com.netflix.hollow.core.read

Class HollowBlobInput

java.lang.Object

com.netflix.hollow.core.read.HollowBlobInput

All Implemented Interfaces:

java.io.Closeable, java.lang.AutoCloseable

public class HollowBlobInput
extends java.lang.Object
implements java.io.Closeable

This class provides an abstraction to help navigate between use of DataInputStream or RandomAccessFile as the underlying resource for Hollow Producer/Consumer Blob to support the different memory modes.

Method Summary

Modifier and Type	Method and Description
void	close() Closes underlying InputStream/RandomAccessFile and releases any system resources associated with the Hollow Blob Input.
BlobByteBuffer	getBuffer()
long	getFilePointer() Returns the current offset in this input at which the next read would occur.
java.lang.Object	getInput()
MemoryMode	getMemoryMode()
static HollowBlobInput	modeBasedSelector(MemoryMode mode, HollowConsumer.Blob blob) Initialize the Hollow Blob Input object from the Hollow Consumer blob's Input Stream or Random Access File, depending on the configured memory mode.
static HollowBlobInput	randomAccess(java.io.File f) Initialize a random access Hollow Blob input object from a file.
static HollowBlobInput	randomAccess(java.io.File f, int singleBufferCapacity) Useful for testing with custom buffer capacity
int	read() Reads the next byte of data from the input stream by relaying the call to the underlying DataInputStream or RandomAccessFile.
int	read(byte[] b, int off, int len) Reads up to len bytes of data from the HollowBlobInput by relaying the call to the underlying DataInputStream or RandomAccessFile into an array of bytes.
int	readInt() Reads 4 bytes from the input (at the current file pointer) into a signed 32-bit int, and advances the offset in input.
long	readLong() Reads 8 bytes from the input (at the current file pointer) into a signed 64-bit long, and advances the offset in input.
short	readShort() Reads two bytes from the input (at the current file pointer) into a signed 16-bit short, and advances the offset in input.
java.lang.String	readUTF() Reads in a string from this file, encoded using modified UTF-8 format, and advances the offset in input.
void	seek(long pos) Sets the file-pointer to the desired offset measured from the beginning of the file by relaying the call to the underlying RandomAccessFile.
static HollowBlobInput	serial(byte[] bytes) Shorthand for calling serial(InputStream) on a byte[]
static HollowBlobInput	serial(java.io.InputStream is) Initialize a serial access Hollow Blob input object from an input stream.
long	skipBytes(long n) This method attempts to skip a specified number of bytes and returns the actual number of bytes skipped.

Methods inherited from class java.lang.Object

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

Method Detail

getMemoryMode

public MemoryMode getMemoryMode()

modeBasedSelector

public static HollowBlobInput modeBasedSelector(MemoryMode mode,
                                                HollowConsumer.Blob blob)
                                         throws java.io.IOException

Initialize the Hollow Blob Input object from the Hollow Consumer blob's Input Stream or Random Access File, depending on the configured memory mode. The returned HollowBlobInput object must be closed to free up resources.

Parameters:

mode - Configured memory mode

blob - Hollow Consumer blob

Returns:

the initialized Hollow Blob Input

Throws:

java.io.IOException - if the Hollow Blob Input couldn't be initialized

randomAccess

public static HollowBlobInput randomAccess(java.io.File f)
                                    throws java.io.IOException

Initialize a random access Hollow Blob input object from a file. The returned HollowBlobInput object must be closed to free up resources.

Parameters:

f - file containing the Hollow blob

Returns:

a random access HollowBlobInput object

Throws:

java.io.IOException - if the mmap operation reported an IOException

randomAccess

public static HollowBlobInput randomAccess(java.io.File f,
                                           int singleBufferCapacity)
                                    throws java.io.IOException

Useful for testing with custom buffer capacity

Throws:

java.io.IOException

serial

public static HollowBlobInput serial(byte[] bytes)

Shorthand for calling serial(InputStream) on a byte[]

serial

public static HollowBlobInput serial(java.io.InputStream is)

Initialize a serial access Hollow Blob input object from an input stream. The returned HollowBlobInput object must be closed to free up resources.

Parameters:

is - input stream containing for Hollow blob data

Returns:

a serial access HollowBlobInput object

read

public int read()
         throws java.io.IOException

Reads the next byte of data from the input stream by relaying the call to the underlying DataInputStream or RandomAccessFile. The byte is returned as an integer in the range 0 to 255.

Returns:

an integer in the range 0 to 255

Throws:

java.io.IOException - if underlying DataInputStream or RandomAccessFile

java.lang.UnsupportedOperationException - if the input type wasn't one of DataInputStream or RandomAccessFile

read

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

Reads up to len bytes of data from the HollowBlobInput by relaying the call to the underlying DataInputStream or RandomAccessFile into an array of bytes. This method blocks until at least one byte of input is available.

Returns:

an integer in the range 0 to 255

Throws:

java.io.IOException - if underlying DataInputStream or RandomAccessFile

java.lang.UnsupportedOperationException - if the input type wasn't one of DataInputStream or RandomAccessFile

seek

public void seek(long pos)
          throws java.io.IOException

Sets the file-pointer to the desired offset measured from the beginning of the file by relaying the call to the underlying RandomAccessFile. Operation not supported if the Hollow Blob Input is an DataInputStream.

Parameters:

pos - the position in bytes from the beginning of the file at which to set the file pointer to.

Throws:

java.io.IOException - if originated in the underlying RandomAccessFile implementation

java.lang.UnsupportedOperationException - if called when Hollow Blob Input is not a RandomAccessFile

getFilePointer

public long getFilePointer()
                    throws java.io.IOException

Returns the current offset in this input at which the next read would occur.

Returns:

current offset from the beginning of the file, in bytes

Throws:

java.io.IOException - if an I/O error occurs.

readShort

public final short readShort()
                      throws java.io.IOException

Reads two bytes from the input (at the current file pointer) into a signed 16-bit short, and advances the offset in input.

Returns:

short value read from current offset in input

Throws:

java.io.IOException - if an I/O error occurs.

readInt

public final int readInt()
                  throws java.io.IOException

Reads 4 bytes from the input (at the current file pointer) into a signed 32-bit int, and advances the offset in input.

Returns:

int value read from current offset in input

Throws:

java.io.IOException - if an I/O error occurs.

readLong

public final long readLong()
                    throws java.io.IOException

Reads 8 bytes from the input (at the current file pointer) into a signed 64-bit long, and advances the offset in input.

Returns:

long value read from current offset in input

Throws:

java.io.IOException - if an I/O error occurs.

readUTF

public final java.lang.String readUTF()
                               throws java.io.IOException

Reads in a string from this file, encoded using modified UTF-8 format, and advances the offset in input.

Returns:

UTF-8 string read from current offset in input

Throws:

java.io.IOException - if an I/O error occurs.

skipBytes

public long skipBytes(long n)
               throws java.io.IOException

This method attempts to skip a specified number of bytes and returns the actual number of bytes skipped. The behavior is differed based on whether the backing resource is a RandomAccessFile or InputStream. For InputStream, (as implemented in FileInputStream) this method may skip more bytes than what are remaining in the backing file. It will produce no exception and the number of bytes skipped may include some number of bytes that were beyond the EOF of the backing file. The next read attempt from the stream after skipping past the end will result in -1 indicating the end of the file was reached. For RandomAccessFile, this method will return the actual bytes skipped and does not go past EOF.

Parameters:

n - number of bytes to skip

Returns:

number of bytes skipped

Throws:

java.io.IOException

close

public void close()
           throws java.io.IOException

Closes underlying InputStream/RandomAccessFile and releases any system resources associated with the Hollow Blob Input.

Specified by:

close in interface java.io.Closeable

Specified by:

close in interface java.lang.AutoCloseable

Throws:

java.io.IOException

getInput

public java.lang.Object getInput()

getBuffer

public BlobByteBuffer getBuffer()