Merge pull request #6107 from eatkins/watch-poll

Fix watch for dumb terminals

internal/util-logging/src/main/scala/sbt/internal/util/Terminal.scala

@@ -327,6 +327,9 @@ object Terminal {
     if (isColorEnabled && doRed) Console.RED + str + Console.RESET
     else str
 
+  private[this] def hasVirtualIO = System.getProperty("sbt.io.virtual", "") == "true" || !isCI
+  private[sbt] def canPollSystemIn: Boolean = hasConsole && !isDumbTerminal && hasVirtualIO
+
   /**
    *
    * @param isServer toggles whether or not this is a server of client process
@@ -337,7 +340,7 @@ object Terminal {
   private[sbt] def withStreams[T](isServer: Boolean)(f: => T): T = {
     // In ci environments, don't touch the io streams unless run with -Dsbt.io.virtual=true
     if (hasConsole && !isDumbTerminal) consoleTerminalHolder.set(newConsoleTerminal())
-    if (System.getProperty("sbt.io.virtual", "") == "true" || !isCI) {
+    if (hasVirtualIO) {
       hasProgress.set(isServer && isAnsiSupported)
       activeTerminal.set(consoleTerminalHolder.get)
       try withOut(withIn(f))

main/src/main/scala/sbt/internal/Continuous.scala

@@ -783,11 +783,20 @@ private[sbt] object Continuous extends DeprecatedContinuous {
     }
     executor => {
       val interrupted = new AtomicBoolean(false)
+      @tailrec def read(): Int = {
+        if (terminal.name.startsWith("network")) terminal.inputStream.read
+        else if (Terminal.canPollSystemIn || terminal.inputStream.available > 0)
+          terminal.inputStream.read
+        else {
+          Thread.sleep(50)
+          read()
+        }
+      }
       @tailrec def impl(): Option[Watch.Action] = {
         val action =
           try {
             interrupted.set(false)
-            terminal.inputStream.read match {
+            read() match {
               case -1   => throw new InterruptedException
               case 3    => Watch.CancelWatch // ctrl+c on windows
               case byte => inputHandler(byte.toChar.toString)