akka.build.version property, #26958 (#26959)

* akka.build.version property, #26958

* and use timestamped snapshot version if "timestamp" is passed in
* to support publishing snapshots with same version for Scala 2.12 and 2.13
  with +publish
* remove stampVersion plugin, since it's no longer needed

* store currentDateTime in system property

* to survive reloads

build.sbt

@@ -2,7 +2,6 @@ import akka.{ AutomaticModuleName, CopyrightHeaderForBuild, ParadoxSupport, Scal
 
 enablePlugins(
   UnidocRoot,
-  TimeStampede,
   UnidocWithPrValidation,
   NoPublish,
   CopyrightHeader,

project/AkkaBuild.scala

@@ -6,6 +6,9 @@ package akka
 
 import java.io.{FileInputStream, InputStreamReader}
 import java.util.Properties
+import java.time.format.DateTimeFormatter
+import java.time.ZonedDateTime
+import java.time.ZoneOffset
 
 import sbt.Keys._
 import sbt._
@@ -21,14 +24,31 @@ object AkkaBuild {
 
   lazy val buildSettings = Dependencies.Versions ++ Seq(
     organization := "com.typesafe.akka",
-    // use the same value as in the build scope, so it can be overriden by stampVersion
+    // use the same value as in the build scope
     version := (version in ThisBuild).value)
 
+  lazy val currentDateTime = {
+    // storing the first accessed timestamp in system property so that it will be the
+    // same when build is reloaded or when using `+`.
+    // `+` actually doesn't re-initialize this part of the build but that may change in the future.
+    sys.props.getOrElseUpdate("akka.build.timestamp",
+      DateTimeFormatter
+        .ofPattern("yyyyMMdd-HHmmss")
+        .format(ZonedDateTime.now(ZoneOffset.UTC)))
+  }
+  
+  def akkaVersion: String = {
+    sys.props.getOrElse("akka.build.version", "2.6-SNAPSHOT") match {
+      case "timestamp" => s"2.6-$currentDateTime" // used when publishing timestamped snapshots
+      case v => v  
+    }
+  }
+
   lazy val rootSettings = Release.settings ++
     UnidocRoot.akkaSettings ++
     Protobuf.settings ++ Seq(
       parallelExecution in GlobalScope := System.getProperty("akka.parallelExecution", parallelExecutionByDefault.toString).toBoolean,
-      version in ThisBuild := "2.6-SNAPSHOT"
+      version in ThisBuild := akkaVersion 
     )
  
   lazy val mayChangeSettings = Seq(

project/TimeStampede.scala

@@ -1,39 +0,0 @@
-/*
- * Copyright (C) 2009-2019 Lightbend Inc. <https://www.lightbend.com>
- */
-
-package akka
-
-import java.time.Instant
-import java.time.LocalDateTime
-import java.time.ZoneId
-import java.time.format.DateTimeFormatter
-
-import sbt._
-import sbt.Keys._
-
-object TimeStampede extends AutoPlugin {
-
-  override def trigger = noTrigger
-
-  override lazy val projectSettings = Seq(
-    commands += stampVersion)
-
-  final val Snapshot = "-SNAPSHOT"
-
-  def stampVersion = Command.command("stampVersion") { state =>
-    val extracted = Project.extract(state)
-    extracted.appendWithSession(List(version in ThisBuild ~= stamp), state)
-  }
-
-  def stamp(version: String): String = {
-    if (version endsWith Snapshot) (version stripSuffix Snapshot) + "-" + timestamp(System.currentTimeMillis)
-    else version
-  }
-
-  val formatter = DateTimeFormatter.ofPattern("yyyyMMdd-HHmmss")
-
-  def timestamp(time: Long): String = {
-    formatter.format(LocalDateTime.ofInstant(Instant.ofEpochMilli(time), ZoneId.systemDefault()))
-  }
-}