Thu, 30 Jul 2009 10:29:53 +0100
6827648: Extremely slow compilation time for visitor pattern code + generics
Summary: Javac unnecessarily recomputates type-substitutions multiple times
Reviewed-by: jjg
1 /*
2 * Copyright 2004 Sun Microsystems, Inc. All Rights Reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
20 * CA 95054 USA or visit www.sun.com if you need additional information or
21 * have any questions.
22 */
24 import java.io.*;
25 import java.nio.*;
26 import java.nio.channels.*;
29 public class CheckClassFileVersion {
31 static String get(String fn) throws IOException {
32 ByteBuffer bb = ByteBuffer.allocate(1024);
33 FileChannel fc = new FileInputStream(fn).getChannel();
34 try {
35 bb.clear();
36 if (fc.read(bb) < 0)
37 throw new IOException("Could not read any bytes");
38 bb.flip();
39 int minor = bb.getShort(4);
40 int major = bb.getShort(6);
41 return major + "." + minor;
42 } finally {
43 fc.close();
44 }
45 }
47 public static void main(String[] args) throws IOException {
48 String cfv = get(args[0]);
49 if (args.length == 1) {
50 System.out.println(cfv);
51 return;
52 }
53 if (!cfv.equals(args[1])) {
54 System.err.println("Class-file version mismatch: Expected "
55 + args[1] + ", got " + cfv);
56 System.exit(1);
57 }
58 }
60 }