freenet.client

Class FECCodec

java.lang.Object

freenet.client.FECCodec

Direct Known Subclasses:

OnionFECCodec

public abstract class FECCodec
extends java.lang.Object

Simple in-memory-only API for FEC encoding/decoding. Does not queue or throttle; see MemoryLimitedJobRunner for how to deal with that. Caches and creates individual codec engines as needed.

Field Summary

Fields

Modifier and Type	Field and Description
static int	MAX_TOTAL_BLOCKS_PER_SEGMENT
static long	MIN_MEMORY_ALLOCATION

Constructor Summary

Constructors

Constructor and Description
FECCodec()

Method Summary

Modifier and Type	Method and Description
abstract void	decode(byte[][] dataBlocks, byte[][] checkBlocks, boolean[] dataBlocksPresent, boolean[] checkBlocksPresent, int blockLength) Execute a FEC decode.
abstract void	encode(byte[][] dataBlocks, byte[][] checkBlocks, boolean[] checkBlocksPresent, int blockLength) Execute a FEC encode.
abstract int	getCheckBlocks(int dataBlocks, InsertContext.CompatibilityMode cmode) Get the recommended number of check blocks per segment for a given number of data blocks for a given compatibility mode.
static FECCodec	getInstance(Metadata.SplitfileAlgorithm splitfileType)
abstract long	maxMemoryOverheadDecode(int dataBlocks, int checkBlocks) Maximum memory usage with the given number of data blocks and check blocks, not including the blocks themselves.
abstract long	maxMemoryOverheadEncode(int dataBlocks, int checkBlocks) Maximum memory usage with the given number of data blocks and check blocks, not including the blocks themselves.

Methods inherited from class java.lang.Object

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

Field Detail

MIN_MEMORY_ALLOCATION

public static final long MIN_MEMORY_ALLOCATION

See Also:

Constant Field Values

MAX_TOTAL_BLOCKS_PER_SEGMENT

public static final int MAX_TOTAL_BLOCKS_PER_SEGMENT

See Also:

Constant Field Values

Constructor Detail

FECCodec

public FECCodec()

Method Detail

maxMemoryOverheadDecode

public abstract long maxMemoryOverheadDecode(int dataBlocks,
                                             int checkBlocks)

Maximum memory usage with the given number of data blocks and check blocks, not including the blocks themselves.

maxMemoryOverheadEncode

public abstract long maxMemoryOverheadEncode(int dataBlocks,
                                             int checkBlocks)

Maximum memory usage with the given number of data blocks and check blocks, not including the blocks themselves.

decode

public abstract void decode(byte[][] dataBlocks,
                            byte[][] checkBlocks,
                            boolean[] dataBlocksPresent,
                            boolean[] checkBlocksPresent,
                            int blockLength)

Execute a FEC decode. On exiting the function we will have all the data blocks.

Parameters:

dataBlocks - The byte[]'s for storing the data blocks. Must all be non-null. Which have valid contents is indicated by dataBlocksPresent. When exit this function, they will be filled with the data blocks in the correct order.

checkBlocks - The byte[]'s for storing the check blocks. Which have valid contents is indicated by checkBlocksPresent.

dataBlocksPresent - Indicates which data blocks were present before decoding. (Will not be changed by this function).

checkBlocksPresent - Indicates which check blocks are present before decoding. (Will not be changed by this function).

blockLength - The length of any and all blocks. Padding must be handled by the caller if it is necessary.

encode

public abstract void encode(byte[][] dataBlocks,
                            byte[][] checkBlocks,
                            boolean[] checkBlocksPresent,
                            int blockLength)

Execute a FEC encode. On entering, we must have all the data blocks. On exiting, we will have all the check blocks as well.

Parameters:

dataBlocks - All the data blocks, which all have valid contents.

checkBlocks - The byte[]'s for storing the encoded check blocks. Must all be non-null.

checkBlocksPresent - Indicates which check blocks have already been encoded.

getInstance

public static FECCodec getInstance(Metadata.SplitfileAlgorithm splitfileType)

getCheckBlocks

public abstract int getCheckBlocks(int dataBlocks,
                                   InsertContext.CompatibilityMode cmode)

Get the recommended number of check blocks per segment for a given number of data blocks for a given compatibility mode.

Parameters:

dataBlocks - The number of data blocks per segment.

cmode - The compatibility mode (so we can exactly mimic the behaviour of older builds when reinserting files).