experimental UI: consider progress bar refreshed on every redraw

Whenever the UI has to write a line to the progress buffer, it removes
the progress bar, write the line and re-adds the progress bar. Of course,
the re-added progress bar is the one that represents the up-to-date state
at the time of it being re-added. Therefore, this also is a refresh of the
progress bar. So update the time stamp tracking the last refresh. In this
way rate-limits on refreshes are honored more correctly; also, requirements
of the progress bar having to be refreshed after a certain point in time
that have been fulfilled by that implicit refresh are recognized as such,
keeping the output less flickering.

--
Change-Id: I44bcd85a149cb88fcde126119100a6e1ff1ba45d
Reviewed-on: https://bazel-review.googlesource.com/#/c/3873
MOS_MIGRATED_REVID=125664608

1 files changed, 2 insertions, 2 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 5fab644b36..cbe3755de7 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
@@ -365,7 +365,6 @@ public class ExperimentalEventHandler extends BlazeCommandEventHandler {
         try {
           if (showProgress && (progressBarNeedsRefresh || timeBasedRefresh())) {
             progressBarNeedsRefresh = false;
-            lastRefreshMillis = nowMillis;
             clearProgressBar();
             addProgressBar();
             terminal.flush();
@@ -498,10 +497,11 @@ public class ExperimentalEventHandler extends BlazeCommandEventHandler {
     terminal.writeString("\n");
   }
 
-  private void addProgressBar() throws IOException {
+  private synchronized void addProgressBar() throws IOException {
     LineCountingAnsiTerminalWriter countingTerminalWriter =
         new LineCountingAnsiTerminalWriter(terminal);
     AnsiTerminalWriter terminalWriter = countingTerminalWriter;
+    lastRefreshMillis = clock.currentTimeMillis();
     if (cursorControl) {
       terminalWriter = new LineWrappingAnsiTerminalWriter(terminalWriter, terminalWidth - 1);
     }