ExecutionDataWriter.java
1/*******************************************************************************
2 * Copyright (c) 2009, 2010 Mountainminds GmbH & Co. KG and Contributors
3 * All rights reserved. This program and the accompanying materials
4 * are made available under the terms of the Eclipse Public License v1.0
5 * which accompanies this distribution, and is available at
6 * http://www.eclipse.org/legal/epl-v10.html
7 *
8 * Contributors:
9 * Marc R. Hoffmann - initial API and implementation
10 *
11 * $Id: $
12 *******************************************************************************/
13package org.jacoco.core.data;
14
15import java.io.ByteArrayOutputStream;
16import java.io.IOException;
17import java.io.OutputStream;
18
19/**
20 * Serialization of execution data into binary streams.
21 *
22 * @author Marc R. Hoffmann
23 * @version $Revision: $
24 */
25public class ExecutionDataWriter implements IExecutionDataVisitor {
26
27 /** File format version, will be incremented for each incompatible change. */
28 public static final char FORMAT_VERSION = 0x1004;
29
30 /** Magic number in header for file format identification. */
31 public static final char MAGIC_NUMBER = 0xC0C0;
32
33 /** Block identifier for file headers. */
34 public static final byte BLOCK_HEADER = 0x01;
35
36 /** Block identifier for execution data of a single class. */
37 public static final byte BLOCK_EXECUTIONDATA = 0x10;
38
39 private final CompactDataOutput out;
40
41 /**
42 * Creates a new writer based on the given output stream. Depending on the
43 * nature of the underlying stream output should be buffered as most data is
44 * written in single bytes.
45 *
46 * @param output
47 * binary stream to write execution data to
48 */
49 public ExecutionDataWriter(final OutputStream output) {
50 this.out = new CompactDataOutput(output);
51 }
52
53 /**
54 * Writes an file header to identify the stream and its protocol version.
55 *
56 * @throws IOException
57 */
58 public void writeHeader() throws IOException {
59 out.writeByte(BLOCK_HEADER);
60 out.writeChar(MAGIC_NUMBER);
61 out.writeChar(FORMAT_VERSION);
62 }
63
64 public void visitClassExecution(final long id, final String name,
65 final boolean[] data) {
66 try {
67 out.writeByte(BLOCK_EXECUTIONDATA);
68 out.writeLong(id);
69 out.writeUTF(name);
70 out.writeVarInt(data.length);
71 for (final boolean b : data) {
72 out.writePackedBoolean(b);
73 }
74 out.finishPackedBoolean();
75 } catch (final IOException e) {
76 throw new RuntimeException(e);
77 }
78 }
79
80 /**
81 * Returns the first bytes of a file that represents a valid execution data
82 * file. In any case every execution data file starts with the three bytes
83 * <code>0x01 0xC0 0xC0</code>.
84 *
85 * @return first bytes of a execution data file
86 */
87 public static final byte[] getFileHeader() {
88 final ByteArrayOutputStream buffer = new ByteArrayOutputStream();
89 try {
90 new ExecutionDataWriter(buffer).writeHeader();
91 } catch (final IOException e) {
92 // Must not happen with ByteArrayOutputStream
93 throw new RuntimeException(e);
94 }
95 return buffer.toByteArray();
96 }
97
98}