ExecutionDataWriter.java revision 6fc14d15bb5458c56d2a4ac4dbbefd4be2763a88 
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.writeBooleanArray(data);
71		} catch (final IOException e) {
72			throw new RuntimeException(e);
73		}
74	}
75
76	/**
77	 * Returns the first bytes of a file that represents a valid execution data
78	 * file. In any case every execution data file starts with the three bytes
79	 * <code>0x01 0xC0 0xC0</code>.
80	 *
81	 * @return first bytes of a execution data file
82	 */
83	public static final byte[] getFileHeader() {
84		final ByteArrayOutputStream buffer = new ByteArrayOutputStream();
85		try {
86			new ExecutionDataWriter(buffer).writeHeader();
87		} catch (final IOException e) {
88			// Must not happen with ByteArrayOutputStream
89			throw new RuntimeException(e);
90		}
91		return buffer.toByteArray();
92	}
93
94}
95