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 *******************************************************************************/
   12package org.jacoco.core.data;
   13
   14import java.io.ByteArrayOutputStream;
   15import java.io.IOException;
   16import java.io.OutputStream;
   17
   18/**
   19 * Serialization of execution data into binary streams.
   20 * 
   21 * @author Marc R. Hoffmann
   22 * @version 0.4.1.20101007204400
   23 */
   24public class ExecutionDataWriter implements ISessionInfoVisitor,
   25        IExecutionDataVisitor {
   26
   27    /** File format version, will be incremented for each incompatible change. */
   28    public static final char FORMAT_VERSION = 0x1005;
   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 session information. */
   37    public static final byte BLOCK_SESSIONINFO = 0x10;
   38
   39    /** Block identifier for execution data of a single class. */
   40    public static final byte BLOCK_EXECUTIONDATA = 0x11;
   41
   42    /** Underlying data output */
   43    protected 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     *             if the header can't be written
   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);
  113        } catch (final IOException e) {
  114            // Must not happen with ByteArrayOutputStream
  115            throw new AssertionError(e);
  116        }
  117        return buffer.toByteArray();
  118    }
  119
  120}