Read stderr from server for a short time before exiting

Previously we exited immediately without waiting to get any
error output.

This patch also adds the command line and directory to the
exception message on failure, in case the failure is due to
getting one of those wrong, for example.

launch/src/main/scala/xsbt/boot/ServerApplication.scala

@@ -95,9 +95,9 @@ object ServerLocator {
 class StreamDumper(in: java.io.BufferedReader, out: java.io.PrintStream) extends Thread {
   // Don't block the application for this thread.
   setDaemon(true)
-  private val running = new java.util.concurrent.atomic.AtomicBoolean(true)
+  val endTime = new java.util.concurrent.atomic.AtomicLong(Long.MaxValue)
   override def run(): Unit = {
-    def read(): Unit = if (running.get) in.readLine match {
+    def read(): Unit = if (endTime.get > System.currentTimeMillis) in.readLine match {
       case null => ()
       case line =>
         out.println(line)
@@ -107,7 +107,19 @@ class StreamDumper(in: java.io.BufferedReader, out: java.io.PrintStream) extends
     out.close()
   }
 
-  def close(): Unit = running.set(false)
+  def close(waitForErrors: Boolean): Unit = {
+    // closing "in" blocks forever on Windows, so don't do it;
+    // just wait a couple seconds to read more stuff if there is
+    // any stuff.
+    if (waitForErrors) {
+      endTime.set(System.currentTimeMillis + 2000)
+      // let ourselves read more (thread should exit on earlier of endTime or EOF)
+      while (isAlive() && (endTime.get > System.currentTimeMillis))
+        Thread.sleep(50)
+    } else {
+      endTime.set(System.currentTimeMillis)
+    }
+  }
 }
 object ServerLauncher {
   import ServerApplication.SERVER_SYNCH_TEXT
@@ -146,16 +158,20 @@ object ServerLauncher {
     // Now we look for the URI synch value, and then make sure we close the output files.
     try readUntilSynch(new java.io.BufferedReader(new java.io.InputStreamReader(stdout))) match {
       case Some(uri) => uri
-      case _         => sys.error("Failed to start server!")
+      case _ =>
+        // attempt to get rid of the server (helps prevent hanging / stuck locks,
+        // though this is not reliable)
+        try process.destroy() catch { case e: Exception => }
+        // block a second to try to get stuff from stderr
+        errorDumper.close(waitForErrors = true)
+        sys.error(s"Failed to start server process in ${pb.directory} command line ${pb.command}")
     } finally {
-      errorDumper.close()
+      errorDumper.close(waitForErrors = false)
       stdout.close()
-      // Note:  Closing this causes windows to block waiting for the server
-      // to close, but it ne'er will, as it is obstinate, and not designed
-      // to close immediately, unlike this process.
-      // We leave it open because this JVM shold be shut down soon anyway,
-      // and that will clean up al this memory.
-      //stderr.close()
+      // Do not close stderr here because on Windows that will block,
+      // and since the child process has no reason to exit, it may
+      // block forever. errorDumper.close() instead owns the problem
+      // of deciding what to do with stderr.
     }
   }
 
@@ -202,4 +218,4 @@ object ServerLauncher {
     } catch {
       case e: Throwable => throw new RuntimeException("Unable to find sbt-launch.jar.", e)
     }
-}
+}