ExecutionDataWriter.java revision 993b89bfa176dfb62485f28499e894c162f4c715 
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	private final CompactDataOutput out;
44
45	/**
46	 * Creates a new writer based on the given output stream. Depending on the
47	 * nature of the underlying stream output should be buffered as most data is
48	 * written in single bytes.
49	 *
50	 * @param output
51	 *            binary stream to write execution data to
52	 * @throws IOException
53	 */
54	public ExecutionDataWriter(final OutputStream output) throws IOException {
55		this.out = new CompactDataOutput(output);
56		writeHeader();
57	}
58
59	/**
60	 * Writes an file header to identify the stream and its protocol version.
61	 *
62	 * @throws IOException
63	 */
64	private void writeHeader() throws IOException {
65		out.writeByte(BLOCK_HEADER);
66		out.writeChar(MAGIC_NUMBER);
67		out.writeChar(FORMAT_VERSION);
68	}
69
70	public void visitSessionInfo(final SessionInfo info) {
71		try {
72			out.writeByte(BLOCK_SESSIONINFO);
73			out.writeUTF(info.getId());
74			out.writeLong(info.getStartTimeStamp());
75			out.writeLong(info.getDumpTimeStamp());
76		} catch (final IOException e) {
77			throw new RuntimeException(e);
78		}
79	}
80
81	public void visitClassExecution(final ExecutionData data) {
82		try {
83			out.writeByte(BLOCK_EXECUTIONDATA);
84			out.writeLong(data.getId());
85			out.writeUTF(data.getName());
86			out.writeBooleanArray(data.getData());
87		} catch (final IOException e) {
88			throw new RuntimeException(e);
89		}
90	}
91
92	/**
93	 * Returns the first bytes of a file that represents a valid execution data
94	 * file. In any case every execution data file starts with the three bytes
95	 * <code>0x01 0xC0 0xC0</code>.
96	 *
97	 * @return first bytes of a execution data file
98	 */
99	public static final byte[] getFileHeader() {
100		final ByteArrayOutputStream buffer = new ByteArrayOutputStream();
101		try {
102			new ExecutionDataWriter(buffer).writeHeader();
103		} catch (final IOException e) {
104			// Must not happen with ByteArrayOutputStream
105			throw new AssertionError(e);
106		}
107		return buffer.toByteArray();
108	}
109
110}
111