ExecutionDataWriter.java revision 20823ddbda94e8855c8528f3e0fc87eee1be2774 
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 ISessionInfoVisitor,
26		IExecutionDataVisitor {
27
28	/** File format version, will be incremented for each incompatible change. */
29	public static final char FORMAT_VERSION = 0x1005;
30
31	/** Magic number in header for file format identification. */
32	public static final char MAGIC_NUMBER = 0xC0C0;
33
34	/** Block identifier for file headers. */
35	public static final byte BLOCK_HEADER = 0x01;
36
37	/** Block identifier for session information. */
38	public static final byte BLOCK_SESSIONINFO = 0x10;
39
40	/** Block identifier for execution data of a single class. */
41	public static final byte BLOCK_EXECUTIONDATA = 0x11;
42
43	/** Underlying data output */
44	protected final CompactDataOutput out;
45
46	/**
47	 * Creates a new writer based on the given output stream. Depending on the
48	 * nature of the underlying stream output should be buffered as most data is
49	 * written in single bytes.
50	 *
51	 * @param output
52	 *            binary stream to write execution data to
53	 * @throws IOException
54	 */
55	public ExecutionDataWriter(final OutputStream output) throws IOException {
56		this.out = new CompactDataOutput(output);
57		writeHeader();
58	}
59
60	/**
61	 * Writes an file header to identify the stream and its protocol version.
62	 *
63	 * @throws IOException
64	 */
65	private void writeHeader() throws IOException {
66		out.writeByte(BLOCK_HEADER);
67		out.writeChar(MAGIC_NUMBER);
68		out.writeChar(FORMAT_VERSION);
69	}
70
71	/**
72	 * Flushes the underlying stream.
73	 *
74	 * @throws IOException
75	 */
76	public void flush() throws IOException {
77		out.flush();
78	}
79
80	public void visitSessionInfo(final SessionInfo info) {
81		try {
82			out.writeByte(BLOCK_SESSIONINFO);
83			out.writeUTF(info.getId());
84			out.writeLong(info.getStartTimeStamp());
85			out.writeLong(info.getDumpTimeStamp());
86		} catch (final IOException e) {
87			throw new RuntimeException(e);
88		}
89	}
90
91	public void visitClassExecution(final ExecutionData data) {
92		try {
93			out.writeByte(BLOCK_EXECUTIONDATA);
94			out.writeLong(data.getId());
95			out.writeUTF(data.getName());
96			out.writeBooleanArray(data.getData());
97		} catch (final IOException e) {
98			throw new RuntimeException(e);
99		}
100	}
101
102	/**
103	 * Returns the first bytes of a file that represents a valid execution data
104	 * file. In any case every execution data file starts with the three bytes
105	 * <code>0x01 0xC0 0xC0</code>.
106	 *
107	 * @return first bytes of a execution data file
108	 */
109	public static final byte[] getFileHeader() {
110		final ByteArrayOutputStream buffer = new ByteArrayOutputStream();
111		try {
112			new ExecutionDataWriter(buffer).writeHeader();
113		} catch (final IOException e) {
114			// Must not happen with ByteArrayOutputStream
115			throw new AssertionError(e);
116		}
117		return buffer.toByteArray();
118	}
119
120}
121