experimental UI: improve message shortening

When a progress message has to be shortened, as it does not fit in a
line in the progress bar, add a new first attempt: if the message the
path implicit to the label, only shorten that path within the message
(if that gets short enough, leaving a reasonable part of the path);
usually, the additional information is more useful than having a longer
part of the path present.

While there, also fix incorrect length computation in a different case
of message shortening.

--
Change-Id: Ied80e03cace1b249fc0f4e11bce41f2b4207b6ad
Reviewed-on: https://bazel-review.googlesource.com/#/c/3670
MOS_MIGRATED_REVID=122818198

1 files changed, 23 insertions, 1 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/runtime/ExperimentalStateTracker.java b/src/main/java/com/google/devtools/build/lib/runtime/ExperimentalStateTracker.java
index 080029f52b..3945efe8fa 100644
--- a/src/main/java/com/google/devtools/build/lib/runtime/ExperimentalStateTracker.java
+++ b/src/main/java/com/google/devtools/build/lib/runtime/ExperimentalStateTracker.java
@@ -214,8 +214,30 @@ class ExperimentalStateTracker {
     if (message.length() + postfix.length() <= desiredWidth) {
       return message + postfix;
     }
+
+    // We have to shorten the message to fit into the line.
+
     if (action.getOwner() != null) {
       if (action.getOwner().getLabel() != null) {
+        // First attempt is to shorten the package path string in the messge, if it occurs there
+        String pathString = action.getOwner().getLabel().getPackageFragment().toString();
+        int pathIndex = message.indexOf(pathString);
+        if (pathIndex >= 0) {
+          String start = message.substring(0, pathIndex);
+          String end = message.substring(pathIndex + pathString.length());
+          int pathTargetLength = desiredWidth - start.length() - end.length() - postfix.length();
+          // This attempt of shortening is reasonable if what is left from the label
+          // is significantly longer (twice as long) as the ellipsis symbols introduced.
+          if (pathTargetLength >= 3 * ELLIPSIS.length()) {
+            String shortPath = suffix(pathString, pathTargetLength - ELLIPSIS.length());
+            int slashPos = shortPath.indexOf('/');
+            if (slashPos >= 0) {
+              return start + ELLIPSIS + shortPath.substring(slashPos) + end + postfix;
+            }
+          }
+        }
+
+        // Second attempt: just take a shortened version of the label.
         String shortLabel =
             shortenedLabelString(action.getOwner().getLabel(), desiredWidth - postfix.length());
         if (shortLabel.length() + postfix.length() <= desiredWidth) {
@@ -223,7 +245,7 @@ class ExperimentalStateTracker {
         }
       }
     }
-    if (3 * ELLIPSIS.length() <= desiredWidth) {
+    if (3 * ELLIPSIS.length() + postfix.length() <= desiredWidth) {
       message = ELLIPSIS + suffix(message, desiredWidth - ELLIPSIS.length() - postfix.length());
     }
     return message + postfix;