Java 9 optimization by caching rt.jar (#239)

* Upgraded Ammonite to 1.0.5-7-f032887 that includes a Java 9 performance optimization for mill's client-server mode (lihaoyi/Ammonite#773).

* Java 9 optimization for interactive mode by caching rt.jar.

* Refactored based on @lihaoyi's comments on #239.

* Removed client side rt.jar caching.

* Propagatio of home path from Cli.

* Propagation, propagation, propagation!

3 files changed, 22 insertions, 6 deletions

diff --git a/core/src/mill/eval/Evaluator.scala b/core/src/mill/eval/Evaluator.scala
index e61c2c4c..1e1b8b35 100644
--- a/core/src/mill/eval/Evaluator.scala
+++ b/core/src/mill/eval/Evaluator.scala
@@ -26,7 +26,8 @@ case class Labelled[T](task: NamedTask[T],
     case _ => None
   }
 }
-case class Evaluator[T](outPath: Path,
+case class Evaluator[T](home: Path,
+                        outPath: Path,
                         externalOutPath: Path,
                         rootModule: mill.define.BaseModule,
                         log: Logger,
@@ -265,7 +266,8 @@ case class Evaluator[T](outPath: Path,
                     throw new Exception("No `dest` folder available here")
                 }
             },
-            multiLogger
+            multiLogger,
+            home
           )
 
           val out = System.out
diff --git a/core/src/mill/util/ClassLoader.scala b/core/src/mill/util/ClassLoader.scala
index a1b42158..b53150c2 100644
--- a/core/src/mill/util/ClassLoader.scala
+++ b/core/src/mill/util/ClassLoader.scala
@@ -5,7 +5,9 @@ import java.net.{URL, URLClassLoader}
 import io.github.retronym.java9rtexport.Export
 
 object ClassLoader {
-  def create(urls: Seq[URL], parent: java.lang.ClassLoader): URLClassLoader = {
+  def create(urls: Seq[URL],
+             parent: java.lang.ClassLoader)
+            (implicit ctx: Ctx.Home): URLClassLoader = {
     val cl = new URLClassLoader(urls.toArray, parent)
     if (!ammonite.util.Util.java9OrAbove) return cl
     try {
@@ -13,7 +15,12 @@ object ClassLoader {
       cl
     } catch {
       case _: ClassNotFoundException =>
-        new URLClassLoader((urls ++ Some(Export.export().toURI.toURL)).toArray, parent)
+        val path = ctx.home
+        val rtFile = new java.io.File(path.toIO, s"rt-${System.getProperty("java.version")}.jar")
+        if (!rtFile.exists) {
+          java.nio.file.Files.copy(Export.export().toPath, rtFile.toPath)
+        }
+        new URLClassLoader((urls ++ Some(rtFile.toURI.toURL)).toArray, parent)
     }
   }
 }
diff --git a/core/src/mill/util/Ctx.scala b/core/src/mill/util/Ctx.scala
index 55cc05ab..99818194 100644
--- a/core/src/mill/util/Ctx.scala
+++ b/core/src/mill/util/Ctx.scala
@@ -20,6 +20,9 @@ object Ctx{
   trait Log{
     def log: Logger
   }
+  trait Home{
+    def home: Path
+  }
   object Log{
     implicit def logToCtx(l: Logger): Log = new Log { def log = l }
   }
@@ -27,13 +30,17 @@ object Ctx{
     def args: IndexedSeq[_]
   }
 
+  def defaultHome = ammonite.ops.home / ".mill" / "ammonite"
+
 }
 class Ctx(val args: IndexedSeq[_],
           dest0: () => Path,
-          val log: Logger)
+          val log: Logger,
+          val home: Path)
   extends Ctx.Dest
   with Ctx.Log
-  with Ctx.Args{
+  with Ctx.Args
+  with Ctx.Home{
 
   def dest = dest0()
   def length = args.length