List.copyOf() redux

Author: Vladimir Kotal

opengrok-indexer/src/main/java/org/opengrok/indexer/history/BoundaryChangesets.java

@@ -61,7 +61,7 @@ private void reset() {
 
     /**
      * @param sinceRevision start revision ID
-     * @return list of revision IDs denoting the intervals
+     * @return immutable list of revision IDs denoting the intervals
      * @throws HistoryException if there is problem traversing the changesets in the repository
      */
     public synchronized List<String> getBoundaryChangesetIDs(String sinceRevision) throws HistoryException {
@@ -75,14 +75,11 @@ public synchronized List<String> getBoundaryChangesetIDs(String sinceRevision) t
         // The changesets need to go from oldest to newest.
         Collections.reverse(result);
 
-        // Add null to finish the last step in Repository#createCache().
-        result.add(null);
-
         stat.report(LOGGER, Level.FINE,
                 String.format("done getting boundary changesets for ''%s'' (%d entries)",
                         repository.getDirectoryName(), result.size()));
 
-        return result;
+        return List.copyOf(result);
     }
 
     private void visit(String id) {

opengrok-indexer/src/main/java/org/opengrok/indexer/history/RepositoryWithPerPartesHistory.java

@@ -26,6 +26,7 @@
 import org.opengrok.indexer.util.Statistics;
 
 import java.io.File;
+import java.util.ArrayList;
 import java.util.List;
 import java.util.function.Consumer;
 import java.util.logging.Level;
@@ -73,7 +74,8 @@ protected void doCreateCache(HistoryCache cache, String sinceRevision, File dire
         // (which can be sizeable, at least for the initial indexing, esp. if merge changeset support is enabled),
         // by splitting the work into multiple chunks.
         BoundaryChangesets boundaryChangesets = new BoundaryChangesets(this);
-        List<String> boundaryChangesetList = boundaryChangesets.getBoundaryChangesetIDs(sinceRevision);
+        List<String> boundaryChangesetList = new ArrayList<>(boundaryChangesets.getBoundaryChangesetIDs(sinceRevision));
+        boundaryChangesetList.add(null);    // to finish the last step in the cycle below
         LOGGER.log(Level.FINE, "boundary changesets: {0}", boundaryChangesetList);
         int cnt = 0;
         for (String tillRevision: boundaryChangesetList) {

opengrok-indexer/src/test/java/org/opengrok/indexer/history/BoundaryChangesetsTest.java

@@ -95,12 +95,12 @@ private static Stream<ImmutableTriple<Integer, String, List<String>>> provideMap
         // Cannot use List.of() because of the null element.
         List<String> expectedChangesets2 = Arrays.asList("8482156421620efbb44a7b6f0eb19d1f191163c7",
                 "ce4c98ec1d22473d4aa799c046c2a90ae05832f1",
-                "1086eaf5bca6d5a056097aa76017a8ab0eade20f", null);
+                "1086eaf5bca6d5a056097aa76017a8ab0eade20f");
 
-        List<String> expectedChangesets4 = Arrays.asList("ce4c98ec1d22473d4aa799c046c2a90ae05832f1", null);
+        List<String> expectedChangesets4 = Arrays.asList("ce4c98ec1d22473d4aa799c046c2a90ae05832f1");
 
         List<String> expectedChangesets2Middle = Arrays.asList("ce4c98ec1d22473d4aa799c046c2a90ae05832f1",
-                "1086eaf5bca6d5a056097aa76017a8ab0eade20f", null);
+                "1086eaf5bca6d5a056097aa76017a8ab0eade20f");
 
         return Stream.of(ImmutableTriple.of(2, null, expectedChangesets2),
                 ImmutableTriple.of(4, null, expectedChangesets4),