49 import org.openjdk.jmc.flightrecorder.internal.util.DataInputToolkit;
50
51 /**
52 * Provides an efficient means to read JFR data, chunk by chunk. The actual method employed will
53 * depend on whether the JFR file is available as a stream or as a file, and whether or not the data
54 * is compressed or not.
55 * <p>
56 * Each chunk will be self-contained and parsable, for example by wrapping it in a
57 * {@link ByteArrayInputStream} and using the {@link JfrLoaderToolkit}.
58 */
59 public final class ChunkReader {
60 private static final byte[] JFR_MAGIC_BYTES = new byte[] {'F', 'L', 'R', 0};
61 private static final int[] JFR_MAGIC = new int[] {'F', 'L', 'R', 0};
62 private static final int ZIP_MAGIC[] = new int[] {31, 139};
63 private static final int GZ_MAGIC[] = new int[] {31, 139};
64 // For JDK 8 this is the size of the magic + version and offset to the meta data event.
65 // For JDK 9 and later, this it the part of the header right up to, and including, the chunk size.
66 private static final int HEADER_SIZE = DataInputToolkit.INTEGER_SIZE + 2 * DataInputToolkit.SHORT_SIZE
67 + DataInputToolkit.LONG_SIZE;
68
69 /**
70 * Chunk iterator for an uncompressed JFR file. Efficiently reads a JFR file, chunk by chunk,
71 * into memory as byte arrays by memory mapping the JFR file, finding the chunk boundaries with
72 * a minimum of parsing, and then block-transferring the byte arrays. The transfers will be done
73 * on {@link Iterator#next()}, and the resulting byte array will only be reachable for as long
74 * as it is referenced. The JFR file must not be zip or gzip compressed.
75 * <p>
76 * Note that {@link Iterator#next()} can throw {@link IllegalArgumentException} if it encounters
77 * a corrupted chunk.
78 */
79 private static class ChunkIterator implements Iterator<byte[]> {
80 int lastChunkOffset;
81 private RandomAccessFile file;
82 private final FileChannel channel;
83 private final MappedByteBuffer buffer;
84
85 private ChunkIterator(File jfrFile) throws IOException {
86 try {
87 file = new RandomAccessFile(jfrFile, "r"); //$NON-NLS-1$
88 channel = file.getChannel();
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49 import org.openjdk.jmc.flightrecorder.internal.util.DataInputToolkit;
50
51 /**
52 * Provides an efficient means to read JFR data, chunk by chunk. The actual method employed will
53 * depend on whether the JFR file is available as a stream or as a file, and whether or not the data
54 * is compressed or not.
55 * <p>
56 * Each chunk will be self-contained and parsable, for example by wrapping it in a
57 * {@link ByteArrayInputStream} and using the {@link JfrLoaderToolkit}.
58 */
59 public final class ChunkReader {
60 private static final byte[] JFR_MAGIC_BYTES = new byte[] {'F', 'L', 'R', 0};
61 private static final int[] JFR_MAGIC = new int[] {'F', 'L', 'R', 0};
62 private static final int ZIP_MAGIC[] = new int[] {31, 139};
63 private static final int GZ_MAGIC[] = new int[] {31, 139};
64 // For JDK 8 this is the size of the magic + version and offset to the meta data event.
65 // For JDK 9 and later, this it the part of the header right up to, and including, the chunk size.
66 private static final int HEADER_SIZE = DataInputToolkit.INTEGER_SIZE + 2 * DataInputToolkit.SHORT_SIZE
67 + DataInputToolkit.LONG_SIZE;
68
69 private ChunkReader() {
70 throw new UnsupportedOperationException("Not to be instantiated"); //$NON-NLS-1$
71 }
72
73 /**
74 * Chunk iterator for an uncompressed JFR file. Efficiently reads a JFR file, chunk by chunk,
75 * into memory as byte arrays by memory mapping the JFR file, finding the chunk boundaries with
76 * a minimum of parsing, and then block-transferring the byte arrays. The transfers will be done
77 * on {@link Iterator#next()}, and the resulting byte array will only be reachable for as long
78 * as it is referenced. The JFR file must not be zip or gzip compressed.
79 * <p>
80 * Note that {@link Iterator#next()} can throw {@link IllegalArgumentException} if it encounters
81 * a corrupted chunk.
82 */
83 private static class ChunkIterator implements Iterator<byte[]> {
84 int lastChunkOffset;
85 private RandomAccessFile file;
86 private final FileChannel channel;
87 private final MappedByteBuffer buffer;
88
89 private ChunkIterator(File jfrFile) throws IOException {
90 try {
91 file = new RandomAccessFile(jfrFile, "r"); //$NON-NLS-1$
92 channel = file.getChannel();
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