alluxio.client.file.cache

Class LocalCacheFileInStream

java.lang.Object

java.io.InputStream

alluxio.client.file.FileInStream

alluxio.client.file.cache.LocalCacheFileInStream

All Implemented Interfaces:

BoundedStream, PositionedReadable, Positioned, Seekable, Closeable, AutoCloseable

@NotThreadSafe
public class LocalCacheFileInStream
extends FileInStream

Implementation of FileInStream that reads from a local cache if possible.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static interface	LocalCacheFileInStream.FileInStreamOpener Interface to wrap open method of file system.

Field Summary

Fields

Modifier and Type	Field and Description
protected long	mPageSize Page size in bytes.

Constructor Summary

Constructors

Constructor and Description
LocalCacheFileInStream(URIStatus status, LocalCacheFileInStream.FileInStreamOpener fileOpener, CacheManager cacheManager, AlluxioConfiguration conf) Constructor when the URIStatus is already available.

Method Summary

Modifier and Type	Method and Description
void	close()
long	getPos()
int	positionedRead(long pos, byte[] b, int off, int len) Reads up to the specified number of bytes, from a given position within a file, and return the number of bytes read.
int	read()
int	read(byte[] b)
int	read(byte[] b, int off, int len)
long	remaining()
void	seek(long pos) Moves the starting read position of the stream to the specified position which is relative to the start of the stream.
long	skip(long n)

Methods inherited from class java.io.InputStream

available, mark, markSupported, reset

Methods inherited from class java.lang.Object

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

Field Detail

mPageSize

protected final long mPageSize

Page size in bytes.

Constructor Detail

LocalCacheFileInStream

public LocalCacheFileInStream(URIStatus status,
                              LocalCacheFileInStream.FileInStreamOpener fileOpener,
                              CacheManager cacheManager,
                              AlluxioConfiguration conf)

Constructor when the URIStatus is already available.

Parameters:

status - file status

fileOpener - open file in the external file system if a cache miss occurs

cacheManager - local cache manager

conf - configuration

Method Detail

read

public int read()
         throws IOException

Specified by:

read in class InputStream

Throws:

IOException

read

public int read(byte[] b)
         throws IOException

Overrides:

read in class InputStream

Throws:

IOException

read

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

Overrides:

read in class InputStream

Throws:

IOException

skip

public long skip(long n)

Overrides:

skip in class InputStream

close

public void close()
           throws IOException

Specified by:

close in interface Closeable

Specified by:

close in interface AutoCloseable

Overrides:

close in class InputStream

Throws:

IOException

remaining

public long remaining()

Returns:

the remaining number of bytes left in the stream, starting at the current position

positionedRead

public int positionedRead(long pos,
                          byte[] b,
                          int off,
                          int len)
                   throws IOException

Description copied from interface: PositionedReadable

Reads up to the specified number of bytes, from a given position within a file, and return the number of bytes read. This does not change the current offset of a file, and is thread-safe. Not all implementations meet the thread safety requirement. According to the documentation of the PositionedReadable interface in Hadoop, those that do not meet the requirement cannot be used as a backing store for some applications, such as Apache HBase. All implementations of this interface in Alluxio must meet the thread safety requirement.

Parameters:

pos - position within file

b - destination buffer

off - offset in the buffer

len - number of bytes to read

Returns:

actual number of bytes read; -1 means "EOF";

Throws:

IOException

getPos

public long getPos()

Returns:

the current position

seek

public void seek(long pos)

Description copied from interface: Seekable

Moves the starting read position of the stream to the specified position which is relative to the start of the stream. Seeking to a position before the current read position is supported.

Parameters:

pos - the position to seek to, it must be between 0 and the end of the stream - 1