org.apache.hadoop.hdfs

Class RemoteBlockReader

java.lang.Object

java.io.InputStream

org.apache.hadoop.fs.FSInputStream

org.apache.hadoop.fs.FSInputChecker

org.apache.hadoop.hdfs.RemoteBlockReader

All Implemented Interfaces:

Closeable, AutoCloseable, ByteBufferReadable, PositionedReadable, Seekable, BlockReader

Deprecated.

this is an old implementation that is being left around in case any issues spring up with the new RemoteBlockReader2 implementation. It will be removed in the next release.

@InterfaceAudience.Private
@Deprecated
public class RemoteBlockReader
extends FSInputChecker
implements BlockReader

Field Summary

Fields inherited from class org.apache.hadoop.fs.FSInputChecker

CHECKSUM_SIZE, file, LOG

Method Summary

Methods

Modifier and Type	Method and Description
int	available() Deprecated. Returns an estimate of the number of bytes that can be read (or skipped over) from this input stream without performing network I/O.
void	close() Deprecated. Close the block reader.
protected long	getChunkPosition(long pos) Deprecated. Return position of beginning of chunk containing pos.
boolean	isLocal() Deprecated.
boolean	isShortCircuit() Deprecated.
static RemoteBlockReader	newBlockReader(String file, ExtendedBlock block, Token<BlockTokenIdentifier> blockToken, long startOffset, long len, int bufferSize, boolean verifyChecksum, String clientName, Peer peer, DatanodeID datanodeID, org.apache.hadoop.hdfs.PeerCache peerCache, CachingStrategy cachingStrategy) Deprecated. Create a new BlockReader specifically to satisfy a read.
int	read() Deprecated. Read one checksum-verified byte
int	read(byte[] buf, int off, int len) Deprecated. Read checksum verified bytes from this byte-input stream into the specified byte array, starting at the given offset.
int	read(ByteBuffer buf) Deprecated. Reads up to buf.remaining() bytes into buf.
int	readAll(byte[] buf, int offset, int len) Deprecated. Similar to BlockReader.readFully(byte[], int, int) except that it will not throw an exception on EOF.
protected int	readChunk(long pos, byte[] buf, int offset, int len, byte[] checksumBuf) Deprecated. Reads in checksum chunks into buf at offset and checksum into checksum.
void	readFully(byte[] buf, int readOffset, int amtToRead) Deprecated. Read exactly the given amount of data, throwing an exception if EOF is reached before that amount
void	seek(long pos) Deprecated. Seek to the given position in the stream.
boolean	seekToNewSource(long targetPos) Deprecated. Seeks a different copy of the data.
long	skip(long n) Deprecated. Skips over and discards n bytes of data from the input stream.

Methods inherited from class org.apache.hadoop.fs.FSInputChecker

checksum2long, getPos, mark, markSupported, needChecksum, readFully, reset, set

Methods inherited from class org.apache.hadoop.fs.FSInputStream

read, readFully, readFully

Methods inherited from class java.io.InputStream

read

Methods inherited from class java.lang.Object

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

Method Detail

read

public int read(byte[] buf,
       int off,
       int len)
         throws IOException

Deprecated.

Description copied from class: FSInputChecker

Read checksum verified bytes from this byte-input stream into the specified byte array, starting at the given offset.

This method implements the general contract of the corresponding read method of the InputStream class. As an additional convenience, it attempts to read as many bytes as possible by repeatedly invoking the read method of the underlying stream. This iterated read continues until one of the following conditions becomes true:

• The specified number of bytes have been read,
• The read method of the underlying stream returns -1, indicating end-of-file.

If the first read on the underlying stream returns -1 to indicate end-of-file then this method returns -1. Otherwise this method returns the number of bytes actually read.

Specified by:

read in interface BlockReader

Overrides:

read in class FSInputChecker

Parameters:

buf - destination buffer.

off - offset at which to start storing bytes.

len - maximum number of bytes to read.

Returns:

the number of bytes read, or -1 if the end of the stream has been reached.

Throws:

IOException - if an I/O error occurs. ChecksumException if any checksum error occurs

skip

public long skip(long n)
          throws IOException

Deprecated.

Description copied from class: FSInputChecker

Skips over and discards n bytes of data from the input stream.

This method may skip more bytes than are remaining in the backing file. This produces no exception and the number of bytes skipped may include some number of bytes that were beyond the EOF of the backing file. Attempting to read from the stream after skipping past the end will result in -1 indicating the end of the file.

If n is negative, no bytes are skipped.

Specified by:

skip in interface BlockReader

Overrides:

skip in class FSInputChecker

Parameters:

n - the number of bytes to be skipped.

Returns:

the actual number of bytes skipped.

Throws:

IOException - if an I/O error occurs. ChecksumException if the chunk to skip to is corrupted

read

public int read()
         throws IOException

Deprecated.

Description copied from class: FSInputChecker

Read one checksum-verified byte

Overrides:

read in class FSInputChecker

Returns:

the next byte of data, or -1 if the end of the stream is reached.

Throws:

IOException - if an I/O error occurs.

seekToNewSource

public boolean seekToNewSource(long targetPos)
                        throws IOException

Deprecated.

Description copied from class: FSInputStream

Seeks a different copy of the data. Returns true if found a new source, false otherwise.

Specified by:

seekToNewSource in interface Seekable

Specified by:

seekToNewSource in class FSInputStream

Throws:

IOException

seek

public void seek(long pos)
          throws IOException

Deprecated.

Description copied from class: FSInputChecker

Seek to the given position in the stream. The next read() will be from that position.

This method may seek past the end of the file. This produces no exception and an attempt to read from the stream will result in -1 indicating the end of the file.

Specified by:

seek in interface Seekable

Overrides:

seek in class FSInputChecker

Parameters:

pos - the postion to seek to.

Throws:

IOException - if an I/O error occurs. ChecksumException if the chunk to seek to is corrupted

getChunkPosition

protected long getChunkPosition(long pos)

Deprecated.

Description copied from class: FSInputChecker

Return position of beginning of chunk containing pos.

Specified by:

getChunkPosition in class FSInputChecker

Parameters:

pos - a postion in the file

Returns:

the starting position of the chunk which contains the byte

readChunk

protected int readChunk(long pos,
            byte[] buf,
            int offset,
            int len,
            byte[] checksumBuf)
                 throws IOException

Deprecated.

Description copied from class: FSInputChecker

Reads in checksum chunks into buf at offset and checksum into checksum. Since checksums can be disabled, there are two cases implementors need to worry about: (a) needChecksum() will return false: - len can be any positive value - checksum will be null Implementors should simply pass through to the underlying data stream. or (b) needChecksum() will return true: - len >= maxChunkSize - checksum.length is a multiple of CHECKSUM_SIZE Implementors should read an integer number of data chunks into buf. The amount read should be bounded by len or by checksum.length / CHECKSUM_SIZE * maxChunkSize. Note that len may be a value that is not a multiple of maxChunkSize, in which case the implementation may return less than len. The method is used for implementing read, therefore, it should be optimized for sequential reading.

Specified by:

readChunk in class FSInputChecker

Parameters:

pos - chunkPos

buf - desitination buffer

offset - offset in buf at which to store data

len - maximum number of bytes to read

checksumBuf - the data buffer into which to write checksums

Returns:

number of bytes read

Throws:

IOException

newBlockReader

public static RemoteBlockReader newBlockReader(String file,
                               ExtendedBlock block,
                               Token<BlockTokenIdentifier> blockToken,
                               long startOffset,
                               long len,
                               int bufferSize,
                               boolean verifyChecksum,
                               String clientName,
                               Peer peer,
                               DatanodeID datanodeID,
                               org.apache.hadoop.hdfs.PeerCache peerCache,
                               CachingStrategy cachingStrategy)
                                        throws IOException

Deprecated.

Create a new BlockReader specifically to satisfy a read. This method also sends the OP_READ_BLOCK request.

Parameters:

sock - An established Socket to the DN. The BlockReader will not close it normally

file - File location

block - The block object

blockToken - The block token for security

startOffset - The read offset, relative to block head

len - The number of bytes to read

bufferSize - The IO buffer size (not the client buffer size)

verifyChecksum - Whether to verify checksum

clientName - Client name

Returns:

New BlockReader instance, or null on error.

Throws:

IOException

close

public void close()
           throws IOException

Deprecated.

Description copied from interface: BlockReader

Close the block reader.

Specified by:

close in interface Closeable

Specified by:

close in interface AutoCloseable

Specified by:

close in interface BlockReader

Overrides:

close in class InputStream

Throws:

IOException

readFully

public void readFully(byte[] buf,
             int readOffset,
             int amtToRead)
               throws IOException

Deprecated.

Description copied from interface: BlockReader

Read exactly the given amount of data, throwing an exception if EOF is reached before that amount

Specified by:

readFully in interface BlockReader

Throws:

IOException

readAll

public int readAll(byte[] buf,
          int offset,
          int len)
            throws IOException

Deprecated.

Description copied from interface: BlockReader

Similar to BlockReader.readFully(byte[], int, int) except that it will not throw an exception on EOF. However, it differs from the simple BlockReader.read(byte[], int, int) call in that it is guaranteed to read the data if it is available. In other words, if this call does not throw an exception, then either the buffer has been filled or the next call will return EOF.

Specified by:

readAll in interface BlockReader

Throws:

IOException

read

public int read(ByteBuffer buf)
         throws IOException

Deprecated.

Description copied from interface: ByteBufferReadable

Reads up to buf.remaining() bytes into buf. Callers should use buf.limit(..) to control the size of the desired read.

After a successful call, buf.position() and buf.limit() should be unchanged, and therefore any data can be immediately read from buf. buf.mark() may be cleared or updated.

In the case of an exception, the values of buf.position() and buf.limit() are undefined, and callers should be prepared to recover from this eventuality.

Many implementations will throw UnsupportedOperationException, so callers that are not confident in support for this method from the underlying filesystem should be prepared to handle that exception.

Implementations should treat 0-length requests as legitimate, and must not signal an error upon their receipt.

Specified by:

read in interface ByteBufferReadable

Parameters:

buf - the ByteBuffer to receive the results of the read operation. Up to buf.limit() - buf.position() bytes may be read.

Returns:

the number of bytes available to read from buf

Throws:

IOException - if there is some error performing the read

available

public int available()
              throws IOException

Deprecated.

Description copied from interface: BlockReader

Returns an estimate of the number of bytes that can be read (or skipped over) from this input stream without performing network I/O.

Specified by:

available in interface BlockReader

Overrides:

available in class FSInputChecker

Throws:

IOException

isLocal

public boolean isLocal()

Deprecated.

Specified by:

isLocal in interface BlockReader

Returns:

true only if this is a local read.

isShortCircuit

public boolean isShortCircuit()

Deprecated.

Specified by:

isShortCircuit in interface BlockReader

Returns:

true only if this is a short-circuit read. All short-circuit reads are also local.