AstSerializer.java revision 1399:eea9202e8930 
1/*
2 * Copyright (c) 2010, 2014, Oracle and/or its affiliates. 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.  Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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24 */
25package jdk.nashorn.internal.runtime;
26
27import java.io.ByteArrayOutputStream;
28import java.io.IOException;
29import java.io.ObjectOutputStream;
30import java.util.zip.Deflater;
31import java.util.zip.DeflaterOutputStream;
32import jdk.nashorn.internal.ir.FunctionNode;
33import jdk.nashorn.internal.runtime.options.Options;
34
35/**
36 * This static utility class performs serialization of FunctionNode ASTs to a byte array.
37 * The format is a standard Java serialization stream, deflated.
38 */
39final class AstSerializer {
40    // Experimentally, we concluded that compression level 4 gives a good tradeoff between serialization speed
41    // and size.
42    private static final int COMPRESSION_LEVEL = Options.getIntProperty("nashorn.serialize.compression", 4);
43    static byte[] serialize(final FunctionNode fn) {
44        final ByteArrayOutputStream out = new ByteArrayOutputStream();
45        final Deflater deflater = new Deflater(COMPRESSION_LEVEL);
46        try (final ObjectOutputStream oout = new ObjectOutputStream(new DeflaterOutputStream(out, deflater))) {
47            oout.writeObject(fn);
48        } catch (final IOException e) {
49            throw new AssertionError("Unexpected exception serializing function", e);
50        } finally {
51            deflater.end();
52        }
53        return out.toByteArray();
54    }
55}
56