1 /* Licensed to the Apache Software Foundation (ASF) under one or more 2 * contributor license agreements. See the NOTICE file distributed with 3 * this work for additional information regarding copyright ownership. 4 * The ASF licenses this file to You under the Apache License, Version 2.0 5 * (the "License"); you may not use this file except in compliance with 6 * the License. You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 package org.apache.harmony.tests.java.util; 17 18 import java.io.IOException; 19 import java.io.Reader; 20 import java.util.Scanner; 21 22 import junit.framework.TestCase; 23 24 public class ScannerParseLargeFileBenchmarkTest extends TestCase { 25 26 /** 27 * Check whether the Scanner will exhaust all heap memory when parsing a 28 * large file. 29 */ testParseLargeFile()30 public void testParseLargeFile() throws Exception { 31 FakeLargeFile reader = new FakeLargeFile(); 32 String delimiter = "\r?\n"; 33 Scanner scanner = new Scanner(reader).useDelimiter(delimiter); 34 35 while (scanner.hasNext()) { 36 scanner.next(); 37 } 38 scanner.close(); 39 reader.close(); 40 } 41 42 private static class FakeLargeFile extends Reader { 43 private static final char[] CONTENT = "large file!\n".toCharArray(); 44 private static final int FILE_LENGTH = 192 * 1024 * 1024; // 192 MB 45 46 private int count = 0; 47 48 @Override close()49 public void close() throws IOException { 50 } 51 52 @Override read(char[] buffer, int offset, int length)53 public int read(char[] buffer, int offset, int length) { 54 if (count >= FILE_LENGTH) { 55 return -1; 56 } 57 58 final int charsToRead = Math.min(FILE_LENGTH - count, length); 59 int bufferIndex = offset; 60 int contentIndex = count % CONTENT.length; 61 int charsRead = 0; 62 while (charsRead < charsToRead) { 63 buffer[bufferIndex++] = CONTENT[contentIndex++]; 64 if (contentIndex == CONTENT.length) { 65 contentIndex = 0; 66 } 67 charsRead++; 68 } 69 count += charsRead; 70 return charsToRead; 71 } 72 } 73 } 74