[GR-55261] Backporting: Remove Unreachable Globs from Trie

PullRequest: graal/18466

substratevm/src/com.oracle.svm.core/src/com/oracle/svm/core/jdk/resources/CompressedGlobTrie/CompressedGlobTrie.java

@@ -33,6 +33,7 @@
 import java.util.Arrays;
 import java.util.Collections;
 import java.util.List;
+import java.util.function.Predicate;
 import java.util.regex.Pattern;
 
 import org.graalvm.nativeimage.Platform;
@@ -123,7 +124,6 @@ public static GlobTrieNode build(List<GlobWithInfo> patterns) {
             starPatterns.forEach(pattern -> addPattern(root, pattern));
             noStarPatterns.forEach(pattern -> addPattern(root, pattern));
 
-            root.trim();
             return root;
         }
 
@@ -340,6 +340,13 @@ private static int comparePatterns(GlobWithInfo n1, GlobWithInfo n2) {
         }
     }
 
+    /**
+     * Trims the Trie and makes it unmodifiable.
+     */
+    public static void finalize(GlobTrieNode root) {
+        root.trim();
+    }
+
     /**
      * Returns list of information from all glob patterns that could match given text.
      */
@@ -708,4 +715,36 @@ private static SquashedParts getThisLevel(List<GlobTrieNode> parts, int begin) {
     private static boolean patternReachedEnd(int index, List<GlobTrieNode> parts) {
         return index >= parts.size();
     }
+
+    public static void removeNodes(GlobTrieNode head, Predicate<String> shouldRemove) {
+        List<String> contentToRemove = head.getAdditionalContent().stream().filter(shouldRemove).toList();
+        head.removeAdditionalContent(contentToRemove);
+
+        List<GlobTrieNode> childrenToRemove = new ArrayList<>();
+        for (GlobTrieNode child : head.getChildren()) {
+            removeNodes(child, shouldRemove);
+
+            /* leaf without additional content should be removed */
+            if (child.isLeaf() && child.getAdditionalContent().isEmpty()) {
+                if (child.getChildren().isEmpty()) {
+                    /* if it is the last node remove it physically */
+                    childrenToRemove.add(child);
+                } else {
+                    /*
+                     * the child still has children, but it terminated some pattern => don't remove
+                     * it, just say that it doesn't terminate any pattern anymore
+                     */
+                    child.makeNodeInternal();
+                }
+                continue;
+            }
+
+            /* internal node without children should be removed */
+            if (!child.isLeaf() && child.getChildren().isEmpty()) {
+                childrenToRemove.add(child);
+            }
+        }
+
+        head.removeChildren(childrenToRemove);
+    }
 }

substratevm/src/com.oracle.svm.core/src/com/oracle/svm/core/jdk/resources/CompressedGlobTrie/GlobTrieNode.java

@@ -31,16 +31,20 @@
 import java.util.Map;
 import java.util.Set;
 
+import com.oracle.svm.core.heap.UnknownObjectField;
+
 public class GlobTrieNode {
     protected static final String STAR = "*";
     protected static final String STAR_STAR = "**";
     protected static final String LEVEL_IDENTIFIER = "/";
     public static final String SAME_LEVEL_IDENTIFIER = "#";
 
     private String content;
+    @UnknownObjectField(fullyQualifiedTypes = {"java.util.HashMap", "java.util.ImmutableCollections$MapN", "java.util.ImmutableCollections$Map1"}) //
     private Map<String, GlobTrieNode> children;
     private boolean isLeaf;
     private boolean isNewLevel;
+    @UnknownObjectField(fullyQualifiedTypes = {"java.util.HashSet", "java.util.ImmutableCollections$SetN", "java.util.ImmutableCollections$Set12"}) //
     private Set<String> additionalContent;
 
     protected GlobTrieNode() {
@@ -72,6 +76,10 @@ protected void setLeaf() {
         isLeaf = true;
     }
 
+    protected void makeNodeInternal() {
+        isLeaf = false;
+    }
+
     public String getContent() {
         return content;
     }
@@ -80,6 +88,10 @@ protected Set<String> getAdditionalContent() {
         return additionalContent;
     }
 
+    protected void removeAdditionalContent(List<String> ac) {
+        additionalContent.removeAll(ac);
+    }
+
     protected void addAdditionalContent(String ac) {
         this.additionalContent.add(ac);
     }
@@ -92,6 +104,19 @@ protected GlobTrieNode getChild(String child) {
         return children.get(child);
     }
 
+    protected void removeChildren(List<GlobTrieNode> childKeys) {
+        for (var child : childKeys) {
+            /*
+             * we need exact name of the child key in order to delete it. In case when we have a
+             * complex level (with stars), all children from the same level will have
+             * SAME_LEVEL_IDENTIFIER, so we must append it here
+             */
+            String sameLevel = !child.isNewLevel() ? SAME_LEVEL_IDENTIFIER : "";
+            String childKey = child.getContent() + sameLevel;
+            children.remove(childKey);
+        }
+    }
+
     protected GlobTrieNode getChildFromSameLevel(String child) {
         return children.get(child + SAME_LEVEL_IDENTIFIER);
     }
@@ -142,5 +167,4 @@ protected void trim() {
         additionalContent = Set.copyOf(additionalContent);
         children = Map.copyOf(children);
     }
-
 }

substratevm/src/com.oracle.svm.hosted/src/com/oracle/svm/hosted/ResourcesFeature.java

@@ -635,6 +635,11 @@ public void afterAnalysis(AfterAnalysisAccess access) {
 
             BuildArtifacts.singleton().add(BuildArtifacts.ArtifactType.BUILD_INFO, reportLocation);
         }
+
+        /* prepare resources GlobTrie for runtime */
+        GlobTrieNode root = ImageSingletons.lookup(GlobTrieNode.class);
+        CompressedGlobTrie.removeNodes(root, (type) -> !access.isReachable(access.findClassByName(type)));
+        CompressedGlobTrie.finalize(root);
     }
 
     @Override