From f6f5e7b2a8459a4724fe4789f947b28f4cc42133 Mon Sep 17 00:00:00 2001
From: Eugene Yokota <eed3si9n@gmail.com>
Date: Sun, 1 Apr 2018 16:08:47 -0400
Subject: [PATCH] Add sbt.launcher.standby

This implements a JVM flag to standby for given duration before doing anything.
The purpose of this flag is for the developers of sbt to acquire Java process ID for the purpose of profiling.

```
$ sbt -J-Dsbt.launcher.standby=20s exit
[info] Standing by: 20
[info] Standing by: 19
...
[info] Standing by: 1
[info] Loading settings from pgp.sbt ...
```
---
 .../src/main/scala/xsbt/boot/Boot.scala           | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/launcher-implementation/src/main/scala/xsbt/boot/Boot.scala b/launcher-implementation/src/main/scala/xsbt/boot/Boot.scala
index be39afe..e72cafa 100644
--- a/launcher-implementation/src/main/scala/xsbt/boot/Boot.scala
+++ b/launcher-implementation/src/main/scala/xsbt/boot/Boot.scala
@@ -8,6 +8,7 @@ import java.io.File
 // The entry point to the launcher
 object Boot {
   def main(args: Array[String]) {
+    standBy()
     val config = parseArgs(args)
     // If we havne't exited, we set up some hooks and launch
     System.clearProperty("scala.home") // avoid errors from mixing Scala versions in the same JVM
@@ -16,6 +17,20 @@ object Boot {
     CheckProxy()
     run(config)
   }
+
+  def standBy(): Unit = {
+    import scala.concurrent.duration.Duration
+    sys.props.get("sbt.launcher.standby") foreach { s =>
+      val sec = Duration(s).toSeconds
+      if (sec >= 1) {
+        (sec to 1 by -1) foreach { i =>
+          println(s"[info] Standing by: $i")
+          Thread.sleep(1000)
+        }
+      }
+    }
+  }
+
   def parseArgs(args: Array[String]): LauncherArguments = {
     @annotation.tailrec
     def parse(args: List[String], isLocate: Boolean, remaining: List[String]): LauncherArguments =