From dea7bdfa89d08134dd4ed94073d120e899ba99d3 Mon Sep 17 00:00:00 2001
From: Ethan Atkins <contact@ethanatkins.com>
Date: Fri, 10 Jul 2020 13:15:16 -0700
Subject: [PATCH] Don't start an ask user thread for dead console

If there is no system console available, then there is no point in
making an ask user thread. An ask user thread can only be created when
the terminal prompt is in the Prompt.Running or Prompt.Loading state.
The console channel will now set itself to be in the Prompt.NoPrompt
state if it detects that there is no System.console available.

The motivation for this change is that jline was printing a lot of extra
text during scripted and server tests. Whenever a jline3 linereader is
closed, it prints a newline so the logs were filled with unnecessary
newlines.
---
 .../sbt/internal/util/ConsoleAppender.scala   | 23 +++++++++++--------
 .../main/scala/sbt/internal/util/Prompt.scala |  1 +
 .../scala/sbt/internal/util/Terminal.scala    |  3 ++-
 .../scala/sbt/internal/ConsoleChannel.scala   |  1 +
 4 files changed, 17 insertions(+), 11 deletions(-)

diff --git a/internal/util-logging/src/main/scala/sbt/internal/util/ConsoleAppender.scala b/internal/util-logging/src/main/scala/sbt/internal/util/ConsoleAppender.scala
index f12e06d1f..ddc2cb647 100644
--- a/internal/util-logging/src/main/scala/sbt/internal/util/ConsoleAppender.scala
+++ b/internal/util-logging/src/main/scala/sbt/internal/util/ConsoleAppender.scala
@@ -644,20 +644,23 @@ private[sbt] object ProgressState {
     val isRunning = terminal.prompt == Prompt.Running
     val isBatch = terminal.prompt == Prompt.Batch
     val isWatch = terminal.prompt == Prompt.Watch
+    val noPrompt = terminal.prompt == Prompt.NoPrompt
     if (terminal.isSupershellEnabled) {
       if (!pe.skipIfActive.getOrElse(false) || (!isRunning && !isBatch)) {
         terminal.withPrintStream { ps =>
-          val info = if (isRunning || isBatch && pe.channelName.fold(true)(_ == terminal.name)) {
-            pe.items.map { item =>
-              val elapsed = item.elapsedMicros / 1000000L
-              s"  | => ${item.name} ${elapsed}s"
+          val info =
+            if ((isRunning || isBatch || noPrompt) && pe.channelName
+                  .fold(true)(_ == terminal.name)) {
+              pe.items.map { item =>
+                val elapsed = item.elapsedMicros / 1000000L
+                s"  | => ${item.name} ${elapsed}s"
+              }
+            } else {
+              pe.command.toSeq.flatMap { cmd =>
+                val tail = if (isWatch) Nil else "enter 'cancel' to stop evaluation" :: Nil
+                s"sbt server is running '$cmd'" :: tail
+              }
             }
-          } else {
-            pe.command.toSeq.flatMap { cmd =>
-              val tail = if (isWatch) Nil else "enter 'cancel' to stop evaluation" :: Nil
-              s"sbt server is running '$cmd'" :: tail
-            }
-          }
 
           val currentLength = info.foldLeft(0)(_ + terminal.lineCount(_))
           val previousLines = state.progressLines.getAndSet(info)
diff --git a/internal/util-logging/src/main/scala/sbt/internal/util/Prompt.scala b/internal/util-logging/src/main/scala/sbt/internal/util/Prompt.scala
index 53c4f3849..bd50e9e75 100644
--- a/internal/util-logging/src/main/scala/sbt/internal/util/Prompt.scala
+++ b/internal/util-logging/src/main/scala/sbt/internal/util/Prompt.scala
@@ -45,4 +45,5 @@ private[sbt] object Prompt {
   private[sbt] case object Batch extends NoPrompt
   private[sbt] case object Watch extends NoPrompt
   private[sbt] case object Loading extends NoPrompt
+  private[sbt] case object NoPrompt extends NoPrompt
 }
diff --git a/internal/util-logging/src/main/scala/sbt/internal/util/Terminal.scala b/internal/util-logging/src/main/scala/sbt/internal/util/Terminal.scala
index 0c2d50414..a416840ac 100644
--- a/internal/util-logging/src/main/scala/sbt/internal/util/Terminal.scala
+++ b/internal/util-logging/src/main/scala/sbt/internal/util/Terminal.scala
@@ -126,7 +126,8 @@ trait Terminal extends AutoCloseable {
   private[sbt] val progressState = new ProgressState(1)
   private[this] val promptHolder: AtomicReference[Prompt] = new AtomicReference(Prompt.Running)
   private[sbt] final def prompt: Prompt = promptHolder.get
-  private[sbt] final def setPrompt(newPrompt: Prompt): Unit = promptHolder.set(newPrompt)
+  private[sbt] final def setPrompt(newPrompt: Prompt): Unit =
+    if (prompt != Prompt.NoPrompt) promptHolder.set(newPrompt)
 
   /**
    * Returns the number of lines that the input string will cover given the current width of the
diff --git a/main-command/src/main/scala/sbt/internal/ConsoleChannel.scala b/main-command/src/main/scala/sbt/internal/ConsoleChannel.scala
index dac0c9565..397dba7a0 100644
--- a/main-command/src/main/scala/sbt/internal/ConsoleChannel.scala
+++ b/main-command/src/main/scala/sbt/internal/ConsoleChannel.scala
@@ -25,6 +25,7 @@ private[sbt] final class ConsoleChannel(
 
   override val userThread: UserThread = new UserThread(this)
   private[sbt] def terminal = Terminal.console
+  if (System.console == null) terminal.setPrompt(Prompt.NoPrompt)
 }
 private[sbt] object ConsoleChannel {
   private[sbt] def defaultName = "console0"