throw better exception if you try to exceed 2GB of taxonomy facet labels

lucene/facet/src/java/org/apache/lucene/facet/taxonomy/writercache/CharBlockArray.java

@@ -65,6 +65,9 @@ class CharBlockArray implements Appendable, Serializable, CharSequence {
   }
 
   private void addBlock() {
+    if (blockSize * (long) (blocks.size() + 1) > Integer.MAX_VALUE) {
+      throw new IllegalStateException("cannot store more than 2 GB in CharBlockArray");
+    }
     this.current = new Block(this.blockSize);
     this.blocks.add(this.current);
   }

lucene/facet/src/test/org/apache/lucene/facet/taxonomy/writercache/Test2GBCharBlockArray.java

@@ -0,0 +1,46 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.lucene.facet.taxonomy.writercache;
+
+import org.apache.lucene.util.LuceneTestCase.Monster;
+import org.apache.lucene.util.LuceneTestCase;
+import org.apache.lucene.util.TestUtil;
+
+@Monster("uses lots of space and takes a few minutes")
+public class Test2GBCharBlockArray extends LuceneTestCase {
+
+  public void test2GBChars() throws Exception {
+    int blockSize = 32768;
+    CharBlockArray array = new CharBlockArray(blockSize);
+
+    int size = TestUtil.nextInt(random(), 20000, 40000);
+
+    char[] chars = new char[size];
+    int count = 0;
+    while (true) {
+      count++;
+      try {
+        array.append(chars, 0, size);
+      } catch (IllegalStateException ise) {
+        assertTrue(count * (long) size + blockSize > Integer.MAX_VALUE);
+        break;
+      }
+      assertFalse("appended " + (count * (long) size - Integer.MAX_VALUE) + " characters beyond Integer.MAX_VALUE!",
+                  count * (long) size > Integer.MAX_VALUE);
+    }
+  }
+}

lucene/facet/src/test/org/apache/lucene/facet/taxonomy/writercache/TestCharBlockArray.java

@@ -27,11 +27,9 @@ import java.nio.file.Path;
 
 import org.apache.lucene.facet.FacetTestCase;
 
-import org.junit.Test;
-
 public class TestCharBlockArray extends FacetTestCase {
 
-  @Test public void testArray() throws Exception {
+  public void testArray() throws Exception {
     CharBlockArray array = new CharBlockArray();
     StringBuilder builder = new StringBuilder();