add JavaModule#runBackground, to allow a task to kick off processes to run in the background that only die when the task is re-run

2 files changed, 23 insertions, 14 deletions

diff --git a/main/src/mill/modules/Jvm.scala b/main/src/mill/modules/Jvm.scala
index be683e4a..3a6dcb9f 100644
--- a/main/src/mill/modules/Jvm.scala
+++ b/main/src/mill/modules/Jvm.scala
@@ -26,20 +26,30 @@ object Jvm {
                             jvmArgs: Seq[String] = Seq.empty,
                             envArgs: Map[String, String] = Map.empty,
                             mainArgs: Seq[String] = Seq.empty,
-                            workingDir: Path = null): Unit = {
-    baseInteractiveSubprocess(
+                            workingDir: Path = null,
+                            background: Boolean = false): Unit = {
+    val args =
       Vector("java") ++
-        jvmArgs ++
-        Vector("-cp", classPath.mkString(File.pathSeparator), mainClass) ++
-        mainArgs,
-      envArgs,
-      workingDir
-    )
+      jvmArgs ++
+      Vector("-cp", classPath.mkString(File.pathSeparator), mainClass) ++
+      mainArgs
+
+    if (background) baseInteractiveSubprocess0(args, envArgs, workingDir)
+    else baseInteractiveSubprocess(args, envArgs, workingDir)
   }
 
   def baseInteractiveSubprocess(commandArgs: Seq[String],
                                 envArgs: Map[String, String],
                                 workingDir: Path) = {
+    val process = baseInteractiveSubprocess0(commandArgs, envArgs, workingDir)
+
+    val exitCode = process.waitFor()
+    if (exitCode == 0) ()
+    else throw InteractiveShelloutException()
+  }
+  def baseInteractiveSubprocess0(commandArgs: Seq[String],
+                                 envArgs: Map[String, String],
+                                 workingDir: Path) = {
     val builder = new java.lang.ProcessBuilder()
 
     for ((k, v) <- envArgs){
@@ -48,7 +58,7 @@ object Jvm {
     }
     builder.directory(workingDir.toIO)
 
-    val process = if (System.in.isInstanceOf[ByteArrayInputStream]){
+    if (System.in.isInstanceOf[ByteArrayInputStream]){
 
       val process = builder
         .command(commandArgs:_*)
@@ -71,11 +81,9 @@ object Jvm {
         .start()
     }
 
-    val exitCode = process.waitFor()
-    if (exitCode == 0) ()
-    else throw InteractiveShelloutException()
   }
 
+
   def runLocal(mainClass: String,
                classPath: Agg[Path],
                mainArgs: Seq[String] = Seq.empty)
diff --git a/main/src/mill/modules/Util.scala b/main/src/mill/modules/Util.scala
index da7407d0..2d71c13e 100644
--- a/main/src/mill/modules/Util.scala
+++ b/main/src/mill/modules/Util.scala
@@ -59,7 +59,8 @@ object Util {
   def millProjectModule(key: String,
                         artifact: String,
                         repositories: Seq[Repository],
-                        resolveFilter: Path => Boolean = _ => true) = {
+                        resolveFilter: Path => Boolean = _ => true,
+                        artifactSuffix: String = "_2.12") = {
     val localPath = sys.props(key)
     if (localPath != null) {
       mill.eval.Result.Success(
@@ -70,7 +71,7 @@ object Util {
         repositories,
         Seq(
           coursier.Dependency(
-            coursier.Module("com.lihaoyi", artifact + "_2.12"),
+            coursier.Module("com.lihaoyi", artifact + artifactSuffix),
             sys.props("MILL_VERSION")
           )
         ),