experimental UI: honor --curses

Bazel can be asked to uses colors, but not to use other curses options.
In this case, the ExperimentalEventHandler cannot rely on the terminal
to ignore all curses output; hence it has to actively refrain from using
curses that move the cursor.

--
Change-Id: I026edade4366a8c5a8e56d376e8a4603f5c73b92
Reviewed-on: https://bazel-review.googlesource.com/#/c/3291
MOS_MIGRATED_REVID=119439855

1 files changed, 5 insertions, 0 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/runtime/ExperimentalEventHandler.java b/src/main/java/com/google/devtools/build/lib/runtime/ExperimentalEventHandler.java
index cfa284f7d9..e13b75b834 100644
--- a/src/main/java/com/google/devtools/build/lib/runtime/ExperimentalEventHandler.java
+++ b/src/main/java/com/google/devtools/build/lib/runtime/ExperimentalEventHandler.java
@@ -42,6 +42,7 @@ import java.util.logging.Logger;
 public class ExperimentalEventHandler extends BlazeCommandEventHandler {
   private static Logger LOG = Logger.getLogger(ExperimentalEventHandler.class.getName());
 
+  private final boolean cursorControl;
   private final AnsiTerminal terminal;
   private final boolean debugAllEvents;
   private final ExperimentalStateTracker stateTracker;
@@ -54,6 +55,7 @@ public class ExperimentalEventHandler extends BlazeCommandEventHandler {
   public ExperimentalEventHandler(
       OutErr outErr, BlazeCommandEventHandler.Options options, Clock clock) {
     super(outErr, options);
+    this.cursorControl = options.useCursorControl();
     this.terminal = new AnsiTerminal(outErr.getErrorStream());
     this.terminalWidth = (options.terminalColumns > 0 ? options.terminalColumns : 80);
     this.debugAllEvents = options.experimentalUiDebugAllEvents;
@@ -224,6 +226,9 @@ public class ExperimentalEventHandler extends BlazeCommandEventHandler {
   }
 
   private void clearProgressBar() throws IOException {
+    if (!cursorControl) {
+      return;
+    }
     for (int i = 0; i < numLinesProgressBar; i++) {
       terminal.cr();
       terminal.cursorUp(1);