ExecutionDataWriter.java revision 37115f4ba4f6126b8c3352ac890c653e428a7dd8 
1/*******************************************************************************
2 * Copyright (c) 2009, 2013 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 *******************************************************************************/
12package org.jacoco.core.data;
13
14import java.io.ByteArrayOutputStream;
15import java.io.IOException;
16import java.io.OutputStream;
17
18import org.jacoco.core.internal.data.CompactDataOutput;
19
20/**
21 * Serialization of execution data into binary streams.
22 */
23public class ExecutionDataWriter implements ISessionInfoVisitor,
24		IExecutionDataVisitor {
25
26	/** File format version, will be incremented for each incompatible change. */
27	public static final char FORMAT_VERSION = 0x1006;
28
29	/** Magic number in header for file format identification. */
30	public static final char MAGIC_NUMBER = 0xC0C0;
31
32	/** Block identifier for file headers. */
33	public static final byte BLOCK_HEADER = 0x01;
34
35	/** Block identifier for session information. */
36	public static final byte BLOCK_SESSIONINFO = 0x10;
37
38	/** Block identifier for execution data of a single class. */
39	public static final byte BLOCK_EXECUTIONDATA = 0x11;
40
41	/** Underlying data output */
42	protected final CompactDataOutput out;
43
44	/**
45	 * Creates a new writer based on the given output stream. Depending on the
46	 * nature of the underlying stream output should be buffered as most data is
47	 * written in single bytes.
48	 *
49	 * @param output
50	 *            binary stream to write execution data to
51	 * @throws IOException
52	 *             if the header can't be written
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	/**
71	 * Flushes the underlying stream.
72	 *
73	 * @throws IOException
74	 */
75	public void flush() throws IOException {
76		out.flush();
77	}
78
79	public void visitSessionInfo(final SessionInfo info) {
80		try {
81			out.writeByte(BLOCK_SESSIONINFO);
82			out.writeUTF(info.getId());
83			out.writeLong(info.getStartTimeStamp());
84			out.writeLong(info.getDumpTimeStamp());
85		} catch (final IOException e) {
86			throw new RuntimeException(e);
87		}
88	}
89
90	public void visitClassExecution(final ExecutionData data) {
91		try {
92			out.writeByte(BLOCK_EXECUTIONDATA);
93			out.writeLong(data.getId());
94			out.writeUTF(data.getName());
95			out.writeBooleanArray(data.getProbes());
96		} catch (final IOException e) {
97			throw new RuntimeException(e);
98		}
99	}
100
101	/**
102	 * Returns the first bytes of a file that represents a valid execution data
103	 * file. In any case every execution data file starts with the three bytes
104	 * <code>0x01 0xC0 0xC0</code>.
105	 *
106	 * @return first bytes of a execution data file
107	 */
108	public static final byte[] getFileHeader() {
109		final ByteArrayOutputStream buffer = new ByteArrayOutputStream();
110		try {
111			new ExecutionDataWriter(buffer);
112		} catch (final IOException e) {
113			// Must not happen with ByteArrayOutputStream
114			throw new AssertionError(e);
115		}
116		return buffer.toByteArray();
117	}
118
119}
120