scala/com/evolutiongaming/conhub/SequentialMapHelper.scala

@@ -1,9 +1,8 @@
 package com.evolutiongaming.conhub
 
-import com.evolutiongaming.concurrent.CurrentThreadExecutionContext
 import com.evolutiongaming.concurrent.sequentially.{MapDirective, SequentialMap}
 
-import scala.concurrent.Future
+import scala.concurrent.{ExecutionContext, Future}
 
 object SequentialMapHelper {
 
@@ -25,7 +24,7 @@ object SequentialMapHelper {
       value: V,
       onUpdated: (K, Set[V], Set[V]) => Unit = (_, _, _) => ()): Future[Unit] = {
 
-      implicit val ec = CurrentThreadExecutionContext
+      implicit val ec: ExecutionContext = ExecutionContext.parasitic
 
       if (before != after) {
         val futureBefore = before.fold(Future.unit) { key => updateSet(key)(_ - value, onUpdated(key, _, _)) }
@@ -59,6 +58,6 @@ object SequentialMapHelper {
   implicit class FutureOps[A](val self: Future[A]) extends AnyVal {
 
     // to execute f strictly in order of future origin
-    def mapNow[B](f: A => B): Future[B] = self.map(f)(CurrentThreadExecutionContext)
+    def mapNow[B](f: A => B): Future[B] = self.map(f)(ExecutionContext.parasitic)
   }
 }