org.openjdk.jmc.flightrecorder.util

Class ChunkReader

java.lang.Object

org.openjdk.jmc.flightrecorder.util.ChunkReader

public final class ChunkReader
extends java.lang.Object

Provides an efficient means to read JFR data, chunk by chunk. The actual method employed will depend on whether the JFR file is available as a stream or as a file, and whether or not the data is compressed or not.

Each chunk will be self-contained and parsable, for example by wrapping it in a ByteArrayInputStream and using the JfrLoaderToolkit.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
private static class	ChunkReader.ChunkIterator Chunk iterator for an uncompressed JFR file.
private static class	ChunkReader.StreamChunkIterator Iterator reading JFR chunks from a stream.
private static class	ChunkReader.StreamState

Field Summary

Fields

Modifier and Type	Field and Description
private static int[]	GZ_MAGIC
private static int	HEADER_SIZE
private static int[]	JFR_MAGIC
private static byte[]	JFR_MAGIC_BYTES
private static int[]	ZIP_MAGIC

Constructor Summary

Constructors

Modifier	Constructor and Description
private	ChunkReader()

Method Summary

Modifier and Type	Method and Description
static void	main(java.lang.String[] args) Program for listing the number of chunks in a recording.
static java.util.Iterator<byte[]>	readChunks(java.io.File jfrFile) Reads a JFR file, chunk by chunk.
static java.util.Iterator<byte[]>	readChunks(java.io.InputStream jfrStream) Reads a JFR file, chunk by chunk, from a stream.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

JFR_MAGIC_BYTES

private static final byte[] JFR_MAGIC_BYTES

JFR_MAGIC

private static final int[] JFR_MAGIC

ZIP_MAGIC

private static final int[] ZIP_MAGIC

GZ_MAGIC

private static final int[] GZ_MAGIC

HEADER_SIZE

private static final int HEADER_SIZE

See Also:

Constant Field Values

Constructor Detail

ChunkReader

private ChunkReader()

Method Detail

readChunks

public static java.util.Iterator<byte[]> readChunks(java.io.File jfrFile)
                                             throws java.io.IOException

Reads a JFR file, chunk by chunk.

Each chunk will be self contained and parsable, for example by wrapping it in a ByteArrayInputStream. Note that Iterator.next() can throw IllegalArgumentException if it encounters a corrupted chunk.

Parameters:

jfrFile - the file to read binary data from

Returns:

returns an iterator over byte arrays, where each byte array is a self containing jfr chunk

Throws:

java.io.IOException

readChunks

public static java.util.Iterator<byte[]> readChunks(java.io.InputStream jfrStream)
                                             throws java.io.IOException

Reads a JFR file, chunk by chunk, from a stream.

Each chunk will be self contained and parsable, for example by wrapping it in a ByteArrayInputStream. Note that Iterator.next() can throw IllegalArgumentException if it encounters a corrupted chunk.

Parameters:

jfrStream - the stream to read binary data from

Returns:

returns an iterator over byte arrays, where each byte array is a self containing JFR chunk

Throws:

java.io.IOException

main

public static void main(java.lang.String[] args)
                 throws java.io.IOException

Program for listing the number of chunks in a recording.

Parameters:

args - takes one argument, which must be the path to a recording

Throws:

java.io.IOException - if there was a problem reading the file