Add PhraseQuery.Builder.setMaxTerms() method to limit the maximum number of terms and excessive memory use

lucene/CHANGES.txt

@@ -174,6 +174,8 @@ Improvements
 
 * GITHUB#15184: Refactoring internal HNSWGraphBuilder's APIs and avoid creating new scorer for each call (Patrick Zhai)
 
+* GITHUB#15332: Add PhraseQuery.Builder.setMaxTerms() method to limit the maximum number of terms and excessive memory use (linyunanit)
+
 Optimizations
 ---------------------
 * GITHUB#15140: Optimize TopScoreDocCollector with TernaryLongHeap for improved performance over Binary-LongHeap. (Ramakrishna Chilaka)

lucene/core/src/java/org/apache/lucene/search/PhraseQuery.java

@@ -74,12 +74,14 @@ public class PhraseQuery extends Query {
   public static class Builder {
 
     private int slop;
+    private int maxTerms;
     private final List<Term> terms;
     private final IntArrayList positions;
 
     /** Sole constructor. */
     public Builder() {
       slop = 0;
+      maxTerms = -1;
       terms = new ArrayList<>();
       positions = new IntArrayList();
     }
@@ -94,6 +96,18 @@ public Builder setSlop(int slop) {
       return this;
     }
 
+    /**
+     * Set the maximum number of terms allowed in the phrase query. This helps prevent excessive
+     * memory usage for very long phrases.
+     *
+     * <p>If the number of terms added via {@link #add(Term)} or {@link #add(Term, int)} exceeds
+     * this threshold, an {@link IllegalArgumentException} will be thrown.
+     */
+    public Builder setMaxTerms(int maxTerms) {
+      this.maxTerms = maxTerms;
+      return this;
+    }
+
     /**
      * Adds a term to the end of the query phrase. The relative position of the term is the one
      * immediately after the last term added.
@@ -128,6 +142,13 @@ public Builder add(Term term, int position) {
                 + " and "
                 + terms.get(0).field());
       }
+      if (maxTerms > 0 && terms.size() >= maxTerms) {
+        throw new IllegalArgumentException(
+            "The current number of terms is "
+                + terms.size()
+                + ", which exceeds the limit of "
+                + maxTerms);
+      }
       terms.add(term);
       positions.add(position);
       return this;

lucene/core/src/test/org/apache/lucene/search/TestPhraseQuery.java

@@ -743,6 +743,20 @@ public void testBackwardPositions() throws Exception {
         });
   }
 
+  public void testPhraseQueryMaxTerms() throws Exception {
+    PhraseQuery.Builder builder = new PhraseQuery.Builder();
+    int termThreshold = 5;
+    builder.setMaxTerms(termThreshold);
+    for (int i = 0; i < termThreshold; i++) {
+      builder.add(new Term("field", "one" + i), i);
+    }
+    expectThrows(
+        IllegalArgumentException.class,
+        () -> {
+          builder.add(new Term("field", "three"), termThreshold);
+        });
+  }
+
   private static final String[] DOCS =
       new String[] {
         "a b c d e f g h",